Missing Watt Hours

[Paul_G]

I was told the Bomber has a 1500 watt hour battery so my 1st ride was 10 miles from home with 43 miles of mixed riding some slow some fast and the battery went dead at 1060 WH....it was mostly all up hill to get home, where is my other 440 WH's?

The battery never even got warm, my Optibike battery's get hot....odd

The motor, just a little warm.

What do you guys get before cut out and is my battery defective? 

Paul G

[John_W]

Dlogic over on the ES forum had the same problem. I believe it was sorted out quickly.

Have you checked what the volage cutout on the Cycle Analyst is set too? This might be cutting the motor out before the BMS.  What voltage did the shut down at? 

[John_W]

43 miles and only 1060 W/hrs.  Looks like 50 miles will be a snack once.

[Paul_G]

Yes I checked, the cut out is set to 72 volts, no clue if thats correct.

Paul G

[remf]

There's your problem! Mine is set to 55V LVC.

[Paul_G]

well that would do it but isn't 55 to low?  55 is factory setting?

Paul G

[John_W]

Li-ion is 3.9V per cell hot off the charger and 3.7V nominal. 20 Cells so I think you will be seeing 78V when fully charged.  Cells can go down to 2.7V which is 54V.  I think the BMS will be set a little higher then this for the sake of battery longevity but the CA is just a last line of defence and as such should be set slightly below the BMS in my opinion.

I cant give direct figures on the stock Bomber as i have always used Lipos but I believe the above is accurate.

[remf]

That's more or less correct for the stock Bomber though of course I don't discuss specific volts or A/hrs on the stock bikes publicly due to a request from Stealth. For whatever reason, those numbers aren't listed on the website. I would guess that these numbers change from time to time and specifying specifics could cause confusion. Speed, power, battery capacity & range estimates are more relevant in any case.

[Voicecoils]

Hey Kepler, Which chemistry are you referring to?

Lithium Manganese or Cobalt chemistries of Li-ion are typically 4.2v charged, 3.7v nominal and 3.0v discharged. Below 2.7v per cell causes damage.

Lithium Iron Phosphate is usually 3.65v charged, 3.2-3.3v nominal and 2.5v discharged. Below 2.0v per cell causes damage.

Individual cell makers tweak the chemistries sometimes which can alter voltages a bit. I've seen thundersky spec'd to charge to 3.8v, 3.2v nominal, 2.8v discharged for example. It can get confusing!

Stealth AUS will have recommended LVC for the CA and then the BMS and likely the controller will have LVC settings too that aren't user settable.

A few general suggestions for getting the most from a new battery with BMS would be to go on a few full discharge rides followed by long charges to help the cells get balanced in their first few cycles. If the Bomber has a 2hr standard charge time, I'd leave it on for 4-5hrs or more.

Also, a battery that's rated at 1500 Wh may not get there if the BMS cuts in early under heavy load. There's a bit of a tradeoff between cell protection and getting max capacity. It should get fairly close though, especially if it's not hammered hard in the last few miles before running flat.

Looks like Paul is already getting impressive range out of the box and that may further improve in a few battery cycles. Thanks for posting your photos and kick stand info Paul, looks great even if I was being a kickstand hater before! :-) Also got your note about the Opti, no worries and good luck with it!

Cheers, Abraham

In rainy Portland, OR at the moment.

I'm tempted to pick up a GoPro here with no sales tax and the weak US dollar!

Sent from my iPad

On May 7, 2011, at 7:05 PM, John_W <eboost...@gmail.com> wrote:

Li-ion is 3.9V per cell hot off the charger and 3.7V nominal. 20 Cells so I think you will be seeing 78V when fully charged.  Cells can go down to 2.7V which is 54V.  I think the BMS will be set a little higher then this for the sake of battery longevity but the CA is just a last line of defence and as such should be set slightly below the BMS in my opinion.

I cant give direct figures on the stock Bomber as i have always used Lipos but I believe the above is accurate

[Paul_G]

Voicecoils It be changed so I'm thinking maybe I did a hard reset pushing buttons and it changed to 72?  

Stealth AUS will have recommended LVC for the CA and then the BMS and likely the controller will have LVC settings too that aren't user settable.

Paul G

[Paul_G]

I think I have a bad battery, charged it overnight, took off charger and within a few mins voltage dropped 7.7 volts same as yesterday and I never rode it yet, same deal on todays ride, volts hit 72 and it dropped dead, so dead the charger wont charge it, light stays green like its charged. CA turns on and right off.

Odd thing with the charger I turn it off and a red light stays on, I even can unplug the 110v to the charger and the red light stays on.

Paul G 

  

[Paul_G]

I left the charger connected and now I see it must have decided to take the charge, the watts used can be read now and show the bike had stopped at 1079 used....so where is my lost 1/3?

Is there a hot battery cut out in the bike? The cover was warm but far cooler than what my Optibike runs.

Paul G

[John_W]

Paul, I spoke to John at Stealth bikes today as I was curious about the CA setting. As Voicecoils said, the CA is set at 72V in the factory so this is correct. It is apparently set as the first limit to reduce current as the voltage get lower before the BMS kicks in.  Also the stock Bomber voltage is a bit higher the I had thought hence my thoughts that the 72V set voltage was too high.  

My apologies for the incorrect information given. I am sure the issue will be sorted without delay.

[Paul_G]

I heard from John today, I gave him the numbers he asked for (watts/amps) and he just got back to me, they are sending a new battery out.

Amazing service!

My Optibike came with a battery that would only go 15 miles and it took me a month of bitching and proving to them it was defective before they replaced it, far diff service here, or maybe just having a CA it was EZ to see the problem as Opti does not and you have to guess if you have a battery problem.

Paul G.

[Paul_G]

New battery arrived, took 11 days to build, test and ship DHL by air

Well done and thanks John

It took all of 3 mins to change, 6 or 7 screws on the side case and it pulls right out after disconnecting two connectors.

A few Pic's 

Paul G.

[Jérôme Daoust]

Sure is nice to see how EZ (using your lingo) it is to swap a battery.

Please weigh one of your batteries (like the "old" one since it is
already out of the bike) to see if it matches your earlier report of
of 23.1 lb (10.5) kg:
http://groups.google.com/group/stealth-electric-bikes/browse_thread/thread/f9be9dd1609494a5/

Thanks for documenting your experiences Paul.

- Jerome

[Paul_G]

bath scale has it at 24 lbs and it reads by .5's 

[John_W]

Great to see the pack has arrived and is so easy to fit. Those packs are a work of art with a full BMS fully integrated into them. Two plugs and job is done.  People should note the massive 75A battery plug used on this pack too. Nothing fancy, just good solid and safe engineering. I am sure we will get an update on the new range very soon.  

[Jim_Kirk]

Paul,
Yes indeed it is nice to see such easy access to the battery and bike internals.  The 75A plug is also very impressive.  I am very impressed with the quick delivery of the battery after you reported the problem to Stealth.

John and Stealth deserve a big congratulations on how they built the bike to be serviced.

-Jim

[Paul_G]

whoops, I see someone cut the black wire (top of the pic)  in picture DSC01410.jpg

Thats the speed limit wire.

[Jim_Kirk]

Ahh, good to know.  You even put the wire out of focus to make it stealthier to find :)

[Paul_G]

so its a cheap camera :)

I ran the old battery down to 0 - 3 times and it was the same watt hours each time, (1050-1060) thats super for knowing when to come home. 

Only problem is I need to take the bike out with the new battery and also run till empty to find the new and hopefully 1500 w cut out point.

Its a heavy beast when you need to pump them peddles with no help but by watching the voltage drop off I will have an idea how close to empty she is. I have my safety cut out at < 72 V.  

Paul G

[Jérôme Daoust]

On May 20, 12:52 pm, Paul_G <pgr...@gmail.com> wrote:
> bath scale has it at 24 lbs and it reads by .5's

Thanks Paul,

For a more precise reading (0.1 lb resolution), you know someone with
a fish scale, or take it to the post office (they have accurate
scale).

What's the plan for the old battery: Return to Stealth or keep it as a
backup for long rides (carry in you backpack)?

I wish you good riding weather,
Jerome

[Paul_G]

I'm sure they want it back and will send me a shipping label.

They say it weighs  23.1 lbs, my scale has it at 24, so 23.6-24.4  would read 24....close enough for horseshoes. :)  Its big and heavy but the weight is all battery unlike my Optibike thats in a case with other goodies inside it with lights blinking both internal and external. I've had the Opti external apart to change a plug and the metal case is empty on the end where the connectors are so its smaller than what it looks. The Bomber is a manly battery with no lights on it....lol

Paul G

[Paul_G]

New Battery Tested

http://connect.garmin.com/activity/87014287

its the same as the old, missing 1/3 of its storage capacity.

 Dead at 1045.7 WH’s....14.12 AH’s

29.5 miles (from my Garmin GPS)

The CA reads 31.5 miles so the wheel size in the CA is wrong.

Emailed Stealth and waiting for an answer.

Paul G

[Jérôme Daoust]

On May 21, 9:00 am, Paul_G <pgr...@gmail.com> wrote:
> *New Battery Tested*
> *its the same as the old, missing 1/3 of its storage capacity.*

It must be you, then.
;-)

I posted a question on Endless-Sphere to the guy (Dlogic) that has a
similar problem, to see if/how it was resolved for him:
http://endless-sphere.com/forums/viewtopic.php?p=408010#p408010

To others...
Are you seing the full use of your 1500 Wh on your Cycle Analyst?

[Paul_G]

If they had advertised the Bomber battery at 1100 and I am getting 1060 as I do now I would not bitch but 1/3 less is not acceptable.

Paul G

[remf]

Definitely, something's not right. I'm sure they'll be onto it. It is strange that both original and new batteries have exactly the same reduced capacity.

[Paul_G]

2nd battery has even less capacity as I dropped the low volts cut off to 65 on the new battery to make it home, the 1st battery had used 1050 watts to dead but cutting off at 72 volts. but prolly not a big diff.

Paul G

[Jim_Kirk]

Remf, Paul and others,
Can you explain how you test the capacity of the battery? 
Does the number you get depend on factors like how rapidly you are discharging the battery [i.e. is your test at 35 mph until it cuts out?]?

Very interested in getting the protocol you use.

-Jim

[Paul_G]

A battery stores energy, if they say it will hold 1500 watt hours (1.5KW/H) the CA should show you used 1500 as the bike drops dead.  Same as buying a quart of milk, it better hold 32 oz's.

This is the reason IMO that Optibike wont install them as the 36 month warranty could put them out of business.

Speed should not have any effect on what it holds, you will just go further running at a slower speeds.  Battery temp can effect it I would thing but its 75 here so thats not an issue.

Paul G

[remf]

Hi Jim, my 1500 Wh capacity is based on my CA's W/hrs used display on many rides and various power settings and throttle use. Peukert effect is minimal, I see virtually the same capacity at full power WOT.

[Paul_G]

the battery's they use run super cool.

laser dot on battery and on bike after my 30 mile ride today.

Paul G

[Jim_Kirk]

Do you need to run the bike till it completely stop starting from a full charge in order to determine the capacity?  Guess if thats true its good to circle the block many many times unless you want to pedal home :)

-Jim

[Paul_G]

yes, but you can get a good idea when to stay near the house and run in circles when you get near 72 volts. You can feel the power drop off when you have a few miles left. The opti I could feel the power drop off on every time the status of the lights changed. You don't feel that with the Bomber, its full power till its out. 

Once you know the number your good to go.

And if yours comes through with a bad battery I'll bet your good till 1050 same as my 2 batterys....so no worry till then :)

[John_W]

I wonder if it your charger.  What voltage are you seing fully charged?  I think it needs to be 88V or 89V fully charged.

[Paul_G]

John thinks it may be my CA is wacky, I will prove it one way or the other.

I will run 3 tests;

 #1 Record the amount of watts the battery will take. This will be off due to losses from the charger and will more than likely show more than 1.5 KW/H’s.

 #2 Hook my Amp-Probe up and see if the CA is recording the correct amount as I ride.

 #3 Or I can buy a new recording Amp-Probe I was looking at..

 

[Jim_Kirk]

I recommend #3 :).   Let's see a link on this as a recording clamp on Amp-Probe looks interesting.

-Jim

[Paul_G]

some solutions

the best but it only goes to 60V and could pop it right in between the battery: http://www.rc-electronics-usa.com/ammeters/dc-amp-meter.html

Rent a hi-end meter and bench test it: http://www.atecorp.com/Categories/more/PowerMeters.asp

some power meters:  

http://www.mouser.com/ProductDetail/BK-Precision/325/?qs=sGAEpiMZZMscOpJzBRvzQkq1AL1V3Wtn

http://www.valuetesters.com/Extech-380976-1000A-Power-Clamp-Meter.php

http://www.valuetesters.com/Amprobe-ACD-51NAV-600A-AC-TRMS-Navigator-Clamp-On-Power-Meter.php

I just need to make sure the one I pick can do DC power as many can't

Paul G

[USV]

What is your start Voltage hot off the charger?

I don't own a Bomber, but for comparison when my Opti USV is powered
by
my old 32 lb 76.8 V nominal 20 Ah LiFePO4 polymer pouched pack
, I can still manage to squeeze 15 Ah or 1.15 Kwh of usable energy out
of the pack for
rides that vary from 24 miles (wot all the time up & downhill) to as
much as 42 miles (wot in the beginning
& slower pace towards the end) & of course more hill climbs = lower
range.

Hot off the charger it is at 83.6 V & settles down to about 83.1 V in
about 5-10 minutes.
I ride it wot (wide open throttle) until it's close to 70 V under
load, then I start pulsing the
throttle & slow down to conserve energy towards the end of the ride.

The stock Stealth bomber battery is 24 lbs...hmmmm, wonder what
chemistry & format they are hiding
under that blue shrink wrap?

On May 21, 9:00 am, Paul_G <pgr...@gmail.com> wrote:
> *New Battery Tested*
> *

> *
> *http://connect.garmin.com/activity/87014287
> *
> *
> *
> *its the same as the old, missing 1/3 of its storage capacity.*
>
> * Dead at 1045.7 WH’s....**14.12 AH’s*
>
> *29.5 miles (from my Garmin GPS)*
>
> *The CA reads 31.5 miles so the wheel size in the CA is wrong.*
>
> *Emailed Stealth and waiting for an answer.*
>
> *Paul G*
>
> *
> *

[USV]

What I would do is to take the blue shrink wrap off the battery to
see
what Chemistry & Format the batteries are then it would be easy to
find out Voltage & Ah rating & test accordingly.

The rest is simple, get a good quality muti tester to double check
your CA voltage reading & a direct plug-in stand alone CA to verify
the CA from stealth is working properly & check the voltage output of
your charger. Finally if everything is checked to spec, buy some
shrink wrap/heat gun & wrap it back up.

***FYI A Watts-up meter rated to read up to 60V will not work, the
screen will blank out if the Battery is higher than 60V***

On May 22, 4:57 am, Paul_G <pgr...@gmail.com> wrote:
> some solutions
>
> the best but it only goes to 60V and could pop it right in between the
> battery:http://www.rc-electronics-usa.com/ammeters/dc-amp-meter.html
>
> <http://www.rc-electronics-usa.com/ammeters/dc-amp-meter.html>Rent a hi-end
> meter and bench test it:http://www.atecorp.com/Categories/more/PowerMeters.asp
>

> <http://www.atecorp.com/Categories/more/PowerMeters.asp>some power meters:  http://www.mouser.com/ProductDetail/BK-Precision/325/?qs=sGAEpiMZZMsc...http://www.valuetesters.com/Extech-380976-1000A-Power-Clamp-Meter.phphttp://www.valuetesters.com/Amprobe-ACD-51NAV-600A-AC-TRMS-Navigator-...

[Paul_G]

I don't want to take battery's apart when under warranty :)

 

[USV]

Will Stealth give you the "top secret" battery specs, it's important
to determine the usable energy of the battery pack.

[Paul_G]

I have no clue what to ask :)

Web site said 1500 and thats what I want.

Paul G

[USV]

I would ask:
I would start with these questions, if Stealth is not trying to hide
anything.

1) What is the Chemistry of the pack: http://www.batteryspace.com/li-ionsinglecell.aspx
has a good chart of commonly used chemistries & a good general
estimate of their useful life tested at a low discharge rate.

2) What is the nominal voltage.

3) What is the Ah rating.

4) What is the continuous & peak discharge rate: C rating.

The actual useful energy of the pack may be lower or higher than the
manufacturer's claims.

When a pack is new, the useful energy output of the pack should be
close to the Ah/ Kwh rating of the pack.

example: a new 76.8 V nominal LiFePO4 http://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery
rated at 20 Ah should read close to 20 Ah used or 1.5 Kwh at the end
of your ride when the LVC (low voltage cut off protection) kicks in.
76.8 V x 20 Ah = 1536 wh or 1.5 Kwh and 38.4 V x 40 Ah = 1536 wh or
1.5 Kwh

[Jim_Kirk]

He guys,
     Stealth is in business to sell e-bikes.  The questions listed by USV are, in my opinion, in the area of proprietary information and I cannot see why Stealth would disclose this.
     If my Bomber has this problem I want it solved so I can go riding.  I'd do whatever they asked to help find the problem but if its suspected to be a CA then Paul should be able to provide enough information so they can send him a new CA to try.  And why not since a CA is a lot cheaper than sending another battery.
    
-Jim

[USV]

this is what I don't understand about e-bike manufacturers...
why do they have to hide the most critical part of their product, the
useful range.
i for one would want to know how far my car, motorcycle or e-bike can
travel...

[Jérôme Daoust]

On May 22, 12:22 pm, USV <1denn...@verizon.net> wrote:
> I would ask:

> 1) What is the Chemistry of the pack:http://www.batteryspace.com/li-ionsinglecell.aspx
> has a good chart of commonly used chemistries & a good general
> estimate of their useful life tested at a low discharge rate.

Stealth USA does indicate it is a LiFePO4 chemistry on their website:
http://stealthelectricbikesusa.com/bomber/bomber.html

[USV]

If it's LiFePO4 then 24 lbs (per Paul G's bathroom scale) & 1.5 Kwh
does
not jive...
My LiFePO4 1.5 Kwh pack = 76.8 V 20Ah pack weighs in at 32 lbs and
it's in a foil pouched format which is the lightest format currently
available.

If the Stealth Battery is a LiFePO4 pouched format
battery, then at 24 lbs, it's likely it's a 76.8 V 14 Ah pack = 1075
wh pack...
which would make sense since Paul G stated he got 1060 wh of usable
energy out of the pack.

[Paul_G]

My ride today may have uncovered the problem. Its possible the CA is bad, I set the max amps on the ride to 7. The CA showed the watts at a max draw of 440 watts and that should be about 560 as 80V X 7A = 560 watts  So it was under reporting.

Volts X Amps = Watts 

Paul G

[Kepler]

It sounds like the shunt calibration could be a little off in the CA.
This is very easy to adjust in advanced settings.

Ideally you need to have a meter to measure the actual and compare it
against the CA.

Another way to get it close is to lift the back wheel off the ground
and run it up to a set speed of say 25mph. Record the Watts.

Other people here in this discussion that know their CA is reading
correctly need to do the same and record their Watts under the same
conditions. Once we have a baseline, we can compare.

Need to make sure the brake is dragging at all when doing the test.

I will check mine when at 25mph (40 kph) when I get home. This method
does work to get the setting close so its worth while doing this test.

[Jérôme Daoust]

On May 22, 1:48 pm, USV <1denn...@verizon.net> wrote:
> If it's LiFePO4 then 24 lbs (per Paul G's bathroom scale) & 1.5 Kwh
> does not jive...
> My LiFePO4 1.5 Kwh pack = 76.8 V 20Ah pack weighs in at 32 lbs and
> it's in a foil pouched format which is the lightest format currently
> available.

So in your case you have 48 Wh/lb (76.8 V x 20Ah / 32 lb = 1536 / 32).

3 years a go a bike I tested with LiFePO4 had 53 Wh/lb (1024 Wh / 19
lb)
http://www.expandingknowledge.com/Jerome/Bike/Gear/Electric/Review/2008_10_29_JeromeDaoust_HPC_CadillacAM24_GearedHubBMC600W_51V/Main.htm

For the Bomber we would have 62.5 Wh/lb (1500 Wh / 24 lb), which
seems reasonable considering 3 years passed since my encounter with a
53 Wh/lb pack.

- Jerome

[remf]

Good idea. I am a long way away from the Bomber but will check when I'm back home later this week.

[Kepler]

Also its interesting that you could squeeze 33 miles out of a recorded
500W/hrs. This would be a 100mile range, double to what Stealth
advertise as the max range.

Sure, this was with lots of pedaling but still seems to be an amazing
range especially considering your a big bloke too.

To me this points to a calibration issue rather then a capacity issue.

I run a 1200W/hr LiPo pack in mine and run it down no further then
1000W/hrs. riding comfortably but economically at around 25mph, best
range I can do is 34 miles. This fits in perfectly with the max range
of 50 miles advertised by Stealth.

[Kepler]

My LiPo pack is 78 Wh/lb.This fits in with LiPo's having about 20%
better power density then the latest LiFePO4 packs (62.5Wh/lb)

On May 23, 10:58 am, Jérôme Daoust <eyestothe...@gmail.com> wrote:
> On May 22, 1:48 pm, USV <1denn...@verizon.net> wrote:
>
> > If it's LiFePO4 then 24 lbs (per Paul G's bathroom scale) & 1.5 Kwh
> > does not jive...
> > My LiFePO4 1.5 Kwh pack = 76.8 V 20Ah pack weighs in at 32 lbs and
> > it's in a foil pouched format which is the lightest format currently
> > available.
>
> So in your case you have 48 Wh/lb (76.8 V x 20Ah / 32 lb = 1536 / 32).
>
> 3 years a go a bike I tested with LiFePO4 had 53 Wh/lb (1024 Wh / 19

> lb)http://www.expandingknowledge.com/Jerome/Bike/Gear/Electric/Review/20...

[Jérôme Daoust]

On May 22, 6:05 pm, Kepler <eboost.ass...@gmail.com> wrote:
> I run a 1200W/hr LiPo pack in mine and run it down no further then
> 1000W/hrs.  riding comfortably but economically at around 25mph, best
> range I can do is 34 miles.  This fits in perfectly with the max range
> of 50 miles advertised by Stealth.

So I gather this test data: 1000 Wh for 34 miles @ 25 mph.
This yields 29.4 Wh/mile at 25 mph.
Converting to a standardized speed (proportional to square of the
speed), this becomes 18.8 Wh/mile @ 20 mph.

Not far off my current ride (Pedego Interceptor): 16.8 Wh/mile @ 20
mph.
And not a Watt-guzzler compared to an Optibike 850 R: 14.5 Wh/mile @
20 mph.

I say: Not bad at all for any motor, and great considering the 4.5 kW
power available.

- Jerome

[Voicecoils]

It's almost always the amps that will read incorrectly of the 2 because it relies on a shunt (stable resistor) to measure the voltage drop across. The shunt value is user settable in the CA. The CA uses either it's own external shunt (CA-SA model) or the shunt in the motor controller (CA-DP model).

The CA's voltage can easily be verified by using an inexpensive multimeter to measure battery voltage.

Cheers, Abraham

Sent from my iPad

On May 22, 2011, at 8:04 PM, Jérôme Daoust <eyesto...@gmail.com> wrote:

> On May 22, 5:40 pm, Kepler <eboost.ass...@gmail.com> wrote:
>> It sounds like the shunt calibration could be a little off in the CA.
>> This is very easy to adjust in advanced settings.
>> Ideally you need to have a meter to measure the actual and compare it
>> against the CA.
>> Another way to get it close is to lift the back wheel off the ground
>> and run it up to a set speed of say 25mph. Record the Watts.
>

> I wonder about recording Watts and adjusting 2 bike's wattage to match
> based on consumption for a back wheel off theground at a given speed.
> I'm not very familiar with the CA, but assume that wattage displayed
> should only be derived data based on measurements of current (Amps)
> and Voltage, so the only error should be with the evaluation of
> current and voltage and not with how they are multiplied to indicate
> voltage. Question would then be: What is the wrong measurement:
> Current or Voltage? This may be answered by comparing what is the
> battery's voltage after a fresh charge (assuming the battery is in
> good working order).
> John_W hinted the freshly-charged voltage should be about 88 V:
> http://groups.google.com/group/stealth-electric-bikes/msg/5d4512dfd2bfb886
>
> What is the voltage you read Paul after charging your battery?

[USV]

huh????
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14615
the lightest nanotech hobby LiCoO2 pouched polymer battery
(LiPo) with no BMS is 18.5 V x 5Ah = 92.5 Whr weighs 715 g / 1.573
lbs
92.5 / 1.573 = 58.80 Whr/ lb or 129 Whr/ kg...

http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=16227
deerfencer1 reviewed this "LiPo" pack
http://groups.google.com/group/tidalforce/browse_thread/thread/8c9e33243a194282
18.5 V x 8Ah = 148 Whr weighs 1054 g / 2.3188 lbs
148 / 2.3188 = 63.83 Whr/ lb or 140 Whr/ kg...

Where are you guys getting your ultra energy dense / light batteries
: )

> > - Jerome- Hide quoted text -
>
> - Show quoted text -

[Paul_G]

I got an answer back from John at Stealth.

Paul,

Each CA needs to be calibrated to the controller that it is paired with.  So if I send you a new CA you're going to need to calibrate it anyway.

The CA always reads the correct voltage but every CA needs to be calibrated to the internal shunt of the controller that it's paired with.  So it's not the Volts that it's reading wrong, it's the Amps.... The Wattage is a function of the Amps so if it's not calibrated to the shunt properly then this will throw out the Wattage reading and also any other reading that uses the Amps to determine its value.

Your battery is delivering what it should be delivering.... but a small percentage error in the CA is multiplying out to give you a false reading.   Not a hard fix... we've just got to make the correct adjustment.

*********************************

I guess now he will contact the CA maker and get the way to a proper adjustment.

Paul G

 

[Kepler]

I based my estimate on the following.

6S 5Ah packs weigh 715g. http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=7639

Due to light load, nominal voltage is more like 3.9V per cell in an
ebike application.
3.9V x 6 cells x 5ah = 117 W/hrs

1000 / 117 = 8.5 packs@ 715g = 6.08kg of LiPo for 1000 W/hrs
6.08 x 2.2 = 13.4lb

So based on the above this is about 75 Whr/lb. A little lower then my
last estimate but not too far off.

I don't run a BMS so no weight there.

Anyway, thats ideal conditions of cause. No doubt its a bit lower then
this in practical terms but still a valid comparison I think.

On May 23, 2:40 pm, USV <1denn...@verizon.net> wrote:
> huh????http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14615
> the latest lightest nanotech hobby LiCoO2 pouched polymer battery

> (LiPo) with no BMS is 18.5 V x 5Ah = 92.5 Whr weighs 715 g / 1.573
> lbs
> 92.5 / 1.573 = 58.80 Whr/ lb or 129 Whr/ kg...

> Where are you guys getting your ultra energy dense / light batteries

> with a BMS?  :  )

[Paul_G]

Let me explain how to get a workout like on a Optibike :)

You ride with fast pace road bikes 15-20 mph average and you set the amps low enough that if you bust your A$$ to keep up on a hill you got the amps set right. And starting off from a stop you need to use the gears to keep up.

I have not been able to do this when by myself as I don't try as hard on hills or I say "screw this" and set the puppy back on hi-power. :)

But when you know your doing a 3 state 67 mile ride to get lotto tickets you want to make it as well as fit in and get a real workout.

Next Lotto Ride is.....come join us...we hit 3 states, NY, Conn and NJ. 

Sunday, May 29, 2011

THE LOTTERY RIDE (QUICK SPIN 15+ MPH)

8:30 AM, Pelham Parkway & White Plains Road, Bronx, 67 miles

Another fast-paced, Quick Spin ride with no Point-Drop-Sweep, speeding through three states and their lottery tickets. 5BBC's bookmakers say it's better than even money you'll enjoy the ride, but the chance of winning the NY Jackpot is only 1 in 45,057,474. Experienced cyclists only, please. Leaders: Jesse Brown and Rodney Millard

 http://5bbc.org/rides.shtml

Paul G

[remf]

Yes it is possible to get a workout on the Bomber. If you don't have a pack to ride with, all it takes is the willpower not to set back to full power. Great post.

[Paul_G]

I heard back from John on adjusting the WH's.

Basically you need to go into the advanced setup menu on the CA and adjust the RS shunt value.... with the wheel spinning at 19mph you should be seeing about 105-110W on the CA.   I can't remember if you need to adjust the value up or down but try going either way by 0.1 and you'll see it straight away.  This is the easy way to do it.

OK so I need to add or subtract 30% to find my reported missing WH's

Paul G

[Kepler]

I just checked mine at 19mph. Mine was showing right on 100W.

[Paul_G]

on the ground or in the air on a lift?

I'll be on a lift.

Paul G

[Paul_G]

I figured I would put the bike on the lift, set the max speed to 19 MPH and lock the throttle and play.

Paul G

[Jim_Kirk]

Paul,
     Again I'm impressed with the response from John on addressing your problem.  Seems like he will now get you the best way to make the proper current calibration adjustment which you can then let us all know.  I see that on page 14 of the CA manual it describes how to input the shunt resistance,
http://www.fareinc.com/Stealth/Documents/Stealth_Electric_Bikes_Owners_Manual_2011.pdf

     ==>It will also be helpful if other Bomber owners post their current calibration value [i.e. Rshunt] so we can see how much variation there is between bikes.

     I recommend John add the adjustment procedure as an addendum to the CA manual in the "Stealth Electric Owners Manual 2011."

-Jim

[Paul_G]

It was EZ and its done

old reading was 1.394 and I was off by 1/3 so I changed to 0.929 and now it reads 96-100 watts at 19 MPH....it was reading 65 watts....also changed by by 1/3

So it looks like the battery is fine. I started to expect that as the range and power just didn't seem bad :)

And I agree, I never got this super service with any other bike maker.

Paul G

[Paul_G]

1.394 / 3 (its off by 1/3) = 0.4646666 X 2 = 0.929

Seems to have worked out...lol

[Paul_G]

I may have gone a tad overboard on the .929 setting as I did get 1060-1070 WH's so 1000 WH's would have been 1/3 of the 1500 true value.

old setting was 1.394 and it showed 1070 used when it went dead so what should the proper setting be?  .927 may be a tad lower than the proper setting. And if your thinking thats close enough I disagree and you will as well the 1st time you peddle home....lol

OK so who is good at math? :)

Paul G

[Jim_Kirk]

Paul,
     Can you put a clamp on ammeter on one of the battery leads and compare to the CA.  Then do your math again.

-Jim

[Paul_G]

I'm not sure most amp-probes will read DC amps but I'll git it a try and see.

Paul G

[Paul_G]

As I expected my AC75B probe will not do DC amps or DC power (watts)

Paul G

[Jim_Kirk]

This is one I use and I find it better than the Fluke:
http://www.sperryinstruments.com/product/dsa2003

Available at: http://www.toolup.com/sperry_dsa2003_digisnap-ac-acdc-digital-snap-around-volt-ohm-ammeter.aspx

With an autoranging clamp on DC ammeter you can calibrate the CA to be correct on current [we assume its fine on voltage] and then see exactly what your battery capacity is.

-Jim

[Paul_G]

That looks like a nice one but I own a few now for work,  maybe I can loan one from my local supply house for a day. 

Paul G

[Jim_Kirk]

Loans are good :).  Once you calibrate the CA current it will be interesting to see the battery capacity you get.

-Jim

[Jérôme Daoust]

Here is my math approach...

Knowing that what is being measured at the resistence shunt is voltage
(U), and we are assuming a resistence (R) to derive current, we use
the formula:
I = U / R
Then we want to get a corresponding power rating at the shunt
resistor, so we can use a linear proportion to match the Power x time
for a battery's capacity (Wh). The power at the shunt resistor would
be:
P = R I^2 (know formula)
P = U^2 / R (after substituring R using the 1st formula)
Now we can set up a "rule of 3"
1070 for 1/1.394
1500 for 1/r (where "r" is the new resistance value in mOhm to
be entered)
Solving...
r = 1 / [ 1500 x (1/1.394) / 1070 ] = 0.994

Let me know if I screwed up somewhere,
- Jerome

[Paul_G]

Kewl, I'll use that but I know where U live if its wrong...lol

Paul G

[Jim_Kirk]

Jerome,
    
     Paul can get a clamp on ammeter and he can set the CA so the current reading is the same in both devices by adjusting Rshunt.

     So I recommend not forcing the CA to an artificial Rshunt value but, rather, getting the current reading to be correct on the CA.  Then go out and run the bike to find the battery capacity.  Let's see what it is

     -Jim

[Jérôme Daoust]

We are in agreement Jim, but what fun is that?

Hopefully, Stealth will own a clamp-on current reader and do this
calibration as part of their QA checks before sending the bikes out to
the customers.

Jerome

[John_W]

What do you mean by forcing the the CA to an artificial Rshunt value? The shunt in the controller is what it is so no matter what, the Rshunt value in the CA needs to be calibrated. Or is that what you mean?

I have a different controller with a modified shunt in mine so no point in giving my shunt reading. 

I will check my calibration again using a calibrated meter and then do the free wheel test again just for reference sake.

[Voicecoils]

John W is on the money with this.

The goal is to know the controller's shunt resistance and then program that value into the CA.

Neither a clamp meter nor comparing no load (unloaded wheel spinning) will be as accurate as using the right shunt value as they are indirect methods, but they would get close. Also worth noting that each hubmotor's performance will vary slightly as small changes in the winding process and hall sensor placement will affect the motor's overall efficiency slightly. Two people with different tyres would throw things off too.

A stock controller shunt value is also not perfect either because when they are soldered to the PCB the resistance between pads will change depending how much solder is used. 

A bit off topic but a common method to mod a controller into sending a motor more power (increasing current and therefore motor thrust) is to add solder to the shunt so the resistance lower and the controller's MCU is tricked into allowing more current when it senses a lower voltage drop across. The result of course can be overheating and failure, but it can be fun for a while :-) 

In practice, even a CA with the wrong shunt value is still useful once you know done a few full discharge rides. If the battery dies at 1000 Wh according to the meter each time then you know how far you can go and when to conserve or splurge despite current, power and energy readings all being incorrect compared to another bike with the correct settings. Always nicer to have the right settings if possible of course.

Cheers, Abraham

Sent from my iPad

[Jim_Kirk]

Let me clarify.
A clamp on ammeter will measure the battery current.  You, the user, can adjust the Rshunt numerical value in the CA.  You don't know the proper value for the Rshunt value as it has to be calibrated so here is how to do it.
What I meant was you then set the bike up in the stand, then power the drive wheel to a certain mph reading on the CA and hold it there.  You then note the clamp on ammeter current and also note the CA current readinig.  These should be identical so you then adjust the numerical value of Rshunt in the CA to get you to the correct CA current reading as noted with your clamp on ammeter.  Now your CA is calibrated for your shunt.  Doesn't matter in the least what the battery Wh are because you're about to find this out.
Now go run the bike to exhaustion and measure your Wh's.  If all is what you paid for you should get 1.5 kWh.

-Jim

[Kepler]

OK. No problems. fully agree.

I Use a Fluke multimeter that can handle 10A in series. Nice and
accurate but I needed to make some custom leads to do the measuring. I
just lift the back wheel up and check the amps at a few speed ranges.

[Paul_G]

R-shunt 1.056 did the trick, I used WOT to set the amps as that stayed the same 4.96-5 no load amps recorded on both the CA and amp-probe. Seemed to top out at 66.6 MPH :) .001 changes it by a few amps.

Meter cost $59 in Sears.

Recharging the battery and I'll go test it but I was stupid as there is an EZ way to see if its close. its a 4500 watt motor, run WOT on the road and watch if it reads near 4500. I was reading 3700 area.  

Man a bike with a CA is fantastic and a bike made where you can work on it rocks. 

Paul G

[Jim_Kirk]

Those final two points you just made in your post were a very big selling point for me.
The final deal maker was Paul's kickstand-still working good I hope as I've now got mine and just waiting on a bike to put it on :)

-Jim

[Paul_G]

Funny you should ask....lol

The top small block of wood just fell out on a ride today but the stand still works as is but leans more. I'll have to re-do the shims better.

Paul G

[Paul_G]

the 4500 watt trick wont work as it pulls more, closer to 5000 watts WOT at times.

I set the cut out volts high at 73 so I won't get stuck peddling home and ran the heck out of it, On a 4 lane road I was passing cars at 45 MPH in the fast lane and peddling like I was doing it. Got some odd looks.....LOL

Power was dropping off as I got home at 1400 WH's so fer sure its got 1500 in it with cut out set lower.

Meter is a Craftsman #82369 at $59 but maybe on sale this weekend.

Paul G

[Kepler]

Blocks of wood just don't belong on a Bomber. High tech materials only
please.

Seriously though that stand is perfect. On my shopping list.

[Paul_G]

I used a single new larger block of wood and its great :)

Paul G

[Jérôme Daoust]

On May 24, 2:45 pm, Paul_G <pgr...@gmail.com> wrote:
> Meter is a Craftsman #82369 at $59 but maybe on sale this weekend.

Link:
http://www.sears.com/shc/s/p_10153_12605_03482369000P

Idea to hold your blocks of wood shims used for your kickstand...
maybe wrap around them (and the stand) with large shrink tube that
would both hold the shims and provide a good in-between material where
it meets the swingarm..
Or drill a hole through your wood shims and secure them with a zip-tie.

[Paul_G]

You should not need the meter as mine was prolly not the norm but its good for peace of mind that you got a real 1.5 KW/H battery.

[Jim_Kirk]

West marine, plastic black lumber [aka: starboard]. 

-Jim

[Kepler]

Block time in the controller program causes the power to peak then
bleed down. So you will see 5000W then it will quickly reduce to
around 3500W. The preset is 1 second so it starts bleeding off quite
quickly. I set mine to 5 seconds so basically I have full power all
the way through to flat out. Adds to the fun but hard on controllers.