why do some LiFePo4 battery have two connectors

5 views
Skip to first unread message

ba...@k7bwh.com

unread,
Jun 3, 2022, 12:26:09 PMJun 3
to issaqu...@googlegroups.com

Hive mind question: Why do some LiFePo4 batteries have separate charge and load connectors? Can I safely charge the battery through the load connector using a suitably intelligent charger?

I’m shopping for a battery for the rover van and there are good prices on “ebike” batteries. Most of these have two connectors, one for the high-current load and another for the charger. Here’s an example picture of a random craptastic lithium ebike battery; this is one that I might buy. I’m just trying to understand how they’re built.

A picture containing text, battery

Description automatically generated

In my van I’ll connect the main battery negative output lead through a Victron SmartShunt for monitoring the state of charge (SOC). This is also how I must charge it, so that the shunt can keep proper track. The “charging” connector will go unused. So I’m trying to understand if charging will work this way, or if the battery has some special electronics (like a BMS) in its charging port. Shucks, I don’t even know if these things have a BMS or not.

Thanks, Barry K7BWH

image001.png
image002.jpg

Mihai Manolache

unread,
Jun 3, 2022, 1:24:56 PMJun 3
to issaqu...@googlegroups.com
Usually, the charging port is only for charging as the circuit should have a BMS. 
The load terminals should be connected to a discharge circuit that will stop discharging the battery under a 10-20%.
If the battery has different ports, I suspect both circuits are present. I wouldn't discharge the battery on the charging terminals. 
This is just theory and I don't know how is the battery. 

73, 
Mihai


Sent from my Verizon, Samsung Galaxy smartphone
--
Your group manager is ba...@k7bwh.com
---
You received this message because you are subscribed to the Google Groups "Issaquah Amateur Radio Club" group.
To unsubscribe from this group and stop receiving emails from it, send an email to issaquah-arc...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/issaquah-arc/004b01d87766%249f5384d0%24ddfa8e70%24%40k7bwh.com.

KC7PBH

unread,
Jun 3, 2022, 1:32:25 PMJun 3
to issaqu...@googlegroups.com
Hi Barry,
The barrel connector allows charging while the battery is connected to the load.  This is how I connect my solar panel to the battery while the transceiver is operating.  When I charge the battery from AC power, I connect the charger to the power pole connectors on the battery.  The barrel connector and power poles are both connected to the positive and negative battery posts.
Brad Smith
W7ETZ

--

ba...@k7bwh.com

unread,
Jun 3, 2022, 1:46:57 PMJun 3
to issaqu...@googlegroups.com

Thanks Brad. Do you know if there’s typically a BMS circuit inside batteries like this? That is, it would be nice if these things have battery-balancing built in. I wouldn’t expect low-temperature cutoff in cheapo eBay batteries.

It’s a relief to hear that charging can be done with either connector. I have access to a 12v battery like this and will try it out. The shunt is set up already and it’s easy to run this little experiment.

73 Barry K7BWH

image001.jpg

Paul Butzi

unread,
Jun 3, 2022, 1:52:22 PMJun 3
to issaqu...@googlegroups.com
I can’t speak to ALL LiFePO4 batteries but I asked Bioenno this question, and the answer is that the two connectors are in parallel, it does not matter if you discharge through the ‘charge’ connector or charge through the ‘discharge’ connector, or charge and discharge through a single connector.

Essentially the two connectors are provided as a convenience so you can leave a dedicated charger connected if you please.

I’ve got a mobile radio installed in my car that is powered off a Bioenno LiFePO4 battery; the battery charges off the car 12v through a step up converter to 14.6VDC and a West Mountain Epic Pwrgate.  Charge and discharge are done through the powerpole connector and the barrel connector is ignored.  It works great.

-p W7PFB

On Jun 3, 2022, at 9:26 AM, <ba...@k7bwh.com> <ba...@k7bwh.com> wrote:

Hive mind question: Why do some LiFePo4 batteries have separate charge and load connectors? Can I safely charge the battery through the load connector using a suitably intelligent charger?
I’m shopping for a battery for the rover van and there are good prices on “ebike” batteries. Most of these have two connectors, one for the high-current load and another for the charger. Here’s an example picture of a random craptastic lithium ebike battery; this is one that I might buy. I’m just trying to understand how they’re built. 
<image002.jpg>

In my van I’ll connect the main battery negative output lead through a Victron SmartShunt for monitoring the state of charge (SOC). This is also how I must charge it, so that the shunt can keep proper track. The “charging” connector will go unused. So I’m trying to understand if charging will work this way, or if the battery has some special electronics (like a BMS) in its charging port. Shucks, I don’t even know if these things have a BMS or not.
Thanks, Barry K7BWH

KC7PBH

unread,
Jun 3, 2022, 2:41:12 PMJun 3
to issaqu...@googlegroups.com
A BMS is a standard feature of LiFePO4 batteries.  I've seen reviews that criticize how well a given BMS works, e.g., how well it balances the cells.  On youtube you can search for Will Prowse LiFePO4 and watch his many reviews of batteries.  He's not a fan of cheap batteries because they often don't quite meet the claimed specs.  If a battery meets 90% of its claimed capacity and costs less than half of its better competitor, I'll go for the bargain battery.

Rod Johnson

unread,
Jun 3, 2022, 6:55:33 PMJun 3
to issaqu...@googlegroups.com
Barry,
 Nearly all those style catteries have a built-in BMS. and with it comes the charging connector.
 If the advertising does not mention a built-in BMS, then I would certainly want to ask specifically.  I suppose some of the dedicated chargers could have the BMS built into the charger; but if so, there would have to be a multi-pin connector, because the BMS must be able to sense the individual call voltages.
  The BMS controls the charge rate per cell.  Charging through the high current port will work, but it bypasses the BMS, so continued use in that manner will defeat the cell balancing function of the BMS.
  I would recommend using the BMS charging circuit when convenient, but for occasional charging and/or Rover use, charging through the high current port will work.
  Note: the output of most of the dedicated chargers I have seen is in the 14.5 volt range.
  Charging off the automotive system, through the BMS (charge port) seems to yield about the same throughput, according to my instrumentation, on a long drive. 
  The BMS tapers the charging current from a nearly constant 8-10 amp rate for several hours, to rather quickly drop to less than 1 amp near the end.
  Charging via the high current output lead may lead to overcharging, if not monitored closely.
  Rod J



-----Original Message-----
From: ba...@k7bwh.com
To: issaqu...@googlegroups.com
Sent: Fri, Jun 3, 2022 9:26 am
Subject: [IARC] why do some LiFePo4 battery have two connectors

Hive mind question: Why do some LiFePo4 batteries have separate charge and load connectors? Can I safely charge the battery through the load connector using a suitably intelligent charger?
I’m shopping for a battery for the rover van and there are good prices on “ebike” batteries. Most of these have two connectors, one for the high-current load and another for the charger. Here’s an example picture of a random craptastic lithium ebike battery; this is one that I might buy. I’m just trying to understand how they’re built.
A picture containing text, batteryDescription automatically generated

In my van I’ll connect the main battery negative output lead through a Victron SmartShunt for monitoring the state of charge (SOC). This is also how I must charge it, so that the shunt can keep proper track. The “charging” connector will go unused. So I’m trying to understand if charging will work this way, or if the battery has some special electronics (like a BMS) in its charging port. Shucks, I don’t even know if these things have a BMS or not.
Thanks, Barry K7BWH

Gerard Hickey

unread,
Jun 3, 2022, 7:38:35 PMJun 3
to issaqu...@googlegroups.com

Sorry coming into this conversation a little late.

Generally most standalone LifePO4 batteries will have a BMS built into the case to manage the individual cells. Many of the battery packs for ebikes and other applications are just the cells and the BMS is built into the device itself. In cases where it is a separate BMS there is usually a second connector that has a wire that goes to the connection between each bank of cells so that the BMS can balance the cells and equalize the voltage across the cells. I have usually seen this as a JST connector.

Most of the low end applications like ebikes, scooters, one-wheel skateboards, etc. do not have a BMS and just use the raw cells. If the battery pack was manufactured with cells that were all from the same lot this is usually not a problem as they generally discharge and charge at pretty much the same rate and the minor differences in voltage don't really matter that much. Over the long term, yes, it does matter as the cumulative difference across the cells will eventually make the battery pack appear that it has reached its lifetime and be replaced. The reality is that in many cases the battery pack can be charged/discharged once or twice with balancing the cells to get it pretty healthy again. Not back to 100%, but usually 85-90% easily.

The image you provided in your email to me appears to be a standard battery pack without a BMS and without the balancing harness. It appears to be the standard blue shrink wrap that is used to hold the cells together. Given it is 48v, I would say that it is probably a 15S battery (that is 15 banks of cells in series to get to 48v) and then depending upon which cells were used any where from 3P to 5P to get the 20 AH (that would be 3-5 packs of 15 cells in parallel to get the current ratings).

Actually just found a reference to the one that you had the picture to. It is a 13S3P battery, but what is not clear to me is if it is LiPO or LifePO4. To me it seems to indicate that it is a LiPO battery which is some thing I would not consider because of the fire hazzard. It makes sense also because 13S would be using a cell voltage of 3.7v which is a LiPO cell.

LifePO4 cells have a voltage of 3.2v which is why I was originally thinking it might be a 15S battery. With a LifePO4 battery you don't have quite the power density that you do with LiPO, but you don't run the risk of the battery bursting into flames either. Given that you would have this battery in your vehicle (even just for a little bit) I would not run the risk.

-- 
Gerard Hickey / WTØF           IRLP:3067/Echolink:529661
hic...@kinetic-compute.com     DMR: 3102272
425-395-4554

ba...@k7bwh.com

unread,
Jun 3, 2022, 7:58:44 PMJun 3
to issaqu...@googlegroups.com

Thanks Rod. Your description sounds sensible for mfrs that offer the lowest possible cost: the charging point is not directly connected to the high current port. My plan is to use a smart charger designed for lithium-style batteries with bulk and absorption phases built in, and connect it to the big bus bar.

I’ll run an experiment this weekend. Rod, remember when we got those blue ebike 12v 20ah batteries years ago? Still have mine. It has two connectors like this. It’ll make a good test case for charging via its high-current port. That old battery came with a 10A charger that’s godawful noisy on 6 meters – it was a big problem on Green Mtn last month. I can hardly wait to replace that charger with something, anything else. Then at home between trips charge it again on the proper port so the BMS can do its cell-balancing act.

Oh, I finally noticed a missing word in my original note. I meant to say a “random craptastic lithium ebike battery; this is NOT one that I might buy.” Jeez. Proofreaders these days, smh.

Anyway, I’ll be specifically using LiFePo4 chemistry and not LiPO.

Thanks to Gerard for more insight. It seems to me the old ebike battery I currently have (not the one in my picture) doesn’t have room inside the blue shrinkwrap for a BMS, nor does it show bumps that would suggest a BMS.

73 Barry K7BWH

PS - I’ve watched many Will Prowse videos about batteries on YouTube. Highly recommended. Each video is short and to the point. It’s been interesting to watch him reviewing successively larger batteries, most recently a 200-lb monster of a server rack 48v battery. I was originally quite enamored with those 48v 100ah batteries that come complete and are so easy to wire into a system. I’ve done the energy budge and It’s big enough to run my whole high-power rover for a weekend, including making meals. But they weigh 107 lbs. Once I admitted to myself I’d never want to manhandle that in/out of a van, I’m looking more at a 30-40 lb weight limit, which puts me in the 40 to 50 amp-hour range of 48v batteries. Why 48v? Because I might be able to direct-drive a 6m solid state amplifier. Anyway, the ebike batteries are looking more sketchy the further I get. My design journey continues.

 

 


Sorry coming into this conversation a little late.

Generally most standalone LifePO4 batteries will have a BMS built into the case to manage the individual cells. Many of the battery packs for ebikes and other applications are just the cells and the BMS is built into the device itself. In cases where it is a separate BMS there is usually a second connector that has a wire that goes to the connection between each bank of cells so that the BMS can balance the cells and equalize the voltage across the cells. I have usually seen this as a JST connector.

Most of the low end applications like ebikes, scooters, one-wheel skateboards, etc. do not have a BMS and just use the raw cells. If the battery pack was manufactured with cells that were all from the same lot this is usually not a problem as they generally discharge and charge at pretty much the same rate and the minor differences in voltage don't really matter that much. Over the long term, yes, it does matter as the cumulative difference across the cells will eventually make the battery pack appear that it has reached its lifetime and be replaced. The reality is that in many cases the battery pack can be charged/discharged once or twice with balancing the cells to get it pretty healthy again. Not back to 100%, but usually 85-90% easily.

The image you provided in your email to me appears to be a standard battery pack without a BMS and without the balancing harness. It appears to be the standard blue shrink wrap that is used to hold the cells together. Given it is 48v, I would say that it is probably a 15S battery (that is 15 banks of cells in series to get to 48v) and then depending upon which cells were used any where from 3P to 5P to get the 20 AH (that would be 3-5 packs of 15 cells in parallel to get the current ratings).

Actually just found a reference to the one that you had the picture to. It is a 13S3P battery, but what is not clear to me is if it is LiPO or LifePO4. To me it seems to indicate that it is a LiPO battery which is some thing I would not consider because of the fire hazzard. It makes sense also because 13S would be using a cell voltage of 3.7v which is a LiPO cell.

LifePO4 cells have a voltage of 3.2v which is why I was originally thinking it might be a 15S battery. With a LifePO4 battery you don't have quite the power density that you do with LiPO, but you don't run the risk of the battery bursting into flames either. Given that you would have this battery in your vehicle (even just for a little bit) I would not run the risk.

-- 

Gerard Hickey / WTØF          

 

image001.jpg

Derek Chauran

unread,
Jun 3, 2022, 8:26:55 PMJun 3
to issaqu...@googlegroups.com
I have been using a 30ah eco worthy lifepo4 and have been pleased with the performance. It has a BMS for charge and discharge and can do either at 1c.

They do let you run them in series, parallel, or series+parallel, but I can't remember if that was the brand that had a limit of 2 (24v) in series. I've seen some that will let you do 4.




From: issaqu...@googlegroups.com <issaqu...@googlegroups.com> on behalf of ba...@k7bwh.com <ba...@k7bwh.com>
Sent: Friday, June 3, 2022 4:58:40 PM
To: issaqu...@googlegroups.com <issaqu...@googlegroups.com>
Subject: RE: [IARC] why do some LiFePo4 battery have two connectors
 

Rod Johnson

unread,
Jun 3, 2022, 8:27:02 PMJun 3
to issaqu...@googlegroups.com
 "... blue ebike 12v 20ah batteries years ago? Still have mine."
  I still use mine, but they were rated as 50 AHr.
   I agree the supplied charger is very noisey on 6m, but a bit less so on HF.
  
  I was sure that those batteries had the BMS built into them, but maybe not...
  I have opened up a couple of smaller (6 AHr) ones, and found the BMS.  It was a circuit board about 2cm  x 3 cm, and about 0.5 cm thick.
  It was on top of the four cells, with a thin rigid plastic cover under the top over-wrap.   There was no indication of a bump or bubble either.
   I may be wrong with my assessment of the BMS only being connected to the charging input.
  As Mihai pointed out, there is the ability to shut off the output when the terminal voltage drops too low.  I had completely forgotten about that capability, so there must be the parallel connection betewen the charging lead and the heavier output leads, as others have mentioned.
  I have to agree, and stand corrected.
  Rod
 
 


Rod Johnson

unread,
Jun 3, 2022, 9:13:19 PMJun 3
to issaqu...@googlegroups.com
Barry,
  Your question is very interesting to me. 
  Thinking about this a bit more, since you apparently have the needed instrumentation...
  I would like to see what the charging current curve vs terminal voltage looks like,  when comparing the charge via the designed  'charge' input;  and with the same source charging via the designed 'output' connector.
  This might yield more fodder for the discussion.   If, in fact, the two connectors are in parallel; the results should be almost exactly the same.
   I had always believed the 'charging' terminal was somehow connected through the BMS in a slightly different manner. 
  I am willing to be corrected,given a bit more information.
  I have a West Mountain battery loading device, but it's loading capability it's discharge capacity is just a few amps.  With the 50 AHr capacity batteries I have, it takes a very long time to complete a test.
  Now that I think of it, the smaller batteries , which have internal BMS circuitry, have only set of terminals, and internally there is only one set of wires attached to the ends of the battery cell string, so
   that does seem to ad some credence to the thought they are all connected the same internally.
  I have also seen the internals of a 48 volt 200 AHr golf cart pack.  It belongs to a neighbor who has two of the batteries for his new Yamaha Golf cart. The original battery seems to have an issue with the BMS, and Yamaha has supplied him with a replacement.  We have one to experiment with.
    The BMS in that is about 9" x 12"  and about 3/4" thick.  There are only two heavy gauge wires going to the battery pack from that board also. 
  More evidence of a possible parallel connection between charging input, and the output, with both going through the BMS controller.
 
Rod J


-----Original Message-----
From: ba...@k7bwh.com
To: issaqu...@googlegroups.com
Sent: Fri, Jun 3, 2022 4:58 pm

Rod Johnson

unread,
Jun 12, 2022, 5:07:53 PMJun 12
to issaqu...@googlegroups.com
Some interesting data, and observations...maybe

I was 'putt-zing' (sp?) around this morning, trying to get organized for some obscure reason.  'Putt-zing' can be dangerous, by the way. It can lead one to find all sorts of reasons to be distracted.
  I found a way to be distracted, from putt-zing', this morning.

  My pair of 50AHr LiFePO4 batteries were in the way, in the middle of the floor (it seems most everything is in the way, and often in the middle of the floor), in my shack.
  I decided to put them on the charger, and remembered the previous discussion; so I put a digital ammeter in line and plugged the charger module into a "Kill-A-Watt" meter.
  The initial  AC amp draw from the wall was about 0.8 amps.  The battery was being charged via the factory supplied charging module, which is rated at 14.4 volts @10A, and through the normal 'charge' connector at a bit over 3 amps ( 3.3 to be specific and the indicated voltage was 14.3).
  Then I plugged the same charging module into the designed 'output ' leads ( they are heavier wire ).
  The AC line current draw went to about 1.7 amps and the charging current into the battery went to 6.7amps, and the voltage at the charger output terminals was down slightly, to 13.8  That may be a bit of self limiting in the factory supplied charger module itself.
  Putting the factory charger back on the 'charging' connector, the output current and charging voltage remained constant at 14.3 volts and 3.3 amps for a couple of hours, while I occasionally checked it.
 From that observation, there must some additional circuitry involved when using the 'charging' connector, and I would have to revert to my original premise,  that the BMS ( internal Battery Management System is at play when using the supplied 'charging' port.
  From others comments, and my observations with a couple of small inexpensive LiFePO4 batteries, apparently not all of the LiFEPO4 batteries come with dedicated charging connector.

Rod Johnson

unread,
Jun 12, 2022, 6:18:00 PMJun 12
to issaqu...@googlegroups.com
Update:
  About 1 hour later, I wandered into the shack to check on progress and the Ccharge rate had dropped to less than 1 amp (still connected to the charging connector), and as a headed out, I saw the charge light (Red) switch to Green.  That means the BMS cut off the charge, because the charge is completed.
  Then, I hooked the factory charger back to the 'output' connector, and the charge current went to 6.5 amps.  I left it connected for several minutes and the charge rate did not go down, even slightly.
  I have to assume the battery 'can' be charged via the output connector, but that the function of the BMS is being bypassed as a result.  Therefore, I think it is not in the best interest for battery life , to do so on a regular basis.
 I suspect short charging periods ( just guessing-maybe a couple of hours at a time) of the higher charge rate would probably not be too detrimental to the life of the battery, but I would definitely not want to use that method for regular long term charging.
  It is all very subjective.
  Rod J


Paul Butzi

unread,
Jun 12, 2022, 6:36:20 PMJun 12
to issaqu...@googlegroups.com
When you hook up a charge controller to a LiFePO4 battery, it will charge the battery for some short time at some fairly low charge rate.  If the battery voltage does not rise to the threshold to switch to constant voltage charging, it will then ramp up the charge rate.  This happens no matter what connector the charger is connected to.  The charger will not immediately jump straight to the maximum charge rate.  If you disconnect the charger and then reconnect it, it will do it again.

Toward the end of the charge cycle, the charge controller will switch from constant current charging to constant voltage.  At this point most charger will switch the LED indicator to green.  The battery is still charging, however.
(Yes, this is a stupid design.  Don’t blame me, it wasn’t my design choice.)  At least on every charge I’ve seen, the green light does not mean it’s no longer charging the battery, it just means the charger is now in constant voltage mode instead of constant current mode.

Some time later, the charge current will drop close to zero.  The battery is fully charged.

LFP:  Why is there a separate DC barrel plug connector and PowerPole Connector on my battery?  Can I charge through either connector?  
On our PVC Pack LiFePO4 batteries, there are two separate connectors.  The first connector has a DC barrel plug and the second connector has an Anderson Powerpole connector.  The two connectors are indeed wired in parallel on the PCM (protection circuit module) that is integrated in every single battery pack.  So it is perfectly okay and fine to charge through the PowerPole connectors. Many customers requested two separate connectors in the batteries, in order to keep the battery's charger attached to the battery, such that the battery and charger can be stored in a portable Go-Box.  At the same time, customers can leave the PowerPole connector attached to the radio communications equipment, without having to repeatedly disconnect the charger from the battery, and attach the radio communications equipment.  However, we understand customers want to charge through the Powerpole connectors and use various other third party products.  We provided the two sets of connectors, simply for convenience purposes.  

-p W7PFB


Mihai Manolache

unread,
Jun 12, 2022, 11:18:30 PMJun 12
to issaqu...@googlegroups.com
If Bioenno chose to wire in parallel, that doesn't mean other manufacturers do the same. 
I mentioned before what you point hear in great details. The charging should be done based on a charging curve. If not, the battery can be damaged in time by reducing the number of charging. Each battery has a current/voltage curve, si a LiIon curve is not the same as NiCd or LiFePO4. I wouldn't use a charger for a type of battery to a different type. 

73, 
Mihai 



Sent from my Verizon, Samsung Galaxy smartphone


-------- Original message --------
From: Paul Butzi <paulf...@gmail.com>
Date: 6/12/22 15:36 (GMT-08:00)

Rod Johnson

unread,
Jun 12, 2022, 11:31:11 PMJun 12
to issaqu...@googlegroups.com

 At least on every charge I’ve seen, the green light does not mean it’s no longer charging the battery, it just means the charger is now in constant voltage mode instead of constant current mode.

Some time later, the charge current will drop close to zero.  The battery is fully charged.
In my brief tests, when the LED switches from Red to Green the output currrent drops to something less than 10ma ( limit of precision of my 2-decimal digital ammeters).
  I have never seen the green light ON with any indication charging current.   I ahve seen multiple occurrences of minimal charging currrent ( less than one amp) reasonably prior to the light turning green, but never after.
  Maybe my charger is designed a bit diffferently, or maybe the internal BMS is programmed slightly differently.
  Rod J


Paul Butzi

unread,
Jun 13, 2022, 4:08:41 PMJun 13
to issaqu...@googlegroups.com
It’s definitely true that the Bioenno batteries may not be the same as other manufacturers.  I’m definitely not an expert on this and don’t claim to be one.

That said, in ten minutes of looking at various BMS units on the web, I cannot find ANY that offer separate charge and discharge connectors.

Every single one I have looked at is essentially wired in between the negative charge/discharge terminal and the negative end of the battery, with leads running to the junctions between cells to be used for balancing.

The positive charge/discharge terminal is then connected directly to the positive end of the string of cells.

If there are LiFePO4 bms’s out there with different arrangements, I haven’t been able to find them.

Can I prove that there aren’t any out there?  No.

Do I believe that there are any that use some other arrangement out there?  Unless someone can provide info about one that uses some other arrangement, my presumption will be that they don’t exist.

And that’s because I don’t see any BMS feature - low voltage cutoff, high voltage cutoff, over or under temp cutoff, cell balancing - that would require any other arrangement.  Looking at Wikipedia (which I admit may not be authoritative)
I don’t see any indication of some other topology

If someone knows of an LiFePO4 charging profile that is different from:
1. Constant current at some current <= the max charge rate for the battery, until the charge voltage reaches the maximum charge voltage for the battery
2. After that point is reached, the charge voltage is held constant and the charging current drops over time as the battery approaches full charge
3. When the current drops to zero, the battery is fully charged.
I would be super interested in hearing about it, as I’m sort of all in on LiFePO4 batteries and I’d hate to damage one.

I agree with Mihai, I would not charge a LiFePO4 battery with a charger not intended for charging LiFePO4 batteries.

-p W7PFB

Rod Johnson

unread,
Jun 13, 2022, 8:39:08 PMJun 13
to issaqu...@googlegroups.com
Paul,
  You may be correct.  I, also, have not seen another setup with separate charging leads.  Barry (K7BWH) and I each have these 'blue' batteries ( I have two). All I can say is that when using the same charger, it definitely makes a difference in the accepted charge rate,  if the charging source is connected to the output, or to the originally designed  input
   I cannot see what is inside this sealed 50 AHr battery assembly. It came with a charger labeled for LiFePO4 batteries.  The charger output is a pair of leads with a different connector, so it cannot be connected to the 'output' wires.  I built a set of adapters ( with mating plugs and PowerPoles) so I can place an ammeter/voltmeter/wattmeter in-line for testing and observation of what is going in.
  The only reason I can swap the charger from the input to the output connectors, is a result of the adapters I made.
  As Barry mentioned, the supplied charger ( small switching supply)  is very RF noisy.
  I had my small Honda generator running close to 100 feet from my rover van.  The charger was plugged directly into the Honda generator, with a decent filter.  I could tell it was running, due to some noise in my VHF receivers, but it was not too bad at that roughly 100 foot distance ( was not doing weak signal stuff at the time). The charger generated interference was much worse the first time I used it, and that first time it was probably no more than 25 feet from the receiving antennas.   Needless to say, I was quite surprised, and very disappointed the first time I used it in the field.
  The last time out, I used a small Astron, with the voltage setting cranked up to 14.4 volts.  I connected to the charging plug and it worked very well.  the meter showed about 4 amps as I recall, when charging, but I was not awake when it shut off, so I did not see just how the final charge was completed.
  Rod J
 



-----Original Message-----
From: Paul Butzi <paulf...@gmail.com>
To: issaqu...@googlegroups.com

Derek C.

unread,
Jun 14, 2022, 4:41:07 PMJun 14
to issaqu...@googlegroups.com
The factory charger is almost certainly a cheap chinese current limited switch mode power supply. I have taken apart a number of cheap lifepo4 specific chargers, and they are all essentially current limited 14.1-14.4v power supplies. They achieve the constant current stage by trying to deliver 14.Xv, but they hit the current limiter, so they have a constant current but low voltage. As the battery voltage rises, the current draw decreases, and eventually they end up in "nearly constant voltage". I have a CC/CV power supply that I use to charge individual cells this way (CC = C*0.2 usually and CV=Charging voltage), and it works great. These chargers are also typically the ones that say to disconnect them after the battery is charged, and for good reason. The best of them set the voltage low enough that the current drops to 0 when they equalize, but you're not going to get 100% of your battery capacity (this is fine, and in fact better for the battery). The worst of them will keep trying to apply 14.4+v indefinitely, and if you have an ammeter on the charging line you will usually see the battery continue to draw around 20ma. This is desirable for lead-acid, but is bad for lifepo4.

I have a very good charger (https://smile.amazon.com/gp/product/B07Q5VYPCF/). I paid almost as much for it as I did for the battery. It's dc-dc, will boost or buck as needed, and it actively monitors the charging process. When the battery is charged (e.g. current drops to 20ma or so), it turns off the charger! It will monitor the battery and top it up using CV mode as needed. I am using it on a 30AH battery that I can technically charge at up to 30a (1C), but I have the charger set to max out at 10a to prolong the battery life. I have this in my go box with an IC-7000 an LDG auto tuner, and a couple of portable antennas. I plug powerpoles into the go box at home, they power the charger. On the road I have a 15a cigarette lighter adapter. On the boat, I can charge the lifepo4 from the trolling motor battery.

-73
Derek
af7ux



John KA7TTY

unread,
Jun 14, 2022, 7:07:58 PMJun 14
to Issaquah Amateur Radio Club

   I have been running an experiment using a Drok 2001802006 Battery Monitor/Charge Controller with a Bioenno Power BLF-1203AB 3 Ah 12 volt Battery. This is connected 24/7 to an old ICOM IC-02AT 2m HT since May 2020. This battery has the Anderson Power Pole discharge pigtail and the concentric connector identified as the charging connector. When I checked the resistance between the 2 positive contacts, and between the 2 negative contacts, I measured zero ohms. Dead short. The experiment connects only to the Anderson Power Pole connector. This setup cycles to charge at 11.2 v and charges to 14.55 v. The battery rating is 14.6 v. When it switches to discharge the voltage measures 14.16 v. It completes a discharge/charge cycle about every 4-5 hours. It uses the charger provided by Bioenno along with the battery.

   I decided to use the 3 Ah battery (about $50) and then replace it with a 20 Ah battery (about $225) if all went well. I just haven’t gotten around to buying the bigger battery.

   Curiously, the larger Bioenno batteries only have terminals (no pigtails) so all the charging and discharging is done through the same connections.

   My overall conclusion is that at least for the Bioenno batteries, you can connect to either one.

John KA7TTY

Reply all
Reply to author
Forward
0 new messages