Tidal Force M750 - Resurect it or Crucify it? That is the question...

[Motobiker]

Somehow, I managed to inherit this very interesting eBike. I am an
embedded electrical engineer and know a few things about motors, power
systems and motion control. That means little when one does not have
plenty of technical information and experience with the system. So, I
am a noob.

The bike was DOA. (Dead On Arrival). It appears to be a stock M750
with a factory original Wavecrest 'B' Battery upgrade option. All the
connectors are in good shape and the wiring harnesses are intact and
beeped out satisfactory on both origination and termination jacks and
plugs. Removing the backing plate from the control panel reveals no
jumper for a non-wavecrest battery, which seems correct.

Both 'A' and 'B' batteries charge to about 42 volts and do not self-
discharge excessively after a 24 hour waiting period. Both batteries
sefl- discharge less than about 5% in a 24 hour period. So, both packs
hold charge just fine and blow a 8A fuse connected across the + and -
battery lugs quickly. So the batteries transfer charge quite fine.

**After enabling the tamper key to 'run' mode, this is what happens
when ONLY the 'A' battery is connected: **

None of the 'Regen', 'Turbo' or 'Cruise' LEDS illuminate. 4 of 5
Charge LEDS on the 'A' capacity display flash and adding throttle does
nothing. No motor movement. Selecting 'Turbo' does not illuminate the
'Turbo' LED and pushing throttle also does not deliver power to the
motor after 'Turbo' button is pushed. No mode LEDS illuminate after
the 'A' battery button is pushed, either.

** After enabling the tamper key to 'run' mode, this is what happens
when BOTH the 'A' battery and the 'B' battery is connected: **

The 'A' battery behaves exactly as described earlier when enabled.
When the 'B' Battery is enabled, only one LED lights up on the 'B'
capacity display despite the batteries having been charged properly at
0.1C for 14 hours (about 1A at 43V). Measuring the 'B' battery voltage
indicated a 38V potential. If it matters, the 'Regen', 'Cruise' and
'Turbo' mode LEDS illuminate momentarily on enabling the 'B' battery.

Applying throttle with the 'A' and 'B' batteries enabled starts the
back wheel turning, but only for a short time before power gets cut
off to it. The bike is upside down in my lab. I applied some force to
emulate road friction and load and the motor still cutts out after a
few seconds. Turning off the key and trying again has the same result.
Removing the motor power and communications cables, waiting,
reconnecting the motor and comms cables and retrying has the same
result - wheel spins and quits.

** Removing the 'A' battery connections and using only the 'B' battery
has the same result - wheel spins and then power is removed. **


I am not going to speculate on what is going on here and hope someone
on the forum can suggest some tests or ideas. I am quite excited to
have recieved this very interesting machine and being over 50 years
old, I sure can appreciate the advantages of this eBike. I promise to
participate in the forums to help others once I master this system. I
was rather hoping (and praying) that I could keep the bike bone stock
rather than having to retool it into a franken-eBike..

So far, no snow out here and I hope to get this cycle running before
the snow flies! Maybe I'll take it to Hawaii with me this coming
winter!

Thank you all.

MotoBiker!

[Ambrose Liao]

Welcome to the group! You are indeed lucky to have received this great bike!

Reading your description of the problems you're having, it sounds like your front A battery is virtually dead and the rear B battery is very weak. This is very typical. It may measure well but won't put out many amps before dropping off. Replace the batteries and your bike should come back to life.

Ambrose

Sent from my iPad

[Narayan]

Replacement stock batteries are quite costly.

I would suggest getting a nice front wheel with a disk brake, and ditch the old batteries.  If you are not comfortable with frankenbiking a new battery on to the bike, you could just hit a bionx battery pack with some black spray paint and slap it on there. 

Also, since you have a dead B battery, you have the option of using the connector from the battery to jump your system rather than messing with the console.

If you cut the data connecter out of the B batt and leave a little bit of wire on it, you can just tie the 2 wires from the bottom pins together, remove the other wires, and connect it to the end of the B-pack data line. 

LEVT used to sell jump plugs for the end of the B data cable that worked this way, but I don't think they do anymore.

Alternatively, you could just jump the 2 corresponding wires inside the connector on the end of the B data cable on the bike if you are sure you won't be using a legit B battery anymore.

-Narayan

[bill_von]

Some suggestions:

Get a meter and monitor system voltage as you run your test.  If it drops precipitously then the battery is toast.

If that's the case, get a 40ish volt supply and connect it across the system power leads (AFTER you have turned everything on.)  If this solves the problem and allows you to run for a while it's definitely the batteries.  In that case:

Dump the batteries, use the disable jumper and get a new battery from either another ebike or batteryspace.com.  Virtually any 36V battery will work.