CAv3 Powering off Low Voltage Cuttoff

[Marcus_E]

I have a 72v 15a Li-On battery with a CRYSTALYTE M3540 and CAv3.

My issue today is that it seems to believe the battery is draining at an alarming rate and shuts off very quickly (less that 2 mins of running or about 3 seconds of max draw from throttle) but when I replug in the battery the CA reads the normal starting voltage (82.5ish) and will run again happily for a few moments then the voltage will drop off very quickly (10v per sec or so) and it will shutdown again. This is with a fully charged battery and after the short run nothing seems warm. I have also checked all the external connection and they seem fine. The one that was loose previously has been reinstalled and is in place. The issue is occuring while dry running the bike so it is unlikely something is getting bumped out of place.

Any ideas what is wrong/how to fix the issue?

Here is my old thread about a somewhat similar issue with my bike -- http://endless-sphere.com/forums/viewtopic.php?f=2&t=67917

More info: When the battery is removed from the controller while the controller is still on I see the exact same reaction as the issue I have described(obviously not while the bike is running, just turned on). This would seem to imply something inside the battery is turning off?

 

[quamau]

One dead/unbalanced cell? Have you access to single-cell voltage?

 

[Marcus_E]

Not easily, I would have to destroy the current packaging to get to single cells. While clearly better than getting a new battery I would rather not. This could be a last resort.

 

[quamau]

Not even access to the balancing plug of the BMS?

 

[Marcus_E]

Nothing besides charging and output. :/

 

[r3volved]

No BMS?
Your cells are likely out of whack

 

[Marcus_E]

There is a BMS, or calibike claims there is one, its just in the hard, sealed case the battery is packaged in.

Here is the description of the battery.
http://calibike.com/?product=lithium-72v-15ah-ultra-light-battery-pack

 

[r3volved]

Ah
Have you left it on the charger for 24 hours to balance?
If you've done all the balancing then it may be a failing cell and will probably still need to be torn down

 

[Marcus_E]

Hmm, Ill try the charger trick now.

If that doesn't work, and no one can come up with a miraculous solution, I'll tear down the battery and start checking cells.

 

[r3volved]

If they're way out of balance it could take all weekend charging...you should see the lights and fan toggle as it tops up and stop - balances a bit - tops up again and stops - balances a bit - and so forth

Do you usually just charge until the charger turns off?

 

[Marcus_E]

I normally charge until the charger turns off. When plugged in today the charger seemed to do nothing but I have left it plugged in and turned on.

 

[quamau]

Yeah, leave it on for a couple of days at least.
AFAIK, when the charger switches on/off (red/gree light), this means that one cell is high and hits HVC. The other situation is when one cell is low, so the charger will go to green and simply stay there. It's at that point that the real balancing action starts. If you have a DMM you could check and see that in this state the charger should provide a tiny current, a few tenths of mA. If this is the case, just let it go!

 

[r3volved]

Hey bro, any luck after the weekend with extended charge times?

 

[dnmun]

his charger may not have a balancing current. it may have a latching output that turns off when it reaches final voltage.

i have one of the calibike packs with no balancing network in the BMS but others have a balancing network on their BMS.

too bad he cannot open his pack and expose the BMS to make measurements and show a picture of it.

 

[rafeh1]

his charger may not have a balancing current. it may have a latching output that turns off when it reaches final voltage.

i have one of the calibike packs with no balancing network in the BMS but others have a balancing network on their BMS.

too bad he cannot open his pack and expose the BMS to make measurements and show a picture of it.

Dunum Our calibike battery packs have electronic balancing circuit not a resistor based one as in older designs. You cannot see any resistors on bms because there aren't any. Just like your intel motherboard. its all integrated inside the bms chip set.
rafe