Controller cutting out...

[townunheardof]

Hi again electric horsemen,

After two months away, I'm back to trying to troubleshoot my setup, which is a...

Cammy_cc 48v 15ah lifepo4 (new)
WE brushless 36v kit (2005)

IN the intervening time, I moved, had an operation, travel, vacation, battled bird mites from hell, all kinds of interruptions.

Here's where we covered some of this before http://endless-sphere.com/forums/viewtopic.php?f=2&t=9882

So, to sum up, when I start to ride, the controller cuts off. I don't think it has time to actually overheat much. If I keep the throttle low, I can go a little longer. But it cuts out whenever there's a substantial load. Mainly on uphills. It's a hair trigger. I never get much more than 1/8 of a mile or so before the controller shuts off, and I have to stop, turn it off, and turn it back on. My commute is 12 miles, so I'd have to stop and start like, 38 times to get to work.

I can't workaround this, somehow I have to fix it.

Some consensus seemed to say that I probably have a bad battery cell, or a "runt". I think this is probably the case.

I did figure out how to measure my voltage. I'm getting 50.3 V.

From what I gather, that's low, right? There's probably a runt in there because it should be 52 or 53.

So now I've got to take this thing apart? Find the runt? And replace the cell?

Now I realize, I never should have bought a Cammy_cc. I don't have the technical chops for this.

When my Charger self destructed, Cammy told me to send it back. $80 for shipping? Forget about it. For $80 I can probably buy a very good charger on Ebay or online somewhere.

I'm charging it now with my original WE 3 Amp charger, which seems to work fine.

I'm going to write to Cammy and ask him if he'll replace a faulty cell if I find one.

Maybe if I just keep charging and discharging over and over it will smoothe out and start working right...

Town
(SLA commuter for 3+ years, and not really interested in becoming a Lithium Tech)

 

[Rassy]

Town, it sounds to me like the BMS may be cutting out, not the controller. Since you are using a BL36 system with a 48V pack, the controller should not be cutting out because of LVC. If you bypass the BMS on your pack and do a test you can determine if this is the problem. Do not bypass the BMS during charge.

This does not mean that you don't have a problem with one or more cells in the pack.

I am a little confused by your statement that you are using the original WE charger, since that would normally be a 36V charger?

 

[townunheardof]

Hi Rassy,

I'll try to clarify...

When I'm riding, and the power cuts off, I assumed that the controller was cutting out, but you may be right.

I'm riding with the throttle on. Power dies, and the WE throttle indicator light, which is normally green, goes yellow/red.

So I stop, and cycle the controller with the little key. Everything is back on again, with green light. I ride again, and it happens again.

Yes, I'm charging my 48v cammy with the 36v WE charger. Seems to work fine.

So, you're suggesting a test bypassing the BMS. Good idea. I'll look the wires and such over and think about how.

Thanks!

Town

 

[dnmun]

stop. you cannot charge a 48V battery with a 36V charger!!!!!!

you have at least 2 parallel sections dead it appears. open your pack to get to the BMS and measure the voltage across each cell sequentially until you find the dead ones, you will need a charger also that will put out 60V, or 58V minimum.

don't damage it any more until you can fix it. what was wrong with his charger that prevented it from working? someone else said they had 2 bad chargers from volgood but never said what was wrong with them.

 

[Rassy]

Town, I took a picture of my 48V 20AH Ping V1 battery and BMS showing where the bypass wire goes. I cut the large black wire between the battery and BMS (blue tape) and reconnected using a basic male/female blade connector. I also cut the large black wire (Negative Discharge) between the BMS and controller (yellow tape) and also reconnected using a male/female blade connector. Then I made a short wire with matching connectors (in the picture it is just laying there) which can be used to temporaily bypass the BMS during discharge.

I also think that your battery voltage is low because you can not charge a 48V LiFePO4 battery with a 36V charger. The charger might indicate full charge because the voltage is somewhere above 44 volts, but that is not enough for the 48V battery.

The reason I think your BMS is cutting out is that they have a maximum amperage limit built in to protect the battery. On my 20 AH batteries this was set at about 30 amps. On my first test, my BMS promptly cut out during acceleration/hill climbing. I had read elsewhere on this forum that the way to reset the BMS was to disconnect the controller and then connect it again, which worked. I later purchased a Watts Up meter (Installed in place of that bypass wire) and verified this was the problem.

I would encourage you to get a 48V charger (One for LiFePO4) and properly charge your battery before you do too much more testing. You will eventually ruin the battery if it discharges too far.

Edit: Yeah, what Dnmun said. Not knowing what you have already done with the battery, you may be right on the edge of ruining it now. Good Luck.

 

[dnmun]

again, i will council you again to stop. if you can repair the battery then rassy has good instructions on bypassing the output FETs, but you will destroy the battery totally if you do this. instead of 2 or 3 dead rows, you will lose most of the cells within minutes of discharging.

you need to charge it once you find the dead cells, but go look for them first and see how bad they really are, then fix it by replacing the dead cells, and get the right charger. then try rassy's idea after you have been able to prove to yourself that all the cells have charged up to 3.62-3.65V. every one of them. getting your pack to balance is the most important thing you can do once you rebuild it. hopefully the marginal cells are not damaged yet and it will only be those 2 rows.

 

[Rassy]

Dnmun, isn't it possible that the battery cells are all still okay and the battery is just sitting at a partially discharged state? In other words, would it be logical for Town to obtain a proper charger and attempt charging the battery before tearing into it? Also, if the BMS is cutting out because of low voltage on a cell instead of high amperage draw, wouldn't just properly charging the battery potentially solve the problem?

 

[dnmun]

i agree. he said it reads 50V and cuts out immediately so he has LVC on at least one row and possibly more cutting off the BMS. his battery should read 58V so he is 8V short and if all the other 14 then are charged up to 3.6 then that leaves nothing for the other 2. but assume 3.2V average over 14S and he has 5V to split between 2 rows, which is his best hope now.

that's why i asked him to measure the voltage on each row and then charge after.

if you only have a 36V charger then it only puts out about 44-45V and if your pack is reading 50V then it is impossible to charge it with that charger. you can use a 12V battery in series with the 36V charger to get up to the 58V but your SLA will go dead charging the pack too unless you keep a 12V charger on it as well.

you need to get a 48V lifepo4 charger, but measure the battery cell voltages first so you know what has happened to it. it is not bad connections, just not charged and the LVC is shutting it down. that's why i said to stop before it gets damaged.

 

[goodluck-2009]

Hi Rassy,

I'll try to clarify...

When I'm riding, and the power cuts off, I assumed that the controller was cutting out, but you may be right.

I'm riding with the throttle on. Power dies, and the WE throttle indicator light, which is normally green, goes yellow/red.

So I stop, and cycle the controller with the little key. Everything is back on again, with green light. I ride again, and it happens again.

Yes, I'm charging my 48v cammy with the 36v WE charger. Seems to work fine.

So, you're suggesting a test bypassing the BMS. Good idea. I'll look the wires and such over and think about how.

Thanks!

Hi,guy,
I am so surprise that you charge the 48v battery by 36v charger.
If floating voltage for 36v charger maybe just reach 45v,but 48v charger should reach 60v
So if you charge battery by 36v charger,battery couldn't be full charged.
The steady voltage for 48v 15ah battery should be 53.5v.
This is my opinion :lol:
Town

 

[317537]

If you bypassed the BMS LVC discharge when only charging to 45v peak you could of well broken it from how I see this.

Its a matter of testing and not to ride when bypassing BMS LVC like this.

Some comtrollers have LVC too, im not sure about this though.

You seem to have overvolted the 36v WE controller so it wont LVC at 50v. Your more likely to burn it out.

Your heading for a real mess. Take Dnmuns advice and STOP!