Help please! I have a QS 205 v3 motor paired with a SVMC 72200 Sabvoton powered by a 72v 50ah 300a continuous BMS.

DaKashmir! · May 21, 2020

Help please! I don’t know anything about the technical jargon I have read in this thread so bear with me. I have a QS 205 v3 motor paired with a SVMC 72200 Sabvoton powered by a 72v 50ah 300a continuous BMS. I purchased the bike from someone who built it for me. He told me he would provide any technical assistance I needed, but he won’t return any of my messages. So this is what’s happening, I charge the battery to 84v and when I ride it for a while and the bolts drop down below 80 it shuts down. Won’t come back in until I plug it in and give it a charge. My lack volt Is set to 60 and my current limiting voltage is set to 62. Any ideas on why it shuts down around 79v?
Another issue I have is the H6 TFT LCD Display, the only thing that works on it is the voltage read out. 00.0 RT MPH, I can go through 0-5 on the assist but it does nothing. Power is always at 0. Error message at the bottom reads [E : a] Failed to receive. Any ideas on that?
Thanks in advance,
Rick

Jonno · May 21, 2020

Hi Rick welcome to the forum and don't panic there are lots of people who will help you out.

Post a picture of the display and the bms if possible and do you have a programing lead for the controller.
It sounds like the low voltage cutout is set too high on the bms

The display problem is due to the two 3 wire plugs that come from the controller should be plugged together these are only unplugged for programming purposes. Your 0-5 will then work

Jonno

DaKashmir! · May 22, 2020

I have attached a photo of the display, where would I find the bms? I think he said it was wrapped into the battery pack.
I’m not sure what cable is needed to go to the controller. I do have the app that I connect through Bluetooth, does it do the same thing?

Jonno · May 22, 2020

All looks ok, have you connected the two 3 wire plugs together?

Bluetooth app is ok you don't need a cable.

When searching with bluetooth can you see a bms or another device?

Jonno

DaKashmir! · May 22, 2020

I connected a plug with three wires on it, black green and yellow. On the other end of the plug the black wire turns to brown. The only bt device that shows up is the MQCON.

However when I have this plugged in it cuts off connectivity to use the app.

Jonno · May 22, 2020

when you connect the plug functions on the screen should work including your your 0-5 power settings. please test this to confirm

Jonno

Jonno · May 22, 2020

when you connect the plug functions on the screen should work including your your 0-5 power settings. please test this to confirm your Low voltage cut should also now be 60v

Jonno

DaKashmir! · May 22, 2020

No difference with the plug plugged. No mph, trip odometer, I can still change the assist 0-5, but I can’t tell it’s doing anything. What is it supposed to do anyway lol? I figured it would make peddling easier with the different numbers but don’t know for sure.

Jonno · May 22, 2020

read this and check the display settings

http://www.sabvoton.net/static/upload/file/20191016/1571196400347812.pdf

John in CR · May 25, 2020

By "shuts down" do you mean everything turns off? If so, then it sounds like the battery is shutting down due to a low cell or a BMS problem. You need to check the battery to see that it is properly balanced. Is it all enclosed with only the primary battery leads coming out of the pack, or can you get to a connector with 23 wires going to it, so you can measure individual cell voltages?

DaKashmir! · May 25, 2020

I’ve been out of town for the holiday, on my way home today. Yes, when I say shuts down the display goes black and all power is shut down. The battery appears to be all enclosed with just red and black coming out of it. I’ll see if I can get it out of the bike and look but it’s in there really tight.
I was able to go into the program mode before I left and I’d not see anything pertaining to the battery or bms. I did see a wheel size and it was set to 26. My tire is a 19, what should it be set to? I know it doesn’t have anything to do with the shut down but thought I’d ask. Thx everyone.

DaKashmir! · May 25, 2020

Ok, got the battery out, I see damage around the edges, can anyone tell if it got into the cells or not? The pack has a blue shrink wrap around it, is it OK to cut it away to see the insides?

DaKashmir! · May 25, 2020

Forgot to attach the photos lol

DaKashmir! · May 25, 2020

Found this in the bottom of the battery tray, wipe’s right off though.

DaKashmir! · May 28, 2020

Hey, where did everybody go lol? Jonno and John in CR you guys still out there?

DaKashmir! · May 28, 2020

I took a closer look and it does appear that a metal casing is punctured. I tested it and it’s positive, not ground.

Jonno · May 28, 2020

Looks very much like the battery wants rebuilding and te damaged cell replaced. I would think that the bms is shutting down the pack because of this.

Jonno

DaKashmir! · Jun 1, 2020

Ok, I’ll unwrap it and see what’s in there. Thanks a bunch! I’ll report back my findings.

DaKashmir! · Jun 3, 2020

I unwrapped the pack, now I’m not so sure any of the batteries were damaged. I’m not sure what to do now, do I break down the battery pack even more? How do I test the cells individually?

DaKashmir! · Jun 3, 2020

I noticed on the top of the pack separations in the aluminum bindings connected to the top of the batteries. If my count is correct, it appears to be 6 separate banks. Checking voltage from what I’ll call the front of the battery, where the positive wires connect to the bank, these are the voltage readings I get. 78.8, 70.9, 63, 55.1, 47.2, 39.6. I see a pattern of voltage decrease as I move from front to back. Should all of these register 78.8v, or is this normal?

Jonno · Jun 3, 2020

The reason your battery pack is not working correctly is that you are taking all your power from one or two packs only due to the bad connect - hence the short range.

All your packs voltages should be equal so the first thing to do is re solder the broken connection on the side(connect the two parts together with a short bit of wire temporarily if you if you have no nickel strip) , this is the parallel connection between the 20s packs. The cells should now start to balance.

Re check your pack voltages after an hour or so and the cell packs voltages will be more even.

When this is done we'll move on to the next bit.

Jonno

j bjork · Jun 4, 2020

It sounds like you are mesuring every other series connection. You go down about 8v with every mesurement.

DaKashmir! · Jun 4, 2020

Thanks guys. I can’t find a broken connection, how do I troubleshoot the pack to find one if there is? Should I check voltage in a different way? Thanks again for all your help!

j bjork · Jun 4, 2020

Measure every series group, one at a time. It is much easier to get an idea if there is something wrong with a group then.
If you don´t find anything wrong,(higher or lower voltage than the rest) you can try to connect the charger and see if one group get higher voltage faster than the others.

Oh, and look closely at all the welds on the cells. Make sure that none are loose.

DaKashmir! · Jun 4, 2020

I have checked each of the “group’s” and as mentioned, the further you go from the front of the pack to the rear the voltage drops 8v. I checked each battery in each of the groups and the voltage is consistent for each battery in that group. Example: group 1 measures 78.8v. Each individual battery I can touch measures 78.8v as well. I couldn’t find any loose connections either. I’ll hook up charger now and check voltage off each group and report back.
Thx

Help please! I have a QS 205 v3 motor paired with a SVMC 72200 Sabvoton powered by a 72v 50ah 300a continuous BMS.

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