BMS Li-Ion Battery died < 2.5 years usage...advice?

[Deleted member 4366]

I updated my schematic so that you can see how a BMS is connected, for those that want to diagnose their own batteries.

 

[flecc]

After that I found a thread on Endless Sphere about this BMS, where people are hacking the software todo all sorts of clever things. The BMS is quite sophisticated. Once the cells go below 3.0v, it goes to sleep and cuts off all activity to save draining the cells further. There must be a wake-up procedure, but I don't know what it is; however, there's a reset pad on the back of the PCB that would probably do it, or my method.

The Panasonic 26 volt battery with this type of sleep facility is woken up by recharging, but that battery/charger combination has a third charging connection, possbly the wake-up trigger. I'm wondering if this BMS had an intended three connection charger?

 

[muckymits]

Dave could the wake up procedure be like the Giants? they need jumping off another battery.

 

[david1949]

Just reading this thread and i see Morphix your are getting a knee replacement you may have it done already i have had 2 replacements last one was November 2012 . Hope all went well for you it takes about a year to heal or longer . My second one done in November is not as good as the last one done November 2010

 

[morphix]

Just reading this thread and i see Morphix your are getting a knee replacement you may have it done already i have had 2 replacements last one was November 2012 . Hope all went well for you it takes about a year to heal or longer . My second one done in November is not as good as the last one done November 2010

Hi David, no knee joint replacement for me..my age is against it too young at (41) plus my PVNS is not severe enough to affect joint so I ended having a synovectomy of the knee lining with open surgery.. I was (fortunate?) to only have localised PVNS so the knee joint itself is ok for now..but there's a 50/50 chance it could return.

Anyway 2.5 months on, I've almost made a full recovery, but I'm limited on the physical activity side of things...can't run or jog even, and riding unpowered is only possible very short distances but the knee aches.. I've been told the strength will be fully back within 6-12 months and to keep cycling and exercising it bit by bit.. This is where having the pedelec is a godsend and enables to gradually get back into it.

For part of the surgery I had a large nerve removed from one side of my knee, so that side is completely numb now. Very weird.. its like touching rubber leg.. the doctors don't know whether that nerve will regenerate or not.

 

[morphix]

I charged up the cells to 3.5v with my BC168 charger that can do up to six at a time. That should have been enough to get it to start workng, but it didn't want to play. With some batteries, you can wake them up by unplugging and re-connecting the multipin connector, but I'd done that during charging. Everything that I checked was OK, put the charging and discharging FETs remained switched off. Then after a bit of brainstorming, I figured it out. There's a white wire directly from the battery +ve that powers the BMS, so unplugging the multipin doesn't reset the software. I unsoldered the white wire then resoldered it and bingo! Everything is working again. Now on final test. Should go back to Morphix tomorrow.

After that I found a thread on Endless Sphere about this BMS, where people are hacking the software todo all sorts of clever things. The BMS is quite sophisticated. Once the cells go below 3.0v, it goes to sleep and cuts off all activity to save draining the cells further. There must be a wake-up procedure, but I don't know what it is; however, there's a reset pad on the back of the PCB that would probably do it, or my method. Apparently you mustn't disconnect that white wire with the multipin in, otherwise it damages something. I was lucky to pull it out just in case. The white wire runs along the edge of the PCB at the top of the photo. It goes to P+ pad.

Is that the blue wire you unsoldered Dave which seem to reset the BMS and allow charging?

 

[Deleted member 4366]

No. It's the white wire that runs along the top edge of the photo to the P+ pad in the corner. You can't disconnect it with the multi-pin plug in. Also, you don't have to disconnect anything. On the back of the board are two pads marked "RST". You just bridge them temporarily to reset the BMS.

 

[banbury frank]

Hi Be VERY careful that thin white wire is connected directly to the battery positive and the pad next to it is battery out negative if your soldering iron touches them together BANG the thin white wire will BURN out

Hope this Helps

Frank

 

[ghost]

very interesting, had no idea a sleeping BMS could be an issue. Learn something new everyday.

 

[Deleted member 4366]

The BMS that Morphix has is controlled by a microprocessor, so it has much more intelligence and features than an average one.

 

[morphix]

No. It's the white wire that runs along the top edge of the photo to the P+ pad in the corner. You can't disconnect it with the multi-pin plug in. Also, you don't have to disconnect anything. On the back of the board are two pads marked "RST". You just bridge them temporarily to reset the BMS.

Got it. I carefully unsealed your tape handy work, spotted the white wire from your photo above, and unsoldered it (after first disconnecting the multipin connector).

Then I soldered an in-line slide switch between the white wire and the solder pad where the white wire was soldered to. This switch acts as a BMS "reset" switch, as it seems to have fixed the problem and my battery is charging again, after sliding the switch to OFF (to open circuit the white wire), then re-connecting the multipin socket and sliding the reset switch position back to ON.

So now I have a BMS "reset switch" for whenever this problem happens again and any individual battery cell voltages fall below a certain voltage the BMS circuit determines unsuitable for charging.

I'll just have to remember to make sure the multipin socket is disconnected BEFORE I use the new "reset" switch to OPEN position (white wire disconnected to cut power to BMS) to avoid damaging the BMS as per your comment above. I'll just make print reset instruction label for the side of the battery to avoid any confusion I think.

It's a pity though about having to unplug the multipin socket to carry out a BMS reset as that will mean opening the battery sealing each time..unless I can get creative, reseal but leave the multipin exposed...

It's a pity just my new reset switch alone won't perform the reset as that would be ideal. I wonder if it's just one or two wires on the multi-pin that need disconnecting? If so, these could have an inline reset switch too, or perhaps just be wired to my existing reset slider switch?

I must say, I think the BMS is poorly designed (or perhaps too well designed!) it should have a "reset button" on the external housing for this situation surely?

 

[morphix]

UPDATE: While the battery was charging I began resealing/taping the battery with selotape and accidently knocked the reset slider switch to off (opening the white wire).

Charging stopped immediately, but no apparent damage was caused. I slided it back within a few seconds, and charging resumed.

I don't know what would happen though if I left the charger plugged in and that new reset switch open..maybe it would have eventually burned out the BMS circuit?

If it's harmless though and doesn't cause any problem, that's great, it means I have a single reset switch to fix this voltage dropping problem and reset the BMS circuit without needing to touch the multipin connector?

d8veh: what's the name of that heavy duty black tape you use and where can I get it? Think I should buy a roll and give this battery a good going over with it since I've re-opened it after you sealed it, just to be on safe side as there's exposed cells and wires now. Maybe it wouldn't hurt to source some rubber sheet off eBay too for added protection, before taping it up, since I won't be able to replace the original plastic skin it had.

 

[banbury frank]

Hi There is space on the board fora 3 pin header and BMS sell a adapter to plug in a usb Programming we tried to bring this to just under the lid as we have had the same problem never got the software BMS have on there site perhaps somebody Can I still have the usb device somewhere

Smart BMS USB I2C Adapter Programmer Reader Writer Monitor - BMSBATTERY


Frank

 

[Deleted member 4366]

There's a lot of useful information about this BMS in these two threads including how to get the programming working.
Endless-sphere.com &bull; View topic - connections for? EcityP Smart S5-13 BMS
Endless-sphere.com &bull; View topic - O2Micro OZ890 Based BMS Units

According to the first thread, if you disconnect the P+ wire with the multipin connected, it damages the balancing ability, but I don't know if that's certain

 

[morphix]

There's a lot of useful information about this BMS in these two threads including how to get the programming working.
Endless-sphere.com • View topic - connections for? EcityP Smart S5-13 BMS
Endless-sphere.com • View topic - O2Micro OZ890 Based BMS Units

According to the first thread, if you disconnect the P+ wire with the multipin connected, it damages the balancing ability, but I don't know if that's certain

Thanks Dave, I'll have a read up and see what can be done.. I have some electronics experience and plenty of parts, so maybe I'll come up with a clever solution that leaves the battery entirely sealed and an outside inline cabled reset option button. But for now, the reset slide switch I've soldered in seems to be working fine, and I'm just glad to be back on the road.

Hopefully having the white cable open with the multipin connected hasn't done any damage, only time will tell.. I will report back.

 

[Deleted member 4366]

You only need to wire a switch to the reset pads on the back side. I haven't done it myself, but I'm told it works.