Posts made by ikaruspint

Hi @weno66 @Lemur

Resurfacing this topic as my Pint BMS appears to have at least 1 - 2 bad Mosfets.

When I charge my board cell 6 slowly drains over subsequent days. If I don't pull the battery it will drain to 0v (ask me how I know). If I charge the pack again (in my pint), all cell voltages come up as they should but cell 5 tends to hit max volts first. When I remove from the charger cell 5 remains high, whilst 6 starts to drop.

So basically I think cell 6 is locked open and is constantly bleeding whilst cell 5 is closed and not bleeding when it should be.

I've found someone local that seems confident to resolder fresh mosfets if I supply them. Could someone confirm if these are suitable?

My soldering guru was also wondering if there is a preferred method for removing the clear coating before beginning soldering?

Many thanks in advance :-)

@lemur Can you talk me through connecting and disconnecting the BMS from the main battery to avoid damage please?

@lemur Thanks for the info. I'm doign some research now.

In a new turn of events, I found a secondhand Pint BMS in the US for reasonable money. I am getting it on the 16th of August. I know their are pairing considerations, but I have an OWIE chip installed (which I undertsand defeats this). Do the BMS's have Firmware updates that can lock you out of OWIE & Quart batteries? The seller couldn't tell me what version the Pint was on before it was disassembled...

Thanks for coming back to me @Lemur . Here are some pics of my BMS. I thought it looked pretty good, save the bit of solder on my XT60's from the VnR. I do however think I had an overheat at some point as some of the plastic coating over the xt60's show evidence of temperature. I think this was during use though and not from the soldering or charging (I was super careful when soldering onto the XT60 legs, but you never know). The component at q15 looks like it may have gotten some heat? Also d5/c37.

How do you remove the clear coating from the PCB to access the components underneath. I have never worked on such small components as this before, do you use a solder rework station?

IMG_7666.jpeg

@lemur thanks for coming back to me. I'm based in Australia but am trolling marketplace in the US to see what I can find.

I'm also happy to offer up my BMS if you think you could fix it?

Hey all,

It’s been a wild ride getting to this point. I bought my first Onewheel, a used Pint (800 miles, Gemini 5050) about two months ago. I love the board, but the battery was pretty cooked, so I decided to VnR it.

Things went downhill from there. I ended up removing the VnR after repeated issues and found that my cells weren’t balancing properly. After a long balancing session, the BMS overcharged several cells, and eventually I lost one completely.

Fast forward: I had the dead cell professionally replaced this week (yes, I know that's not best practice, but I’ve got a Chi battery en route and just needed this to limp me through). After the first ride, I noticed the pack was still a bit out of balance, but figured it might be the new cell settling in.

Unfortunately, after a few more rides, the issues persisted. Cell 5 is getting overcharged again, and the new cell 6 is still lagging. I left it unplugged for a few days, and when I checked today, Cell 6 had dropped 0.4V, while all the others remained stable.

It’s looking like the BMS is bleeding the wrong cell... or worse.

So, does anyone here have a spare Pint BMS they’re willing to part with? At this point, I think it’s time to cut my losses and replace it.

Appreciate any help or guidance you can offer.