Gotway msuper v3S+ battery not charging

[Eyss]

I have a msuper v3s+ and one of the battery packs isn't charging above 79.9v. the other one seems to work. 

It's done about 6400km and the batteries have been flung out a few times as the shell broke. 

I.e.

 

One of the local battery repairers didn't think the battery was worth repairing due to the age. 

It seems to work fine apart from that. Could I use the batteries with the reduced range? 

Or Could I just remove the dodgy pack and run with one pack? 

[Chriull]

1 hour ago, Eyss said:

I have a msuper v3s+ and one of the battery packs isn't charging above 79.9v. the other one seems to work. 

Then this pack has one or more degraded cell groups.

1 hour ago, Eyss said:

It's done about 6400km and the batteries have been flung out a few times as the shell broke. 

Mechanical stress can accelerate/start degradation.

1 hour ago, Eyss said:

It seems to work fine apart from that. Could I use the batteries with the reduced range? 

The degraded cell group(s) are the ones who get beaten most when discharged and charged. Once dead enough they'll get reverse charged by the rest of the pack during burdens.

As li ion cells seem to stand astonishingly much mistreatment sometimes they'll start to burn.

Such a pack with degraded cells not only gives less range but also less peak current to help balancing over irregularities, so leads more easily to face plants.

The second, till now hopefully good pack will not get balanced anymore - so could start a bit more easily to degrade too once it gets out of balance.

1 hour ago, Eyss said:

Or Could I just remove the dodgy pack and run with one pack? 

Giving half the range and half the peak current...

[meepmeepmayer]

84V - 4.2V = 79.8V, so this looks suspiciously like a bad cell. I would consider this pack unsafe now. I would ride with just the one good pack.

[Eyss]

11 hours ago, Chriull said:

Then this pack has one or more degraded cell groups.

Mechanical stress can accelerate/start degradation.

The degraded cell group(s) are the ones who get beaten most when discharged and charged. Once dead enough they'll get reverse charged by the rest of the pack during burdens.

As li ion cells seem to stand astonishingly much mistreatment sometimes they'll start to burn.

Such a pack with degraded cells not only gives less range but also less peak current to help balancing over irregularities, so leads more easily to face plants.

The second, till now hopefully good pack will not get balanced anymore - so could start a bit more easily to degrade too once it gets out of balance.

Giving half the range and half the peak current...

So essentially, using the bad pack will work but will not for very long.

Using one pack will work but gives me half the range and peak power.

I only really use this wheel to train people how to ride so it should work with one pack. 

[chanman]

It's potentially a little more insidious than having half the peak power. The controller might not stop you from trying to draw similar amounts of current as on two packs, but the battery pack won't hold up to it over time, and will degrade, and potentially develop problems or just catch on fire one day.

Edited April 13, 2022 by chanman

[alcatraz]

You have the older "safer" packs with panasonic cells.

Those I'd personally repair. It's not hard to find used panasonic 18650 cells. Used are better than new because they have a more similar characteristic with the other ones. The capacity will tell you their age. A cell that measures 3100mAh will be at a different age than a cell that measures 2950mAh etc. (I'm talking about the exact same cells, but at difference amount of cycles.)

After replacing it won't be the same as the other pack (good), but likely good enough.

ONLY if you're willing to accept that a repaired pack will never be completely maintenance free again, you can attempt a repair. If you're lucky you won't need to do much maintenance later.

Sadly there needs to be some much needed testing done to see that the bms works fine (not just for 1 hour but several days later). After it has tested fine you can come down from DEFCON1. 

If you don't you could have a fire break out when you're charging etc. Very bad.

Edited April 13, 2022 by alcatraz

[alcatraz]

I have to warn you though that there are a few IF's.

If it's a cell failure then it can be fixed by replacing cells.

If it's a bms failure then you need to replace the bms too.

[Eyss]

9 minutes ago, alcatraz said:

You have the older "safer" packs with panasonic cells.

 

Apparently the v3s+ 1600wh edition uses Sanyo NCR18650GA cells as opposed to Panasonic according to ewheels. 

Ok. Sounds like I'll just have to part the wheel out. I don't use it except for training so I'd rather dispose of it than take a risk 

[alcatraz]

They're called "Sanyo/Panasonic". It's a joint venture.

The NCR18650GA are amazing cells and they're actually in many ways superior to the cells in most new wheels today. It's a shame not to use them.

However, old is still old. If you have several cell groups out of balance (odd voltages) it could mean either a bad bms or old worn out cells. If the cells are too far gone then no amount of love for the cells will produce a good pack.

[alcatraz]

The packs are believe it or not still valuable. DIYers can get good use out of the parts. You can get some good money for them.

Many DIYers would love to get their hands on them.