Sherman Max battery flashing on screen, and only charging to 96 volts? Why? (VIDEO INCLUDED)

[BKW]

Things I've noticed today:

First time this has happened. I've used the same stock veteran sherman max charger since I've had the EUC. I was charging it and noticed the battery on the EUC flashing (see video). The charger light was green indicating it was done. I looked on DarknessBot and EUC World and both read the volts at around 96V (the Sherman Max has 100.8V). Is this anything to be worried about? What might this mean? Should I not charge it anymore? Would it be dangerous to charge?

The other night I went to about 9% battery on my SherMax, which I've never gone that low before. I charged it up after and rode it. Fine. The next charging cycle is when I get this battery flashing thing and it reading 96V.

About the battery:

I've had this battery for probably 2.5 years. It's been through he ringer. I would estimate anywhere from 15-20K miles of usage, definitely 500+ cycles charged. It did have some crashes well over a year ago but nothing strange since that time.

 

Edited November 11 by BKW

[BKW]

here is another video where i noticed the screen battery is flashing as well:

 

[alcatraz]

96v could mean different things. If you want to do the individual pack charge test remember that you can't connect them back together if they're at a different level of charge. 

If you want to jump over the charge test you can proceed to opening the suspected pack up and measure individual group voltages. 

Maybe it'll be something obvious like corroded cells that are at near 0v.

An indivieual charge test can tell you if interpack communication is malfunctioning etc. It can identify which pack is acting up and which one is good and can be ridden in the meantime.

If none of the packs charge above 96v individually then focus your attention on the charger.

[BKW]

1 hour ago, alcatraz said:

96v could mean different things. If you want to do the individual pack charge test remember that you can't connect them back together if they're at a different level of charge. 

If you want to jump over the charge test you can proceed to opening the suspected pack up and measure individual group voltages. 

Maybe it'll be something obvious like corroded cells that are at near 0v.

An indivieual charge test can tell you if interpack communication is malfunctioning etc. It can identify which pack is acting up and which one is good and can be ridden in the meantime.

If none of the packs charge above 96v individually then focus your attention on the charger.

Dang, I'm glad you replied because I was about to do an individual pack charge test, and I likely wouldn't have thought to have both packs at same volts when I reconnected them.

I was also told another way to check is to go to the " advanced menu and check the stats on the battery packs. You're looking for br/bl or bU/bd values."

I have tried to change firmware, but still same issues.

 

I have a lot of questions, some of which I could try to look up myself, but sometimes the answers are hard to find, so I'll ask here if anyone wants to answer them:

1. What happens if they are at different level charge per battery pack and I charge it? Fire?
2. If the packs have a different level of charge from each other, is this relatively easy to fix?
3. To charge them separately, all I need to do is disconnect one of the battery pack's XT connectors and charge the other one as I usually would on the EUC?
4. I have another veteran sherman max charger, perhaps I should try this first before anything else?
5. I probably shouldn't ride it when the battery LCD is flashing and the max volts read 96V, but I wonder what might happen if I do? I ask only because I'm curious if discharging it then charging it again somehow changes things back to normal (I doubt it).
6. Is there any added risk of riding the EUC with only one battery pack besides just having less overall capacity? Is this even safe?

 

Edited November 12 by BKW

[alcatraz]

44 minutes ago, BKW said:

What happens if they are at different level charge per battery pack and I charge it? Fire?

Individually you can charge the packs and nothing will happen. If you connect them both at the same time, most wheels will not have any way to block the massive current rush except with fuses. So best case you'd have to replace fuses, worst case, melted cables, rare chances fire. 

If you want to connect them back safely just ride the higher pack down to the other pack's voltage within lets say 0.5v and you're safe.

49 minutes ago, BKW said:

To charge them separately, all I need to do is disconnect one of the battery pack's XT connectors and charge the other one as I usually would on the EUC?

Yes. When switching, just don't make the mistake of plugging the second pack before unplugging the first. 

52 minutes ago, BKW said:

I have another veteran sherman max charger, perhaps I should try this first before anything else?

Good idea.

52 minutes ago, BKW said:

I probably shouldn't ride it when the battery LCD is flashing and the max volts read 96V, but I wonder what might happen if I do? I ask only because I'm curious if discharging it then charging it again somehow changes things back to normal (I doubt it).

At 3600Wh a single pack is 1800Wh. Seeing as an RS19 can do 80km/h on 1800Wh tells me you don't really have to worry. To be safe however, don't accelerate and brake like crazy. That pushes a lot of amps and your amp budget is cut in half.

54 minutes ago, BKW said:

Is there any added risk of riding the EUC with only one battery pack besides just having less overall capacity? Is this even safe?

No problem, but as I said, you'll want to ease up on the amps. Accelerate and brake more gently. At winter temperatures especially. That cuts your amp budget further.

[alcatraz]

Each pack probably has its own fuse. Let's say it's 40A. With two packs you can for short moments pull a lot of amps 80A and not be afraid of tripping a fuse.

When your ceiling is cut in half to 40A (assuming there are fuses) then you must keep in mind that even a short moment over 40A amps can lead to a faceplant.

Those fuses were chosen to work together for a total of 80A. You can ride with one pack but just don't forget you have half the ceiling. 

On some begode there aren't fuses and you can technically pull all the amps the cells can give until they selfdestruct. I call that "safe" because the wheel sacrifices itself to save the rider from a faceplant. It will however burn up if you ignore the limitation.

[BKW]

Thank you so much!

This really helps me because I don’t want to spend over $1,000 on a new battery pack if I don’t have to. If my current battery pack is bad, I might just take parts from it, since buying a used Sherman Max could be cheaper than a new battery.

What’s strange is that this issue came out of nowhere. The battery seemed fine until I started charging it today. I think riding it down to 9% the other day might have caused the problem, but I usually don’t ride below 30%. I’ve only used one stock charger for it, but the batteries have been used a lot, likely with hundreds of charges.

I’m curious about the flashing battery indicator on the LCD screen. I’ve never seen it before. I looked online and in the manual, but I couldn’t find anything. I assume it means there’s an issue with the charging, the cells, balancing, or the battery management system (BMS).

I plan to try the other charger first to see if that fixes the issue. If not, I’ll check the advanced settings to see if anything stands out. If I still can’t find a diagnosis, I’ll test each battery pack by charging them separately.

The advice about re-balancing the packs within 0.5V is really helpful. I wonder if the apps will read each pack accurately by itself? Or would it be better to use a multimeter?

Edited November 12 by BKW

[alcatraz]

34 minutes ago, BKW said:

The advice about re-balancing the packs within 0.5V is really helpful. I wonder if the apps will read each pack accurately by itself? Or would it be better to use a multimeter?

Either will be very accurate as it's a difference and not an absolute. They aren't trustworthy absolute readings, meaning that you try to compare two readings made with different meters. Avoid that and you'll be good.

You don't have to ride a pack down in voltage. You can also charge the other to the other pack's voltage. Whatever is convenient.

A repair that's common on computer batteries is to charge low cells up manually. I'm not sure it's relevant for your situation but it might be. Let's say you get access to the cells and measure them. If you have a couple of low groups that the bms somehow has deemed bad and refuses to charge, you can manually charge them if they're over let's say 2.0-2.5v and "rescue" them. Even though it isn't a guaranteed fix, because maybe the bms is bad and you'll just have a working wheel for another week, it's perhaps worth a shot. It can help you determine if it's the cells or the bms that are bad. 

Trying to replace either one isn't easy. But it's nice to figure out what caused the problem.

[alcatraz]

I'd try individual charging and the second charger first though.

I'm afraid I'm not familiar with the error codes on this wheel. I'm just speaking generally.

[BKW]

Thanks @alcatraz!

I'll have to diagnose given the information provided in this thread, and I'll report back if I find anything interesting. Might be a while..

[alcatraz]

Please do. It's always interesting to figure these things out. Veteran wheels are fascinating and we're still getting long term ownership data in from people like you.

There's a guy with Msuper v3 that's done 45000km on the original packs. My MSX84 is close to 20000km on the original packs. When these wheels are done we need wheels like the Veteran Sherman (maybe) to upgrade to.

[Blkfri]

@BKW that's what Marty wrote about battery flashing on the Leaperkim telegram group, hope it'll help you : "Flashing battery outline means that there is a battery fault. Charging should disabled.

You can disconnect the left or right battery pack and see if the flashing stops. This will tell you where the problem is."

You can also check the advanced settings battery flags for br and bl (right and left battery): 

Here's how to access advanced settings:

 

These are the output codes & what the condition represents.

111  Normal

101  Overdischarge

110  Overcharged

100  Cell disconnected. (often see this when an IC component is damaged)

0 Battery not present

[BKW]

On 11/15/2024 at 3:47 PM, Blkfri said:

@BKW that's what Marty wrote about battery flashing on the Leaperkim telegram group, hope it'll help you : "Flashing battery outline means that there is a battery fault. Charging should disabled.

You can disconnect the left or right battery pack and see if the flashing stops. This will tell you where the problem is."

You can also check the advanced settings battery flags for br and bl (right and left battery): 

Here's how to access advanced settings:

 

These are the output codes & what the condition represents.

111  Normal

101  Overdischarge

110  Overcharged

100  Cell disconnected. (often see this when an IC component is damaged)

0 Battery not present

Hey, thanks! For some reason I missed your post. I'll check out the video now!

Also, I found a video today about basically the same issue I'm having: