Veteran Sherman Low Battery indication and tilt back even though battery is charged

[Planemo]

4 minutes ago, ShanesPlanet said:

 I wonder how hard it is to get the stock sherman bms? I too would be a little nervous about sending a pack of good batteries off, to only get a new bms on a pack of shit batteries, back.

It would be nice if you could buy direct from Veteran, maybe you can. I know you can/could from Gotway, and the prices weren't that bad either. A new GW BMS is about £50.

I agree, if it's known that the cells themselves are good, I would be highly reluctant to let them go out of my grubby little hands tbh.

[Planemo]

11 minutes ago, supercurio said:

I guess that since it's safety critical (both operation and fire), these packs are serviced only by specific authorised professionals.

Hahahaha good one

11 minutes ago, supercurio said:

Seeing how the huge BMS board covers the entire pack

Yeah same as GW for donkeys years

11 minutes ago, supercurio said:

What about flipping the pack so the BMS board would lay on the inner shell instead of the side cover?
Wouldn't this inversion reduce the risk to the boards significantly?

I'm not convinced, pressure is pressure whichever side it's applied to. Neither am I convinced that it's still a side panel ribbing issue, not unless the ribs that have been removed are in the wrong place. Either way, we never had this issue with GW and the setup is virtually identical, with the panels directly pressing on the packs. I appreciate that GW don't have the ribs, but if the correct ribs have been removed on the Shermans then the panel should be even less likely to press on the critical parts of the BMS compared to GW.

[supercurio]

I'm now thinking about designing reinforcements that would be attached to the areas highlighted in green in this picture.

So even though the side covers would still flex some, they would a lot less because also resting on a long vertical support in the center.
Transferring significantly less forces to the BMS boards.

 

But yea @Planemo, previous Gotways didn't have this issue. Are the boards also on the outer side in Gotway's packs?

Some gotway shells have ribs, although fewer and less pronounced.

 

Edited June 11, 2021 by supercurio

[Planemo]

2 minutes ago, supercurio said:

I'm now thinking about designing reinforcements that would be attached to the areas highlighted in green in this picture.

It's a sound idea, but like I say we really need to confirm it has anything to do with the panels/ribs. It would be nice to take off a panel, get a BMS, put white paint on all the rib edges and lay the BMS in exactly the same place it would be in when installed and see exactly what is making contact. Theres a lot of empty real estate on the BMS, so it can't be hitting components in too many places. 

2 minutes ago, supercurio said:

But yea @Planemo, previous Gotways didn't have this issue. Are the boards also on the outer side in Gotway's packs?

Yes.

[supercurio]

33 minutes ago, Planemo said:

It's a sound idea, but like I say we really need to confirm it has anything to do with the panels/ribs. It would be nice to take off a panel, get a BMS, put white paint on all the rib edges and lay the BMS in exactly the same place it would be in when installed and see exactly what is making contact. Theres a lot of empty real estate on the BMS, so it can't be hitting components in too many places. 

Yes.

You're right. Proper root cause analysis would be best to have.

For now, we can only build a link between events (wheel falls on its side on a rock, wheel lays on its side for maintenance) and result: unspecified BMS failure.

It's good enough for me to attempt to design the support described once I receive my unit - at some point.

Plus I'll attach power pads there and exert quite a bit of force on these side covers while riding - and much more in case the wheel would fall on its side even at low speed.

In all cases, transferring some of these forces onto the inner shell instead of the battery packs seems reasonable

[Planemo]

I wonder if any of the failures have occurred when using the stock pads. I use them, and they are placed quite high (nor are they deep). The hangers take the lower weight. So in effect, if my wheel is on the side theres very little pressure anywhere around the middle although obviously the BMS' do extend pretty high up the wheel. Dunno, just a thought.

[.....]

23 minutes ago, Planemo said:

I wonder if any of the failures have occurred when using the stock pads. I use them, and they are placed quite high (nor are they deep). The hangers take the lower weight. So in effect, if my wheel is on the side theres very little pressure anywhere around the middle although obviously the BMS' do extend pretty high up the wheel. Dunno, just a thought.

This also occurred to me when re-designing pads. I ALMOST made some the would have placed the pivot point more center shell. IN the end, I favor similar to stock style and my wheel has NEVER been ridden without top pads. One would suspect that the pedals and pads being the low spot, would easily prevent ANY shell hits. My shell is pristine, so its obviously a solution. Pads at top, pedals at bottom, no side case risk. Of course, of roaders and rock climbers excluded. Top pads also help prevent damage to top and rollover. Less worry when laying it on its side at rest. Or at least I would hope so.

Edited June 11, 2021 by ShanesPlanet

[supercurio]

1 hour ago, Planemo said:

I wonder if any of the failures have occurred when using the stock pads. I use them, and they are placed quite high (nor are they deep). The hangers take the lower weight. So in effect, if my wheel is on the side theres very little pressure anywhere around the middle although obviously the BMS' do extend pretty high up the wheel. Dunno, just a thought.

I thought about that too. The stock pads are only at the top and would prevent significant force to be applied on the BMS board in most scenarios.
It's not unreasonable tho think that at least some of the design and testing was completed with the stock pads in mind.

However the most common pads nowadays are power+jumping pads.
These are at their widest above where the pedals close, which matches in height with where the grooves were removed by Leaperkim.

[shellac]

Just an update on this, ewheels has a spare battery pack in stock that they are sending me. I'm still a bit worried though. Why did I get an unbalanced battery to begin with and could it happen again?

Does anyone know how putting the wheel on its side and pumping up the tire to 30 psi could possibly effect the battery? Maybe that was just a coincidence and it was going to happen anyways?

On 6/11/2021 at 5:13 AM, supercurio said:

Thanks @shellac for sharing with us your bad news with precise recount of the wheel history.
Do you remember on which side it fell at low speed?

It sounds like the BMS fault occurred directly after you laid the wheel on its side to adjust the tire pressure.
Looks pretty clear-cut cause and effect...

I still have a Sherman on order currently shipping. Wondering if I should cancel.
Given the battery shortage and limited duration of warranty on the battery, this issue seem like it could become an annoying and costly endeavour down the line.

Do you know if it's possible to replace the BMS board only and get the battery pack re-wrapped by a local battery shop?

My fall at low speed was also on the left side, the same side I put it on to pump up the tire. That was a few weeks ago and I had probably done one full recharge since then. I was basically practicing doing tight 180s at low speed and it fell over. I mean if that was enough to damage the battery then the Sherman might a well be made of glass lol. It was truly a benign fall.

Well I'm going to try the new battery and I hope I am not missing something that will cause this to happen again.

[Ben Hatfield]

4 hours ago, shellac said:

Well I'm going to try the new battery and I hope I am not missing something that will cause this to happen again.

did you get (an email) notification to dremel out the ribs on the case?  

my understanding is the problem lies in damaging the battery BMS, that is part of the battery pack.  apparently if the battery management system is damaged, that error message comes up.

I also had to do a battery pack swap, and the damage came from setting the wheel on its side.  

[supercurio]

5 hours ago, Ben Hatfield said:

did you get (an email) notification to dremel out the ribs on the case?  

my understanding is the problem lies in damaging the battery BMS, that is part of the battery pack.  apparently if the battery management system is damaged, that error message comes up.

I also had to do a battery pack swap, and the damage came from setting the wheel on its side.  

Since @shellac had his wheel only for 3 weeks, he most likely had the new version of the side panels already, which are manufactured without the ribs as described.

I'm sure we'll know soon since he'll have to open the wheel to swap the pack.

Edited June 14, 2021 by supercurio

[shellac]

43 minutes ago, supercurio said:

Since @shellac had his wheel only for 3 weeks, he most likely had the new version of the side panels already, which are manufactured without the ribs as described.

I'm sure we'll know soon since he'll have to open the wheel to swap the pack.

I already opened it. I posted pics in my original post, they are the links at the bottom. They are the newer side panels with the ribs already removed. 

[supercurio]

1 minute ago, shellac said:

I already opened it. I posted pics in my original post, they are the links at the bottom. They are the newer side panels with the ribs already removed. 

Oops!   that's why I got so confident that the removal of the ribs wasn't sufficiently addressing the BMS failure to begin with.
Thanks for the reminder.

[shellac]

If you look at the pic of the batteries inside the Sherman, you can see an imprint on top of them from the side panels. I wonder if that is normal? Are the batteries under too much pressure from the side panels? (pic attached)

Maybe mine is just a fluke since I haven’t heard anyone else with a newer batch Sherman having this problem.  

[supercurio]

15 minutes ago, shellac said:

If you look at the pic of the batteries inside the Sherman, you can see an imprint on top of them from the side panels. I wonder if that is normal? Are the batteries under too much pressure from the side panels? (pic attached)

It is normal in a sense that all Sherman will show the same imprint into the foam placed between the panel and the battery pack.

Now:

• is this layer of foam sufficient to make the ribs harmless to the board underneath?
• are the ribs sufficient to prevent the cover from deforming and transfer forces into the BMS boards?

Most likely, the answer is no to one or both questions, leading to the failure you experienced.

15 minutes ago, shellac said:

Maybe mine is just a fluke since I haven’t heard anyone else with a newer batch Sherman having this problem. 

There isn't many Sherman with the modified side panels out here yet, and there won't be that many for a while since production stopped due to the battery cell shortage.

I was hoping for 0 and the problem being fully addressed, unfortunately it is not the case.
The way you described your wheel usage is absolutely normal.

Good that your dealer is covering that quickly! It would be best to know how to prevent it to happen in the future tho.

[shellac]

14 hours ago, supercurio said:

It is normal in a sense that all Sherman will show the same imprint into the foam placed between the panel and the battery pack.

So I don’t think there is foam between the battery pack and the side panel. Certainly mine doesn’t have it, and looking at a Marty Backe sherman video doesn’t looks like his does either. You can see the same grid pattern on his battery. 

Anyways hopefully mine was just a fluke and nothing recurs after the new battery. 

[null]

It’s the thin layer of black foam with part of the sticker film left in, there wasn’t ever any other foam in there. Never liked those imprints myself, I’m spite of no problems till now. I hope like you it was a singular fluke and the new will be fine. Probably will, we’ve had Sherman’s around for a year now, other than the specific place to remove ribs there haven’t been any widespread issues.

[Planemo]

On 6/14/2021 at 1:24 PM, shellac said:

If you look at the pic of the batteries inside the Sherman, you can see an imprint on top of them from the side panels. I wonder if that is normal? Are the batteries under too much pressure from the side panels? (pic attached)

Maybe mine is just a fluke since I haven’t heard anyone else with a newer batch Sherman having this problem.  

Ok, so the ribs removed are in the area of 2 largish chips. The weird thing is, the 2 chips are also present on the sister pack. So why are they only removing the ribs on one pack  not two...?

[shellac]

11 minutes ago, Planemo said:

Ok, so the ribs removed are in the area of 2 largish chips. The weird thing is, the 2 chips are also present on the sister pack. So why are they only removing the ribs on one pack  not two...?

Good question. On the sister pack is the board located closer to the center or more towards the front of the pack? If it’s towards the front then I guess they figure there is less force on that area, as it’s closer to the very front of the EUC where there’s a lot of side support, so less likely to compress. 

[Planemo]

Yeah you could be right there, hadn't thought of that. On the pic above of the BMS's, taking them as fitted to the left side, the chips on the left pack would be quite close to the front on the wheel. If fitted to the right hand side, they would be close to the back of the wheel. As you say, theres probably less 'give' in the panel near the edges. Still, I think I would be happier taking out ALL ribs which are near these chips. Come to think of it, the bleeding resistors etc aren't much closer to the board either really. Part of me is inclined to remove all the ribs where there are components beneath. After all, MSX panels never had these ribs at all. I agree the Sherman ribs will add strength to the panel but at what cost? Localised pressure onto BMS components

 

[Planemo]

Ok so today I pulled both side panels and took out more ribs where the BMS components are, according to the pics above and the existing Veteran mod. I extended the already 'missing' ribs further down so that theres also clearance for the resistors lower on the board, and also removed material from the other side so that the sister pack also has clearance. Surprisingly, the stock panel doesnt show any allowance for the sister pack. Admittedly, some of the sister pack area cannot be reduced further because its moulded to take into account the pedal recess, but there was certainly some ribbing which sat proud and it showed on the battery pack sponge. So I removed it. For sure, if I get a 'bt loy' error now, it certainly aint cos of the side panels hitting any components.

The panels are strong, the removal of this material made no noticeable difference whatsoever to the integrity of the panel. Whilst I was in there I also cable tied some support for the loose motor wires, and added some sponge discs to the motor cable entry point through the shell, which was a bit of a rough edge. We'll see how it goes...

Edit: sorry, the panel area in question which I modded for the sister pack isnt moulded to take into account the pedal recess, the moulding recess appears to be nothing other than for styling purposes. I hope all areas I modded can be seen ok in the pic below, it makes more sense if you can lol

Further edit: I have also realised that you probably can't see the ribs I removed from the corner of the wheel where the sister pack would be (shown right most corner below). the section of ribs in question are actually higher than the nearby flat section, so I also took these ribs down to the same level or below. To summarise, I am left with two vertical strips that span from just above the centre of the wheel to very near the bottom, where no ribs touch the packs at all. These 'strips', to the best of my measurements (and some guesswork), avoid the chips and resistors on both BMS's.

Edited June 22, 2021 by Planemo

[shellac]

So just an update on my own situation. I got the new battery pack from ewheels. Replaced the previous one and ran the headlight some to bring the voltage closer to the opposite pack on the right. 

Both are now fully charged to 100.4V and the wheel rides fine as it before. The hardest part about the battery change was opening the top compartment. It was a real bitch because of the sealant inside and my own fear of breaking the thing. After a lot of cursing got it open and it was fine from there. 

Hopefully ewheels will do some diagnostics to figure out what happened with the battery pack. 

One thing I should mention is I did have the charger hooked up to a smart outlet on the wall which stops charging after 4 hours. Since I’m well aware of the need for battery balancing I only used it like once though, for fear of something like this happening. I can’t imagine that would be enough to throw the packs out of balance and I still think there was something wrong with the battery. 

[.....]

It wasnt your fault. If stopping a charger once before a wheel is full, would ruin packs... well, I wouldnt be owning any eucs.

[Boogieman]

On 6/11/2021 at 2:47 PM, supercurio said:

.ome gotway shells have ribs, although fewer and less pronounced.

 

Fewer ribs would be even worse, less surface area to divide the pressure on.

Less pronounced would be good, but of course it also depends how much pressure there is on the pack.

Just adding an extra layer (or thicker) self adhesive foam to adhere the pack (gotway amd sherman love this but forgot a few noteworthy spots where it actualy makes a difference) would increase pressurendramatically.

Edited July 6, 2021 by Boogieman

[Planemo]

Just to update this, I did another pic with it hopefully being clearer exactly where I modded the ribs. I actually ground down the ribs located on the non-flat sections to well below the flat section to give plenty of clearance.