Battery Discharging while off

[privateer703]

So I had a code 36 error pop-up on me about two weeks ago, I got all the cables but I haven't had time to hook it and get screenshots yet. I noticed after charging it up to about 75% then riding it down to about 60%, I put it away. A few days later I checked it and the battery was down to around 35%. I thought maybe I was wrong and had actually ridden it down that far, but mis-remembered. I did the same thing the other day, this time after riding it down to 25%, I made sure that I charged it exactly to the halfway bar. I just checked and it's down to 35% again. They key was not in it at all during those times. Has this happened to anyone, or is this typical of a code 36 error? This all started happening after a code 37 showed up after the winter, if that has anything to do with it.

 

[snydes]

This isn’t typical of a code 36, definitely need to get a view of the battery in MT ASAP. Definitely keep checking the SOC as often as possible until we have a better idea what’s going on.

 

[privateer703]

poop. Just noticed I've added a code 35. 35, 36, 37, it's looking like a nice poker hand. And this battery was replaced under warranty for a code 36.

 

[privateer703]

So pretty obvious I have a bad p-group. So now, what's the deal with the discharging issue?

 

[privateer703]

Sounds good.

 

[snydes]

Ahh, it’s at 100%…I’d say note the voltage, and take a look at it tomorrow and see if it’s dropping.

I believe @Mark911 recently had worked on a similar one recently where a hvpcba component failed and killed a few p-groups. Not sure if that’s what’s happening here, but I’m comfortable saying this is likely not a wirebond failure. I’d say it probably has to come apart unfortunately.

 

[privateer703]

Here's the battery at 75%. So it looks like it's charging slightly, should I continue charging to 100% and let it balance?

 

[Mark911]

At 4.1 volts I'd say that pack should be reading more like 90-95%, not 75%. That's strange. The one low P-group looks like a wire bond issue and probably won't balance no matter how long it's on the charger. The worse thing that can happen is that during charging any P group goes above 4.2 volts and/or during discharge/storage any P group goes below 2.5v. I'd keep on eye on both.

 

[privateer703]

That's really weird, the display shows something closer to 65%. Maybe the drop in battery charge I'm noticing has more to do with how the bike is reading voltage than cells actually losing charge. I'll be monitoring over the next few days to see what happens.

 

[Mark911]

Agree, somewhere between the cells and the display actual cell voltage is being misinterpreted/and or not displayed properly. I'd try loading another (older) version of the Display, BRDs and BCU firmware first. You can always go back if there's no change.

 

[snydes]

Just for the sake of discussion let me add some points to consider. When a wire bond lifts, there is a point in the SOC where the pack will still be relatively balanced based on where it was when the bond failed. For example if the bond fails at 50% the pack will look balanced at 50% and the p group voltage will extend higher as the bike charges or drop lower as it discharges. A break at 100% would look balanced at 100% and drop out of balance as soon as the pack starts discharging, etc. There is no wire bond failure scenario that I can think of that would result in a p group voltage being that low when the rest of the pack is at a fully charged voltage, at least not on a fairly recent failure which from the sounds of it this seems to be.

Since this is the bottom module, and there is also a code 37 triggered, I’d want to pop the bottom cover off and be sure this isn’t a moisture/corrosion issue and proceed from there.

 

[privateer703]

I'm guessing I can remove the lower cover without taking the battery completely out?

 

[snydes]

You can. I think @Bloak has done it like that before. The biggest PITA is dealing with the butyl cover seal. It’s a mess. You can get a suitable roll of replacement butyl to reseal it from Amazon. There is a thread on it here somewhere. If you can’t find it let me know.

 

[Rashid510]

I'm guessing I can remove the lower cover without taking the battery completely out?

You can...but that will be a nightmare for removal/install if the module needs to be removed. Taking the pack out the first time is a pain...but its much safer to deal with.

 

[snydes]

You can...but that will be a nightmare for removal/install if the module needs to be removed. Taking the pack out the first time is a pain...but its much safer to deal with.

Agreed. It’s only 3 more bolts, two connectors and you can drop the pack out and flip it upside down to work on it properly.

 

[Bloak]

I've changed silica packets without complete battery removal. In or out, that butyl is a pain to clean off.