WW 52V Battery Issue

[Cuz Vinny]

I’m first going to preface this post by saying this is not a complaint post but merely a request for advice on how to fix an issue with my batteries without having to get Watt Wagons involved. If your only comment is to blame WW please keep it to yourself and out of my post.

I generally tend to not ride in the cold months and have several different e-bikes in my collection. This can result in bikes not being ridden for several months. Out of the two WW 52V batteries I have, one has dropped below the BMS safety limit and will not take a charge. The other I was able to get to take a charge and charged it up to 60%. I’ll give it a full charge later today or tomorrow. Last year I had the same problem where the batteries had drained below the safety cutoff point of the BMS and wouldn’t take a charge. This resulted in both batteries, I have two bikes, being sent back to WW who was able to correct the issue and returned the batteries to me. Upon receiving the batteries I put them back in the bikes and test road them and everything seemed fine. Both batteries were stored out of the bikes and were kept inside my house.

Im using a Grin charger and even using the force charge feature it has the one battery seems to be DOA. The Grin charger display show “Connect Battery”. I’ve used this charger many times on the bikes so I know it works.

Is there any way I can get this one battery to take a charge without having to send it back to WW and what do you guys do to prevent battery drain if the bike sits for an extended period of time? It almost seems like during the cold months I’ll have to keep these two batteries on a trickle charger or something. None of my other bikes have this problem and this time the batteries were not in the bikes so I’m not sure why they drain so quickly.

Any advice will be greatly appreciated.

 

[TPEHAK]

It is the user responsibility to keep the battery charged above the lower limit and monitored during storage. It has to be charged maybe 50-70% for long storage and if it is below 50% it has to be charged as soon as possible above 50%. It means if you are not planning to use it for more than a day and it is below 50% you have to charge it above 50%.

I do not see the information about how long you stored it at which charge level but if you stored it for a week below 10% charge level I do not see how the battery seller can be responsible here for this issue.

You will likely not be able to recover the battery without hacking the BMS or without disassembling the battery and charging the cells using different methodsods. It can be quite dangerous if you do not know exactly what you are doing. The cells can also be damaged after dropping the charge below the lowest limit and can be dangerous after such event or lost capacity.

 

[Cuz Vinny]

It is the user responsibility to keep the battery charged above the lower limit and monitored during storage. It has to be charged maybe 50-70% for long storage and if it is below 50% it has to be charged as soon as possible above 50%. It means if you are not planning to use it for more than a day and it is below 50% you have to charge it above 50%.

I do not see the information about how long you stored it at which charge level but if you stored it for a week below 10% charge level I do not see how the battery seller can be responsible here for this issue.

You will likely not be able to recover the battery without hacking the BMS or without disassembling the battery and charging the cells using different methodsods. It can be quite dangerous if you do not know exactly what you are doing. The cells can also be damaged after dropping the charge below the lowest limit and can be dangerous after such event or lost capacity.

Both batteries were above 60% charge and stored inside my house. For the record I’m not passing blame on anyone, just trying to get the battery to work.

 

[TDA78]

I've only lost 0.3V from my WW 52V battery over the last month. The same for my custom 52V, 20Ah battery with the same BMS. I charge to 80% (55V) for storage because I'm lazy and that's the minimum setting for my charger. My packs would take years to self-discharge to the hardware undervoltage protection of 2.5V/cell. I wonder if there is something wrong with your BMS? I've read about balance transistors getting stuck on and killing cell groups.

The dead battery has to come apart and have each cell group measured. If they're all equal and not dangerously low, the pack can be charged with a current and voltage limited, benchtop power supply connected to the battery side of the BMS.

 

[Cuz Vinny]

I've only lost 0.3V from my WW 52V battery over the last month. The same for my custom 52V, 20Ah battery with the same BMS. I charge to 80% (55V) for storage because I'm lazy and that's the minimum setting for my charger. My packs would take 5 years to self-discharge to the hardware undervoltage protection of 2.5V/cell. I wonder if there is something wrong with your BMS? I've read about balance transistors getting stuck on and killing cell groups.

The dead battery has to come apart and have each cell group measured. If they're all equal and not dangerously low, the pack can be charged with a current limited, benchtop power supply connected to the battery side of the BMS.

This is the second time this has happened. I’m wondering if the battery is even salvageable at this point.

 

[Cuz Vinny]

Ok, WW responded. My choices are have the one battery rebuilt which I’m not too keen on or purchase a replacement. I’m currently waiting on pricing information.

The other battery I was able to charge to 88% percent today. I’m going to charge it to 100% and then check it 24 hrs later to see how much it loses over one day while being out of the bike.

 

[Cuz Vinny]

Getting a new replacement battery at a discount. This is resolved.

 

[greeno]

That’s odd your battery’s loosing their charge as you describe.
What state is the charge in when you let it sit?
I have been making battery packs for about three years or so and haven’t run into any issue like you describe.
My wife rides her bike 2-3 times a YEAR and it can sit with a 50% charge for six months in my garage (San Diego) and no problems.
Sounds like the packs you have a minute current draw going on either through the bms or on/off switch or some sort of …
If you have a decent charge when you let it sit and it drains down to below charging level.
All that WW is doing is flashing your bms to wake it up to take a charge.
Kinda odd your having the same issue, gotta be a common denominator yeah?

 

[Cuz Vinny]

That’s odd your battery’s loosing their charge as you describe.
What state is the charge in when you let it sit?
I have been making battery packs for about three years or so and haven’t run into any issue like you describe.
My wife rides her bike 2-3 times a YEAR and it can sit with a 50% charge for six months in my garage (San Diego) and no problems.
Sounds like the packs you have a minute current draw going on either through the bms or on/off switch or some sort of …
If you have a decent charge when you let it sit and it drains down to below charging level.
All that WW is doing is flashing your bms to wake it up to take a charge.
Kinda odd your having the same issue, gotta be a common denominator yeah?

This is the second time this has happened with both batteries. First time the batteries were stored in the bikes. I sent them back to WW and they got the batteries to take a charge. I then tested them in each bike and left one battery at 60% and the other was at 75%. The battery with the higher percent charge I was able to charge to 88%. I’m checking that battery in a few days to see what it’s lost if anything. The other battery is completely dead.

I initially thought that storing them in the bikes created some draw which is why they drained. I accepted fault as I never checked the bikes or the state of the batteries. This time they were out of the bikes and inside my house. WW is willing to work with me on the price of a replacement battery which is an acceptable solution for me. I’ll keep a close eye on the replacement and current battery and if they drain quickly again I’ll just be selling the bikes and moving on.

 

[JRA]

So you have two suspect batteries from a supplier and getting a third? Perhaps their battery supplier is not providing them with a premium product? I would seek another battery manufacturer and if you are paying any more than $400 for one you are paying too much.

 

[greeno]

There shouldn’t be any reason you can’t store your battery on the bike.
Your display should 100% disconnect any load from your battery.
Now if you live in an extremely cold area storing outdoors could be an issue.
Not sure what kind of battery’s your pack has. I would open it up and check it out.
18650?
21700?
48v or 52v?
BMS manufacturer?
I have been using my WW Innotrace X1 motor/ for a couple years and have had zero issues so my guess is it’s something in the pack itself drawing it down.

Sounds like you’re a hands on guy. Get a meter and check the voltage on the battery at the main bike connect terminals and then check the voltage at your charging port.
If they have different values your BMS needs to be reset.

Open up the dead battery and find the BMS then unplug the sensor harness for 10 seconds then plug back in and your bike/ charging terminals will probably be the same value.
Then it should take a charge.

Gotta be the BMS.

 

[Cuz Vinny]

Update. After charging the one ”good” battery to 88% and letting it sit for five days I checked it and it was at 82%. So a 6% loss over five days. Battery was inside the house and not stored in the bike. This time I charged the battery to 91% although the display read 99% while plugged in. I’ll let it sit again outside the bike and check it in a few days to see what percent charge is lost.

 

[m@Robertson]

Has WW weighed in on whether the pack should lose charge over time? I don't need to tell you that loss seems like a lot.

One thing I note from my own garage where I connect to a power supply. If I leave the battery plugged in even though the power supply is shut down (power cut from the wall) I get a similar drain. I have to unplug the battery so it sits on the bike, shut down from there.

 

[Cuz Vinny]

Has WW weighed in on whether the pack should lose charge over time? I don't need to tell you that loss seems like a lot.

One thing I note from my own garage where I connect to a power supply. If I leave the battery plugged in even though the power supply is shut down (power cut from the wall) I get a similar drain. I have to unplug the battery so it sits on the bike, shut down from there.

I charge the battery in the bike and use the display to monitor charge percentage. With the charger plugged into the outlet and the bike the display reads 99%. Unplug the charger from the bike and it drops to 91%. Not so much worried about that vs the 6% loss over five days sitting inside a heated house and not in the cold garage in the bike.

This is the second time this has happened with both batteries. First time I admitted it was my fault for not keeping an eye on the batteries and maintaining charge levels. However now I‘m convinced there was an issue with the batteries from day one.

 

[TDA78]

I've lost another 0.1V off both my packs since my last last post 8 days ago. That's only about 1% according to a chart I found online.

 

[greeno]

Just a tip on monitoring your battery charge.
Those % readings are usually bogus as you can have the same battery but a different display and get different values.
Switch your display to Voltage to better monitor your capacity.

Did you ever check the voltage at the charging port compared to the bike main port?

 

[Cuz Vinny]

Just a tip on monitoring your battery charge.
Those % readings are usually bogus as you can have the same battery but a different display and get different values.
Switch your display to Voltage to better monitor your capacity.

Did you ever check the voltage at the charging port compared to the bike main port?

No I haven’t bothered. There is something obviously wrong with the packs. I’m going to look into having them rebuilt vs buying new ones as I don’t trust the new ones won’t have the same issue.

 

[Fast n' Furious]

You have (at least) one bad (lower voltage) cell. BMS trying to balance keeps draining until it reaches low voltage fail-safe and that cell is unable to charge. Well documented condition. Not unusual. (at least) One cell is most always off a bit. BMS doing is it's job.
You can jump the charger input and bypass, bringing the cell alive. Again, well documented, not my opine.

Tp verify this condition: remove battery for several days, reinstall and see if voltage has gone down.
I've torn a few dead laptop batteries down and one cell was bad, the rest had tons of life left.
My (52v) solution is don't go below 46 - 47v.
For 48v it's 43v.

 

[Cuz Vinny]

You have (at least) one bad (lower voltage) cell. BMS trying to balance keeps draining until it reaches low voltage fail-safe and that cell is unable to charge. Well documented condition. Not unusual. (at least) One cell is most always off a bit. BMS doing is it's job.
You can jump the charger input and bypass, bringing the cell alive. Again, well documented, not my opine.

Tp verify this condition: remove battery for several days, reinstall and see if voltage has gone down.
I've torn a few dead laptop batteries down and one cell was bad, the rest had tons of life left.
My (52v) solution is don't go below 46 - 47v.
For 48v it's 43v.

I’m not messing with the batteries. I‘ve contacted WW about purchasing new batteries and was supposed to be notified when they got a new batch of 52v batteries in stock. Never got notified. Called the other day and left a message about replacement batteries. Waiting to see if I get a call back.

 

[Fast n' Furious]

Not sure if WW is using the same company here in CA, but when my first battery was damaged in shipping the 'new' battery they sent had blue painters tape over a crack in the case and scratch evidence showed it was used.
Six months later I was curious, so I checked the first battery. At first it seemed dead, display would not come on. I checked w/ a meter and it was live. Close inspection showed one of the plastic, bottom end nubs was damaged. I sanded it a bit, reinstalled and it worked.
It was 52v - near 60% charge.
The odds against two battery's in a row having a bad cell are up there with two damaged in shipping.
What are the odds of two batteries in a row with a bad BMS or having a voltage leak ???
Could this be your charger? Overvoltage damaging a cell? I'd think by now you'd know if that was it.
TPEHAK or evixone would be sources of reliable information, but I assume you resolved the matter.