Battery cutting out.

[Ros]

I have a 13A 36v Silverfish battery that I bought from Enerpower.de about 30 months ago.
The battery has been good, but has recently started cutting out, with the bike losing all power.

Sometimes it is possible to turn the power back on after a few minutes, but yesterday (in very high temperatures) the fault returned quickly and stayed 'hard'. As I was close to home, I phoned my husband and asked him to bring me my spare battery and then I continued on my journey and he took the first battery home.

When the fault was there yesterday, the indicator lights on the top of the battery would switch on for a second and then immediately switch off. (Same with the display if I tried to switch the power back on.)

When I got home later, the lights on the top of the battery would flash on and off. I put a meter on the connections at the bottom of the battery and the volts were pulsing on and off. (Up to c 40v, but it was hard to see exactly as the needle was never still!)

The battery has been in the house overnight (I haven't charged it) and the lights on the top stay on when the button is pressed, so although I haven't tried it on the bike, it seems reasonable to assume that it would now switch on normally.

I'm nervous about trying to take the battery apart - is this safe to do? I'm suspecting that there may be a problem with the BMS.
Is there somewhere reasonably close to me (Mid Sussex) that I could take the battery to?

 

[Andy-Mat]

I have a 13A 36v Silverfish battery that I bought from Enerpower.de about 30 months ago.
The battery has been good, but has recently started cutting out, with the bike losing all power.

Sometimes it is possible to turn the power back on after a few minutes, but yesterday (in very high temperatures) the fault returned quickly and stayed 'hard'. As I was close to home, I phoned my husband and asked him to bring me my spare battery and then I continued on my journey and he took the first battery home.

When the fault was there yesterday, the indicator lights on the top of the battery would switch on for a second and then immediately switch off. (Same with the display if I tried to switch the power back on.)

When I got home later, the lights on the top of the battery would flash on and off. I put a meter on the connections at the bottom of the battery and the volts were pulsing on and off. (Up to c 40v, but it was hard to see exactly as the needle was never still!)

The battery has been in the house overnight (I haven't charged it) and the lights on the top stay on when the button is pressed, so although I haven't tried it on the bike, it seems reasonable to assume that it would now switch on normally.

I'm nervous about trying to take the battery apart - is this safe to do? I'm suspecting that there may be a problem with the BMS.
Is there somewhere reasonably close to me (Mid Sussex) that I could take the battery to?

It is not something I would recommend to anyone, unless they were far better trained than the average electrician......it can get dangerous!
Here is someone doing something wrong with two batteries on the same bike:-

Regards
Andy

 

[vfr400]

I have a 13A 36v Silverfish battery that I bought from Enerpower.de about 30 months ago.
The battery has been good, but has recently started cutting out, with the bike losing all power.

Sometimes it is possible to turn the power back on after a few minutes, but yesterday (in very high temperatures) the fault returned quickly and stayed 'hard'. As I was close to home, I phoned my husband and asked him to bring me my spare battery and then I continued on my journey and he took the first battery home.

When the fault was there yesterday, the indicator lights on the top of the battery would switch on for a second and then immediately switch off. (Same with the display if I tried to switch the power back on.)

When I got home later, the lights on the top of the battery would flash on and off. I put a meter on the connections at the bottom of the battery and the volts were pulsing on and off. (Up to c 40v, but it was hard to see exactly as the needle was never still!)

The battery has been in the house overnight (I haven't charged it) and the lights on the top stay on when the button is pressed, so although I haven't tried it on the bike, it seems reasonable to assume that it would now switch on normally.

I'm nervous about trying to take the battery apart - is this safe to do? I'm suspecting that there may be a problem with the BMS.
Is there somewhere reasonably close to me (Mid Sussex) that I could take the battery to?

You can't do much harm by opening the battery and measuring it with a meter. Only measuring will tell you what's wrong. if you open it and take some photos, we can give a step by step guide on how to measure it.

 

[Nealh]

The issue might be a heat issue and some battery BMS do have a temp sensor, if the heat was to much it is possible that thermal cut out occurred.

We often refer cutting out as due to low battery voltage or voltage sag, it might be a clue if we new under what circumstances the battery cut out Ros, may be high assist was being used or a hill was encountered or simply a fairly depleted battery (voltage wise). Or simply the battery might be out of balance.

Certainly to test for a balance issue some minor surgery will be required to get it in to the battery to take readings via a meter.

 

[wheeliepete]

The switches on the back of the lock can give trouble on this style of battery.

 

[Ros]

The issue might be a heat issue and some battery BMS do have a temp sensor, if the heat was to much it is possible that thermal cut out occurred.

We often refer cutting out as due to low battery voltage or voltage sag, it might be a clue if we new under what circumstances the battery cut out Ros, may be high assist was being used or a hill was encountered or simply a fairly depleted battery (voltage wise). Or simply the battery might be out of balance.

Certainly to test for a balance issue some minor surgery will be required to get it in to the battery to take readings via a meter.

If this battery has the Enerpower BMS, then I believe it has a temperature sensor.

The circumstances have varied. The first time it happened we were riding to a nearby town to pick up an order for some car parts, we had probably covered about 5 miles (battery fully charged) and I was cruising on flat ground. After it cut out we agreed that my husband would carry on for the last couple of miles and I would start cycling home alone. After about a mile, I decided to try to power on and it worked. It cut out once more on flat ground, but restarted immediately and got me home, including a steep hill.

I then did quite a few trips, both long and short, with my old battery - all without incident.

I put the newer battery back in and did quite a few short round trips (mainly to the local pub, which involves a steep hill ) of about 2-3 miles, all in the evening. All seemed well.

Then yesterday, I dropped the car off for service in the morning and rode the bike home. It sat on the driveway for a few hours, then I started to ride it back to the garage - I had just freewheeled down a long hill (about a mile from home) and was about to start pedalling again to start the motor when I realised it had cut out. It restarted immediately, but cut out again a few hundred yards later. This time it wouldn't restart and pressing the button on the top of the battery resulted in a brief flash of light. My speedo registered just under 9 miles from my last charge, so there was plenty of juice left. The rest of the detail is in my first post.

The main common denominator that I can see is that both days it cut out it was on very hot days. The battery was between two thirds and a half full and wasn't under any particular load when it cut.

 

[Ros]

The switches on the back of the lock can give trouble on this style of battery.

Thanks for that. I've pulled out the ignition and lock, waggled everything around and can't get the fault to occur again, so it's probably not that.

 

[Nealh]

Nothing out of the blue to suggest any one thing is the cause, except maybe as alluded to both times the weather was very warm. A check for cell balance might show up something or a poor interconnection on a cell group could be a cause but until the pack is removed one won't know.
If the battery discharges and charges normally then one can rule out the BMS, though the temp sensor could be sensitive and at fault. Simply replacing the temp sensor might solve the answer.

 

[Ros]

Thanks to Nealh, who kindly took my battery apart and checked it. He didn't find anything untoward, apart from 2 cell groups slightly out of balance. He rebalanced them manually and also ascertained that the BMS does indeed have a temperature sensor.
Since having the battery back, I've done a couple of short trips and a longer trip of about 9 miles yesterday - all without incident.
Unfortunately the warm weather seems to have deserted us, so it may be that the battery will cut out again if it gets hot - in which case it probably means a change of BMS.
In the meantime, I shall be making all longer journeys with my old battery strapped on the back!