Is my battery dead?

First of all, I want to describe a problem with my battery that happened around 10 months ago during late fall. I left my ebike with the battery attached in the basement overnight. Basement temperature was probably around 5C. The battery stopped working while I was riding it to work the next day. I had to human pedal it the rest of the way to work. When I got off work, I tried the electric system again and it started working. The problem had fixed itself.

Yesterday, I ebiked to work, without problems. It started to rain pretty heavily during the day and the bike was wet when I was off work. I rode it home with no problems. When I got home, I took out the battery and brought it upstairs. I connected it to the charger and it would not charge. The battery just kept showing full charge. Today, I took the battery downstairs and I tested the electrics to see if the battery has any problems. I gave it a tap on the throttle and it worked. Then I gave it another tap and it did not work. I checked the battery level and there were no lights. I took the battery upstairs and then I got lights on the battery level, but it was at the lowest level. I plugged the charger in and it would not charge. I checked the voltage of the charger and it was 43V. I checked the voltage of the battery and it was 3V.

Is my battery dead? It's been less than 1 year of use. I bought it here:
http://www.greenbikekit.com/headway-36v-38120-rack-battery.html

you need to post up pictures of the battery and the BMS so we can help

So I need to open it up I guess? You mean you need pictures of the battery cells? The link above shows the battery as a "package"

Best first guess wihtout any other info or measurements is a connection problem, but that could be anywhere inside the battery (or possibly charger, or both). A poor solder joint or crimp could have high resistance when cold, or damp, and either prevent connection to the bike and/or charger if it's on a main power wire (at either end, internal or external), or cause the BMS to react inappropriately if there's a cell-monitoring (sense) wire connection problem.

amberwolf said:

Best first guess wihtout any other info or measurements is a connection problem, but that could be anywhere inside the battery (or possibly charger, or both). A poor solder joint or crimp could have high resistance when cold, or damp, and either prevent connection to the bike and/or charger if it's on a main power wire (at either end, internal or external), or cause the BMS to react inappropriately if there's a cell-monitoring (sense) wire connection problem.

Click to expand...

I see. Thanks for the info. Should I go ahead and open it up? I've never worked with batteries before (except replacing 1.5V batteries )

I'd start by looking very hard at the plugs. Both to the bike and to the charger. look at both sides for poor connection. Both the battery charge plug, and the charge plug on the charger. Same for other plugs.

Other poor connections on the bike itself can cause more symptoms, this might be multiple bad connections, some on the battery, some on the bike. and make sure you have voltage coming out of the charger as well.

In other words, check every plug you have before ripping open the battery.

yep, no need to take it apart but if we cannot see it then how can we offer any observation. no way to know who made it or what kinda battery it is or if it has obvious problems. if you don't want to do anything then that is ok too. lotsa people will offer all kinds of advice even with no info.

I think you have two problems. The battery might be one, but wet plugs on the bike might be the other.

Hi guys,

I haven't done anything to the battery yet since my screwdriver is too thick to fit into the hole where the screws are located. However, since it is a sunny day today, the balcony doors are opened and the battery has been in the sun since this morning. I checked the power level again and it is back to 2/3 lights on, which makes sense. I plugged the charger in and it started charging again! I will try it on the bike soon and let you know how it is.

Can anyone make sense out of this?

Horace

Just took the ebike out for a spin, went approximately 15 km. Seems to work fine. Everything working as it should. I have no idea what happened.