I just got home from my commute . The battery gage shows half empty. However, when I go to charge the battery it goes from yellow to green in only 5 seconds. When I check the battery gage it shows half empty. For some reason the battery charger thinks the battery is charged even though it is half empty.

Do you have a multimeter?

I do. I tried to charge it with the battery connected to the bike with the controller on. It for some reason worked.

How long have you used the battery pack? Was it new when you bought it? Also, is it a lifepo4 pack? I've heard of something with lithium where if you go for several months without fully depleting the pack, the battery gauge gets messed up and thinks it's full when it's not or something to that effect.

It probably charges with the controller on because the controller is sapping out energy and the charger is replacing it.

The battery is around 3 month old. I charge it everyday. The only mistake I made the other day was I disconnected the battery at the end of the charge without turning off the power switch.

You might need to ask your question here in battery technology forum:
https://endless-sphere.com/forums/

Jerry:

You should try to determine if you have problem with the battery or the charger. Let's start with battery, after you fully charged the battery, take a volt-meter and measure the voltage of your battery. In the charge port, there are 4 pin, put you red (positive) in pin 4, and put your black (negative) into pin 2. What voltage do you have? reference the following link:

https://www.flickr.com/photos/56497617@N00/4546190159/


If your battery is fully charge, then you should get some where between 41v - 42v.

If you are getting the voltage that are specified, then move onto the charger. Do the similar thing, plug the charger onto the wall outlet, and measure the voltage of the charger, measure pin2 and pin4, what voltage do you have?

Ken
___________________________________________________________________________________________
https://www.powerinmotion.ca/

The charger is a smart charger which first checks to see if the battery needs to be charged. Therefore, when the charger is turned on there is no voltage coming out.

I brought the bike in with the charger to my LBS. It turned out to be the charger.

Thank you for all your help!!

I've occasionally had the same problem. Just last week I charged my half dead pl350 for the weekend only to discover that when I took it out, it was still only half charged.

When I got it home, I plugged in the charger and it indeed almost immediately went green. I turned it off, waited a couple of seconds and turned it back on, It went yellow, indicating a charge state. I watched it for a minute to be sure it stayed yellow and it of course did.

Because you are using a smart charger, you might try this a couple of times as I think the charger is just a cheapo charger that is not properly sensing the battery state. It could be the electronics in the battery too but...

Now after the charge, I turn the controller on to verify that the battery is indeed charged.

Be sure you plug the charger into the battery BEFORE plugging the charger into the wall outlet,
like the instructions probably say.

It's because the charger reads the condition of the battery when you plug it into the battery.

If you have it already plugged into the wall outlet first, then the charger thinks the battery is already charged.