Dewalt 36 volt battery - how to charge up only one cell?

[steppedup]

Sorry for this newbiie post!!!

Anyone know of any screenshots that show how to test and charge only one cell? The reason I ask is because one of the batteries no longer charges and I get all 3 red lights blinking rapidly. Per this link http://visforvoltage.org/forum/bicycles-and-pedelecs/1654, that indicates probable bad cell.

I assume get it disassembled like this: http://www.rcgroups.com/forums/showthread.php?t=587606

But, then how to charge up only cell?

Thanks a million either way,

stepped up....

 

[Ypedal]

Good Day . Welcome to the forum !


You could use one of these

https://s.p10.hostingprod.com/@www.voltphreaks.com/ssl/catalog/product_info.php?cPath=3&products_id=28

I use 16 of them ! lol.. ( 48v pack = 16 cells )

However, if you open up the pack and that one cell is below 2v.. like .. 0v.. charging it won't help.

 

[EMF]

Sorry for this newbiie post!!!

Anyone know of any screenshots that show how to test and charge only one cell? The reason I ask is because one of the batteries no longer charges and I get all 3 red lights blinking rapidly. Per this link http://visforvoltage.org/forum/bicycles-and-pedelecs/1654, that indicates probable bad cell.

I assume get it disassembled like this: http://www.rcgroups.com/forums/showthread.php?t=587606

But, then how to charge up only cell?

Thanks a million either way,

stepped up....

One thing you can try is to keep plugging the battery into the charger, like about 40 times. Sometimes it will finally take and charge. Leave it on the charger overnight. If this does not work, Find your local service center for Dewalt and send it back for a new one. http://www.dewalt.com/us/service/center_finder.asp

You'll only have to pay the UPS freight one way and you will get a brand new battery in a blister pack. If you open the case, you own that puppy. The service center was 60 miles from my house - I got a new battery in 48 hours. E.g. I sent it in on Monday and I had one on my porch Wednesday! They get tons of these back and don't ask any questions. I just put a note in the box explaining it wont charge.

I got 2 batteries replaced before I stopped having problems. Also, be darn careful how far you run down the pack, this IMHO is what causes the problem. because I don't think folks leave the batteries on the charger long enough for them to balance. Also, *word on the street* is the Dewalt charger does not do a good job of balancing anyway. Couple that with no way for each pack to shut down when it hits a low voltage cutoff and presto- messed up battery. If I was using the Dewalts in the case- I would not let the pack(s) go below 30 volts. If you have a Cycle Analyst for low voltage cutoff or some way to monitor voltage and it starts cutting out at that voltage- start pedalling and shut the pack(s) off. If you don't have a CA you should be very careful and also very conservative on your range estimates. When the voltage starts to drop on A123 cells - it goes very, very fast.

 

[Jonathan]

You can charge up your single cell with the use of a regulated power supply (eg. Mastech) or just simply put couple 3x NiMh together if it's a one time use.

The Dewalt BMS indead leaves alot to be desired. After wasting hours of trying to make my rig compatible with the Dewalt 36V charger, I decided that it's not worth it for ebikes.

 

[steppedup]

Great tips all - much appreciated!

I ended up snagging a single cell charger and very carefully pulling the batteries out without desoldering it. Just unplugged the two connectors that hold it onto the body of the battery.

If you look at each cell, you'll see a plus and minus at each end. Put the red on the plus, and the black on the minus.

Used electrical tape to tape the charger prongs to it....it took an hour to charge up (about)....

Got all of them charged up...stuck on the Dewalt charger - bingo!

(Regarding the 30 volt limit - I'm in the process of getting the CA installed, so will definitely do that!)