Hi gang. Well I am having my tech upgrade my xm3500 this week, should be out and about with regen within a week. Been down for about 6 months but that also is our rainy season.
I have a funky old 2000 watt 48 volt hub motor metro that has bad silicon batteries in it. For about $500(same cost to get new silicon batteries) I can upgrade to Lithium (I already have 5 3.2 40ah batteries). My question is this: at 3.2 volts/battery can I put in 15 40ah batteries? Also I have a stock 20 cell 40ah charger left over from my oem xm3500. Can I use that even if I only have 15 cells to charge up? I really do not want to put any more money in this then the batteries-- then I can sell or trade it. Thanks for the help I really appreciate it and I hope you all are riding fine and are staying healthy....sure been looking at the current bike and hoping to sell a big piece of art to get one. Lets throw in the wish list one of the new BYD cars to boot, anyone hear if they have any distributors out yet? Best....Mikie
I would not use that charger, it wouldn´t stop charging until your 15 cells reaches around 4.8V/cell = damaged...
Theoretically you could stop the charger manually when the pack reaches around 60V, but that´s kind of dangerous...
You can get away with using ur 48v charger (prob cuts out around 54v) on 15 Lifepo4 batts (15x3.65=54.5)
Problem is that doesnt balance them, u would need to keep an eye on individual cell voltages from time to time.
I like parallel charging, (all off one 3.65 terminal voltage 20amp source, gets balanced perfect, but u need a different harness structure for charging, then series one for using)
The others have given good answers I just want to state it a different way.
20 cells at 3.2v nominal is 64v and if I'm remembering the numbers right LiFePO4 cells have a upper voltage without causing damage slightly above 4v. The 20 cell charger you have is for a 64v nominal pack.
Hence 15 cells have a 48v nominal voltage. Your 20 cell charger will definitely overcharge the 15 cell pack. And Lithium cells are very prone to damage on over- or under- voltage.
This is most definitely to be avoided.
- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki
Ok guys that helps, so it looks like I buy another 10 batteries for a total of 15 cells and then buy a 48 volt charger also from elite.
Now I will be putting these new batteries in places where there once were silicon ones stacked on top of each other like steps. Do I have to bind all these batteries together tightly? even 1 or 2 cells should they also have wire wrapped around them tightly/ when and why do lithium batteries want to swell? Thanks so much for your advice I really appreciate it. Best....Mikie
mikie