How to pick a charger?

TheKubs

1 µW
Joined
Mar 21, 2022
Messages
1
Location
Wisconsin
Hi,
New member, first post, kind of nervous.

Years ago I converted a gas motorcycle to electric running on 5 Gel deep cycle batteries, 50Ah rating. Worked well but I'm finding the batteries only last me about 2 years, I'm on my third set, and my range isn't real good. So I'm planning an upgrade to something more high tech.

What I'm looking at is the LiFePO4, 32650 cells at 6Ah. I'm looking to double the Ah, which I hope will double my range. I figure 18p will get me 108Ah and 20s to get 64v to match the 60v I have been using. Would like to go to the 72v that my components will handle but not sure I have the space.

At any rate, I'm trying to figure out what kind of battery charger I will need. Voltage is pretty obvious but I'm unsure of the current I will need. The batteries are rated at 6A continuous charge max so I'm thinking 5A/cell to be kind to the cells.

So here's my question, if it is true that I can draw 324A from this pack. Figuring they are rated at a max continuous discharge of 18A times 18 cells in parallel. Does it also stand to reason that I should look for a 90A charger, figuring 5A * 18 cells? Guess I'm looking for confirmation that the current is additive in both directions in a parallel circuit. My gut tells me it is but it's been 40 some years since I've given ohm's law much thought.

Also, where would I source such charger? Ideally I want to mount it on the bike and even charge it from my L2 charger I have for my Nissan Leaf. That would be cool but not necessary.

Or, if I've made some obvious noob mistake in my design or calculations please let me know, I'm here to learn.

Thanks in advance!
 
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