Advice on a lifepo4 pack

[mskwood32]

Hi,
Ready to start building my E-bike and I am at the battery purchase part of the project. Could use some help on making a decision on the battery pack. Thinking of running either a ping lifepo4 48v 20a, or two-36volt 16amp lifep04 ping in series with an Schottky Diode. Motor is a crystalyte rear 5304 26" with 36-72V 48A Start Immediate Digital Controller (IRFB4110 Mosfets) and Direct Plug-in Cycle Analyst. I've got a 5-mile short round trip commute to work with a few small hills and of course I plan on using the bike for recreational trips. I live in Maui and the bike will have to deal with the trade winds. I am not sure which battery configuration would make more sense. Any help from you guys that have run either of these two configurations would be greatly appreciated.
Mike

 

[fechter]

The 4110 controller should be good, but there have been issues with the main capacitors exploding. It will be more prone to failure at the higher voltage. You could see if the caps were already upgraded, and if not, you might consider getting that done.

Two 36v you describe will contain much more energy and will allow much higher speed.

If you can keep off the throttle, the two 36v packs will be capable of more range. At full speed, the range will be much less, but still more than you need for commuting. With two packs, you have the possible option to wire them in parallel for a slower speed, but incredible range.

I'd say the choice depends on what kind of top speed you're looking for.

 

[pwbset]

If I'm not mistaken (which I usually am so take this with a grain of salt :wink: ) that motor/controller combo will be happiest pulling more juice than those ping packs are likely to give or are the new 4ah/cell ping packs 3c+ (48a/16ah=3c)? CA current limiting would help, but I bet you'll be popping that BMS without some sort of throttle restraint... and who likes that?

Have you thought about BMS bypassed toolpacks like Milwaukee or DeWalt? The trade winds wouldn't stand a chance then!

 

[dogman dan]

I agree, the Ping packs sold last spring are much happier when used on moderate sise motors and controllers, well under 1000 watts. Ask Ping for the best info on if your setup can be run on his battery. If you bypass the bms or modify it you may be ok, at the price of less cycles if the battery gets run too hard.