[lou-ace]

Ok guys here's my quandry! I'm not quite satisfied with my build, using PB's its a little slow and a little short ranged so, this wendsday I will augument my 120v pack with an additional 24 volts ( I happen to have a couple of GP 27's 12 volts in my RV) and see how they preform on the highway for a short range. ( just an experiment) If that is good I will consider adding another 4 GC 225's to my pak ( another 270lbs arrrrrg) my 1231c and FB4001 are rated to 144v, I would also need to reconfig the Zivan charger for 144 volt charging OR try to sell the PB's ( their almost new) and switch to your Lipos which I know would be great but still expensive. now If I chose the switch to Lipo's could I still use the Zivan ( top charge 165 volts) to charge the Lipo pack ? (#44 to 3.75volts top ) for a pak voltage of 140.8 yipee? is the PB algorythem not acceptale for lipo's? see my lou-ace in the garage for spacifics. ya know it's almost criminal that they can advertise a PB battery at 225 amps that really will only put out about 100 Ah at 2C oh well.

 

[MN Driver]

There is a HUGE difference between LiFePO4, which is the lithium that pretty much all of this forum is using and LiPo, which is Lithium Polymer, a completely different chemistry.

You should be able to get away with using a lead acid charger with lithium iron phosphate(LiFePO4) but I would go near a lead-acid charger with LiPo since an overcharge with lithium polymer is typically cuasing a devastating fireball, while LiFePO4 is typically tolerant to all but the most extreme overcharge, usually just venting if it gets a little too overcharged. Since you said 3.75 charged voltage, you are discussing the properties of LiFePO4, although I'd probably stop at 3.6 volts, less if you are going without a BMS and bottom balancing since the charged voltage will vary with varying cell capacities.

As far as your lead-acid pack, it's well known and constantly discussed that usually half the capacity can be pulled out of a lead-acid pack compared to its 20 hour nameplate rating. Peukert effect isn't very fun. To go along with that, the voltage sag also requires you to pull more amperage to get the same power output too.

It's possible with a higher voltage, since it requires less amps to get the same power that your battery pack will have less voltage sag, with less amperage used you have have slightly less peukert losses, and more motor efficiency since you can run a higher motor RPM.

Lead-acid is tough since it is heavy stuff, more power to move more weight but you get more power to move the extra weight. Usually the extra weight still gives you better performance and range, especially if you aren't in a stop and go situation, constant speed travel has less losses in acceleration, braking, and hill climbs.

 

[cyclops2]

DO NOT EVER USE A .....LEAD ACID CHARGER....ON A LIFEPO4 BATTERY !!!!!!!!!!!!!!!!!!!!!!

You will sure as I am typing, overcharge the cells & cause the rubber PRESSURE SEALS to open & release all the chemicals.
That will leave you with plenty of paperweights.

I know as I have done that 2 X...............

LIFEPO4 charger....OR....Use a charger that has a TRUE LIFEPO4 charge mode.

LIPO batteries ALSO have their own special Charge Cutoff Voltages. Again a TRUE LIPO charger mode is required. LIPOS DO smoke & burst into fire if run down too low & recharged............. You will NOT be able to stop the fire of a big LIPO.

 

[JimDanielson]

You might be able to send back your Zivan and get it reprogrammed for a LiFePO4 charger curve. When I considered switching chemistries, Elcon said they would switch it if I paid for shipping.

Worth sending them an email and asking