Lifepo Spec's explanation help for a bean counter

[Spanky]

Can some one explain what the discharge spec's mean? I have a 48 volt X-5 that I been running with SLA's with for a year, and looking to purchase a lifepo setup. I'm an accountant and don't understand the discharge limitations and how it will effect my ride or prematurly kill the battery ie.-
Rated Discharging Amperage: ≤20 Amps
Max Discharging Amperage: 40 Amps
Max Discharging Current: 60 Amps
Discharging Cut-off Protection: 40 Amps

Using the specifications above, does the "Discharging Cut-off Protection: 40 Amps" mean anytime I exceed the 40 the battery shuts down? Or is it 60 amps when it shuts down? Thanks in advance for any help!!

 

[Ypedal]

That's a mix of both battery and BMS specs ..

Discharge Cut-Off protection is the BMS.. 40 amps and it shuts you down.

Max Discharge Current is the maximum of a cell in this pack, so in theory the BMS would never allow this battery from outputing more than 40 amps.. even if the cells themselves could do it, for example if you bypassed the BMS.

Specs are thrown around like crazy.. alot of vendors don't even understand what it means in real life.

Your X5 needs a battery that can comfortably give 40 amps continuous.

Get a BMS that cuts out at 60+amps if you can find one. What often happens is that BMS's rated at 40 amps trip

( Trip : no power, the BMS disconects the controller from itself and you get no throttle until you disconect, and reconnect the pack to reset the BMS, some BMS's will automatically reset.. YMMV )

And not only that.. but a motor controller that is rated " 40 Amps " can actually allow spikes of much higher amps at low speed that are perfectly safe for the battery, but they can cause some BMS's to false trip leaving you pissed off at green lights trying to keep up with traffic...

Give us a link and someone on this forum likely has one and can comment on it ! :wink: