AGM vs Flooded Bulk Times

jharrell wrote:

BFL13 wrote:
If the "old wets" would only accept 40 amps at 50% SOC start, that seems a tad low for amps. Say those were 85AH 12s, then that would be 170AH and 40/170 = 23.5% charging rate. That would have them start tapering from 40 amps constant at about 73% SOC, so they should have been able to accept way more than 40 amps at 50% SOC.

They could accept more, don't remember how much, seems like around 80 amps, but I was limiting bulk rate according to the recommended C/5 or 20% rate. Lifeline on the other hand says they can take 5C!

What do you guys say, is C/5 an old wives tale for wet cells? I just didn't want to harm them, although doesn't matter now with the Lifelines.

Thanks for the clarification.

From my reading of this book here,

http://www.bestconverter.com/Books_c_67.html


batteries have a "natural acceptance rate" which is the highest amps they will accept at any given SOC and voltage. As SOC rises, they will accept fewer max amps at any given voltage. At any SOC they will accept more amps if you jack up the voltage and vv. You cannot harm the batts by using higher amps---they just won't accept them. That is why your amps taper during Absorption.

So in the past discussing this we have heard that a Trojan tech said that they will accept any amount of amps at a low SOC. We have Xantrex saying they recommend a 30% charging rate for deep cycle batts, and also saying 10% is preferred for longest life (most cycles)

This means you can use way high amps initial charging for a fast recharge to save gen time and it won't harm the batts (much) It is also true that the batts won't accept the high amps unless they have been drawn down to a low SOC. They also say that cycling them low will mean fewer cycles in their life before you need new batteries than if you only did shallow cycles.

So, the harm might not be so much from the high amps as from cycling them to such a deep DOD. It all goes together.