Battery Cable Sizing - PD9260

doughere wrote:
When I installed a PD9260 I installed it in the compartment next to the battery; a pair of GC. I used battery cables from the local auto parts store, 3 feet each.

My intent was to get as much into the battery as possible when on gen.

I seldom see anywhere near 60A; usually not much over 40A and that only for a short time.

I'd think of upgrading the cable if the intent is to charge as rapidly as possible. For general use the existing is fine.

If the intent is to run an inverter somewhere then you need to rethink everything.

Regards,
Doug

To understand this we need the battery bank's true capacity and SOC at the beginning of the recharge.

Let's say the PD 60amper will do 55 amps when wired so it can. On two batts at 220AH you have to be under 72% SOC to get any bulk stage, after that it is all tapering amps in Absorption (due to the battery's "natural acceptance rate" )

If it kicks off at 40amps and tapers that should mean you are starting at approx. 77% SOC.

However if it is not wired so it can do 55a then it acts like it is on a smaller battery bank than that 220AH example (higher wire R looks like a smaller battery to the converter)

On a smaller battery that means your 40a is like having a higher charging rate (amps/capacity) so your taper starts at a lower SOC so now you have to be even lower than that in SOC to get any bulk stage.

Same thing if batts are sulfated to have less capacity than thought. Smaller capacity means higher charging rate, earlier tapering. (lower acceptance rate)

So you can have any, some, or all of these to explain the 40a:
-wiring too long/thin
-connections
-batteries sulfated
-starting at high SOC

(I left out any 120v input issues)