MrWizard wrote:
I need to do a standard 50-80 recharge and see if the gen has to supply as much to the converter at 50% as it does at 70% SOC.
got it backwards again
at 50%soc the battery will accept more amps and converter will be using MORE power, VA will be higher than when when SOC is 70% and the battery is accepting less amps
UNLESS the bank is so large that it can still accept (converter max amps) at 70%SOC, in which case VA will be up, watts into converter will be up because voltage to battery has risen
what size is the battery bank ?
at point does amps into bank start to drop ?
i know in my case amps drops off long before converter reaches 'set point' voltage, set point voltage is not reached until batteries are almost fully charged
The point where amps start to taper depends on the charging rate (and type of battery it seems) but as you suggest, a larger battery bank for the same amps means a lower charging rate and thus a higher SOC when amps start to taper. That is what my ugly graph shows so well (IMO!)
In my example above, I meant that the charger keeps 75 amps constant to 75% SOC then amps taper. I have 450AH of AGMs so 75 amps is only a 17% charging rate. That would correspond to a 37 amp charger on a 220 AH bank. So I would expect Bulk to end at about 80% SOC.
I have not checked that for real with my existing bank. I have lots of graphs from when using the Honda 3000 and Flooded batts in the 5er over the years, but can't be sure they count for anything with these AGMs.
Of course Mex has thrown a scuz into everything with his 20% charging rate requirement so I have to split the bank and do part of it at a time to get the charging rate up over 20% I only do that at home, so no gen required for that. My gen is just for when camping and not enough solar and it will be under the 20% rule for the 50-80 or whatever I do. Too bad so sad! Can't be helped. None of this would be happening if the stupid compartment in this class C would have held the Honda 3000. Oh well.
