Inverters with Mix of 6s and 12s
I have posted in various places lately about my attempt to find a good way to run the mixed bank of 6s and 12s. As a sort of update, here is what I have found out so far.
(Two beat up T-1275s are in their own bank (approx. 265AH or so) running the 2000w inverter, which runs the MW, kettle, and toaster. Four 6s (458AH) run the rig including the smaller inverter to run the TV, laptop etc.)
I think this would also all apply generally to a bank of two 6s and a separate 12 as an alternative to banking them as a three.
The idea is to give up some Peukert in exchange for:
- keeping the 12s away from the 6s in case of bad interactions
-not having to find a way to balance three pairs of batts in parallel, which takes too much wiring
-being able to run the 6s down farther than 50% now that they are free of the inverter alarm
After a few days, both banks have come down fairly evenly, with morning voltages now at 12.1 (12s) and 12.2 (6s)
Final use of the 12s prior to recharge was to run the kettle. 12.1v start. Kettle draws 90a. Voltage drop 0.6v to 11.5v, ended at 11.3/4 when kettle done.
Suggests the 12s could go lower in SOC than 50% and still run the inverter, but after their golf car days, I think they should be kept no lower than 50% (12.1v by Trojan spec) in regular use.
The 6s can go another day or two before needing a recharge. They are "allowed" to go down to 30% but they do have the small inverter on them. However, it turns out that the voltage drop from using that with the furnace also on--say under 25a total with a light on-- is only 0.2v (which I had not thought of before, still worrying about the 1.0v drop the four 6s get with the big inverter running the MW) so that means the 6s could go to 11.3v and still be over inverter alarm at 11v.
Of course, letting them go down to 11.3v before a recharge is not the idea. 11.82 is 30% on the Trojan spec for 6s. So it is not necessary to put the small inverter over to the 12s to keep the 6s free of inverter alarm tyranny.
One objective is to be able to still do a two-hour recharge within provincial park gen time rules. I don't have enough generator to run enough chargers to get enough amps to do six batts in two hours from say 40-80 or 50-90. But I can do just the pair of 12s or the four 6s in that time. The split bank with different days for recharging leaves that all possible.
Anyway so far so good. I am liking this set up and procedure very much.
(Two beat up T-1275s are in their own bank (approx. 265AH or so) running the 2000w inverter, which runs the MW, kettle, and toaster. Four 6s (458AH) run the rig including the smaller inverter to run the TV, laptop etc.)
I think this would also all apply generally to a bank of two 6s and a separate 12 as an alternative to banking them as a three.
The idea is to give up some Peukert in exchange for:
- keeping the 12s away from the 6s in case of bad interactions
-not having to find a way to balance three pairs of batts in parallel, which takes too much wiring
-being able to run the 6s down farther than 50% now that they are free of the inverter alarm
After a few days, both banks have come down fairly evenly, with morning voltages now at 12.1 (12s) and 12.2 (6s)
Final use of the 12s prior to recharge was to run the kettle. 12.1v start. Kettle draws 90a. Voltage drop 0.6v to 11.5v, ended at 11.3/4 when kettle done.
Suggests the 12s could go lower in SOC than 50% and still run the inverter, but after their golf car days, I think they should be kept no lower than 50% (12.1v by Trojan spec) in regular use.
The 6s can go another day or two before needing a recharge. They are "allowed" to go down to 30% but they do have the small inverter on them. However, it turns out that the voltage drop from using that with the furnace also on--say under 25a total with a light on-- is only 0.2v (which I had not thought of before, still worrying about the 1.0v drop the four 6s get with the big inverter running the MW) so that means the 6s could go to 11.3v and still be over inverter alarm at 11v.
Of course, letting them go down to 11.3v before a recharge is not the idea. 11.82 is 30% on the Trojan spec for 6s. So it is not necessary to put the small inverter over to the 12s to keep the 6s free of inverter alarm tyranny.
One objective is to be able to still do a two-hour recharge within provincial park gen time rules. I don't have enough generator to run enough chargers to get enough amps to do six batts in two hours from say 40-80 or 50-90. But I can do just the pair of 12s or the four 6s in that time. The split bank with different days for recharging leaves that all possible.
Anyway so far so good. I am liking this set up and procedure very much.
