Charging a Battery Bank
I am planning on upgrading my batteries to 4 6v batteries wired in series and parallel to have a 12v system with plenty of Amp Hours. There is a ton of information on how to wire things up but nothing...
Forum Discussion
Fast charging means voltages in the mid 14s but also keeping that voltage there during the Absorption stage. If the voltage drops to 14.2 (Iota) or 13.6 (PowerMax/BoonDocker) for Absorption, then the amps to the battery will be much fewer than at mid-14s Vabs, and waste a bunch of generator time.
The PD with Charge Wizard gives you a way to keep the Vabs at 14.4, so that is good (although might not match battery specs), but the PD has a weakness during Bulk where it does not seem to hold constant amps so you get fewer amps and longer time, and it seems to also do a few amps less than rating at first. You can get around that by buying a higher rating PD and that will work fairly well.
The Adjustable charger is a better way where it will hold constant rated amps for Bulk. It lets you select your Vabs and it stays at that, which is what you want for fast charging right to the time you stop the recharge. If that is when it is full, you have to then lower the voltage to 13.6 yourself, or just detach your fast charger and go onto the rig's converter doing 13.6.
The selection of Vabs at say 14.8 means you have a single voltage charger at 14.8. That means it does two charging stages, Bulk and Absorption. That is what you want for the fast charging part. Of course you would stop the recharge early at say 90% SOC if on generator time.
The choice of voltage for Vabs is based on the battery maker's own spec. Trojan says 14.8. Others have their own specs, especially AGMs vary. That is based on 77F outside, so if it is 35F out you would crank the Vabs to 15.2v to get it right. If your charger has temp compensation, it will do that for you.
The rig is safe up to 15.3 volts, never mind the temperature, Norcold says 15.4 is the input limit, eg. If you want to equalize at 16v, you should do that with the batts disconnected from the rig (the rig can run its 12v with the converter, no batts while you do that)
Another wrinkle is with temp comp, your 14.8 setting might get to 15+ in the cold. With solar (you wouldn't be using the inverter if the gen is on), this can be over the inverter's imput limit, where many have 15v for that. To run the inverter you would need to turn off the solar, let the BatV drop below 15v and then start the inverter, and now turn the solar back on--with the inverter running BatV will stay below 15.
The PD with Charge Wizard gives you a way to keep the Vabs at 14.4, so that is good (although might not match battery specs), but the PD has a weakness during Bulk where it does not seem to hold constant amps so you get fewer amps and longer time, and it seems to also do a few amps less than rating at first. You can get around that by buying a higher rating PD and that will work fairly well.
The Adjustable charger is a better way where it will hold constant rated amps for Bulk. It lets you select your Vabs and it stays at that, which is what you want for fast charging right to the time you stop the recharge. If that is when it is full, you have to then lower the voltage to 13.6 yourself, or just detach your fast charger and go onto the rig's converter doing 13.6.
The selection of Vabs at say 14.8 means you have a single voltage charger at 14.8. That means it does two charging stages, Bulk and Absorption. That is what you want for the fast charging part. Of course you would stop the recharge early at say 90% SOC if on generator time.
The choice of voltage for Vabs is based on the battery maker's own spec. Trojan says 14.8. Others have their own specs, especially AGMs vary. That is based on 77F outside, so if it is 35F out you would crank the Vabs to 15.2v to get it right. If your charger has temp compensation, it will do that for you.
The rig is safe up to 15.3 volts, never mind the temperature, Norcold says 15.4 is the input limit, eg. If you want to equalize at 16v, you should do that with the batts disconnected from the rig (the rig can run its 12v with the converter, no batts while you do that)
Another wrinkle is with temp comp, your 14.8 setting might get to 15+ in the cold. With solar (you wouldn't be using the inverter if the gen is on), this can be over the inverter's imput limit, where many have 15v for that. To run the inverter you would need to turn off the solar, let the BatV drop below 15v and then start the inverter, and now turn the solar back on--with the inverter running BatV will stay below 15.
