work2much wrote:
NRALIFR wrote:
If you want better alternator charging, consider a DC-DC charger instead of an inverter.
:):)
Can you give me an example of a unit that can charge at 100Ah and is programable for specific bulk, absorption and float voltages for my LFP? , Serious question I am interested. Also looking at a voltage drop calculator I would need 4/0 cable to stay under 3% line loss with such low voltage and high amperage. That is heavy and expensive. Weight isn't my friend.
You’d probably have to look at a marine type DC-DC charger for one like that. The RV models I’m familiar with typically max out at about 40 amps.
ProMariner has models up to 130 amps. That model spec’s 1 AWG wire for up to 25’, and 0 AWG up to 30’. I’m not sure if it supports lithium batteries though. I’d be surprised if the marine market didn’t have exactly what you’re looking for (for a small fee :P )
Just for wire size comparison, I’ve got a Redarc BCDC1225 installed in my camper. The total circuit length from the truck batteries, through a CB and isolation solenoid, down along the frame rail, into the camper umbilical at the front of the truck bed, and to the Redarc unit installed next to the battery box is about 25 ft. I’m using 4 AWG welding cable, and I see full rated output from the Redarc (25 amps) all the time. The wire doesn’t even get warm. Redarc actually spec’d 6 AWG wire for my circuit length. Redarc DOES support lithium, and they have a 40 amp model.
work2much wrote:
For those who have upgraded their cable sizes what amperage are you seeing the alternator delivering? I wonder if the starter batteries close proximity to the alternator may cause them to see have higher voltage than the camper batteries thus slowing down the alternators current rate to the batteries farther away, even with massive cabling.
BTDT on my current truck, and was disappointed with the results. The starting batteries do cause some issues, but the “smart” charging systems on the newer trucks cause problems as well. That’s why DC-DC chargers are becoming more popular for RV’s. Connect the charger to the starting batteries, and the truck alternator and ECM don’t know it’s there.
:):)
