Chadx
Advanced Member
Thought I'd start a thread about using your camper battery bank/solar to recharge batteries on another battery bank. This came up on a recent thread so thought I'd start a new one to discuss. Though in my application, I'd be charging batteries in a fishing boat, this thread isn't isolated to just boat batteries as it applies to charging any batteries that are not part of the camper battery bank.
On my FWC with 180 watt solar panel, I have a lot of excess solar capacity going unused each day. I've been considering options to harness some potential current being as 50% of our trips include pulling the fishing boat which is rigged with 4 batteries (one main starter battery, two deep cycle electric trolling motor batteries, and one deep cycle for kicker motor, live well, sonar, downriggers, etc.) The starter battery and kicker battery are fine as they recharge off of the alternator of each of those two gas motors, so I'm looking at pushing the current into the two electric trolling motor batteries.
The simplest scenario would be to fashion cables to go from my camper battery bank to the boat batteries. I have a good handle on which boat batteries I'd charge and how, so won't dive into the specifics of that layout, but I want to at least note that those with trolling motor batteries hooked up in series (for 24v and 36v trolling motors) should take care in how you plan to charge since you'll be charging with 12v source. It is fine as long as you hook the 12v source up to ONLY the terminals on one of the batteries at a time (12v to 12v). Don't connect a 12v source to a 24v or 36v battery bank by spanning all the batteries in series or you'll be mismatched voltage wise. It's important to understand how the wiring must be attached).
For me, it is probably not worth the extra expense of purchasing a portable solar panel and controller specifically for this purpose, but for some, that might be the best way to do it. But with my current setup, I'm at 100% charge by noon so have extra potential going unused so thinking I might as well consider options. Note, since installing the solar, I have disconnected the camper batteries from the truck battery since the solar has performed so well. I still have the wiring in place in case I ever need it.
Length of cable runs and associated compromise between cable length, voltage drop, and cable size will need to be a consideration. We typically unhook the boat/trailer and pull the camper next to the boat, which would shorten those lengths compared to stringing wire to a trailer in the tow position, however it would limit charging to being parked and unhooked. I can see there being times where it would be convenient to charge the boat batteries while towing, such as driving from one location to the next.
I'd probably attach a pigtail to the camper battery bank and run that through the shunt so my trimetric knows what current is going where (which it wouldn't know about if I tied directly to the battery bank). Other than that, should be pretty straight forward.
I may not even end up doing it, but fun to go through the mental exercise and I'm curious if others are charging external battery banks.
On my FWC with 180 watt solar panel, I have a lot of excess solar capacity going unused each day. I've been considering options to harness some potential current being as 50% of our trips include pulling the fishing boat which is rigged with 4 batteries (one main starter battery, two deep cycle electric trolling motor batteries, and one deep cycle for kicker motor, live well, sonar, downriggers, etc.) The starter battery and kicker battery are fine as they recharge off of the alternator of each of those two gas motors, so I'm looking at pushing the current into the two electric trolling motor batteries.
The simplest scenario would be to fashion cables to go from my camper battery bank to the boat batteries. I have a good handle on which boat batteries I'd charge and how, so won't dive into the specifics of that layout, but I want to at least note that those with trolling motor batteries hooked up in series (for 24v and 36v trolling motors) should take care in how you plan to charge since you'll be charging with 12v source. It is fine as long as you hook the 12v source up to ONLY the terminals on one of the batteries at a time (12v to 12v). Don't connect a 12v source to a 24v or 36v battery bank by spanning all the batteries in series or you'll be mismatched voltage wise. It's important to understand how the wiring must be attached).
For me, it is probably not worth the extra expense of purchasing a portable solar panel and controller specifically for this purpose, but for some, that might be the best way to do it. But with my current setup, I'm at 100% charge by noon so have extra potential going unused so thinking I might as well consider options. Note, since installing the solar, I have disconnected the camper batteries from the truck battery since the solar has performed so well. I still have the wiring in place in case I ever need it.
Length of cable runs and associated compromise between cable length, voltage drop, and cable size will need to be a consideration. We typically unhook the boat/trailer and pull the camper next to the boat, which would shorten those lengths compared to stringing wire to a trailer in the tow position, however it would limit charging to being parked and unhooked. I can see there being times where it would be convenient to charge the boat batteries while towing, such as driving from one location to the next.
I'd probably attach a pigtail to the camper battery bank and run that through the shunt so my trimetric knows what current is going where (which it wouldn't know about if I tied directly to the battery bank). Other than that, should be pretty straight forward.
I may not even end up doing it, but fun to go through the mental exercise and I'm curious if others are charging external battery banks.