How to charge a battery

We run our genset while coffee is brewing and breakfast is cooked in the morning. Then we run for dinner. That run time normally takes care of batteries except when furnace runs a lot.

BFL13 wrote:
If you do two nights so the batt is 12.2v, then the gen can't run the 55 amper at 55 amps like it will at first.

If you recharge each day at 12.4v, then the 55 amper will be charging at more like 30 amps at first so the gen can do that.

30 amps beats 6 amps by miles.

Agreed. The plan is to try to run everyday. At worse, the spare battery will be for running the jack when I need to move it. Once i got back on shore power, I'd just swap the batteries out and let the few days at the 30 amp site charge it.

If you do two nights so the batt is 12.2v, then the gen can't run the 55 amper at 55 amps like it will at first.

If you recharge each day at 12.4v, then the 55 amper will be charging at more like 30 amps at first so the gen can do that.

30 amps beats 6 amps by miles.

BFL13 wrote:
You will have to learn what will be enough gen time to get you by till next day. If you can, be worth trying it at home to get an idea what works.

I know I can last about 2 nights boondocking. I also will be bringing a second battery. We are boondocking for 3 nights. That is why the question is between using my 6a portable charger connected and using the on board charger.

You will have to learn what will be enough gen time to get you by till next day. If you can, be worth trying it at home to get an idea what works.

BFL13 wrote:
If you recharge when the batts are not very low, they will not draw as many amps, so the 1000w gen could do that, although it will take longer to get back up in the higher SOC range.

You can't get a true resting voltage but just use the voltage when nothing much is on and recharge at 12.4v instead of waiting for 12.2v.

Have access to gas for the gen as you might have long running times. Still beats using that 6a charger.

The goal will be to optimize the time that I can run the generator. I'll have a few cans of gas ready to go to let it run as long as I can.

If you recharge when the batts are not very low, they will not draw as many amps, so the 1000w gen could do that, although it will take longer to get back up in the higher SOC range.

You can't get a true resting voltage but just use the voltage when nothing much is on and recharge at 12.4v instead of waiting for 12.2v.

Have access to gas for the gen as you might have long running times. Still beats using that 6a charger.

The converter is a 55A one.

My 1000 watt Yamaha does just fine with my 45 amp converter. Make sure fridge is set to run on propane and water heater 120 volt is turned off if so equipped.

A 1,000 watt generator is really around 800 watts usually. I doubt it would handle a 45 amp charger.You need at least a 2,000 watt unit to run a 45 amp I would think. You could just pick up a 15 to 25 amp smart charger and connect it manually. I've used my 15 Amp Stanley charger with a small generator.


Open the door to your "breaker panel" or power center. Inside will be a label with the brand and model. Most RV's I've owned had the converter in the bottom of the power center box. I had one big 5th wheel with a separate converter wired to the power center, not sure why. The converter was mounted right behind the power center, I would expect to find it next to the batteries. But instead it was below the bathroom sink cabinet.

When your batteries are down to 12.40 volts, how fast do they charge? Whats the charging voltage? The WFCO converters I've had did okay plugged in for days at a time, but on generator power I never saw any of mine hit the 14.4 volt mode. On generator you want the "boost mode" for faster charging.

I prefer something like this in my rigs: https://www.bestconverter.com/PD4655MBA-WildKat-55-Amp-Main-Board-Assembly-for-WFCO-8955-or-Parallax-7155-Includes-4600-Remote_p_616.html

You want the charge wizard pendent so you can manually control the boost mode. At least I do. The Boondocker version doesn't come with the pendant last I checked. I like the four stage wildkat or the name brand progressive dynamics converters with manual control pendant.

The last one I installed replaced a 8955 that charged at 13.23 volts, my WildKat converter starts out at 14.33 at the battery terminals. Then it drops down to the mid 13.50 range in auto mode. It does a good job, batteries get fully charged much quicker now. Healthy and fairly new batteries should rest at 12.70 or more when fully charged.

You can use a basic digital voltage meter at the converter and at the batteries to see how much drop there is in the cables. When testing the health of the converter, take your voltage reading at the converter's DC terminals.