Battery charging

[offroad71]

I will be dry camping for this summer for about 8 days. I'm very conservative using power. I have a Yamaha EF3000iSEB generator. How many hours a day or how often would I need to run the generator to keep the batteries charged? Campground has time frames when the generator can be run. Just trying to have a idea, so I can plan ahead. I have a 2009 3000RK.

[RipNC]

There are too many variables w/o any info on your setup. Batteries have a charge acceptance rate (CAR) and lead acid is typically 25% - so if you had a 100 amp hour battery you can charge it at 25 amps. Lithium can be charged at 50 to 100%. If you are using your converter in your rig to charge your battery bank it is probably capable of 50 amps but won't deliver it unless your battery accepts it. Also, the last 5-10% takes a long time to get on a lead acid battery.

Since you should never deplete lead acid more than 50%, the simple math would be (using 2 - 100 Ahr batteries) - 200x50%=100 Ahrs x 25% (lead acid CAR) = 25 Ahr charge rate. 100 Ahr / 25 Ahr charge rate = 4 hrs charging BUT the last 5-10% will drag that time out. This is part of the reason many (myself included) use lithium instead of lead acid.

[dieselguy]

Although I don't dry camp much ... I've always carried a regular 120 VAC battery charger in case our boat battery or someone else's battery needs a charge. It seems to charge faster than the onboard converter/charger.

[RipNC]

Dieselguy,

I know what you mean, but I was kind of surprised by the converter when I put in my lithium I changed the charge "profile" switch to lithium and it put out mid 60s amps. It is off now and when on shorepower my Victron inverter will charge my 618Ahr bank at 120 amps (my choice). When towing I have a dc to dc charger that charges at 60 amps from my truck. Today it put back over 150Ahrs in less that 3 hours of driving (probably a little solar help too).

Now I just need a little more solar - we have the 300 watt panel that came with the rig and we'll probably add 1 more. I already changed the MPPT out to Victron 100/50 to take the additional panel - thought the Jaboni was a little light for the second panel.

[offroad71]

I think I read some time ago, it was better to use the charger on the coach rather than a car charger. Which do you think is a better way? Using the generator with the charger on the coach or generator with a car charger?

[Daryles]

We just did 10 days dry camping on Ocracoke Island OBX NC. I have 400W solar panels and 552Ah lithium batteries.
Everything worked fine until we had rain for three days straight. No sun.
I had installed a 60A DC-DC charger. For those three days I ran the truck an hour in the morning and an hour in the evening to bring the batteries to 100%. Lithium batteries charge really fast. Way faster than lead acid. We ran RV fridge in propane mode, TV, Satellite, Nintendo, in the evening. Furnace at night.
Your variables are your power use, batteries capacity and how many amps they can charge per hour and how many amps your generator can put out.

[mlh]

When I’m boondocking I use the battery very sparingly. All I need is lights and water so an hour a day is all I need the generator. I might watch the news I few minutes in the morning and the afternoon.
Lynwood

[Clyde n Deb]

Carry a DVOM and check the battery periodically, or get a 12v monitor that plugs into a 12v wall socket.

[LeAnna]

We have a 2012 3000RK. If you have both the refrigerator and water heater on propane and are just using the batteries for lights and water pump you should be able to go at least four days. Just run the generator to power the electric appliances you want to use (TV, coffee maker, hair dryer etc.) When the batteries start to get low run the generator for a couple of hours to charge back up.

[sonofcy]

Originally Posted by offroad71

I will be dry camping for this summer for about 8 days. I'm very conservative using power. I have a Yamaha EF3000iSEB generator. How many hours a day or how often would I need to run the generator to keep the batteries charged? Campground has time frames when the generator can be run. Just trying to have a idea, so I can plan ahead. I have a 2009 3000RK.

Complex subject but the simple answer is get a battery monitor with a shunt. Either Victron bluetooth or Trimetric from Bogart. It will help a lot if you switch to Lithium, but they are a long term investment.