EventHorizon

Running a gen to power a battery charger, weather the built-in or external, is extremely inefficient and slow. Best way to charge a battery is buy a cheap set of jumper cables and use the engine of your truck to charge. Way faster, don't need to drop $1000+ on a gen and you always have it with you. Downside is no 110v power while charging but get a good size inverter and problem solved.

Dirttracker18

Actually you have it backwards. Although partially correct.

The alternator on our trucks is relatively inefficient, especially at idle. Unless you are going to put a brick on the pedal to keep the truck up around 1800 RPM you will be waiting a long time to recharge. Even at that, a high amp 120v charger will be considerably faster. Deep cell batteries can take a high charge unlike our standard vehicle batteries which require a slower low amp charge to better their lifespan. This is why vehicle alternators do not deliver a high amp charge. All of this does not even take into account the waste of fuel running a V8 engine to use as a quasi generator.

The charging system on most RVs from the factory is also inefficient. Most are low amp chargers. You can upgrade them and make them far more efficient, better than most battery chargers. A few of us in my hunting group have done the upgrade so that we no longer need to bring an alternative charger to keep our batteries up during the cold and dark hunting in the late fall. It makes the world of difference and you can upgrade to an intelligent charger which is better for your battery.

The best way to charge is by the use of a generator and a high amp charger. Keep in mind most batteries can only take a little less than 40 amps charge rate.

FIY

I have $200 into my 300 watt generator. It is a little noisier than my buddies Yamaha but the price was right.

bubbabud

Do the math it all depends on the size [capacity] of the battery's. A pair of say group 4 truck battery or group 2 cart battery's will have more capacity than a single group 31 12 volt but when you consider the weight and the cost compared to a single 12 volt and the power you need. As stated a small generator even if it is dedicated to running a charger or a portable 100 watt solar panel might be a better option than the cost and maintaining 2 battery's.
Just a side note Harber freight sells a small 2 stroke 800 watt generator which will power 30 amp charger for under $100 and they are very quiet only down side oil gas mixture not a problem if you run a 2 stroke out board or weed eater, chainsaw, etc

smokeywren

No experience with 6-volt batteries in an RV, but I have an older John Deere 310A diesel loader/backhoe that came with them. Huge batteries, connected to provide 12-volts to the engine.


The 6-volt batteries were a hassle. I bought a special 6-volt battery charger to charge them up to full power a few times per year. And you couldn't buy them just anyplace. So I replaced them with two 12-volt batteries of the same size hooked up to provide 12-volt power to the engine. Much less hassle, and my ordinary 12-volt battery chargers/maintainers worked fine.

acadianbob

If you have two 6 volt batteries hooked in series, they will function exactly like the 12 volt battery. So, no charging issues if you hook up the batteries and the charger correctly.

bubbabud

Just as a side note when you connect two or more battery's as in 2 6volt to form a 12 battery the amp hour capacity remain the same. if you connect 2 12volt batterys together in parallel to form a single 12 volt battery the voltage remains the same but the amp hour capacity is doubled. The term battery is what is formed when you connect 2 or more cells together in series or parallel or any combination is a single battery.

69Shark

LOL!
Just to stir the pot here,
In our boat we have 4 6 volt batteries at 100lbs each!

Two banks of two batteries each in series to create the desired 12v then the two banks are tied in parallel for a huge supply of amp hours.
. . . . then add a 12 starter battery !!

We can spent a lot of time at anchor and do!

Yeah, I know unrelated.


Whatever setup you use, do yourself a favor and regularly check the water levels on your batteries. Proper levels with distilled water will increase battery life.

Scott

PerryB

OK Smokey, I gotta ask. Why didn't you just charge them in series?

SKBORDERS

What are the amp hours of the 6 volt?
Two batteries in series does not increase amp hours because you double the resistance.
Two batteries in parallel more than double the RC or amp hours because you lower the total resistance.
I.E. a group 31 725cca in has 180 min of reserve capacity
2 in series has 24 volts but still only 180min of RC
2 in parallel have 420 min. IRC
Just looked it up a group 31 6volt only has 190 min of RC. So they will not last much longer than even one group 31 12 volt battery

smokeywren

My automatic battery chargers didn't like it. And my old manual battery charger wouldn't tell me the state of charge - plus it would overcharge the batteries if you didn't pay close attention. So I used a good 6-volt automatic charger that worked good but took a long time to completely charge both batteries.