What kind of Battery Charger?

[NotyetMHCowner]

I am curious about having a separate battery charger to charge my batteries with the generator while boondocking. I am planning on buying four 6 volt golf cart batteries from Costco this spring to be able to boon dock 2 to 3 days a few times a year. I don't have solar yet. I do have an on board Onan 5500 generator. If I need to run it to charge batteries, I don't want the converter/charger to do it because it is just a trickle charge. I would prefer to be able to charge as fast as safely possible so as not to run the generator for hours on end. Any thoughts?

[cw3jason]

The converter in your Montana actually has 3 charging modes. A boost mode, a regular charge mode and a maintenance or trickle mode all with different voltages and activated depending on the voltage level your battery is at. In boost mode it puts out over 14volts to bring the battery up quick and should be more than sufficient.

[NotyetMHCowner]

That sounds good. I was reading about people saying their converter/chargers were just single stage chargers, but I also think they were older models. Will my factory charger charge as fast as regular chargers?

[Festus2]

Using your onboard converter in conjunction with the Onan generator is all you need in order for you to charge the bank of 6V's. Depending upon how much battery draw you anticipate using over 2-3 days of boon docking, 4 6v's should be sufficient to get you by over that time span.

With prudent use, those batteries should provide you with enough "juice" to last beyond 2-3 days.

[JRTJH]

I believe you have a WFCO 9900 power center in your trailer. You can read the specifications and owner's manual here: http://wfcoelectronics.com/wp-conten...0-brochure.pdf

A couple of "interesting comments" on the WFCO webpage are:

"WFCO’s automatic three-stage converter handles every charging need for the RV while extending the battery’s life. Well-maintained batteries should never need more than two-stage (Normal and Trickle) charging. Our third stage (Bulk) is provided for the rare times a battery needs extra-power for charging. See wfcoelectronics.com for details."


In the WFCO FAQ section is this Q&A:

How many amps does the converter supply to the battery?

It is based on which model converter you have. The converter will provide only the amount of amps that the battery is asking for. This is based on the condition of the battery. Note that the converter defaults amperage to the RV load first, then what is left over goes to the battery. In other words if you reduce the RV’s electrical load then more amps go to the battery causing it to charge faster.

So, if you have a WFCO 9960, you'll have 60 amps of DC power available. Depending on the furnace, lights, water pump, refrigerator, and other 12 volt loads, you may have anywhere from 0 amps to 60 amps available to charge your batteries. I'd "guess" that you'll have probably 15-45 amps available for charging. That's about right for "four golf cart batteries" when you consider that a "typical golf cart charger" works almost like the WFCO with "boost, normal and trickle" charging rates. Most golf cart battery chargers that operate on 12 volts (most golf carts are 36 or 48 volt systems) usually don't deliver much more than about 20 amps max and most use a "trickle charge' of about 2 amps to "maintain the battery bank".

If you don't use a lot of lighting, run your furnace, etc, you should have more than enough battery charging capability from your WFCO without a need for an "add on" charger. If you do decide to buy an additional charger, be careful on which ones you consider. You'd get better information from a golf cart service center than from an RV dealer.

[NotyetMHCowner]

Thanks guys! Lots of great information. Our camper has been at Camping World getting warranty work done since December 1st, and all the owners manuals are in the camper, or I would have looked to see what model I have.

We have never dry camped, but would like to from time to time for no more than 4 days. Some of the campgrounds we want to go to don't have hook-ups, so there is little choice. We eventually plan on a Go Power solar kit or similar, with a bank of AGM batteries, but 4 Costco 6volt batteries with a little conservation should work fine until then. We ordered the camper with the generator, but just don't want to run it more than necessary, especially is camping somewhere that is nice and quiet.

[JRTJH]

We have a somewhat smaller RV and have found that with LED lighting, "judicious use" of the TV and furnace, we can easily camp for 4 days with only two 6volt batteries. We don't have a "built in" generator, but carry a 2000 watt generator with us and very seldom do we need to use it as the two battery system has kept us above 75% charged for up to 4 days.

With 4 batteries (assuming you have an RV refrigerator, not a "110VAC home refrigerator) you'll be "good to go" without a solar system for a 4 day stint.