When we get our class c, and dry camp for more than a few days, if the batteries need charging, is it better to start the generator and use the onboard charger, or start the generator and plug in an external charger?... Just thinking that I would rather not run the generator for a long time so an external charger might be faster?

Depends on your onboard charger. If you have a single stage charger like the Magnetek/Parallax, it is crap. You are better off replacing it with a real converter/charger or using an external charger. If you have a modern 3 stage charger like a Progressive Dynamics (w/charge wizard), just let the onboard charger do the job.I replaced my fully functional and operating Magnetek 7345 a few years ago with a Progressive Dynamics 4655 and am very happy.

If changing the convertor doesn"t appeal to you, use a external battery charger AND your convertor. You got the genny running anyway. My convertor will not charge the batterys by running the genny all day 8 am to 8 pm . (You can run your generator those hours in Federal parks such as Yellowstone) Mine ran all day to recharge, much to the consternation of neighbors. I now use both

Which is faster charging ?;.; Only you have the answer to that.You gave no info on your converter charger, nor any info on the external charger you mite be talking about. How could we possibly knowthe answer ?

For boondocking with a "C", I'd look into a few things:1: Check your converter. Chuck it if it is a single stage model. If it is, chuck it. A couple C-notes gets you a five-stage "charge wizard" converter. If you are willing to pay more, you can get a converter/inverter like Magnum Energy's MMS (50 amp, four stage converter, 1000 watt, pure sine wave inverter.) This is the first thing someone should do. In fact, when I buy my next MH, this will be done by the local dealer.2: Consider a solar system. A class "C" can handle at least 100-200 watts of solar, perhaps a lot more. Add a MPPT controller that does multi-stages, and that will allow much longer boondocking trips without the need of constant generator running.3: If you want a way to maintain a battery, Battery Minder sells an 8 amp multi-stage maintainer with a desulfate mode that can be permanently installed by the batteries. This can come in handy if you have a very low wattage connection, or are using a very long extension cord when you have the motorhome in storage (and plugging into the charger may overload things.)4: Depending on batteries, sometimes you can run the onboard charger and an external charger. However, this depends on the type of batteries. AGMs may be able to handle this better than flooded cel.

Tell us what converter brand and model and the portable charger brand and model. No one can possibly answer the question accurately without this info.

Use onboard charger or external charger? | Good Sam Community

16 Replies

MEXICOWANDERER
Explorer
Apr 21, 2014

Please tell me again, the best way to drive 50 miles to the gas station so I can charge my batteries...
NinerBikes
Explorer
Apr 21, 2014
OP needs to get their class C first, then determine if there is a problem or not with charging. Who knows, with the cost per watt these days, maybe solar panels is a better option to their existing charge controller and listening to a generator?

Determine your usage first, real world, then determine how to go about keeping things charged.
wa8yxm
Explorer III
Apr 20, 2014
As others have said: Depends, It depends on the converter

Magnetek 6300 Upgrade the converter
Paralles 7300 You should consider an upgrade
Progressive Dynamics 9200.. You can not upgrade
Many many others. In between

IF you have a good 3-stage or 3-stage PLUS converter. odds are that is the best way to re-charge.. A well matched 3-stage converter is the very best it gets. (Well 3+ like the 9200)

What is a 3+ A 3 stage with one other feature THe 9200 has "Auto equlization" my other 3-stager has temp compensation. Both put em in the 3+ group.
Bobbo
Explorer III
Apr 20, 2014
Oh yes. I have about 13 feet, each way, of 4g wire between the converter and battery, and it readily goes into bulk mode.
brulaz
Explorer
Apr 20, 2014
Bobbo wrote:

...
And I have heard a LOT of folks say they couldn't get a WFCO unit into bulk mode.

Thanks. Guess I'm not alone.

So I guess your PD does go into bulk mode?
Bobbo
Explorer III
Apr 20, 2014
I don't think isolating the two functions is necessary. All of the devices in the RV seem to tolerate the 14+ volts fine, or a LOT of RV's would be replacing parts all the time. I know that the BOOST MODE and EQUALIZATION MODE of my PD4655V is 14.4v, and I haven't had any problems in the 3+ years since I installed the PD unit.

And I have heard a LOT of folks say they couldn't get a WFCO unit into bulk mode.
brulaz
Explorer
Apr 20, 2014
Bobbo wrote:

...
If you have a modern 3 stage charger like a Progressive Dynamics (w/charge wizard), just let the onboard charger do the job.

I replaced my fully functional and operating Magnetek 7345 a few years ago with a Progressive Dynamics 4655 and am very happy.

Always thought the problem was in part that the converter and charger functions were not isolated.

Despite what its documentation said, my old WFCO just seemed to sit at 13.6V no matter what condition the battery was in. It would never go into float mode (13.2V), but that seemed to be because of all the small ongoing 12V loads in the trailer. If I pulled all the DC fuses I could force to lower the voltage for a short while but think there were some loads I couldn't remove. Or maybe the WFCO was just a POS.

And I never saw it go into bulk mode (>13.7V) either. But we never drained the batteries that much. And I wondered if high bulk mode voltages (>14V) might be bad for other DC circuits in the trailer?
EDIT: Guess not as there are a lot of Solar systems out there that bulk charge the batteries at >14V on bright days while the system is connected to the DC circuits.

Was thinking that having separate converter and charger would be the best solution? When on 110V isolate the charger and batteries from the DC circuits and let it charge. Let the separate converter handle the DC circuits. EDIT: Again, with solar off-grid charging the loads are always connected but they somehow manage not to over-charge the batteries or over-volt the DC circuits. hmmm ...
mlts22
Explorer II
Apr 19, 2014
Very good thing pointed out. The OP needs to ask the dealer, if not the RV maker. I was looking at one brand of "C" with a good reputation... and surprisingly enough, it came with a single stage converter, and because of the space premium, only one of the "dogbone" Magnum Energy converter/inverters would fit that area. Maybe have it financed as part of the package, since a converter will pay for itself when you don't have to replace batteries every season.
Canadian_Rainbi
Explorer
Apr 18, 2014
Canadian Rainbirds wrote:
If you read his post carefully it seems that he doesn't have a class C yet: "When we get our class c. . . . " so he likely doesn't have the required answers yet either. But now he knows what to ask the dealer!
Canadian_Rainbi
Explorer
Apr 18, 2014
If you read his post carefully it seems that he doesn't have a class C yet: "When we get our class c. . . . " so he likely doesn't have the required answers yet either. But know he knows what to ask the dealer!