Going to RMNP next week. No hook ups there, so need to recharge two 6 volt batteries daily. I will be using a Honda 2000 EUi generator. Couple questions:1. Can I use external charger hooked to batteries while also charging batteries from trailer inverter. This would occur when I plug trailer power cord into generator. 2. Will external charger charge faster than trailer inverter?Basically, I'm trying to determine the fastest way to recharge the batteries each day. Thanks, Mark

Yes, but it's called a converter.

Depends. Need brand and model number of each.

You will need to post what brand and model CONVERTER you have before we can tell you how fast it will charge.Also, bear in mind that you will be limited to the output of your generator. Within that wattage, you can certainly use BOTH converter and supplemental charger at the same time.

I am assuming this is the Rocky Mountain Natl Park in COlo. Depending where you are staying they have generator restriction times. This is from their brochure "Where allowed, generators can run from 7:30 a.m. – 10:00 a.m. and 4:00 p.m. – 8:30 pm."Not a whole lot of time to charge your batteries so hopefully you have the smart-mode technology charging capabilities.My on-board converter is a smart-mode PD9160C charger and I connect my 30AMP Trailer Shore Power Cable directly to my 2KW Honda Gnerator 120VAC receptacle using a RV30A-15A long adapter (WALMART). This will allow my on-board converter to re-charge my 255AH battery bank back up to its 90% charge state in as little as three hours. This time should fit into the allowed generator run time stated in the above brochure. However it seems there may be other locations at the Natl Park park where generators may not be allowed at all. Probably something to check with the Natl Park folks first...I like using my generator direct connected to the trailer for this short time as this gives us a chance to make some good fresh ground bean coffee for the day while the generator is running.I am setup with a 600WATT PSW Inverter connected to my 255AH battery bank and we can draw some 20AMPs from the batteies using the 600WATT PSW Inverter watching HDTV and running some other 120VAC items between the 8PM to 11PM time frame. This drops my 255AH capacity battery bank down to around 12.0VDC each morning at 8AM when I re-charge it all back up to to its 90% charge state so we can do all of this all over again from the next day/night run off the batteries... I can do this 50% to 90% charge cycle for about 12-14days before I have to re-charge to a full 100% charge on my batteries without doing harm to them. The problem to doing a full 100% charge state is it takes 12-13 hours of generator run time to do this... Most places we go to here on the East side of the USA does not allow that much generator run time.Works great for us camping off the power grid but it does take some planning to be successful about it.Food for thoughtRoy Ken

Use your digital voltmeter (an essential part of every RVers kit) to measure voltage accross the two batteries in series while converter is running, then voltage while external charger is connected. Current into batteries will be a function of that voltage, so use the arrangement with higher voltage.

Charging batteries: inverter vs charger | Good Sam Community

RVpullinGuy
Explorer
Aug 17, 2013
I have questions about charging two 6-volt batteries connected in series using a 40amp portable battery charger.

1. Do I connect the 40amp battery charger using the pos/neg lead on a separate battery? Meaning... the neg lead on one battery and the pos lead on the other battery? Or, do I connect both leads to just one of the batteries?

2. Which mode (6-volt or 12-volt) do I set/use on the 40amp portable charger when doing this?
BFL13
Explorer II
Aug 17, 2013
A pair of 6s in series is a 12. Put the pos clamp on the free post of one 6 and the neg clamp on the free post of the other 6. Use charger 12v this way.

Actually, if the batts are installed in the rig with the neg post of one 6 grounded to the rig's frame,(which ought to be the case) then you are supposed to put the charger's neg clamp on the frame too, and put the pos clamp on the other 6's free pos post. (no sparks, safer)

If you have a Trimetric that safe way will not show up as any amps returned. So you need to clamp to the outer end of the shunt to get your charging amps and AH returned figures.
RVpullinGuy
Explorer
Aug 17, 2013
BFL13 wrote:
A pair of 6s in series is a 12. Put the pos clamp on the free post of one 6 and the neg clamp on the free post of the other 6. Use charger 12v this way.

Actually, if the batts are installed in the rig with the neg post of one 6 grounded to the rig's frame,(which ought to be the case) then you are supposed to put the charger's neg clamp on the frame too, and put the pos clamp on the other 6's free pos post. (no sparks, safer)

If you have a Trimetric that safe way will not show up as any amps returned. So you need to clamp to the outer end of the shunt to get your charging amps and AH returned figures.

That's what I thought. Thank you very much for your quick reply. I'm not an expert with this, so I didn't want to mess anything up.

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