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solar charger and battery

MadFinnHockey
Explorer
Explorer
I use a small solar charger to maintain my battery when camping and when I can't turn on my generator. My question is, when I use my generator should I disconnect my solar charger?
thanks
2 REPLIES 2

RoyB
Explorer II
Explorer II
I charge alot with my generator when camping off the power grid. My battery setup is planned to get to 8AM the next morning running all the things we want to run in the one day/nite battery run off the power grid.

This is planned out to drain my batteries to around their 50% charge state. Then I will hook my shore power cable to the generator 120VAC receptacle using one of those RV30A-15A long dogbone type adapter. This allows my on-board smart mode converter/charger recharge my batteries correctly in a three hour generator run time to get them back up to their 90% charge state.

I can do 12-14 of these 50% to 90% charge state cycles before having to run the generator for a full 12 hours run to get them batteries up to their 100% charge state. A 12 hour run of the generator at most all of the camp grounds we go to on the East side of USA is not allowed.

If you are just using the 12VDC at 8AMPS charge coming directly from the generator front panel you will not be doing justice to your batteries. This will not get anywhere near a 90% charge state in a short generator run. Actually you would need to run your generator for around 24 hours to get anywhere near a 90% charge state with only 12VDC available.


My 2KW Honda EU2000i front Panel

The same thing goes with the SOLAR PANELs. A typical 120WATT SOLAR PANEL Controller will only produce 14.4VDC coming out of the solar charger at around 5-6AMPS when in the full sun. Running this all day long may not get your multiple batteries back up to the 90% charge state.

The battery science says you need to have your battery bank at its 90% charge state to get almost full performance when running things for a long time. Just a short charge here and there won't do much good for us with the way we run our camping off the power grid...

You sure don't want to ruin your batteries as they cost too much to replace.

When I finally get two or three panels installed on my off-road camper I really won't expect them to replace my generator but just reduce the initial generator run time down to around maybe one hour when I need to develop 50-60AMPS of DC charge from my on-board converter/charger. After that then the solar panels only producing around 17-20AMPS of DC current into each battery will get them back up to at least their 90% charge state during the high sun day. Solar panels should have REVERSE DIODEs in place to isolate them from using other chargers on the same battery terminals at the same time.

I learned to not start my day/night run off the batteries unless they are at their 90% charge state other they will drop out around 10PM each night and I have to stop using them when they get below the 50% charge state which is close to being 12.0VDC.

Just passing along our charging techniques and experiences we have run into doing our camping off the power grid.

I suspect your 2003 model camper trailer does not have a smart mode converter/charger on-board. If you really are into camping off the power grid you should upgrade to a smart mode multiple charge DC VOLTAGE converter/charger unit and run multiple batteries.

Roy Ken
My Posts are IMHO based on my experiences - Words in CAPS does not mean I am shouting
Roy - Carolyn
RETIRED DOAF/DON/DOD/CONTR RADIO TECH (42yrs)
K9PHT (Since 1957) 146.52M
2010 F150, 5.4,3:73 Gears,SCab
2008 Starcraft 14RT EU2000i GEN
2005 Flagstaff 8528RESS

2oldman
Explorer II
Explorer II
no
"If I'm wearing long pants, I'm too far north" - 2oldman