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Motorhome05 · 04-21-2005, 10:00 AM

We are thinking of adding 3 120 watt solar panels along with 4 - 6 volt batteries to our MH. We have a 2000 watt inverter. Question: should we wire the new 6-volt batteries to the existing 12 volt batteries, or wire direct to the inverter?

Thanks for any input.

Motorhome05 · 04-21-2005, 10:00 AM

We are thinking of adding 3 120 watt solar panels along with 4 - 6 volt batteries to our MH. We have a 2000 watt inverter. Question: should we wire the new 6-volt batteries to the existing 12 volt batteries, or wire direct to the inverter?

Thanks for any input.

757driver · 04-21-2005, 10:52 AM

Mororhome05:

I would replace the 12v batteries and only use the 6v batteries. What size/type of 6v batteries do you have? You shuld not mix 12v with 6v or new batteries with old batteries.

I have a simular set-up to yours, 4 6v T-105's with a 2000w Magnum inverter and 310watts of solar. Works great, I can even run the built in vacuum off the inverter for 5 minutes on a sunny day and replace what was taken out in about 1/2 hour.

Motorhome05 · 04-21-2005, 11:40 AM

Thanks for the reply. I do not know what size or type of battery we have. That is my DH's department. I just want to turn it on and have it work. LOL

Cruzer · 04-21-2005, 03:06 PM

It's true, you shouldn't mix different battery sizes, let alone voltages. You will overcook the small ones or undercharge the bigger ones.

I also wonder where you plan on putting the four 6 volt batteries if you aren't removing the two 12 volt OEM batteries. Batteries release hydrogen gas when being charged so they need to be in a vented compartment, not basement storage. If you put them in an enclosed area you might want to rename your coach "Hindenburg".

If you modify your user profile to include your coach information to your signature maybe some of the other members who are more familiar with that model might be able to help out.

zetron · 04-23-2005, 03:26 PM

I would not mix batteries either. However, I do have two relatively new 6 volt batteries in one bank and two old 6 volt batteries in the second bank, the third 'bank' is the single 12 volt OEM battery under the hood.

My banks are switchable in or out. and the 6 volt batteries are under the oven and under the seat in the dining area. They are vented to the coach. Hydrogen gas is not poisionous. Also, the batteries are not going to produce 'a load ' of it. Hydrogen being the lightest element will head for the ceiling anyway.

The batteries also give off oxygen when charging. One half as much oxygen as hydrogen (H2O). The real danger is having your batteries without a top vent for the hydrogen. Hydrogen and oxygen tend to react violently to form water.

Again we have to qualify, the batteries will only give off hydrogen and oxygen in the later part of the charging process. If you are using solar panels and your system voltage does not go above 14.0 volts you will have little or no gassing and you will not fully charge your batteries. I have 7 solar panels (one dedicated to the starter battery). I can get 355 watts out of my panels in the summer in Arizona at the middle of the day. I can also get 300 watts out of my wind generator if the wind is blowing all the time at about 20 miles/hr average. My panels are divided into two arrays with controls on each array. The controls can be switched in , out, or off. If they are switched 'out' I need to monitor the system voltage as it will rise to 15.0 volts on a sunny day. I have a high DC voltage 'alarm'. I did not plan this it just works out that way. The propane detector is my high DC voltage alarm! As the voltage in the system rises to about 14.8 volts the propane alarm will go off. Then it is time to switch the arrays back into the controllers.

I also have a high and interupted AC alarm. This is my second propane detector. It is wired with an AC to DC converter. When using the main 1200 watt Inverter this propane detector will 'chirp' if the AC voltage is interrupted. VERY CONVENIENT.

David/Zetron

Ron1247 · 05-04-2005, 03:33 AM

Run 4-90w panels,six 6V-T105's w/3.0 Prosine and included 7.1 btu AC in BR of inverter for a few hrs. as needed. Might check rvsolarelectric.com for a set of battery caps that will prevent leak of hydrogen and reduce the need to ck water level to 3 times per year or less. New and old batteries should not be mixed, best will be no better than worst. Better battery life if you use only top 50% of charge. I don't tilt my panels but it would help, not going to climb up and auto tilt to costly.

zetron · 05-05-2005, 07:23 AM

I do not think the caps can prevent the hydrogen and oxygen from evolving due to electrolysis. These caps are meant to keep the water from boiling out of the cells.

Above 14.2 volts you will have some electrolytic action;gaseous hydrogen and oxygen being produced on opposite plates in the cell.

So long as there is a way for the hydrogen gas to rise out of the enclosure in which the battery (s) are mounted there should be no problems.

Another thing that you might consider to lengthen the life of your lead acid battries is a 'Desulfator'. This is a little back box that has come on the market in recent years and is simply connected into your battery system.

It is suppose to remove lead sulfate deposits from the battery plates. It does this by producing an alternating current electrical wave that is the same frequency as the wave that excites the lead sulfate molecule.

Every chemical compound has a frequency at which it vibrates and is radiates.The lead sulfate on the plates VIBRATES because of this wave and is suppose to go back into solution or fall off the plates; I do not know which.

A NEAT idea, if I was going to get rid of lead sulfate this is the idea I would eventually have come up with.

David/Zetron

kayo · 05-06-2005, 06:11 AM

Here is a tip that I got from RVsolar in ARizona that worked very well for me.
Because of the location of the existing 6V batteries (under the steps)I put my additional batteries in the compartment right next to them.
I found a polyethelne (sp) tool box at Wallmart that would hold (4) 6V batterieswith enough height at the top for all of the cables, etc. I ran a 2" plastic pipe to a outside compartment wall for ventilation, and sealed all of the other holes in the box with silicon.
Because of weight limitations of the compartment, I had a steel 2" channel frame built for the box and hung it from the floor of the RV with threaded rod.
It will be a ***** to change out the batteries at some time in the future, but for the present it works great, with more than enough room to service the batteries.