Batteries For Dummies

guymon.hall · 01-24-2010, 10:49 PM

I'd like to put an inverter in our '07 Adv. 33V, but, I'm not so smart when it comes to battery and electrical discussion and throwing around terms like amps, volts, amp-hours, battery capacity, etc. I have 2 house batteries and a solar panel on the roof that recharges them, but no inverter. What I would like to know is, how long would my batteries last under certain electrical loads (on just a basic, moderate temp., sunny day)?

For instance, with no shore power if I wanted to run the TV, A/C, maybe a hair dryer (wife), and a couple lights, how long would the batteries last before having to be recharged? I know there's probably some electrical load management that has to be done while on battery power, so maybe the aforementioned is unrealistic. I mean, can you even do all that with a couple house batteries and an inverter?

Should I think about adding more batteries? I think I have room in the battery compartment under the stairs for one more; will that buy me anything worthwhile in terms of electrical capability? I've seen some posts where users have as many as 8 house batteries...

Anyway, some education here would be appreciated. Thanks.

Sammie · 01-24-2010, 11:25 PM

Guymon.hall,
At this website you will find a lot of usefull information explained a whole lot better than I ever could.

Sammie

The 12volt Side of Life (Part 1)

skigramp · 01-24-2010, 11:55 PM

I am not an engineer so I will answer in the broadest terms ...

With either 2 or 3 12volt batteries in parallel ... you will probably have enough capacity to run your TV for a few hours, your wife's hair dryer for minutes (most of an hour), ... but you will not have enough capacity to run your A/C ...

Crank up your generator ... it probably burns less than 1 gallon of fuel for an hour ..

wa8yxm · 01-25-2010, 12:03 PM

Well. two pair of U-2200's should run TV and lights most of the night.. Air Conditioner,,, about 15-30 minutes.

So it's a trade off.. Do not power the A/C with the inverter

Normal install of a top of the line inverter such as the Xantrex Prosine is like this

Main panel... 30 amp breaker---Inverter--Sub panel 15 amp breakers to TV's and to GFCI loop and perhaps the microwave.

That way you have TV/Radio. You can 'lectric shave, and you can make a quick cup of instant coffee

The AC hooks to the main panel, as does the 'Fridge and water heater and converter (if not included in the inverter, the Prosine you dump your existing converter (or keep it just-in-case)

And to the Generator lover.. Yes, that's a good option.. Less it's the late show ye be watching and park rules say "No generators after 10 pm"
I need more battery on mine.

dirko · 01-25-2010, 01:16 PM

Hi Ho: You have received good answers. What you really have to decide is what you want to do with the inverter. That will tell you how big it should be and how much battery capacity you need.

Do you dry camp alot (a little?) and if so, how long? Does your TV run on 12 volts or 115 vac? Does your generator noise create problems where you camp? For example, we often find ourselves in places where we don't want to run the generator but want to watch a DVD or a movie on the satellite system. Our TV and audio system run on 115 vac, so we need enough capacity to run that, lights, etc. for 4 or 5 hours. We also run the furnace at night. And we don't want to run the battery bank to less than 50 percent capacity. However, we seldom stay for more than a day under these conditions without moving the motorhome to another location and recharging the batteries.

So, we have four 6-volt golf cart batteries and a couple of 300 watt inverters for the entertainment system. That works for us.

Dirk

guymon.hall · 01-25-2010, 09:15 PM

Quote:

Originally Posted by Sammie

Guymon.hall,
At this website you will find a lot of usefull information explained a whole lot better than I ever could.

Sammie

The 12volt Side of Life (Part 1)

Thanks a lot for the point out. The link was a big help with explaining power requirements and capabilities at the basic level I'm at. Now I gotta get in my MH manuals and do some math. Might even have to take off my shoes and socks for this one, hehe.

So with all the inputs, I won't figure the A/C into the picture. Still deciding on the microwave/convection oven. Am considering replacing the current batts. with some new Lifeline AGMs. Have to measure and see if I can fit an extra one in the compartment and before that see if just the 2 house batts. will be adequate for my power needs.

Thanks for the help.

DAN L · 01-26-2010, 02:02 AM

Quote:

Originally Posted by guymon.hall

Thanks a lot for the point out. The link was a big help with explaining power requirements and capabilities at the basic level I'm at. Now I gotta get in my MH manuals and do some math. Might even have to take off my shoes and socks for this one, hehe.

So with all the inputs, I won't figure the A/C into the picture. Still deciding on the microwave/convection oven. Am considering replacing the current batts. with some new Lifeline AGMs. Have to measure and see if I can fit an extra one in the compartment and before that see if just the 2 house batts. will be adequate for my power needs.

Thanks for the help.

my battery compartment is under the stairs.
i was able to install 2 6v 300ah lifeline batteries in series by mounting them on their sides about 1.5 years ago. they are working well.
i found the best price from bd batteries online. the price included shipping.

guymon.hall · 01-26-2010, 08:44 AM

Quote:

Originally Posted by DAN L

my battery compartment is under the stairs. i was able to install 2 6v 300ah lifeline batteries in series by mounting them on their sides about 1.5 years ago.

Pardon my lack of basic electrical knowledge...does that give you 600ah? I get that 2 x 6V = 12V, but does the same hold true for amp-hrs?

wa8yxm · 01-26-2010, 10:08 AM

Many people have a problem when it comes to adding up batteries

If you are adding batteries in series You add voltage

So six volt plus six volt = 12 volt

And all RV's have only 12 volt batteries (Some of them one piece, some of them two pieces in series but they are all 12 volt batteries)

If you have batteries in parallel you add Amp Hours (Capacity)

So 150 amp hours plus 150 amp hours = 300 amp hours

If you have series/parallel (4, 6, 8 or more six volt) Then you first add up each series pair... 6v at 150 amp hour plus 6v at 150 amp hour = 12v at 150 amp hour PER PAIR

Then you add the pairs

12v at 150 amp hour plus 12v at 150 amp hour = 12v at 300 amp hour

Now to Dan L... .Just out of coursity.. What's the make and model of those six volt batteries? (I know they do make them in about that size just wonder what ones you have)

DAN L · 01-26-2010, 08:33 PM

Quote:

Originally Posted by guymon.hall

Pardon my lack of basic electrical knowledge...does that give you 600ah? I get that 2 x 6V = 12V, but does the same hold true for amp-hrs?

in series, voltage adds, in parallel, amps add.
i went from 2 12v 95 ah marine batteries in parallel, 190 ah capacity, to 2 lifeline agm 6v batteries in series for 300 ah capacity at 12v for an increase in capacity of 50%.

wa8yxm: my battery upgrade is listed in my sig block, lifelines. the lifelines weigh 90# each.