specific deep cycle battery recommendation

[natotx]

Guys -

I have read the FAQs on batteries linked to from this forum. I am looking for a specific recommendation for a sealed, deep cycle battery for my teardrop. Am in Houston, so heat plays hell with batteries down here.

My teardrop has a ~ 5 amp window AC unit, a 750 watt microwave, the regular 12v lights and ventilation fan, and a 20" lcd tv. Not a huge load, most interested in being able to run the window AC all night on battery.

Most of the time the teardrop runs on shore power, but when the power is out or otherwise not available, I like to charge the battery with a generator/charger during the day, and then sleep in silence at night with everything running off the battery. My old battery was an walmart everstart max marine 875MCA/125amp hrs, and to be honest, I wasnt that impressed with it.

Cost isnt really much of an issue, as this is an important piece of equipment, so the diff between a 100 or 200 battery isnt too crucial to me. Anyone have any thoughs on the Optima blue top D27? Or others?

thanks

nate

[eamarquardt]

When you say you have a 5 amp a/c unit are you talking 120 VAC or 12 VDC? I suspect 120 VAC. That's 600 watts or 50 amps of 12VDC if your inverter is 100% efficient. That will drain a battery quickly.

I think runniing an ac unit on a portable battery is the "height of optomisim" but I could be wrong.

I'd see how much time your AC unit runs under the conditions you're expecting to be in. If it needs to run 2 hours out of eight to keep you cool that's 120 amp hours. Depending on the type of battery you buy (deep cycle golf cart), marine, etc you can extract 80% to 50% of the amp hour capacity of the battery before you recharge it. In addition the faster you pull current out of the battery the less you can get.

You also have to figure out how you're gonna charge the battery. Generally for good battery life you shouldn't charge it at more than 10% of capacity (100 amp/hour battery max 10 amps). So you'll have to have a big enough charger and enough hours to put the charge back in. Let's say you have a 200 amp true deep cycle battery, pull 120 amp hours out of it and you have to recharge it. If you have a battery charger putting out 20 amps it's gonna take 6 or more hours to charge the battery. You can charge it faster but battery life and perfromance will be degraded. Do you want to listen to a generator for 6 hours a day?

Do some testing, do the numbers ahead of time, and then decide if running an AC unit off of batteries is practical.

If you do your homework up front you won't be disappointed and won't put a lot of money into a battery and inverter that may not do what you expect.

Cheers,

Gus

[madjack]

sorry, can't be done with anything less than a WHOLE TRUCKLOAD OF BATTERIES...there is a ten fold conversion ratio when you go between AC and DC, so that 5A 120vac air/con unit will draw 50A of 12vdc power to run it about 1hour worth of usage from a 100AH battery(never draw a battery down more than 50%)...consider the size of the cables to carry that power and the other appliances you wish to run and it becomes a not very practical thing to do................
madjack
p.s. I see Gus has covered the recharging issues as well......................MJ

[wannabefree]

A quiet little genny will run your AC all night on a gallon of gas.

[dh]

Your set up sounds a lot like mine. I'll just nix the ac and microwave when off grid and make due with the stove and vent fan.

[oklahomajewel]

Here's a thought.... where and how do you often camp? State parks , on the beach, out in the middle of nowhere? and for what length of time usually (weekends?) and what time of year? if staying in south Tx all the time then always hot , right?

I found in the past 3-4 years, only one weekend was I camped in a spot that didn't have electric . And that was on a mild weekend that I didn't really need AC anyway. I've camped in NE, MO, KS, AR and TX and OK between Feb and Dec but usually pay up to $23 a night for a sight with electric but not for much use --

That's what's coming to mind on my re-build and the AC etc and what kind of camping I do.

Good luck .
Julie

[asianflava]

Not gonna happen. If it could be done, we all would have a/c running off of batteries. We are all just left to use a fan when on battery power.

[afreegreek]

what the hell is an "air conditioner" asks the Canuck...

[eamarquardt]

what the hell is an "air conditioner" asks the Canuck...

The thing sitting in the corner of my yard is an air conditioner (compressor/condensor) unit. It gets turned on every three or for years for a few hours (mostly to drown out Suzy). It kinda cools the inside of the house but mostly it makes distracting noise. A while back I got a letter from the power company. They said that if I allowed them to put a doo dad on the unit that would allow them to turn it off at their will, they would credit me a bunch of money each summer month. Since it is rarely, if ever, on it seemed like a "win/win" for me! A couple of months each summer, as a result of allowing them to turn off my air conditioner that is already off, my eletric bill is pretty near twenty bucks for a whole month.

So an air conditioner can be kinda like "money in the bank" if used/not used properly. Of course you have to live within a few miles of an ocean that never gets above 65F and generates a nice breeze each summer afternoon.

Cheers,

Gus

[michaelwpayton]

A quiet little genny...

No such thing... to your neighbors.

[afreegreek]

Cost isnt really much of an issue, as this is an important piece of equipment, so the diff between a 100 or 200 battery isnt too crucial to me. Anyone have any thoughs on the Optima blue top D27? Or others?

thanks

nate

I have 2 Optima blue tops in my van.. they're about 5 years old and need to be replaced.. I got a lot of good use out of them too.. as I actually live in my van, it's not just a part time camper.. lots of good things to say about them but I'm not sure I will get two more.. I'm thinking of getting two Interstate SRM-4D's

http://www.interstatebatteries.com/cs_e ... Commercial).aspx

they will give me double the capacity for the same dollar.. they are heavy though, over a hundred pounds each.. and of course, they have to be maintained.

[afreegreek]

BTW, I have a red top as the starter battery in the van and I WILL get another of those when it dies.. it's a great battery as are the blue tops.. I just think they're a bit pricy for the power they deliver and I don't need the advantages of a sealed battery..

[asianflava]

I have an Optima blue top (gray body) in my tear. It's about 5yrs old but it's still OK since I don't use it much. Just used it at IRG to run my CPAP for 4 nights. Partially recharged it after the second night, it ran my machine just fine. I bought it at Sam's Club, kinda pricy but I think it's worth it.