Deep cycle battery

[Lorelei L]

We need help choosing a new battery for our Uhaul, please. We plan on installing a 100w solar panel. What would be optimal and what would be good enough?

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[David Tilston]

I would go for two 6 V, 240 Ah golf cart batteries from Costco.

[Raz]

Hard to say without knowing the demand. If you are trying to run a microwave then David is leading you in the right direction. On the other hand if all you have is a few LED lights and a water pump that gets occasional use, a group 24 battery might meet your needs. We use less than 10 amp-hrs a day so a smaller battery works for us. You need to find the current rating of each item you use and multiply it by the time (in hours) it gets used. Add the numbers and find a battery with an amp-hr rating at least double that. Raz

[Perry J]

I like group 29 deep cycle battery's.
I have a slide in Camper that I use when I tow my ATV trailer or sail boat.
I have had a 50W panel on it and the same group 29 battery for 5 years and have never run out of power.
I do a lot of cold weather camping and run the furnace all night.
I have 60W panel on my Scamp only because it was on sale and less expensive than the 50W.

[Carol H]

I have a Costco Group 27 Deep Cel and its worked well for me for the past 4 years along with my solar panel. I also do a far amount of off grid camping & haven't ever run it down.

[Jon Vermilye]

I use a pair of 232 amp hr 6V batteries combined with a 95 watt panel & a 1000 watt inverter. No problems keeping up with my 15 -20 amp hr per day usage, however if I add another 10 amp hrs by making a pot of coffee using the inverter, there better be full sun!

One point - while the deep cycle 6V batteries are best for deep cycling, a pair of deep cycle 12V batteries with the same amp hr capacity will be better if you are going to drive an inverter since they will have lower source resistance. The problem is true deep cycle 12V batteries are hard to find, and expensive.

[mary and bob]

If this Uhaul is fairly original it will have a battery box inside at the extreme rear under the bench area. The original box has a cover with a gasket to seal it, and a vent hose attached to an outside vent. This box is sized for a group 24 battery I believe. For those recommending a pair of 6 volt batteries, a whole new set up will have to be made, and there is not enough room in that area. Think back on all the discussions about interior batteries, and weight distribution issues by adding whatever to the front or rear of a trailer when answering the OP's question. She most likely just wants a battery to fit in the original box. Correct me if I'm wrong Lorelei. Note also that Uhauls have a single square tube tongue with the propane tank mounted on it, no place for a battery there.

[Larry C Hanson]

Hello,

If your battery capacity needs are modest I would stick
with the 24 series battery that will fit the trailer, much
easier than making all the mods required for larger capacity.

If you are meticulous about your battery maintenance you
should stay away from the cheap stuff sold at WalMart.
A Trojan 24TMX Renewable energy 12V would be suitable.
I have a series 27 on my trailer and it is still good after 4 years.
Of course I leave a small battery maintainer connected and
check the electrolyte level about once a month.

http://www.trojanbatteryre.com/PDF/d...ata_Sheets.pdf

I planned to put two Trojan 145's on the tongue of my Trill
but decided that the extra capacity was not worth the
extra tongue weight and cost.

It would be helpful to know the expected load on the battery.

Good Luck on your project.

Larry H

[Lorelei L]

Mary & Bob, our Uhaul is all original. It has an old 40w solar panel that I'd like to replace with a new 100w. Battery needs to be replaced and I want the most power storage I can cram in there. I would like to be able to charge our many devices and run a blender. We like to go to national parks and forests, so no hookups.

[mary and bob]

I would charge my devices in the car and get a hand crank blender (I've seen them) and keep it simple.

[Ice-breaker]

Originally Posted by mary and bob

I would charge my devices in the car and get a hand crank blender (I've seen them) and keep it simple.

Or even one of these:

[peterh]

First, if you're going to install a solar panel, you should plan on making sure your daily electric consumption is less than your solar panel's energy production. For this it's good to know the math.

So, how much solar power does your panel produce on a "perfect" day?

First, on a perfect day with perfect solar energy generating conditions and perfect alignment of your panel to the sun's incoming light, your panel can olny generate about 67 Amp Hours of power. (100w / 12v = 8.33 Amps/hour. 8.33 Amps * 8 hours = 66.66 Amp Hours.)

Alas, your solar system will almost never operate at 100%, so, let's reduce that output by about third, to 45 Amp Hours per perfect day. This is the maximum number of Amp Hours in your daily energy consumption budget, but be aware that there are many days when your solar panels won't achieve this goal. Like when you park in a forest or during the winter time, when there is much less sunlight. You might want to budget for just 22.5 Amp Hours of energy use, just to be safe.

Next, let's consider your battery. It's good to be able to carry at least one full day's sunlight in your battery. It's also preferable to make sure your battery doesn't fall below 40% charge. So, if you only ought to use, at most, 60% of your battery's charge and you want to carry a full day's worth of sun in your battery, that means you should have a minimum 75 Amp Hour battery. (45 Amp Hours / 60% = 75 Amp Hours.)

You might want to store some multiple of a day's sunlight, particularly if you like to park your solar panels in un-sunny locations. (Many National Forest locations come to mind.) The next larger battery sizes are 100 and 120 Amp Hours. If you have a daily energy use of 22.5 Amp Hours a day (which I think of as a luxurious amount of power), you could camp for more than 3 days on the energy stores in a fully-charged 120 Amp Hour battery.

My next thought on batteries is there are really just two ways to go: Really expensive or really cheap. A really expensive battery will never let you down and can last a decade if you keep it on a BatterMinder trickle charger/desulphinator when you're not using your trailer. A cheap battery will last you a couple years, maybe less.

My choice for an expensive battery would be a group 24 or 26 Trojan AGM battery with a Battery Minder trickle charger. They cost around $200, but they're maintenance-free batteries and they last pretty much forever if you keep them on a desulphinator when you're not using them.

For cheap, I'd go with a Walmart Marine batteries. They cost $80-100 and have one or two year, full-replacement warranties, and you can find a Walmart just about anywhere to get a replacement. The downside is you *will* need to replace them every few years, and they'll hold less and less charge over time.

[Carol H]

Originally Posted by mary and bob

I would charge my devices in the car and get a hand crank blender (I've seen them) and keep it simple.

Yup - I picked up a great little hand crank blender at a second hand shop for under $10. You can also pick up a new Votex Blender from REI or Mt. Equipment co-op for more.

[Lorelei L]

Great info! Thanks so much!

[padlin00]

Lorelei
If you have to stick with a Group 24 to fit the box I've had great luck with my Interstate SRM-24. Have had it for 8 years and it's still kicking, takes minimal water when I check it a couple times a year.
Also worth looking at may be the Trojan 24TMX, harder to find though. No direct experience but folks seem to think Trojans are the best. About $20-30 more then the Interstate.

Might want to measure the insides of the box to see how big of a battery you can fit in it, Larry says it's a single group 24 (11" x 6 7/8" x 9 1/2")

[Lorelei L]

I see we can order a Trojan 24TMX 12v for $158 total from Webosolar, so I think we'll go with that.

[Perry J]

Originally Posted by Lorelei L

I see we can order a Trojan 24TMX 12v for $158 total from Webosolar, so I think we'll go with that.

My Scamp, motorhome and slide in camper all have group 27 or 29 deep cycle Wal-Mart batteries.
The oldest is my Mo Ho house battery and it's 6 years old.
My slide in camper battery is 5.
The Scamp battery is 3 year's old as it didn't have a battery when I bought it.
The only battery I ever had go bad was in my 16' camp about 6 years ago.
I took it back and they replaced it with no problems.

The most expensive was the group 29, it was about $90.00.
They've never let me down.

Are you going to ship it back if it goes bad and wait for a new one?

John

[Gardnpondr]

Thank you guys soooo much for sharing your knowledge. I have never heard of a desulphinator before. Had to google that one. Learn something new everyday. Our camper had a battery but it's been sitting up so I have no clue if it'll even take a charge. Going to try and see though.

[dleverton]

PeterH. Very nice assessment.


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Doug L