12 volt 100 AH batteries

weirdjim

weirdjim

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weirdjim
I'm getting ready to do my next Kitplanes article on getting the hangar off-grid and am looking around for a good source for 12 volt moderately high amp-hour units. I'll be charging with a Harbor Freight 100 watt solar panel, so 8 amps or so at full sun.

I don't want to do one-off sources (surplus, one-of-a-kind etc.) because my readers might want to copy my design and buy one like mine.

A good source for charge controllers would help also.

All suggestions appreciated.

Jim
 
Might look into what the off-road RVers are using.
 
I would consider using Group 31 batteries. Truck starting batteries go on sale in the fall and they can be picked up for about $75 each. Two of them would replace one deep cycle Group 31 for about $250.

It is just a suggestion.
 
Can’t help re battery....but definitely stay away from Harbor Freight or Northern Hardware charge controllers. I’ve had excellent experience with WindyNation controllers.
 
NoHeat said:
What load will be powered in the hangar? Lights and door?
Click to expand...

Lights -- 12 volt LED strip lights (5 meters/strip) glued to 4' long thin plywood strip the same size as a 4' shoplight fixture. 6 strips should do it at about 1.5 amps/strip. Door is operated by Armstrong method. On occasion a small soldering iron for a few minutes at a time. Small 12 volt compressor for tires and annual leakdown testing (*). Hangar radio small handheld on charger. Small camper size three or four can adult beverage cooler. I'm sure I've missed something.

(*) May just go hybrid and use gas generator for 110 AC compressor unless I can find a 12 volt compressor that doesn't take 20 minutes to get up to 100 psi.

I have a 100 watt 4-panel solar charger from a Kitplanes article I did over 10 years ago that I hope to be able to press into service.

Jim
 
Last edited:
Looking forward to the article, I see you already have the solar panel so makes sense to use it. Last time I checked (and purchased one) 100 Watt solar panels we much cheaper and smaller (single panel) off of ebay than the HF panels.

Brian
 
weirdjim said:
Lights ... small soldering iron for a few minutes ... compressor for tires ...radio... beverage cooler."
Click to expand...

This sounds a lot like the load requirements for somebody living off the grid. I wonder if that community has a how-to-do-it wiki or book.
 
In the RV, we use 6V golf cart batteries like you can buy from Sam's Club or Costco. Wire them in serial to make 12V, then wire the sets in parallel to increase the amount of amp hours required. You can wire as many sets together as you like. Get the connecting wires from Ebay for cheap.
 
The cooler is the tough one unless you're talking one of those thermoelectric ones, which don't work very well unless the contents are already cold.

I've had good luck with a Viair 12V compressor, I use it for a pneumatic lift on our popup camper. Much better quality than any other 12V compressor I've ever used, and I didn't get their "best" one. But you're still going to be limited, cfm is proportional to input power.
 
Jim, I bought a couple of these for the Airstream a few years ago. I think that AGM is worth the extra cost to not worry about fluid levels/etc. NOTE (I'm sure you know this, based on your background). The charge voltages required for AGM are different than flooded cells and even vary by brand

https://www.amazon.com/Universal-Po...words=100ah+agm+battery&qid=1584670962&sr=8-4

you can also charge them very fast if needed, so if the scenario is occasionally using a genset to top them off, they'll drink the current quickly.
 
Send me a message. I’ll send you a 110ah AGM gratis for mentioning my battery in your article

we manufacture and sell solar panels, batteries and charge controllers for the off grid SCADA world. Oil and gas automation and measurement.

Doug at rdasolutions dot net
 
Jim,

You might find some of the stuff in this article helpful. The guy's writing style and site formatting aren't the greatest, but he knows his stuff.

https://marinehowto.com/mppt-vs-pwm-solar-controllers/

A 100w panel would seem to be sufficient for the needs you detailed, but keep "mission creep" in mind.. once you've got the system up and working well, the desire to use a few more amphours now and again for things not currently envisioned might arise. A 100AH battery, for best longevity, shouldn't routinely be discharged to more than half it's capacity, so realistically figure it's capable of 50AH before requiring charging. Your 8A output estimate for your panel is reasonable given strong even sunlight, but that's for how long on a given day, and how many overcast or rainy days to you get? You might get 500 watt hours out of the panel on a perfect day, translating into 41AH of charge before allowing for losses and inefficiencies in wiring and a controller. Realistically, you'll get less than that... maybe significantly less.

What I'm getting at is that it might be worth getting a good MPPT controller to make sure you're getting the most out of your panel. I've got an el cheapo PWM controller that came with a Renogy 50w panel I use on my small sailboat. The panel works great.. the controller is a piece of garbage. I have no personal experience with this one, but it looks like a good choice although it is a lot more money than a $25 pwm controller...

https://tinyurl.com/wvr8o7t (link to product on amazon)

MonkeyClaw's suggestion re/ wiring two 6v golf cart batteries in series (or four in series-parallel and put in an electric hangar door opener and bigger fridge... ;) ) above is a good one; lots of capacity for minimal cost. Downside is that they are heeeeaaaaavvvvvyyyyyy....
 
C&D makes nice large SLAs that get used in data center battery banks — I have 12 75Ah high current ones here that were mandatory “pull and replace” from a data center over a decade ago.

Three have only recently died and wouldn’t have with better care.

So I get the desire for lead-acid as simple as can be. But...

If I were buying, I would look hard at price and possible charging hassle of the LiFePo replacement packs designed to replace certain sized lead-acids.

Moving these fat asses around is backbreaking. A LiFePo equivalent is a nothing-burger weight wise.
 
I would definitely consider using lithium considering they last longer and have more long term usable capacity.

You shouldn’t be discharging Lead Acid batteries regularly before 50% and they should be floated at 100% regularly.

LifePo4 is mostly a drop in replacement for 12v systems. They are nowhere as combustible as lithium ion. Cost is higher upfront and you will want to pick an appropriate charge controller with programmable voltage settings.
 
I know someone who works for this mob -

https://www.victronenergy.com/products

who seem to make every kind of charge controller / inverter / whatever known to mankind. I have no experience of them. Can have remote management /monitoring.

Consider if you want an MPPT charger which can increase the efficiency of the power transfer from the Solar array to the batteries.
 
MuseChaser said:
Jim,

You might find some of the stuff in this article helpful. The guy's writing style and site formatting aren't the greatest, but he knows his stuff.

https://marinehowto.com/mppt-vs-pwm-solar-controllers/

A 100w panel would seem to be sufficient for the needs you detailed, but keep "mission creep" in mind.. once you've got the system up and working well, the desire to use a few more amphours now and again for things not currently envisioned might arise. A 100AH battery, for best longevity, shouldn't routinely be discharged to more than half it's capacity, so realistically figure it's capable of 50AH before requiring charging. Your 8A output estimate for your panel is reasonable given strong even sunlight, but that's for how long on a given day, and how many overcast or rainy days to you get? You might get 500 watt hours out of the panel on a perfect day, translating into 41AH of charge before allowing for losses and inefficiencies in wiring and a controller. Realistically, you'll get less than that... maybe significantly less.

What I'm getting at is that it might be worth getting a good MPPT controller to make sure you're getting the most out of your panel. I've got an el cheapo PWM controller that came with a Renogy 50w panel I use on my small sailboat. The panel works great.. the controller is a piece of garbage. I have no personal experience with this one, but it looks like a good choice although it is a lot more money than a $25 pwm controller...

https://tinyurl.com/wvr8o7t (link to product on amazon)

MonkeyClaw's suggestion re/ wiring two 6v golf cart batteries in series (or four in series-parallel and put in an electric hangar door opener and bigger fridge... ;) ) above is a good one; lots of capacity for minimal cost. Downside is that they are heeeeaaaaavvvvvyyyyyy....
Click to expand...
I have used a similar battery controller from the same company for a Boy Scout camping project and it worked well. The MPPT is a nice feature that makes it work much more efficient than the ones with the older algorithm. You really wouldn't need the 30 amp version for your requirements and could easily get along with a 10 or 20 amp variety which are less expensive. We are also using a 20 watt panel with a $15 battery controller to keep a 12v lawn mower battery charged and that works fine. You will need an on-off switch for wires from solar panel and the panel needs to be off until you have connected the battery to the battery controller. Once the display is active on the battery controller, then turn on the solar panels. If you do not do this, the battery controller can default to a higher voltage battery (24v) and start charging your battery at 28v. You do not want to do that.
 
Below is an overview of the solar system we developed for the Boy Scouts.
 

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