amp hours and agm batteries

[Randog]

My first post. I had asked Solar Boondocker and Bob how many ah were in the agm batteries to power their rigs. My question was read as how many agm's. I could have miss asked the question. Common these days with chemo brain.
I guess I'm asking what formula is out there.
I want to use a 700 watt microwave, a 5000 btu air conditioning unit, may end up with a swamp cooler, a wynter 45 quart refer or maybe an ice maker and cooler, and a smart tv. I now have 4 / 100watt panels with a pmw? controller. I'm going to upgrade to an mppt. I revived 2 agm 43 ah wheel chair batteries so they now accept a charge.
Currently the controller is showing I'm taking in 13.4 amps into the batteries.
I haven't hit the road yet but target date is July 19th 2018 and heading to the Winthrop Blues Festival in Washington.
I also bought a Harbor Freight 2000 watt generator.
Heading out in a 84 chevy 3/4 ton van and a 6 x 10 cargo trailer. I'm taking Mr Wells suggestions.
Addicted to TV and want to stay connected.
Any and all knowledge shared is greatly appreciated.
Thanks to all!

 

[John61CT]

That is a **lot** of power draw, needs a half ton or more of battery bank.

And even if your truck can carry that big a bank around all the time, can you afford the extra gasoline expense?

The bigger problem is how are you recharging that bank every day? Maybe $5000 worth of solar if you have 30' x 8' roof space, but what about when the sun's not shining?

Better I think to lower your expectations, increase your knowledge first, then plan on much more efficient devices.

 

[John61CT]

OK, re-read and saw the genny this time.

As long as you are always running that during very heavy loads, you can likely get away with a smaller bank.

I'd say 600-800AH will give you a decent buffer

The best battery value by far is Duracell (actually Deka/East Penn) FLA deep cycle golf cart batteries, 2x6V, around $200 per 200+AH pair from BatteriesPlus or Sam's Club

So 3 or 4 pair of those.

AGM will recharge a little bit faster, but **lots** more expensive, as in thousands.

Odyssey, Northstar or Lifeline. See if you can find 2-4V units, over 3 12V in parallel you'll get balance problems and reduce longevity.

You will need to fill your roofs with as much solar as possible to fit, make sure you charge as full as you can early every morning so solar is able to get a good start on the last 10-15% the whole solar day will take, hopefully get to 100% Full at least most days.

The key will be turning the genny on soon as you start drawing more than say half the power the solar is supplying in order to keep the bank charging.

You will need to get up to speed on measuring amps and AH per time period in order to get decent lifespan out of your bank, otherwise will be replacing it pretty often.

Best to get back to overnight mains pretty often as well to ensure those Full charges.

You will need to buy very high-amp chargers, especially if you get AGMs.

 

[rvwandering]

Welcome to the CRVL forums randog! You'll probably get more answers if you post again in this section Electrical: Batteries, Generators, Solar https://vanlivingforum.com/forumdisplay.php?fid=18

To help you learn the ins and outs of these forums, this "Tips & Tricks" post lists some helpful information to get you started. We look forward to hearing more from you.

 

[Randog]

OK, re-read and saw the genny this time.

As long as you are always running that during very heavy loads, you can likely get away with a smaller bank.

I'd say 600-800AH will give you a decent buffer

The best battery value by far is Duracell (actually Deka/East Penn) FLA deep cycle golf cart batteries, 2x6V, around $200 per 200+AH pair from BatteriesPlus or Sam's Club

So 3 or 4 pair of those.

AGM will recharge a little bit faster, but **lots** more expensive, as in thousands.

Odyssey, Northstar or Lifeline. See if you can find 2-4V units, over 3 12V in parallel you'll get balance problems and reduce longevity.

You will need to fill your roofs with as much solar as possible to fit, make sure you charge as full as you can early every morning so solar is able to get a good start on the last 10-15% the whole solar day will take, hopefully get to 100% Full at least most days.

The key will be turning the genny on soon as you start drawing more than say half the power the solar is supplying in order to keep the bank charging.

You will need to get up to speed on measuring amps and AH per time period in order to get decent lifespan out of your bank, otherwise will be replacing it pretty often.

Best to get back to overnight mains pretty often as well to ensure those Full charges.

You will need to buy very high-amp chargers, especially if you get AGMs.

 

[Moxadox]

Like everyone else has said, that's an awful lot of power you're talking there.

Most of us who run "regular size" solar setups get used to managing our power usage. For instance, if you're running a fridge, you might want to turn it off while using something else. I have 760 watts of solar on my roof with 6 AGM batteries. If I want to run my 13 kw AC unit, that's generator. Microwave, except for a very brief burst--genny. Fridge gets turned off at night.

Living in houses we get used to just running everything at once. Not so when you're running on solar, not unless you're blessed with acres of solar real estate on the roof and many thousands of do-re-mi. It can be done, and people do it, but that's what it takes. I've seen people with full size skoolie buses covered with panels running, for instance, a ham radio station, lots of watts! Fills me with admiration.

Good luck on your project! I look forward to following along and learning with you.

Sent from my SM-N950U using Tapatalk

 

[jonyjoe303]

If you do a swampcooler instead of AC, even your modest 86 ah of agm batteries will run it even at night when the sun goes down. But you need massive insulation which is no big deal to install and easier to carry around then 400 pounds of batteries. For the microwave and fridge you might need a bigger battery. I say at least 100ah plus the 86ah you have. 400 watts of solar is plenty.

This is results I get on my van, front of van is uninsulated back is heavily insulated and only have a small 2 amp swamp cooler running. notice the humidity, it been high lately. It got as high as 89 (humidity) but swampcooler kept me cool. This is parked in the sun with all my windows/doors/vents closed. You can stay cool without an AC and minimal power. Even on hot day, I might use 2 liters of water on the swampcooler, so even that isnt a big problem. Carrying alot of batteries will affect you van performance, on mine it takes longer to stop, I use to carry about 300 pounds of batteries, now that I moved to lithium I carry less then 100 pounds.

 

[ISAWHIM]

The way you do the math can be simplified if you do it all in watts... Amp-hours is a useless number, without voltage.

For lead-acid, you need to use HALF the amp-hours for your calculations, because you can't drain past 50%, without causing damage. Even in a deep-discharge battery. It just gets less damage at that point, and lower.

A 100 amp-hour battery is normally rated for a "perfect world delivery". Low power draw. Drawing a high-load will give you a lot less. This is why it is better to have more batteries or larger batteries, so each will see a smaller individual load and give you a more expected number to these calculations. It will deliver 100 amps of power, to a load that pulls 100 amps, in an hour, for an hour. Then your battery will be 100% dead. (No more usable charge, not unable to be charged.)

100 amps, per hour... We use 50, since that is half the load/power...
Multiply that by 12v (A battery will charge higher and fall lower, but this is the "expected formulated average".)
You get... 12 x 50 = 600 watts for one hour, which will leave the battery half-full.

That would be 300 watts for 2 hours, or...
200 watts for 3 hours, or...
100 watts for 6 hours

You could push those results to 2x longer, at the cost of damaging your battery...

A 100 amp-hour lead-acid battery will weigh about 50-60 lbs. (Or more) {600 watts} $100-$300
A 200 amp-hour lead-acid battery will weigh about 100-120 lbs. (Or more) {1200 watts or 1.2 kW} $200-$550
A 400 amp-hour lead-acid battery will weigh about 200-240 lbs. (Or more) {2400 watts or 2.4 kW} $400-$1000

2400 watts will run a 5000-btu AC, (400w), for about 6 hours. That is running continuously, without cycling on and off.

On the other end, is something like the Tesla PowerWall 2, which weighs about 275 lbs and gives you 13.5 kW of usable power. This is a Lithium battery, which comes with its own charge regulator. But it is expensive, yet, the cheapest of all other Lithiums that exist. $6000-$8000 installed.

13500 watts will run a 5000-btu AC, (400w), for about 33.75 hours, or about 1 and a half days.

 

[Randog]

If you do a swampcooler instead of AC, even your modest 86 ah of agm batteries will run it even at night when the sun goes down. But you need massive insulation which is no big deal to install and easier to carry around then 400 pounds of batteries. For the microwave and fridge you might need a bigger battery. I say at least 100ah plus the 86ah you have. 400 watts of solar is plenty.

This is results I get on my van, front of van is uninsulated back is heavily insulated and only have a small 2 amp swamp cooler running. notice the humidity, it been high lately. It got as high as 89 (humidity) but swampcooler kept me cool. This is parked in the sun with all my windows/doors/vents closed. You can stay cool without an AC and minimal power. Even on hot day, I might use 2 liters of water on the swampcooler, so even that isnt a big problem. Carrying alot of batteries will affect you van performance, on mine it takes longer to stop, I use to carry about 300 pounds of batteries, now that I moved to lithium I carry less then 100 pounds.

 

[lenny flank]

It got as high as 89 (humidity) but swampcooler kept me cool

How do you even get a swamp cooler to physically work in 89% humidity............

 

[Randog]

Hey there!
If your running 6 agm's, what are the amp hours of each? I revived 2 agm's with 43 ah each. They were free and I'd like to ad to my 400W system but am unclear on adding to the existing set up. I am going to up my inverter from 400w to 3000w and exchange controller from a pmw? to a mppt before I ad batteries.

 

[highdesertranger]

if you already have batteries take note, batteries in banks should be of the same type, age, and capacity. highdesertranger

 

[Randog]

Thank you highdeasertranger. I managed to revive my bro's wheel chair batteries to accept a charge. Learned from jehugarciayoutube a battery guy. The VA got my bro new batteries.
I've called the golf courses and wheel chair outfits in the Coure D Lane area and Spokane. Haven't been able to locate old batteries yet. They, of course offer new.
I wasn't aware I'd need to use similar age, batteries.
My thought was find used close to the 43ah each agm's I'm using and add 2 or 4 more to each of my batteries close to the same ah. I also was thinking of buying a couple new ones providing 200 ah each giving me a total of around 243 ah each to equal 486 total ah.
Goal to power;
fridge / winter 45-85 quart
5000 btu A/C or a swamp cooler
48 inch smart TV- may need to buy a new 32 inch - I'm trying to avoid buying new here
700 watt micro wave
phones,laptop,coffee, misc
Thx again

 

[highdesertranger]

that's pretty heavy power needs, especially AC and micro. you need to add up all your power needs then size the battery bank to that. remember you only have 50% of the amp hour rating of your battery bank. you also need a charge source to recharge your bank ASAP, think recharging everyday. with those power needs a cobbled together battery bank will not preform like you envision. highdesertranger

 

[John61CT]

You need to get realistic about living within the limitations of DC electrics.

Or be ready to spend thousands, and learn the techie details of how to delay replacing the batt bank often.