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Discussion Starter #1
I recently purchased a lot of 8x 220AH 6v batteries that are all less than a year old. They came off a food truck that was built, but only used once before selling. The batteries were on a connected charger the entire time, so they were charged and are all in great shape.

This would give me 880AH of 12V power.

Part of this lot is a nearly new Prostar MPPT controller.

My original plan was to have a Sterling B2B charger and no solar - but I'm wondering if I should go to panels and utilize this huge bank to bridge the gap between not-so-sunny days.

Does anyone run this big of a bank? If so... why?

Thanks!
 

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It all depends.
Make your use and charging estimates.
Your 880 Ah at 6V is 440Ah at the typical 12V and double of mine.
With at most 50% discharging I can get 110Ah * 12 V = ~1320 Watt hours (1.3 kWh) out of mine.
As you see below I use maybe 0.3- 0.9 kWh.

In your situation I would maybe leave some room in the battery box area for expansion but fit your estimated use cals until you see that is not enough.
Batteries are heavy and take up valuable room in the van and if you can store the extra for a little while you see if you need to add them!

My calculation three years ago was pretty spot on and as far as I can tell the battery is still great shape and seldom touches 12V when discharging.
For me a single AGM 220 Ah 12V with 200 W solar panels did the trick.
I can charge my battery if needed from the engine but have only needed this twice (since early 2017, 120 days /year use), even when traveling in Oregon and Washington.
We are nice weather campers and only have a heating blanket to take the chill off the mattress.

My biggest user is the fridge: Watt * Hours or Amp * Hours (Ah) at 12Volts (mine runs 10 min per hour when constantly on) 24 Ah/day
Then occasional the use of the water pump and air fan together are at most 10 Ah/day.
Minor users are phone chargers, LED lights, propane sensor 5 Ah/day
The heating blanket (75W) would add another 5-10Ah for 30 to 60 min preheating the bed.
I also heat my water tank in the morning with the 300W water heating element (2.5 g water storage) =300Wh or (12V * 25A * 1 hr = 25 Ah at 12V) after an hour the water is used for dishes and washing up.
That water heating is about 25% of the 110Ah I can use from my battery storage.
So on the largest use days 60-70% of the 110Ah is used, more typical 30-40%, and the 200W solar panels replenish that before the sun goes down.
I can easily switch the water heating to the engine CCP during driving, which is what typically happens and allows the solar to recharge the battery even faster.

If we would add an electric coffee grinder, microwave, hair dryer etc I will need more storage. Before that, I will probably add another 100W to my solar as I value my indoor space highly.
 
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The only drawbacks are the weight and physical size.
Can you have too much reserve Ah?
 

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I would love that much battery capacity so I could run my A/C all night.

That 880 Ah is 10.5 kWh, of which 5~6 kWh is usable. That’s almost exactly the same as the Winnebago Travato with lithium option. While 8 batteries are a lot of weight and size, and also cost, it’s not that much energy storage compared to Travato and other Volta systems.

I see where charging that much battery capacity without shore power could be too slow. That’s where the new dual 250-Amp alternator option should make it more practical.
 

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I would love that much battery capacity so I could run my A/C all night.

That 880 Ah is 10.5 kWh, of which 5~6 kWh is usable. That’s almost exactly the same as the Winnebago Travato with lithium option. While 8 batteries are a lot of weight and size, and also cost, it’s not that much energy storage compared to Travato and other Volta systems.

I see where charging that much battery capacity without shore power could be too slow. That’s where the new dual 250-Amp alternator option should make it more practical.
Chance, the 880Ah is at 6V --> total 5.2 kWh of which you should only use 50% to keep the batteries healthy, so 2.6 kWh not 10.5!
 

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Discussion Starter #9
Thanks for the perspectives everyone. I just want to confirm- this is 1760AH at 6V. So 880AH at 12V and effectively 440AH usable.

Although it begs the question. Is this enough power for AC? 50% of usable AH is the metric for most builds, but on those particularly miserable nights where you need AC - can these batteries be run to 25% SOC? We are talking a few times per year.

That would be tempting.
 

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Thanks for the perspectives everyone. I just want to confirm- this is 1760AH at 6V. So 880AH at 12V and effectively 440AH usable.

Although it begs the question. Is this enough power for AC? 50% of usable AH is the metric for most builds, but on those particularly miserable nights where you need AC - can these batteries be run to 25% SOC? We are talking a few times per year.

That would be tempting.
Any lead acid CAN be run to 25% the thing to realize is how running below about 70% will shorten the overall life of the battery to some degree. The further and more often you go beyond that the more is taken off the life. Go to the manufacturer's site and get the datasheet for the battery. It should include a graph or table that provides accurate information to base a decision upon.

Though, if you got them for a song, WTH. Just keep in mind how, if you get used to using that much Ah, you will be paying full price come replacement time. Whether that is in 10, 5, or 3 years will be determined by use. Maybe Lithium or other similar technology will be cheap by then.

Looks like a great start with a fantastic bargain. I'd just as likely would have put half in the van and half in my shop with a couple of 200 Watt panels, charger, and inverter to get it off the grid.
 

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That's over 400AH of useable capacity. If you do actually need that much, it would take a 60A Sterling 8 hours to recharge. I would add some solar to help cut down the driving time required.
If you have the HD alternator install the Sterling 120A B to B charger. I installed one over the weekend and going from a 40A to 120A was incredible. Now I can run the 120V roof AC while traveling.
 
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