Series or parallel...

[MTVR]

In looking at lithium batteries, I'm running into some challenges- a lot of the manufacturers recommend not putting them in series, and yet I'm also learning that it's not a good idea to parallel more than two batteries.

So if I want 400Ah at 12 volts, I need to buy a pair of 200Ah batteries and parallel them, because it would not be a good idea to parallel four 100Ah batteries.

And if I want 200Ah at 24 volts, I pretty much need to use four 100Ah Battleborns in series-parallel, because most other manufacturers don't recommend putting them in series.

I see that AIMS has 200Ah 12-volt batteries- I could parallel two of them to get 400Ah at 12 volts.

Am I missing anything?

 

[Buliwyf]

You can parallel as many batteries as you want to. As long as they all get charged properly. And that they don't start dualing with each other. Which they rarely do when kept on a charger.

I wouldn't run them too low without checking each batteries voltage directly.

Just finished servicing an engine with just 2 starter motors, and had 8 batteries. Two chargers. Seemed like a simple two sets of 2s2p batteries setup with each bank having it's own charger and starter motor. No more complex than a dual battery setup on anything 24v. Then I noticed the jumper cable between the starters. Each bank was connected to each other.

Your phone companies land line might have 100 48v batteries in parallel.

 

[jonyjoe101]

Yes you should be able to parallel more then 2 lithium. Once you hook them up together they equalize and you can charge and disharge them together. My house battery is 4x 55ah lifepo4 batteries parallel together, they been hooked up together for the past 3 years without issues. Just make sure they are all at the same voltage when you connect together, though if the voltage is slightly off not much will happen, amp transfer between a battery that is 13.3 and one that is 13.1 will be very low.

 

[MTVR]

Okay, thanks.

Any input on the AIMS 200Ah batteries? They're only about $1,500 each...

 

[MTVR]

If we sprung for three of those, to give us 600Ah of capacity and could thus only muster a charge rate of 0.2C, would there any other side-effects (as opposed to a charge rate of 0.4C) other than taking longer to charge our house bank?

 

[Jman99]

All I can say is do your research... If the maker of the battery says they can be than it should be fine, if they say no, than don't. But dropins usually have poor quality so it don't really matter imo. The basic concern is some dropins have no balancing & overtime the cells can go out of balance more quicker than if used on its own, espelley with high C rates. Or if the individual BMS is crap & can't handle the big loads if the other one disconnects for some reason.

 

[MTVR]

Battleborn specifically states that their batteries have passive cell balancing.

I'll have to call AIMS tomorrow to find out about theirs...

 

[86scotty]

For those curious, which I was, the AIMS 200ah lithium above is only 56 lbs. Amazing. Half the weight, or maybe less, of a 200ah 4d lead acid.

If only I could find out how long they will really last in real world circumstances.....

 

[MTVR]

For those curious, which I was, the AIMS 200ah lithium above is only 56 lbs. Amazing. Half the weight, or maybe less, of a 200ah 4d lead acid.

If only I could find out how long they will really last in real world circumstances.....

Our truck has a 62,200 pound GVWR, and a 30,000 pound payload capacity- I don't care how much they weigh...

 

[dreadlocks]

You do Realize 400AH @ 12V == 200AH @ 24V right, thats the same power.. 400AH @ 24V would be twice the power.

You could run 4x12v 100AH BB's, 2 in a series, 2 in parallel.. 200AH @ 24V, just because your AH went down dont mean your runtimes did, because all yoru 24v appliances now take half as much amps.

 

[Alloy]

Our truck has a 62,200 pound GVWR, and a 30,000 pound payload capacity- I don't care how much they weigh...

......until you're stuck or sliding sidways on a muddy/icy road

 

[MTVR]

......until you're stuck or sliding sidways on a muddy/icy road

The last time I was stuck, unintentionally, and required the assistance of others to get unstuck, was when the peanut farmer was in the White House...and I wasn't driving...and it wasn't my vehicle.

A hundred pounds here or there is like spit in a rain barrel for us...

 

[MTVR]

You do Realize 400AH @ 12V == 200AH @ 24V right, thats the same power.. 400AH @ 24V would be twice the power.

Yeah, sorry. Third-grade math was the longest three years of my life.

You could run 4x12v 100AH BB's, 2 in a series, 2 in parallel.. 200AH @ 24V, just because your AH went down dont mean your runtimes did, because all your 24v appliances now take half as much amps.

Yeah, I got that...

 

[Buliwyf]

If you need ballast weight, plain old 4d batteries and a jug of water, might be a better option.

Personally, I'd rather have a rack of Group 31's. As long as they had removable plugs to check fluid levels.

 

[Alloy]

The last time I was stuck, unintentionally, and required the assistance of others to get unstuck, was when the peanut farmer was in the White House...and I wasn't driving...and it wasn't my vehicle.

A hundred pounds here or there is like spit in a rain barrel for us...

In my experience it's amazing how fast rain barrels get filled with weight. Before you know it there are a bunch of barrels that weren't there before.