Battery Bank Size

[electricthot]

My battery (Renogy 12v 100Ah AGM) manufacturer recommends up to four batteries paralleled in a battery bank. I need 800Ah capacity. What is a simple solution here?

 

[Mattb4]

Pick up a good quality bus bar and you can either hookup the batteries individually to it with same length cables or in series of two connected in parallel with each other and than wire to bus bar on opposing battery terminals.

 

[Rednecktek]

Simple solution is to get the big 400Ah batteries and parallel those. Easier to connect up and keep 2 batteries balanced than it is to find room and cableage and all for 8 batteries.

 

[electricthot]

Pick up a good quality bus bar and you can either hookup the batteries individually to it with same length cables or in series of two connected in parallel with each other and than wire to bus bar on opposing battery terminals.

I take all my batteries to a central point (bus bar style) with same length cables, both positive and negative, and feed my loads from there. Does this eliminate the need for a battery balancer?

 

[electricthot]

Simple solution is to get the big 400Ah batteries and parallel those. Easier to connect up and keep 2 batteries balanced than it is to find room and cableage and all for 8 batteries.

I need lighter batteries. And cheaper to replace.

 

[Mattb4]

... Does this eliminate the need for a battery balancer?

The need and use of an active battery balancer is more often for individuals cells wired in series versus parallel batteries. But my knowledge on whether it would be a good, or needed thing, to use for your stated purpose is non existent. Perhaps someone else can answer.

 

[yabert]

My battery (Renogy 12v 100Ah AGM)

You plan 10 kWh AGM battery?
Do you took time to look at lifepo4 batteries price?
You can be surprise to realize that lifepo4 can be cheaper / kWh (usable).

 

[Robbert]

The need and use of an active battery balancer is more often for individuals cells wired in series versus parallel batteries. But my knowledge on whether it would be a good, or needed thing, to use for your stated purpose is non existent. Perhaps someone else can answer.

You are right. A balancer does not make any sence to add to batteries in parallel.

 

[Rednecktek]

I need lighter batteries. And cheaper to replace.

In that case, bus bars and equal length wires and you should be fine.

 

[electricthot]

My battery (Renogy 12v 100Ah AGM) manufacturer recommends up to four batteries paralleled in a battery bank. I need 800Ah capacity. What is a simple solution here?

Here's my solution: The understanding I can gain from this device I put together will let me make comparisons that will answer my questions.
These 100 amp shunts are only 16 bucks apiece--it takes two to view both charge and discharge rates simultaneously. Put one set on each battery or battery group, or just on a battery in question. Daily use is re-settable. At the end of the day, I can tell who the hogs were, and in the morning I can tell who the workhorses are.
This shows a current current discharge of 13.59 amps.

 

[Mattb4]

I would suggest if you are going to install large battery banks that you pickup some tools to put on proper terminals for all your wires. Various crimpers, heat gun and and heat shrink tubing makes a better installation. Do not forget proper wire sizing.

 

[electricthot]

I would suggest if you are going to install large battery banks that you pickup some tools to put on proper terminals for all your wires. Various crimpers, heat gun and and heat shrink tubing makes a better installation. Do not forget proper wire sizing.

I use liquid electrical tape where needed. I use lugs everywhere, and just hammer them flat. I keep various sizes of copper tubing on hand to make my own lugs/connecters. I buy only welding cable, and nothing smaller than 6ga.

 

[Mattb4]

I use liquid electrical tape where needed. I use lugs everywhere, and just hammer them flat. I keep various sizes of copper tubing on hand to make my own lugs/connecters.

Your choice. May cause problems with unequal resistance.

 

[electricthot]

Your choice. May cause problems with unequal resistance.

Every unsoldered connection anywhere near my batteries gets regularly brushed with WD40. That enhances conductance, and prevents corrosion.

 

[Q-Dog]

Every unsoldered connection anywhere near my batteries gets regularly brushed with WD40. That enhances conductance, and prevents corrosion.

All of my battery connections are well crimped and sealed with heat shrink, and don't really need any additional maintenance or special voodoo sauce to keep them working.

 

[pollenface]

You plan 10 kWh AGM battery?
Do you took time to look at lifepo4 batteries price?
You can be surprise to realize that lifepo4 can be cheaper / kWh (usable).

3.8x cheaper over their lifetime by my napkin calculations.

 

[yabert]

3.8x cheaper over their lifetime by my napkin calculations.

Over the lifetime, of course.
My point was they can be cheaper day one considering usable energy of lead is around 50% if you want to have more than 100 cycles of life.
Compare to LFP who are rated for thousand cycle of life 100-0%.
So, 100Ah LFP = 200Ah lead day one.

I prefer to let know people why to stop spend on crappy lead battery.

 

[Bop]

Over the lifetime, of course.
My point was they can be cheaper day one considering usable energy of lead is around 50% if you want to have more than 100 cycles of life.
Compare to LFP who are rated for thousand cycle of life 100-0%.
So, 100Ah LFP = 200Ah lead day one.

I prefer to let know people why to stop spend on crappy lead battery.

Far cheaper (which is why practically all offgrid installs here in Aust (apart from some 'diy' homebrews lol) use LFP (or LYP for those in the hotter regions here)
A L/A set costs about half the price initially for the same 'Ah written on the case', but straight off the bat- you get more actual storage on a LFP than a L/A
Taken to a 50% DOD daily (any more than a 50% DOD discharge will very quickly kill your battery bank, down to a few tens of discharges if that...), you get 800-1200 cycles on a L/A usually before noticeable loss of capacity is evident ie 3-5 years used daily in an offgrid system), decrease the DOD to 25% of the 'label' capacity and you are looking at the 1500-1800 cycles region, and drop it to a 10%DOD and you might get up to 2500-3000 charge cycles (8-10 years)- but at that level you are only using 1/10th of he label' capacity ie you need a HUGE bank to get what the 'label' says and a 10 year life span...

Meanwhile the LFP can use up to 80% of the 'label' rating (there's a 30% increase there) and will last 5000 cycles minimum, decrease it to 70% (still 20% more than that L/A bank) and that stretches out to 7000 plus cycles(20 years)- at only twice the initial price for the same 'label' Ah's...

Effectively- to get a L/A bank to 10 years/3000 charge cycles, you need to 'oversize' it by a factor of ten to get the actual Ah you need, and replace it again to get to 20 years...
While the LFP (which costs twice as much initially) only needs to be 'oversized' by a factor of 1.3 to get that same 20 years...

10x the desired storage capacity, bought twice- but half the initial price per Ah, versus twice the initial price per Ah, but need only 1.3 times the desired capacity, bought once...

Geeee... which one should I chose?????



L/A really is a poor choice these days in comparison...

 

[electricthot]

All of my battery connections are well crimped and sealed with heat shrink, and don't really need any additional maintenance or special voodoo sauce to keep them working.

Heat shrink is inferior to liquid electrical tape. Heat shrink isn't waterproof. And connections can corrode under heat shrink.

 

[Bop]

Heat shrink is inferior to liquid electrical tape. Heat shrink isn't waterproof.

There are heatshrinks available for use with waterproofing compound inside (in fact they are rated for use completely underwater, and in explosive gas environments like coal mines lol)
Not a fan of 'liquid tape' as it has dubious ratings, depending on the thickness of it