Battery Size Large VS Small

[wcurtin1962]

Thinking out the house system for my van.  Should I go with multiple smaller batteries VS a few large batteries?

My thoughts:

Small:

• Cheaper per unit, Allowing me to build my system at more of a steady rate as my needs become apparent .  Replacement due to failure cheaper.  Positive
• More flexible use of mounting space. Positive
•  Requires more mounting hardware, more wiring and more connections. Negative 
• More weight due to casings, mounting hardware and wiring. Negative

Large:

• Less mounting hardware, wiring and connections. Less weight per capacity. Positive
• Easier to connect battery minders, solar controllers, inventers , etc.   Positive
• I’m going to use AGM batteries mounted inside.  
• Any thoughts?

 

[jonyjoe303]

it depends if you got the room to parallel 2 batteries right next to each other. Originally I was going to buy a second kinetik kh2000 agm to connect with my other kinetik, but they are huge heavy batteries I couldnt figure out how I was connect them together in the space I had. I just went with the one battery. You would almost have to buy both batteries at the same time, so they would be of the same condition. You don't want to parallel a new with a used battery.

Right now I have 3 agm's and 3 lithiums all over my van, they are backups to my backups, and I'm getting ready to build another lithium. If one of my batteries goes low, I just connect another battery. To me that is more convenient than to try and parallel 2 batteries. 

I carry one small agm (fullriver 28 ah) which I only use for emergencies, to jumpstart my start battery, I can also remove the start battery and slap that battery in and run the van with it fulltime. 

Once I build my other lithium 100 ah, I can get rid of all the agm except the fullriver. All 4 of the lithiums (almost 300ah total) would weigh about 70 pounds,  the same as my kinetik (102 ah but actual 51 ah usable).

You can never have too much batteries, you just have to make room for them.

With some charge controllers you can charge 2 agms at the same time. My ecoworthy 20 amp mppt, if I connect another battery to the load out, it will charge that battery. Why parallel if you can do that?

 

[highdesertranger]

all batteries in a bank should be the same size, type, and age. I other words if you have 2 batteries in a bank and one goes bad you shouldn't just replace the one battery. highdesertranger

 

[akrvbob]

The one critical thing in the decision is you can't mix batteries of different sizes or much different ages. Once you start using the batteries, you may have a month to add another but no longer.

So you want to get it right the first time, not keep adding to it.

The best battery bank is a pair of golf cart batteries bought the same day--IF you can fully recharge them nearly every day.

 

[jimindenver]

I will add that it is recommended to parallel no more than three 12v or pairs of 6v in order to maintain balanced discharge and charging. You can exceed it but then additional battery interconnects becomes complicated. Also it takes lead to hold Amp hours. Lead is lead no matter what form big or small. There is not going to be a big difference between two solutions holding the same Ah's.

 

[jonsun]

more smaller batteries can handle higher loads. More overall surface area of the lead.