Mix Matching LiFePO4 Batteries

[wpns]

I honestly can’t parse your drawings. You’ve got missing wires, you’ve got added wires, you’ve got wires shorting out battery terminals. If you don’t understand what you’re doing and you start building this you are going to have at the very least excessive currents as you assemble it, and worst case, overheating, venting, and explosions. Please do not do this without a thorough understanding of batteries and electricity.

Series connections of batteries should all be the same battery type , manufacturer, model, and capacity.

Each set of series batteries should have an interbattery balancer/equalizer.

Putting different capacity batteries (or strings of batteries) in parallel works just fine if your wiring is done properly and you have the appropriate over current protection devices.

Honestly, you are adding complexity and confusion, you should really be using batteries that are at the intrinsic voltage of your inverter, or you going to be back here in six months or a year asking us what went wrong.

 

[50ShadesOfDirt]

If you look at any battery vendor's user guides, you'll find rules on how many batteries can be series'd or parallel'd ... and a primary rule of don't mix battery makes (vendors), and a secondary rule (sometimes, most times) of keep them close together in calendar purchase times (not years apart).

Each battery has it's own BMS in it, and these mostly don't play well together ... best to keep them all the same, and follow the vendor guidelines for just one vendor's battery model.

You can do what you want, but perhaps not safely ...

I'd pick the best from the multiple makes you have, and plan on that battery-bank(s) having one model only, being expanded, over time, and up to the limits that the vendor of that battery imposes. Confirm with the vendor (to get access to the engineers, who might bless what you are trying to do, or who might point out the ticking time-bomb). Above all, use bus-bars, matching cable lengths & sized right, etc ...

See the many 12v battery-bank design websites and calculators, and get the diagrams done for you ...

Hope this helps ...

 

[SolarAntics]

I honestly can’t parse your drawings. You’ve got missing wires, you’ve got added wires, you’ve got wires shorting out battery terminals. If you don’t understand what you’re doing and you start building this you are going to have at the very least excessive currents as you assemble it, and worst case, overheating, venting, and explosions. Please do not do this without a thorough understanding of batteries and electricity.

Series connections of batteries should all be the same battery type , manufacturer, model, and capacity.

Each set of series batteries should have an interbattery balancer/equalizer.

Putting different capacity batteries (or strings of batteries) in parallel works just fine if your wiring is done properly and you have the appropriate over current protection devices.

Honestly, you are adding complexity and confusion, you should really be using batteries that are at the intrinsic voltage of your inverter, or you going to be back here in six months or a year asking us what went wrong.

It’s a 24v inverter. So you say I should only be using 24v batteries, not series up to 24v?

 

[ScrotpusGobbleBottom]

Or is this my best bet in attempts to equalize energy amongst all units:

View attachment 253466

This looks the best. You would get the most capacity out of it.
But, as Supervstech said, You will have problems. One of the 6 batteries cuts out and you would be drawing too much from the remaining 1-2 on either side.

The problem with putting batteries of different manufacturers in series is that ALL settings and calculations are different. They could individually have different resistances, over current settings, low v disconnect settings....ect

Some BMSs CANT be put in series. That is something big to consider. You need to verify that the manufacturer says its ok to wire is series.


Also

 

[SolarAntics]

I honestly can’t parse your drawings. You’ve got missing wires, you’ve got added wires, you’ve got wires shorting out battery terminals. If you don’t understand what you’re doing and you start building this you are going to have at the very least excessive currents as you assemble it, and worst case, overheating, venting, and explosions. Please do not do this without a thorough understanding of batteries and electricity.

Series connections of batteries should all be the same battery type , manufacturer, model, and capacity.

Each set of series batteries should have an interbattery balancer/equalizer.

Putting different capacity batteries (or strings of batteries) in parallel works just fine if your wiring is done properly and you have the appropriate over current protection devices.

Honestly, you are adding complexity and confusion, you should really be using batteries that are at the intrinsic voltage of your inverter, or you going to be back here in six months or a year asking us what went wrong.

Like this? (will put fuses into diagram in the future)

 

[SolarAntics]

No matter what you do, you are going to have difficulties.

Story of my life

 

[ScrotpusGobbleBottom]

You should leave your 12v system as is and ADD an additional 24 or 48v system. You wouldnt lose anything besides the cash.

 

[wpns]

Like this? (will put fuses into diagram in the future)
View attachment 253535

Better, but you need 3 balancers and that’s not how they connect.

 

[wpns]

It’s a 24v inverter. So you say I should only be using 24v batteries, not series up to 24v?

That’s really the best way, and what a number of people here have been telling you.
You _can_ kludge something up, but you are going to be disappointed.

 

[SolarAntics]

Better, but you need 3 balancers and that’s not how they connect.

They connect to the middle terminals of the series?

 

[wpns]

They connect to the middle terminals of the series?

Go look up the manual for the H02 battery balancer

 

[SolarAntics]

Better, but you need 3 balancers and that’s not how they connect.

Like this?

 

[wpns]

Like this?

View attachment 253568

No, one balancer per series pack. My concern is that with all this thrashing you don't understand series battery connections, or the function of a balancer, or a lot of the fundamentals. This is going to come back to bite you in the butt no matter how many iterations we go through until you can produce the correct drawing.

 

[SolarAntics]

No, one balancer per series pack. My concern is that with all this thrashing you don't understand series battery connections, or the function of a balancer, or a lot of the fundamentals. This is going to come back to bite you in the butt no matter how many iterations we go through until you can produce the correct drawing.

Well, I am here to learn. Thank you for taking the time to point me in the right direction and address my forum.

 

[Supervstech]

Ok...
Since you are planning to buy batteries, now is the best time to save you.

What exactly do you have now.

How are you using it?

What do you want to use?

 

[SolarAntics]

Ok...
Since you are planning to buy batteries, now is the best time to save you.

What exactly do you have now.

How are you using it?

What do you want to use?

I have 2 180ah 12v lifepo4 batteries from Brands C, and 2 100ah 12v lifepo4. I want to add two more 100ah batteries because of the major capacity disproportion between the 180ah group and the 100ah group. I want to power a 24v 2500w inverter, and charge from 800w solar.

 

[Horsefly]

Reading this thread feels like it is some sort of prequal to a "Up In Smoke" thread that hasn't been started yet.

 

[wpns]

Reading this thread feels like it is some sort of prequal to a "Up In Smoke" thread that hasn't been started yet.

Trying to prevent that, but at some point you have to just break out the

 

[SolarAntics]

Better? If at least I don't get to successfully create a design here, I would like to at least get some theoretical discussion and knowledge here. All these condescending comments are the opposite of constructive. Like what is the point of a forum? To help teach, learn and grow a scientific community, or to restrict the attainment of knowledge and development? I say humbly.. I am very new to this, and wasn't BORN with the knowledge of electrical engineering. Funny thing about knowledge, is your aren't born with it; so everything you know, you learned at some point.

 

[SolarAntics]

Reading this thread feels like it is some sort of prequal to a "Up In Smoke" thread that hasn't been started yet.

I'll name it "You won't believe these 'Shocking' results!"

 

[wpns]

Better? If at least I don't get to successfully create a design here, I would like to at least get some theoretical discussion and knowledge here. All these condescending comments are the opposite of constructive. Like what is the point of a forum? To help teach, learn and grow a scientific community, or to restrict the attainment of knowledge and development? I say humbly.. I am very new to this, and wasn't BORN with the knowledge of electrical engineering. Funny thing about knowledge, is your aren't born with it; so everything you know, you learned at some point.

View attachment 253579

Sorry, don't mean to be snarky, but while you are getting better at drawing, you still have some ways to go on comprehension. For instance, what is the purpose of the balancer in the center?

 

[SolarAntics]

Sorry, don't mean to be snarky, but while you are getting better at drawing, you still have some ways to go on comprehension. For instance, what is the purpose of the balancer in the center?

Was a mistake, that was connected to parallel buses - removed

 

[wpns]

Was a mistake, that was connected to parallel buses - removed

OK, and why the three separate bus bars?

 

[Supervstech]

I meant wxactly what do you have?

Not just batteries, what inverter do you have?

What are you planning to load on it?

 

[Supervstech]

Oh, and unfortunately, in a public forum, everybody can comment, ya have to weed through the trolls and seek out the teaching information...

Reporting posts that simply insult or goad you is what moderation tries to fix, but bad apples happen.

A thick skin is often needed to glean info in forums.