Battery mix or not? (1 Viewer)

[Happy1]

Get not mixing different battery types but is it ok to mix sealed and vented lead acid? Same size, age, different brand ok?

 

[pappajohn]

Yes, they all have the same charge needs.

 

[HandyAndy]

Yes crack on, same chemistry / voltage. ??

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[Happy1]

Fab compartment has space for four batteries but two on outside edges tuck under the flooring so not enough access to top up hence sealed, just saved hours of work so thanks all

 

[Bill and Tracey]

Just make sure all batteries are the same age. Once one starts to die it will drag the rest down with it. You can get round this by isolating each one but it's a lot of hassle.

 

[OS51EEE]

If 2 or more batteries are connected to same charger they must be same age ,same amp hour same type i.e. Lead,gel,what ever. That is because they need to be charged at same rate from charger as if there one battery. mix them up and they won't charge up to full capacity

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[pappajohn]

If 2 or more batteries are connected to same charger they must be same age ,same amp hour

Why?

 

[HandyAndy]

If 2 or more batteries are connected to same charger they must be same age ,same amp hour same type i.e. Lead,gel,what ever. That is because they need to be charged at same rate from charger as if there one battery. mix them up and they won't charge up to full capacity

when you connect more than one battery together they BECOME one battery..
Just like the six cells that actually make up what we know as one 12v battery..
Any discrepancy in charge level will bleed off from the charged one to the flat one until they balance..
A charger will do EXACTLY the same, the charge will go to the flat cells if the charged one is err charged..
It's just voltage potential (difference).
You supply a higher voltage to something flat and those little old electrons (current) will trundle off to fill the flat one (with a little shove as there is some resistance in the makeup and it requires slightly higher voltage to get the electrons to move) until what's coming out of the charger equals what's in the battery and flow of electrons stops. i.e It's charged.
You cannot really over charge one or under charge the other if they are different sizes, Just that the small one will be charged before the bigger one. You won't over charge the smaller one (in the time it takes to fully charge the bigger one) as the charger will still be outputting the same voltage whether it's flat or not, simply no current will flow to it as the voltage potential has leveled out to a point electrons stop flowing (i.e both the charger and the battery are the same. Curent will continue to flow to the larger "not yet charged" one until that is then also charged.
The only time you'd over charge a lead acid is if you left it on 14+ volts for longer periods.
In fact some time time at 14 + volts will HELP lead acids as this is what equalisation is..
But for all intents and purposes, having two (of the same chemistry) battery types but of differing sizes in a Motorhome in the way in which they get charged by solar / EHU / Alternator will not make a shit of difference.

You are however totally correct in saying you shouldn't mix chemistry types, and the reason for this is Gels have a LOWER fully charge state than a lead acid so you CAN over charge these if mixed.

 

[mitzimad]

If 2 or more batteries are connected to same charger they must be same age ,same amp hour same type i.e. Lead,gel,what ever. That is because they need to be charged at same rate from charger as if there one battery. mix them up and they won't charge up to full capacity

thats incorrect any sizes can be put together, charger just sees them as one battery

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[StillGoing]

The charger will see different capacity batteries, linked together in parallel, as one battery. However, this means that neither battery will be charged correctly. The smaller capacity battery will be overcharged (not recommended) and the larger capacity battery will be undercharged.

 

[pappajohn]

Bugger!
I was waiting to see if science/technology had come up with a genuine reason not to mix ah ratings.

 

[pappajohn]

The charger will see different capacity batteries, linked together in parallel, as one battery. However, this means that neither battery will be charged correctly. The smaller capacity battery will be overcharged (not recommended) and the larger capacity battery will be undercharged.

Why?
The two batteries will balance each other out, even off charge.
Both will be charged to the same state.

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[HandyAndy]

The charger will see different capacity batteries, linked together in parallel, as one battery. However, this means that neither battery will be charged correctly. The smaller capacity battery will be overcharged (not recommended) and the larger capacity battery will be undercharged.

A charger does not and cannot see the capacity / size of the battery.
All a charger sees is voltage. Either flat or not flat. It's that simple.

 

[StillGoing]

I stand corrected

 

[OS51EEE]

thats incorrect any sizes can be put together, charger just sees them as one battery

No they don't as somebody else has said one will be overcharged and one over charged why do you think they bother putting capacitys on batteries in first place

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[OS51EEE]

Why?

Best practice for best performance if and old battery starts to fail connected to a new battery in parallel it won't charge properly so u don't get a good out

 

[mitzimad]

No they don't as somebody else has said one will be overcharged and one over charged why do you think they bother putting capacitys on batteries in first place

every 12v battery is 6x 2v batteries joined together but you still get 12v not 2v

 

[HandyAndy]

Its like educating pork on this forum sometimes what with batteries and climate change posts?

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[joka250]

Its like educating pork on this forum sometimes what with batteries and climate change posts?

I think you could have put that a little differently. The reason it sometimes seems hard work to get a message across is that many members see conflicting advice from so called expert professionals and their websites and it becomes hard to sort the wheat from the chaff. The positive side to that is that it promotes healthy debate and ultimately an increase in knowledge.

 

[HandyAndy]

I could have worded that better. ? obviously got out of the wrong side of bed this morning ??

 

[eddie]

Well most vans are running around with a lead acid battery in Parallel with who knows what, when the engine is running, and have done for decades

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[pappajohn]

Best practice for best performance if and old battery starts to fail connected to a new battery in parallel it won't charge properly so u don't get a good out

That wasn't what I queried.
Why do they need to be the same capacity, as I outlined in red in my original question.

If 2 or more batteries are connected to same charger they must be same age ,same amp hour

 

[mitzimad]

agree with eddie and pappa john size really doesn't matter ,chemistry more so

 

[Onemanandhisdog]

I think you could have put that a little differently. The reason it sometimes seems hard work to get a message across is that many members see conflicting advice from so called expert professionals and their websites and it becomes hard to sort the wheat from the chaff. The positive side to that is that it promotes healthy debate and ultimately an increase in knowledge.

We need negative side too or the whole thing won't work ? ? ?

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[HandyAndy]

We need negative side too or the whole thing won't work ? ? ?

I nearly spat my chinese takeaway out

 

[joka250]

We need negative side too or the whole thing won't work ? ? ?

Must be getting old, it's taken me all this time to work that out. Very good.

 

[OS51EEE]

That wasn't what I queried.
Why do they need to be the same capacity, as I outlined in red in my original question.
[
So the all the individual cells of 2 volts charge at same rate and discharge at same rate, larger amp batteries have bigger cells of 2 volts and smaller amp batteries have smaller cells of 2 volts as an example if u got a small can and a large can both filled with water to the top and the same size hole drilled in bottom which can do u think would empty first?
So if both cans were the same size ,same size hole drilled in bottom filled to the top they would both empty at same rate and recharge at same rate which is better for the charger ,don't get me wrong you can have a small battery and larger battery it will still work ok but not best practice when your trying to get the best from discharging and charging in my experience hope this helps

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[HandyAndy]

They don't though because of simple manufacturing tolerances, ALL battery cells are not equal. As Eddy mentioned, there have been starter batteries linked to "god knows what" since campervans have been invented.

 

[Lenny HB]

No one has mentioned that doubling the battery bank size you will probably need a bigger charger.

 

[OS51EEE]

They don't though because of simple manufacturing tolerances, ALL battery cells are not equal. As Eddy mentioned, there have been starter batteries linked to "god knows what" since campervans have been invented.

It’s just best practice if u can use the same size but when in the desert u use anything !

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