has anyone tried different capacity LifePO4 batteries in parallel?

[jongood]

There's a tempting offer on Fogstar drift eco £500 for 305Ah. I'm wondering if it would run ok in parallel with my existing 200ah Life PO4 from a different manufacturer?

 

[Ditcha]

There's a tempting offer on Fogstar drift eco £500 for 305Ah. I'm wondering if it would run ok in parallel with my existing 200ah Life PO4 from a different manufacturer?

I have 2x Buttner 110Ah batteries in parallel with my DIY 280ah and they have worked flawlessly for the last 6 months.

 

[jumar]

I'm adding a different capacity battery this week when it arrives....the supplier Roamer said it would be OK...but also said batteries of equal capacity work in practice much better...
Battery 1...160ah
Battery 2 ...230ah

Why didn't I fit a second 160ah...good question...much cheaper....well I only had an underseat space available...

 

[MichaelT]

I haveva 200a KS underseat coupled with a 280a Fogstar drift one. So long as you connect through a bus bar it will be fine. Mine just about charge and discharge fairly equally and the shunt just sees them as 1 big battery.

 

[Flairy]

I didn’t know you could do that,put different AM Battery’s together?mine are all 80amp but thinking of going 300ampx2 Lithium’s.

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[MichaelT]

I didn’t know you could do that,put different AM Battery’s together?mine are all 80amp but thinking of going 300ampx2 Lithium’s.

Lead Acid, AGM and Gel should be paired the same and of the same age but lithium you can mix but connect via a bus bar not just together.

 

[jongood]

I didn’t know you could do that,put different AM Battery’s together?mine are all 80amp but thinking of going 300ampx2 Lithium’s.

These seem a good deal if you don't need heating and programmable

Drift ECO 305Ah 12V Leisure Battery

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www.fogstar.co.uk

 

[Ditcha]

These seem a good deal if you don't need heating and programmable

Drift ECO 305Ah 12V Leisure Battery

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www.fogstar.co.uk

These are a good buy get great reviews on YouTube and are available now.

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[Saucer]

Can you pair ann AGM and a lithium? I’ve actually chosen that as an option on a rapido I’ve ordered, so it must be at least possible.
From my reading this seems fine.

 

[Ditcha]

Lead Acid, AGM and Gel should be paired the same and of the same age but lithium you can mix but connect via a bus bar not just together.

Why a busbar ?

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[Carpmart]

I’ve got three lithium in parallel, 2x204Ah 3yr+ old KS and one 105Ah Fogster Drift. I don’t use a bus bar. I quite frequently discharge the Fogster to 20% SOC (used as a trolling motor power supply) and reconnect it in parallel with the other two which are often a very different SOC to the Fogster. Got a big kill switch which avoids any spark etc.

 

[LithiumConvert]

I have had 3 Sterling Power lithium batteries in parallel for about 4 years. 1x150Ah, 1x120Ah and 1x60Ah.

And without any use of bus bars, just wired in parallel a bit like the picture above but longer cables.

They are discharged to about 65% (sometimes a bit more) every day. and recharged witthout any problems

Not in a motorhome, but that should not make any difference. I use a Sterling Power 30amp charger.

 

[MichaelT]

Why a busbar ?

So the shunt sees just 1 battery plus I think you get more even charge and discharge.

 

[CAB96]

Can you pair ann AGM and a lithium? I’ve actually chosen that as an option on a rapido I’ve ordered, so it must be at least possible.
From my reading this seems fine.

There is a few threads about hybrid systems, it seems to be a legitimate setup.

 

[LithiumConvert]

There is a few threads about hybrid systems, it , [Mixing AGM and Lithium], seems to be a legitimate setup.

I assume that the charger(s) have to be set for lithium as the AGM voltage would be too high for the lithium.

Has anyone seen the voltage discharge curve. Which discharges first? (And, probably more importantly. last?)

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[Carpmart]

I assume that the charger(s) have to be set for lithium as the AGM voltage would be too high for the lithium.

Has anyone seen the voltage discharge curve. Which discharges first? (And, probably more importantly. last?)

The parallel batteries share load and charge proportionate to their capacity. With my all lithium setup, the smallest battery (nominally 2x 200A and 1 x 100A) sees roughly 1/5th of the charge and delivers roughly 1/5th of the grunt to run ‘stuff’!

 

[Steve and Denise]

The parallel batteries share load and charge proportionate to their capacity. With my all lithium setup, the smallest battery (nominally 2x 200A and 1 x 100A) sees roughly 1/5th of the charge and delivers roughly 1/5th of the grunt to run ‘stuff’!

I’m just listening and waiting but do find this interesting

 

[bigtwin]

There is a few threads about hybrid systems, it seems to be a legitimate setup.

It is, but some seem to struggle with the concept.

Has anyone seen the voltage discharge curve. Which discharges first? (And, probably more importantly. last?)

The LiFePO4 batteries always discharge (and charge) first as they have a lower internal resistance than the lead.

The parallel batteries share load and charge proportionate to their capacity.

That’s true of a ‘pure’ LiFePO4 bank but not in the case of a hybrid bank which is what the question relates to.

Ian

 

[Hoovie]

I assume that the charger(s) have to be set for lithium as the AGM voltage would be too high for the lithium.

Has anyone seen the voltage discharge curve. Which discharges first? (And, probably more importantly. last?)

If you have the Lead and Lithium connected directly in parallel, then yes, you should configure any chargers with a Lithium profile for the reason you state. But if you have a way to disconnect the Lithium when it is fully charged, then you can set up the chargers in a more optimal way so that once the Lithium is done they will continue to charge the Lead fully and correctly.
If you are interested, there is a full explanation on a way to run Lead and Lithium in combination here - https://wildebus.com/hybrid-battery/ . I've been running a Hybrid Lead+Lithium configuration for around 3 years now and find it a great setup.

As far as the original question goes, I have not tried different capacities of Lithium together so can't comment on that.

 

[John Russell]

Wired in parallel, the voltage will be the same on both lithium batteries. Current will be different but I can't see it's any different to the contents of the battery - lots of lithium cells wired in parallel.

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