# Can you run a lithium battery and dc battery in parallel?



## mjfwv (Dec 19, 2019)

Can you run a lithium battery and dc battery in parallel?


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## Burgess (Dec 19, 2019)

Short answer:

NO


Longer answer:

* HELL NO ! ! !*



Welcome to CandlePowerForums !

:welcome:


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## peter yetman (Dec 19, 2019)

Sorry, I'm not being disingenuous, but aren't all batteries DC?
Is it a US expression that I haven't learned yet?
P


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## bigburly912 (Dec 19, 2019)

I thought it was dry cell but I hoped not.


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## josiahg52 (Dec 19, 2019)

peter yetman said:


> Sorry, I'm not being disingenuous, but aren't all batteries DC?
> Is it a US expression that I haven't learned yet?
> P



I was thinking the same thing. In any case, it's generally not wise or advised to run cells/batteries of different chemistries or cells/batteries of vastly different age or condition in series OR parallel.


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## peter yetman (Dec 19, 2019)

Ah, Dry Cell, thank you.
OP, we don't even mix brands, let alone cell types.
That way madness lies.
P


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## RetroTechie (Dec 20, 2019)

@mjfwv:

Please define "run".
What lithium battery? (chemistry / brand / type / size / # of cells in series or parallel)
What DC battery? (same)

If with "run" was meant "discharge" (use), then YES. For example with a diode in series of each battery & using batteries with _roughly_ equal voltage & current capability. This has some drawbacks though - therefore more details needed.
If "direct connect, charge and discharge" was meant, then NO. Different chemistries need different charging methods. Serious troubles may result if eg. lead-acid or NiMH charging method is applied to Li-ion battery. Differences in voltage / capacity / current capability only makes this worse.

In general if 1 battery doesn't suffice then a) use a bigger battery, or b) use more of the *same* batteries in series or parallel.


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## peter yetman (Dec 20, 2019)

if we haven't already scared you off, may i ask the question, "why?"
P


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## Katherine Alicia (Jul 4, 2020)

Yes you can, I used to do it quite regularly as backup power for CMOS SRAM.

Edit: it might be worth a mention that if you Did go the Diode route, there will be a 0.7v drop across it, so your 3v will be more like 2.3v


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