Adding an AC dual output charger with REDARC and Lithium Battery

[puchfinnland]

If you have a Redarc and a Lithium battery
this circuit allows you to add a conventional Dual output charger.

the REDARC will do its job and regulate the charge to the Lithium regardless of the input source

with IGN OFF the relay is connecting the AC charger to the REDARC

with IGN ON the relay connects the DC from the start battery to the REDARC.
same as if wired normally

the relay is only energized with the IGN on, it pulls no power when at rest.


relay avail from Amazon- https://www.amazon.com/dp/B08BHNYQYY

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ABYC marine master technician , EX European auto technician, new business- EASTCOASTWEST , custom work on campers, only systems, no mechanical

[revolution337]

Excellent information, thanks for the post.

Question, what is the advantage of setting it up this way with a relay and a dual bank charger? VS Using a single bank charger and connecting it directly to the start battery.

Then, when the AC charger is on, the starter battery is getting charged, and the REDARC also would sense the increase voltage (thinking that the alternator is charging). The REDARC could then modify the incoming voltage to whatever parameter you have it set to (AGM, LiFePo, etc) and charge the house battery correctly.
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1982 Westfalia AEB 1.8t
2017 VW Golf Sportwagen
2001 Audi A4 4.2 V8 swapped
2000 BMW Z3 roadster
-Mark

[puchfinnland]

So if you have a single charger hooked to the start battery, it will bleed over thru the redarc and charge the LIPO, but lets say your start is full and the lipo needs charging, you are subjecting the start to a charge and its already full, which may cause the battery to get hot and boil in theory.

with a dual charger set up as I drew one leg per battery and each is regulated.
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ABYC marine master technician , EX European auto technician, new business- EASTCOASTWEST , custom work on campers, only systems, no mechanical

[randalieren]

Thanks for this post. It is exactly what I am looking for.

Could you clarify (and please forgive my ignorance -- trying to learn):

When you say the relay draws no power with the ignition off, are you suggesting that the ignition needs to be on in order to be charging from AC?