martyhoff avatar image
martyhoff asked

DC-DC and solar charger priority

I am looking to buy a Orion Tr Smart DC-DC Charger and a Smart Solar MPPT charge controller for installation in a caravan. Will these work together - if both are able to supply current into the battery, does one have priority or do they both supply simultaneously? I am conscious of the maximum battery input current of 40A. (I have two 100 Ah GEL batteries).

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1 Answer
JohnC avatar image
JohnC answered ·

Hi @martyhoff

They will charge together fine. Until they reach their target V, the set Absorb level(s). The one that has the lower setting will back off first, so if the Orion was set just slightly lower, the solar mppt would take priority.

I don't think the Orion has an adjustable charge rate, but in a similar way you could lower it's target charge V to control it's output. It will still charge, but slower, as you choose.

Guessing that your 40A is a '20%' (0.2C) limit. Gels aren't known for their fast charge rates, and if you ever did reach 40A it likely wouldn't be for long anyway. So I wouldn't let that limit restrict you to a smaller Orion, as you can control it's output via target V. You may need to service loads too at the same time, so consider that as well.

The two devices don't communicate with each other (apart from V), so you may also need to look at the V they each read, the Temp Compensation applied, and the charge algorithm of each.

Sounds a bit complex, but it isn't. You'll work it out, hey..

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martyhoff avatar image martyhoff commented ·
Thanks John, makes sense. Good explanation.
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