Combining MPPT, DC2DC and battery charger

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walto asked Nov 22, '21

Combining MPPT, DC2DC and battery charger

Hi All,

We are building a camper van. I have a 200ah gel battery which has a recommended max charging current of 40A.

I want to add a 12|12 - 30 (alternator while driving) charger, but also have solar (100/30 MPPT) and also a 30A 220v charger. So each individually are fine, but if the camper is connected to 220V, the sun is out and I start the engine, I guess that adds up to 90A?

Any suggestions on how to make this a safe charging combination (other than: make sure only one is engaged at the time, because at some point you'll simply forget once).

Thanks!

Walter.

battery charging mppt charging

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Answer 1 · 2021-11-22T15:16:03Z

harold answered · Nov 22, 2021 at 03:16 PM

Add a CCGX or a Cerbo and you can control max current from MPPT and Charger

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kevgermany ♦♦ commented · Nov 22, 2021 at 05:04 PM

CCGX won't do that, not sure about the Cerbo.

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steffen-graap kevgermany ♦♦ commented · Nov 22, 2021 at 05:21 PM

Every GX device should be able to do this. The keyword is DVCC, and here the charging current limitation.

This means that all components can be connected to the GX device, i.e. via the direct port or CAN.

You also need a shunt or BMV so that the charging current of the battery is known, because some of the electricity generated can be consumed, e.g. by an inverter.

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kevgermany ♦♦ steffen-graap commented · Nov 22, 2021 at 06:01 PM

Will have a look, because it's worrying me as well.

Danke

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kevgermany ♦♦ steffen-graap commented · Nov 22, 2021 at 07:05 PM

Looks like I'll be setting up DVCC tomorrow. Danke.

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Answer 2 · 2021-11-23T07:26:23Z

walto answered · Nov 23, 2021 at 07:26 AM

Thanks! Hadn't heard of those yet, but seems like a solution. I'll definitely look into those.

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Answer 3 · 2021-11-23T11:38:48Z

kevgermany answered · Nov 23, 2021 at 11:38 AM

Looks like DVCC is not as good as I hoped. But maybe I'm missing something.

It can manage some devices, but not Bluetooth devices that miss VE direct/ve can. Downside is that smart Orion for battery to battery is not managed. No idea if it will recognise this for current through the shunt and throttle back the managed devices properly. Haven't fitted that Orion yet.

Unless you're using a BMS or batteries with inbuilt BMS that are supported, you still have to set battery/charge parameters in each device. For me that means veconfigure for the multi, veconnect for the Orion and solar. Real pita. And no real overview, just different apps and screens.

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Answer 4 · 2021-11-23T12:51:01Z

JohnC answered · Nov 23, 2021 at 12:51 PM

Hi @walto

You really should test this to see if you can actually exceed 40A. Gel batts aren't famous for reactivity, and if you can get >40A in, then it likely won't be for long.

And you don't have to have every charger set to the full aggressive charge profile. Fair enough for the solar to do an Absorb cycle, but once a day is enough, you don't need to do that with the other chargers as well.

So just set the other chargers to a mild profile, even a flat Float level. That will give the solar priority, and the other chargers might only wind up when you have a load on or bad sun. The batts will still charge, just a little slower. You may need to experiment for the best settings, but this can work really well.

The other way is to use 2x batts in parallel, with an 80A max. That would be money better spent than on high-end monitoring/control, just to avoid a charge limit.

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