Design Question on Electrical (Alternator and solar charging) (1 Viewer)

Oct 16, 2022
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Hey forum, new member here.

I am designing the electrics for my motorhome project and have a few questions.

I would like to charge the leisure batteries from solar, from the alternator and also by a 240v direct power input.

After doing some research it looks like I need a MPPT controller for the solar and battery to battery will be the best option to charge from the alternator.

Will I need to purchase two separate units here or there one single product that can manage both of these two power sources? Surely it would be best to have each system know about the other one to best determine where to send the power? e.g if it is very sunny then no need to charge from the alternator (and improve fuel efficiency when driving).

If I do need to purchase two separate units then how will they know about each other and when to switch on / off depending on what the other is doing?

Also, how would one wire up the 240v input charging method?

Many thanks
 
Oct 9, 2019
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Take a look at Victron units they do a Inverter/charger but they also do all sorts of other kit for self builders
 
Dec 2, 2019
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Votronic trio all in one, solar B2B and mains. Good but expensive.
Otherwise all victron gear to match. You can take victron one step further with remote monitoring, and certain controls miles away.
 

Tombola

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Nov 21, 2020
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and remember with all in one units, if one part fails have you lost the lot

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Lenny HB

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Oct 18, 2007
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Renogy 12V 30A DC-DC On-board Battery Charger with MPPT for Gel, AGM, and Lithium Batteries Using Multi-Stage Charging, in RVs, Cars, Boats, Yachts, Recommended to Match with 40A ANL Fuse https://amzn.eu/d/bs27A5j
One problem with the Renogy is if it detects solar it half's the charge from the alternator so you need to fit a switch to turn off the solar when driving.
 
Aug 4, 2019
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One problem with the Renogy is if it detects solar it half's the charge from the alternator so you need to fit a switch to turn off the solar when driving.
I wouldn’t use one….in fact don’t, but it was just an example that combined units are available.
 
OP
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poindexter
Oct 16, 2022
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Thats great thanks for all of your suggestions this is really helpful.

Very good point about failure of the 3 in 1 unit.

What would you all recommend is the best solution to cater for the three power sources. I am feeling that having one unit to control alternator and solar and another to receive power from the mains is the way forward.
 
OP
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Oct 16, 2022
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What are the consequences of not doing this?

Sounds like a flaw (or even a bug if it has firmware) maybe the manufacturer has addressed this?
 
OP
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poindexter
Oct 16, 2022
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One problem with the Renogy is if it detects solar it half's the charge from the alternator so you need to fit a switch to turn off the solar when driving.
What are the consequences of not doing this?

Sounds like a flaw (or even a bug if it has firmware) maybe the manufacturer has addressed this?

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Apr 27, 2016
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I have a Victron IP67 15A charger and think it is ideal. It has multi-stage intelligent charging, and can be set for various battery charging profiles, including Lithium. It also has a 'storage' mode, so if it's been on continuously for a week it switches off until the charge level drops a bit, then it switches back on, to keep it topped up without overcharging.

They do the same charger in various amps outputs, I have the 15A version. I think their 'IP22' charger is basically the same electronics, without the weather protection of IP67.

Edit: Sorry, just actually looked at it, and it's an Victron Blue Smart IP65 charger, 12V 15A
 
Last edited:

Nedge68

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Feb 28, 2022
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Have a look at a Redarc DCDC1240D it will charge from the alternator and/or a solar MPPT, you will need a separate mains charger.
 

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