question

Peter avatar image

Car 12v dual battery solar and alternator charge

Hi

Keen on Victron

Looking for confirmation, and a wiring diagram

Having a DCDC charger and solar regulator is OK but I don't think I can run them together with solar and alternator.

First battery is a lead acid for starting the motor and the second battery is a lithium.

Can charge a 12v car dual battery system with both solar and alternator?

Other DCDC chargers are combined and do this

system design
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2 Answers
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trinasgarden answered ·

I'm looking for an easy solution for this also and know it's common for RV installs.

My understanding is initially the solar recharges your housebank (in this case the lithium) and monitors the starter if you want, and your alternator charges the starter battery as normal but with the BMS (or a cheap battery select switch on the vehicle side) can also top off or also charge your housebattery as things don't fight charging the same battery - least not the MPPT's which is why you can use more than 1 to charge one bank.

Commonly I'he seen the 4x4 crowd just use a battery select switch in their trucks on the alternator output side and the more into nice setup and RV people use a BMS or such on the solar/MPPT side to automate things.

It's a common thing though either way!

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heidi answered ·

I‘m planning the same in my installation.

Actually I’m charging the lithium battery by alternator with a BMS 12/200 and an MPPT 150/35 is charging the lithium battery by solar (at the same time).

As soon as the Li-battery hits 14,0V, I’m going to utilitize the integrated relay (MPPT or BMV) to switch on a relay that powers on the DC/DC charger (isolated) for the starter battery (low current).

To avoid building a circle, the ignition plus is connected to the Li+, and the DC/DC is connected to the other output of the relay in the car (it is controlled by CAN, so you can‘t trigger it during dc/dc charging, and you can‘t charge your starter battery with alternator and dc/dc at the same time (1-um)).

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