Connecting a Victron Smart Solar MPPT to a Votronic charging converter

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rodel asked Dec 8, '23

Connecting a Victron Smart Solar MPPT to a Votronic charging converter

Hello,

This is my first post here. I hope someone can help me with this.

In my motorhome (Mercedes Marco Polo, 2015) I have an AGM starter battery and a LifePo4 on-board battery (Wattstunde Lix 100-D LT).

A VCC 1212-30 charging converter and a D+ simulator (both Votronic) are also installed. The system is working perfectly so far.

Now I have two solar panels (= 2x 100W) mounted on the roof and a Victron Smart Solar MPPT 75/15 charge controller in the car.

My question is;

What is the best way to connect the charge controller to the system so that both batteries are charged?

I think there are two ways:

I can connect it directly to just my lithium battery, I think that will work without any problems. Because in the Votronic operating instructions I read: “Built-in on-board network filter: problem-free parallel operation with other charging sources (.., ..,.., solar systems) on one battery.
I will also ask Votronic whether the starter battery is also charged this way.

A second way to connect the charge controller to the system is using the wiring that comes from the outside socket. That's how I have it installed at the moment. But that doesn't work perfectly. I think the charge controller doesn’t reach floating mode. (I'll send a PDF with the settings in the app as they are now).

I don't know if it's even possible connecting it this way.

If that were to work, what values should I enter into the charge controller? The values that the lithium battery needs, or other values?

I really hope that you can help me, because even after a long search I still haven't found the answer.

Specs LifePo4.pdf

victron community

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votronic.jpg (358.9 KiB)

specs-lifepo4.pdf (619.4 KiB)

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Modifications Space

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Answer 1 · 2023-12-09T05:12:37Z

kevgermany answered · Dec 09, 2023 at 05:12 AM

Tricky. You're asking for recommendations, but it really depends on how the Votronic unit works and this is a Victron site. Most, if not all, of us have no knowledge of Votronic.

The MPPT mut be connected directly to a battery. It's settings must match the battery.

Usually the MPPT feeds the leisure battery and the starter battery is charged by the alternator as a primary source, with an optional trickle feed to maintain it when stationary for longer periods. Starter batteries need no more than this and will have a shorter life if they're permanently kept at absorption voltage.

A separate unit charges the leisure battery from the alternator when driving. This appears to be your Votronic.

So if the Votronic provides 2 way charging, simply go direct to the leisure battery. If it doesn't you'll need to add a trickle charger. Votronic sell an inexpensive trickle charge for this, but it is not recommended by them for lithium house batteries. A low power Victron Orion will do the job, but be careful to get the settings right.

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Answer 2 · 2023-12-09T21:46:40Z

rodel answered · Dec 09, 2023 at 09:46 PM

@kevgermany

The Votronic is trickle charging the starter battery (with 1 A) from the leisure battery, when the engine is not running for some days, and the leisure battery is on AC and has enough power. (I read in the manual).

I asked Votronic whether the trickle charging also starts if the leisure battery is full enough and powered by solar panels. Or does it only work with an AC cable plugged in? I hope to get an answer from Votronic to that soon.

But as I read your answer, it would be best to connect the MPPT directly to the leisure battery. Then it's easier and safer to get the MPPT settings for that LifePo4 right.

I hope and expect that trickle charging the starter battery works that way.

When not I'll buy an Orion.

Thanks for your answer! Very helpful.

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