Running solar and alternator charging simultaneously

Hello all! I have recently achieved being 2 years in remission from Cancer. So, me and my partner as a celebration bought a semi converted sprinter van so we could do it up and go away for weekends whenever we wanted. This is the purpose at the moment, but in the future want to travel for several weeks at a time and we would have a fair amount of electrical items that would need power, so we would need solar panels to help charge the battery.

The van already has a house battery that is wired up to the alternator.

PROBLEM: I am not electrically minded, so I am struggling with what I need to charge the battery (we will be buying a bigger 230ah battery within a couple of weeks) using both solar and the alternator.

As you can see the alternator is connected, but I need help with what to buy to connect the solar system alongside this alternator charging! I’ve attached a video and photos of the current set up, any advice you can give would be amazing!! As this is my first post I shall put more images in the comments if I’m able

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Also, I haven’t bought anything extra yet before I know what I need!

Just get a premium solar kit from renogy. Literally everything you need and takes no time at all to install.

They have an entry housing and there is a little tool as well that is helpful.

You should have your house and starting batteries separated by an isolator official you do not already.

It should be fine to run them simultaneously. Be sure to use a good quality solar charge controller, and also be sure that your alternator doesn’t supply more than about 14.8 volts to the battery when the engine is running - that could cook the battery.

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First, congrats on 2 years!

There are some nice dc-to-dc chargers that incorporate both alternator and solar charging of the same battery bank.

I’ll probably get some flack for this but I’d ditch the lead-acid batteries and switch to lithium, if you can swing the cost. My .02. :slight_smile:

It would be a waste of money and resources to “ditch” the lead-acid batteries. Use them until they’re spent and then upgrade to lithium (if you think you need lithium).


My under $20 used lead acid deep cycle batteries from junkyards last 5-7 years. That’s the best bang for your bucks that I’ve found.

Reports are now starting to come in where the lithium batteries are dying after just a couple of years. I’m not convinced the technology is capable of living up to hype yet.


"Opportunities are everywhere, but only action makes it happen." ~ Van_Dweller

I haven’t heard any negatives about the new lithium technology lifepo4 but the older lithium ion batteries did have their issues.

My lithium batteries have a 10 year warranty so I’m not worried.

They are superior to lead-acid in every way. One problem you can run into charging them from an alternator is because they have so much less internal resistance than lead acid they can take a huge charge that would ruin a lead acid battery. That also means they can cook your alternator. If you go lithium and want to charge from an alternator I’d suggest a dc-to-dc charger.


Warranties are no good when the companies are out of business… Plus when you read the fine print, most are worthless anyway.

A battery can’t pull more than what’s available to it, no matter how much it would prefer.


"Hope for the best, but prepare for the worst." ~ Murphy

By all accounts it appears that the lithium-iron-phosphate chemistry is pretty safe (LiFePO4). They don’t have the propensity to catch fire or overheat despite abuse. Although I haven’t tried them in my van yet, I do use them as starting batteries in two of my motorcycles and they’ve been great.