DC to DC chargers?

I’ve seen a couple build posts where people mention using DC to DC battery chargers. I’m planning my buildout and interested in what people are using?

I’ve got a marine deep cycle battery already and would like to integrate this into the buildout with some sort of DC to DC charging solution.

Let’s hear what y’all are using!

I use the National Luna DC charger… loving it

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I got a free renogy charger to replace the Victron energy that would only charge once in while when it felt like it. even when forcing it to it’s job. I never could figure it out. I’m surprised how well the renogy has work so far. it is no frills and the fan is LOUD

I’ve been using the Victron Orion one with my LiFePO4 battery for a while now and it works great, but it did take some tinkering to dial it in. If you’re just using an AGM battery I think you’re able to go with a much cheaper option since they don’t require fancy charge cycles. Back in the day I used THIS with my AGM and it worked great for almost a decade.

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@Rengle is 100% on point. Unless the plan is to upgrade to Lithium there is no need for a DC to DC charger. You just need an isolator and it’s helpful to have a switch to disconnect the vehicle source.

There are charge controllers out there that will do Solar, Alternator inputs so that’s helpful in being able to monitor all sources.

This will be what I use in my next upgrade. I currently run a Renogy 40A DC to DC charger, Renogy Wonderer 30A ( I think), Renogy 100aH Smart Battery w/ Heater (not worth it), 100W Renogy flexible solar panel.

In the process of planning out a purchase to keep the battery warm which will include an AC input, 5A charger, Thermal battery warmer 80W.

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I just got done with my setup with the Renogy DCC50S.

Short-term review of the Renogy DCC50S:
It’s nice that it’s all integrated with alternator charging [DC/DC] (Max 25A IIRC), + Solar [MPPT] (Max 25A IIRC). Simple install and works with most battery types. Big perks are there’s no need for battery isolators and when the house battery is fully charged, it’ll trickle charger the starter battery if ya got solar.
If your looking for simple and room for growth, this is it. Other manufacture to look at are Redarc and CTEK.

House battery wise, i opted for a 100aH LiFePO4 by SOK with integrated heater and bluetooth. Great value at $600 with quality components that’s serviceable. I ski and winter camp so I wanted to make sure I could charge the house battery in low temps. AGM’s are great because you don’t have to worry about low temp conditions, but you’re limited to only using 50% of the capacity before you sacrifice the health of the battery

Here’s some pictures of my setup. Don’t mind the mess, I’ll get around to tidying it up later.


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I really learned a lot watching this ExploristLife guy on youtube. I timestamped this video to the relevant bit, https://www.youtube.com/watch?v=MLIGbFsH-5w&t=1530s

He also has this relevant blog post.

I have the “fancy” victron bluetooth dc/dc charge controller. What’s nice with that is I can actually open the victron app when driving to see how much juice it’s adding.

The one thing I’ll mention is that not only do you have to size your wires correctly, there’s a very, very small gauge sensor wire you have to hook up to something that tells the dc/dc charge controller that your vehicle is actually running. For me that was easy because my sPOD’s switch box was right by truck camper electric box in the truck bed. But I did have that brief panic attack where I thought it was defective until I looked at the wiring diagram again and noticed I forgot to connect that sensor wire to the dc/dc controller and an ignition active circuit. It’s easy to miss in the diagram if you don’t read the instructions. I added the red text and arrow.


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The Renogy setups have Bluetooth connectivity as well. It’s the only way for me to monitor the system as I have no display.

If someone is interested I would sell my DCDC charger and controller to fund the MPPT DCDC charger upgrade :joy:


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Thanks all for the info and responses. I have set up a house battery with isolator in other vehicles before and based on the battery tech I’m planning right now sounds like that might be the simplest and most economical option.

I like the options and flexibility of some of the high end options like the Redarc but am trying to use what I already have around as much as possible to keep it budget friendly.

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Im using a CTEK D250se with my amazon Lithium 100ah battery. Have a AGM as my starting battery. And 200w of solar too.

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Is that steel or aluminum, that plate?

Aluminum. Got it in the beginning of 2021 for ~$147 shipped along with another piece the same size

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I think a DC-DC charger is better than an isolator ever for an AGM.

I’ve had the renogy setup working flawlessly for a couple years now. It does have an AGM specific output, multi-phase charging, and will charge the house battery at a higher voltage than the ALT is putting out if needed.

As mentioned, It also works great with solar and trickle charges the starting battery when the house if full. Both my batteries are 100% charged quickly on any day with a little sun.

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It also futureproofs you if you decide to switch to lithium down the road. My previous vehicle had a basic isolater setup and I was constantly killing house batteries because it never charged it properly.

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Spend the extra money for a DCDC charger and skip the isolator. Faster charger on AGM, keeps alternator healthy, and keeps battery healthy with multi-stage charging algorithms. Plus, if you do ever upgrade to a different battery type, no need to buy a DCDC charger or modify the wiring (I spent more on wiring then my DCDC charger).

Isolators are a thing of the past.

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Stop judging my isolator that I have has since 2004…


No isolator shaming here. Just facts.

One item people fail to consider is the alternator and the amount of output to all of your electrical uses. Usually not a big problem, but if you’re running multiple batteries, lighting systems, radio, amps, etc., you may want to review this and check the box that all is good. The OEM alternators did not account for all of the add ons we’re doing these days. Just something to consider.

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Tagging on here - when I look at DC to DC charger options (Renogy specifically) how do I calculate the amperage level I should buy?