Battery Station plus House Battery

Hi, this is Matt and I’ve been converting my 2005 Honda Odyssey for camping and road trips. It’s no sprinter but it’s good for a weekend away or a few days driving between destinations. I’ve so far tried to build it out with off the shelf components that i can use elsewhere as needed, one of those being an Energizer Arc5 battery station. Similar to a Jackery or others, 550 Wh, I like that it is portable, can be used for other things, has all the different ports, and a variety of charging options. I’m in the process of installing a 175W solar panel on the roof that generally should be good for recharging the battery during the day when parked, and I’m building a little relay box to switch from solar to accessory power when driving. So far so good…

I have a high load between a cooler and a medical device that pretty much drains the battery over night so I’m kind go at the mercy of the sun at that point. I’m wondering about adding another battery to the system as a backup that I could charge from shore or vehicle power when available and use to recharge the battery station (the battery station is still where I plug everything in). Yes, I know I should have designed a bigger system from the start but no regrets. Since the battery station take 12-24V input, has a charge controller, and can be used while charging what would I need to do to charge it from a second battery - just hook it up and let 'er rip?

I’m not trying to integrate these seamlessly. The battery station is not wired into the car electrical apart from tapping into accessory power. The second battery would be completely standalone, just there as a backup charger for the power station.

Does anyone have any thoughts about this?

Greetings & Welcome!

Batteries need to be charged, and in most of the country solar isn’t reliable enough for a medical device.

You’ll need a way to charge that second battery… The three best choices are isolator, generator, or shore power.

You need to start with an energy audit, and figure out how much you actually need for 24 hours, then multiply by it at least 3. With those figures we should be able to give better advice.


"Be the reason someone smiles today!" ~ Van_Dweller

Thanks Van Dweller. Those are good questions and I’ll need to consider them. My first question before I go there is more basic. Given that I can charge my battery station from an AC adapter, 12V accessory power in the van, or a solar panel up to 200W: can I also charge it directly from another 12V battery or would I need some sort of controller in the middle (in addition to the battery station’s own controller)? I may decide in the end that this is too much of a frankenbuild but just exploring my options so far.


Given that you can charge it from an accesssory/ciggy port, yes you could theoretically charge it from a second battery, however in the best case scenario they can only equalize, without the second battery having a charging source.

Ideally the charge should be going to the larger battery, and then to the power pack.

A 100ah deep cycle battery is ~$90 at Walmart, a cheap isolator is under $20, a good set of jumper cables to manufacture the wiring for the isolator is ~$20, and the connectors to add on the jumper cables are only a few dollars. That essentially describes my house battery system, except that I have been buying used deep cycle batteries from junkyards for ~$20, and they tend to last 5-7 years. Totally acceptable for me.

Then to complete the system, I put the house battery in a marine style battery box, and added a 4 acc. port jobber on each of 2 sides for a total of 8 acc. ports. In one of the acc. ports, I have one of those USB adapters, which gives me 2x USB ports. More would be easy to add.

I don’t have solar, I have a generator for a backup plan for the rare times that charging while driving isn’t enough.


"Be the reason someone smiles today!" ~ Van_Dweller