Hello.

Before saying "this has been discussed a million miles" let me tell you that it has not. I am not looking for the hardcore dual battery system and involvement of the alternator, thousands of dollars by other-than-dealer shops. Nope, I am looking to have the second battery, a gentle, deep cycle 12v AGM or LiFePO sitting inside the 4R powering my 12v cooler BUT while being charged off the 12v 10A accessory port of the T4 at the same time while I am driving. I could do this using the built-in inverter but then I have to carry the 120v charging brick with me and they usually don't have the power to charge and to power at the same time, I don't think.

I have looked at a few options, Victron Orion Tr, DC-DC chargers for example, and similar Renogy devices. But neither one of them tells me if I can plug it into the 12v accessory port and charge a 12v battery while the battery is powering the cooler and they all are thinking that the alternator will be involved. Victron especially has been all over the place with responses to my inquiry and some of their ideas are more contradictory than others.

On the occasions of my roadtrip it would be for astronomy, and I will have solar cells on my Prnisu charging my astronomy battery during the day, so I have also looked at devices that can do MPPT at the same time and just taking DC from a source other than PV and charging the 12v.

All that I want is to have a battery that can keep my cooler running while I stop many times during a roadtrip, especially at night and during breaks at rest stops.

Thanks a lot for any thoughts and suggestions.

Farzad

Sounds like a Jackery or something similar would be a good solution for you if all you're looking for is fridge/cooler maintenance and overnight device charging. These type of devices can be topped off with solar and managed with 12v DC or 120v AC supply. Plus they're mobile so you can carry it anywhere.

I am afraid it is boiling down to that, unfortunately. These products come with a lot of bells and whistles that I don't know of their quality and some that I don't even need. I feel like I should be able to do the same thing as Jackery and similar are doing minus the other parts of them that I don't need or want. I would much rather get a device like this Renogy instead if I could get enough support for it, and unfortunately support is a thing of the past.

You could give the good folks at Overland Power Solutions a call - they build custom box units with quality components tailored to your needs.

I would strongly consider a Jackery. The Jackery is the reason that I dumped my dual battery setup. It's way more convenient than a dual battery setup (more power with LiPO in a smaller package). Easy to connect solar. No wires, no fuse, and no weight penalty. You can also remove it from the vehicle, and move it around your campsite (use it in a tent) power camp lights, power music/speakers, or even, around your home to charge or use it for other things, not vehicle related.

They also go on sale fairly often.

How to make a cheap isolated dual-battery setup for $50 | Expedition Portal

Here's my setup. Not really too difficult. can easily be moved to any vehicle if you ended up changing your vehicle in the future. The only thing you needed to do is wire the positive from the front battery to the back and the negative to the the body somewhere. DC-DC charger works great. i was able to use that battery for 2-3 days powering my 55 liter fridge during my camping trip. multi purpose as a storage of wires and some tools. it gets recharge when we go around visit places too. I have the option to connect a solar panel with that dc-dc charger which i don't need rightnow.

Portable Dual Battery using REDARC DC-DC charger - YouTube

Just sent them a message, thanks.

Yeah, I agree with MrBlah above. ^

I think the simplest and most flexible solution these days is the Jackery or something similar. They just had an anniversary sale, it might still be happening if you check on their site or Amazon.

Anyway, I just bought a 1500. And I think I saved $250.

These are serious pieces of equipment designed in California by American engineers. They use Panasonic commercial batteries.

The nice thing about the Jackery is that you can plug it in to the lighter socket, and plug your fridge into the Jackery. The car will charge the Jackery and the Jackery will power the fridge all at the same time. When you turn the key off the Jackery will continue to power the fridge. Works the same as it it were and dedicated wired battery, but portable.

Different models can do different things, but the 1500 can take two charging inputs at the same time. Say, a 12v lighter plug and a solar panel, to charge faster.

Its also very portable, you can just take it out of your 4R, and use it for backup power should the power go off at home. It has a very high quality and powerful 110V inverters. It will run a full sized home refrigerator for instance.

Its got USB and USB-C too.

It does all this stuff without much wiring in your vehicle, and you can use in in more than one vehicle, at a picnic, or tent camping away from your vehicle.

They just released a 2000 version that just has a bigger battery.

They seem quite expensive, but if you consider the cost of an advanced chemistry battery, the wiring, and the fact that it has to stay in the vehicle, the Jackery (and similar), with high power inverters, and portability is the way to go.

The reason I mention Jackery is that I've been using this brand for a few years and they are very reliable.

I put a dual battery system in my boat years ago, and its good to keep the big stereo amps from draining the starting battery. But its a pain in the ass to wire.

If you don't need that kind of power, and just want to run a 12v fridge and a few lights and such. Get a Jackery the flexibility is amazing. And I suggest keeping a NOCO starter brick in your 4R. The NOCO can be charged by the Jackery if necessary.

The Jackery is a high quality solid piece of equipment, read the reviews. Most complaints are like, the XYZ brand has a certain plug I need, or the Bluetti brand is a little cheaper, etc.

You will see very few failures if any. Of course they can be misused.

My experience for about three or four years is that my samples have been rock solid. And I just bought a Explorer 1500 which is quite amazing.

They are not cheap, but simple, powerful, portable and flexible.

YMMV

Another vote here for a Jackery setup.

I have a smaller Dometic (since its just me or me +1 use) and use it with the Jackery 500 (into 12V Jackery input, Jackery into rear 12V of the 4runner).

When stopped for longer periods of time or once to destination I'll plug the 100W panel in (crack the rear window 1/4" for the cable) and hopefully it's sunny. Then things remain topped off.

When not traveling the fridge and Jackery go inside for backup/poweroutages/garage use.

If I was doing longer trips (now usually just long weekends) I'd consider the 1000W or 1500W Jackery and a bigger fridge but so far great set up for me. I added the cover to the Domestic and that helped even more with efficiency in keeping it cool during warmer months.

Jackery is a solid unit. I'm always considering quality 1st, then portable/mobility and also weight/space.

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I use a Jackery 500 with our Engel fridge. The Jackery is dependable and portable. I have three dislikes:

1. That handle doesn't work so well for tying it down.
2. The Engel plug into the Jackery is a little loose, so I worry that it will pop out during travel. I rely on duct tape to hold it in place.
3. 500 WH is enough for about two days of camp use. After that I need a full day of travel to charge it back up, or a clear day out in the sun. No multi-day camps under shade or clouds.

I'd be happier with the Dometic PLB40, but the capacity is the same as the Jackery 500. A Dometic 80, if there were such a thing, would be the sweet spot.

The problem I found with the Jackery 1000's 12v Cigarette output port is that it could come loose over night especially when it gets colder. I would like a more positive connection in general for astronomy gear that includes an onboard PC that doesn't like power interruptions.

The packaged systems like the Jackery, the Dometic PLB40 and similar come with things like inverters, USB portals, maybe the solar charge controllers of which we know nothing about their quality or performance. The best is if we build our own package: one very good LiFePO battery with sufficient capacity for our needs, a reliable and efficient charger, a reliable power connector, a reliable and efficient inverter (if one needs such a thing), and a battery monitor.

Just a note on the rear stock DC accessory outlet is not quite ready to handle sustained high loads to run a fridge.. chances are your rear battery would still drain a bit while plugged in during a long trip as it powers the fridge. I experienced this with my ARB fridge several times before installing my dual battery setup and new wiring to the back.

Mine keeps up with a Jackery and an Engel 45 - pulls ahead by 10-15% per hour. Even so, two days in camp will require a long drive to recharge back above 90%. I'm thinking the replacement will involve heavy gauge wire to the battery and an Anderson plug to a house battery in the rear. I need to figure out the best way to run the wire.