Recommend a DC to DC converter

[ccasanova22]

Hi,

Looking for a quality DC to DC converter/charger that I can mount in my travel trailer and use to run some 12V lead acid deep cycle batteries for accessory power. I'm guessing the 7-pin harness on the Ranger has a limited current output on the Black (+12V) pin, does anybody have a recommendation on maximum amperage (20A? 30A?) for a DC to DC converter/charger that I should use?

Also, I'm assuming that since the trailer power does not turn on unless the vehicle is running, it's not going to try and charge the trailer batteries with the ignition off, draining the truck batteries when sleeping.

Last, if the battery is mounted inside the travel trailer, does anyone have recommendations on a good quality vent so the gases from charging don't impact the occupants of the trailer?

Below are some DC to DC converters/chargers that I found with a quick Google search, are any of them better than the others?

https://www.etrailer.com/Battery-Charger/OptiMate/MA99JR.html
https://www.redarcelectronics.com/us/battery-chargers/20a-in-vehicle-dc-battery-charger
https://www.renogy.com/12v-20a-dc-to-dc-on-board-battery-charger/

Edit: This is the type of battery I plan to use in the travel trailer.

Thanks!

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[brroberts]

If you use an unsealed lead acid battery inside the trailer, even with a vent, you will have some charging off gassing. That’s the nature of unsealed liquid electrolyte batteries. You will have occasional CO2 / propane alarms go off. You would need to put the batteries in a sealed compartment that only vents to the outside to keep off gassing outside. Or move to one of the sealed battery chemistry’s.

As far as a DC to DC charger, it depends on how hard you want to push the alternator, and how much you want to replenish into the battery bank in what a mount of time. Some folks say don’t try to take more than 10 amps extra, others say you can go 20 or 30.

You will need to size wiring appropriately for the load you choose.

I have not yet installed a DC to DC charger in my trailer, but plan to in the future and am planning around 20 amps. I currently have two 6V golf cart batteries in an outside box on my trailer. I plan to go to 600 amps of lithium.

 

[ccasanova22]

Thank you brroberts,

I'm now thinking of placing the lead acid battery inside a storage compartment inside the trailer, which is mostly sealed away from the inside of the trailer but may still have a few gaps in the trim where offgassing could leak out. I am thinking of getting some sort of vent to the outside (the compartment is very close to the outside) to prevent issues from offgassing.

I usually take long trips (mostly cross country with 10-12 hours of drive time per day) so even 10A per hour would fully charge the battery in 8-9 hours. Is there a recommended maximum that Ford wants us to draw (20A? 30A?) from the 7-pin harness? Did not find one in the owner's manual but also didn't look too deeply.

I hope the DC to DC charger would fully automatically top off the battery when running and stop charging when full, so I'm looking for a "hands free" solution. Having to stop every so often and open the compartment, switch things on/off, etc, would not be desirable.

Appreciate the heads up and I look forward to getting this project completed!

 

[Frenchy]

For a good DC to DC Charger I would highly recommend RedArc. Depending on the setup of the camper trailer I recommend going with a charger that can accept solar as well. Why you ask? To start it makes it easier down the road if you decide to add solar. Second, if you are staying put somewhere for a few days it makes it much easier to keep charge in the batteries.

With all that said I also recommend going with either a AGM or Lithium Battery over the flooded Battery. Better capacity and reliability especially with a good charger on board.

 

[ccasanova22]

frenchy,

I’d like to eventually add solar but it’s not in the budget right now. The goal is to power some interior task lighting and maybe an inverter to power some AC outlets for charging laptops, etc. that are separate from the rest of the trailer’s wiring.

I also plan to add a brake controller to the 7 pin so that may use some amps from the Aux +12V (black) wire.

Would the 2A from eTrailer be too small to actually charge the battery, knowing that I don’t plan on using it for anything besides accessory loads?

2A at 10 hours = 20Ah, and four days of driving would equal a topped off battery…

 

[Frenchy]

Think about it this way. When you are charging a battery, the rate that it will charge will be limited to what the charger can do at max per hour which we like to call Amps per Hour. If the charger only is capable of charging at 2 amps then it will only charge 2 amps per hour. For a 100 amp hours battery that is at 50 amps of capacity, it would take 25 hours for that charger to get the battery up to par. A battery charger that has a maximum charge rate of 25 amps has the ability to cut that down to almost 2 hours(depends on the charge profile).

If solar is not in your budget right now but you would like it in the future then now is a good time to get a DC DC Charger that is Solar capable. This does not mean you need to buy all the other solar components. This just means that once it is in your budget, you already have the controller you need to do the job and don't have to buy a second one.

If you feel the RedArc solar capable controller is a bit out of your price range for the time being then look at either KickAss Products or Schumacher as they both have DC DC Chargers that are Solar Capable and cost a bit less than the RedArc.

 

[Joeiconic]

Why not go with something purpose built like this:

https://www.bluettipower.com/products/ac180

The sale price is not far off from buying a battery and converter and has multiple charging options including solar. Safer too.

 

[ccasanova22]

Thanks for the detailed response Frenchy!

My dilemma is on stock wiring (my Ranger is stock), would going with a bigger charger yield me any benefit before I go solar? I don’t want a 60A charger that is limited to 20A (because I need to leave some current available for the brake controller, an Autowbrake unit), and then end up blowing a fuse because it got bumped to a higher 40A or 60A setting.

Since the Autowbrake would take some current from the 7 pin and the charger would also take some while driving, is there a safe “maximum load” on a stock Ranger with stock 7 pin I should stick to?

 

[Frenchy]

Why not go with something purpose built like this:

https://www.bluettipower.com/products/ac180

The price is not far off from buying a battery and converter and has multiple charging options including solar. Safer too.

Those are much more expensive and don't have near as much available power as one would think. My lithium 100 amp hour battery has way more power than that particular unit. Got to look at what you are trying to to do in order to figure out what all you need for available power

 

[Frenchy]

Thanks for the detailed response Frenchy!

My dilemma is on stock wiring (my Ranger is stock), would going with a bigger charger yield me any benefit before I go solar? I don’t want a 60A charger that is limited to 20A (because I need to leave some current available for the brake controller, an Autowbrake unit), and then end up blowing a fuse because it got bumped to a higher 40A or 60A setting.

Since the Autowbrake would take some current from the 7 pin and the charger would also take some while driving, is there a safe “maximum load” on a stock Ranger with stock 7 pin I should stick to?

My suggestion is to go to RegArc's site and take time reading up on their knowledge base for that kind of setup. As for the available amps from the factory alternator on the Ranger, you will be fine. If I remember correctly(someone correct me if I am off) the Ranger has a 160 or 180 amp alternator.

 

[ccasanova22]

It looks like on other RV forums (not my post just reading) a properly equipped trailer with Autowbrake and 2 electric brakes could exceed 20A already:

https://tab-rv.vanillacommunity.com/discussion/10634/7-pin-installed-with-12-gauge-and-20amp-fuse

Does anybody have experience with the 7 pin doing a “little more” or is it the cheapest low bidder wire where the fuse is already too big for the wire and any attempts to draw near it will result in wire failure? I mean on the truck, not trailer wiring, and do not intend to ever override or overfuse anything…

Basically, what is the REAL maximum current you can draw from that 7 pin to stay within safe levels? 20A? 25A?

 

[Frenchy]

I can't speak for the wiring, but again if you go to the knowledge base at RegArc's site you will get a lot of information to help yourself out

 

[Joeiconic]

Those are much more expensive and don't have near as much available power as one would think. My lithium 100 amp hour battery has way more power than that particular unit. Got to look at what you are trying to to do in order to figure out what all you need for available power

Agreed, just throwing it out as an option. I have no idea what OP needs to power. At $650, the price doesn’t seem much greater than the cost of a battery and the $400 converter OP referenced.

 

[Frenchy]

Here you go

https://www.redarcelectronics.com/us/battery-chargers/trailer-battery-charger

 

[ccasanova22]

Agreed, just throwing it out as an option. I have no idea what OP needs to power. At $650, the price doesn’t seem much greater than the cost of a battery and the $400 converter OP referenced.

Just a laptop (60W USB-C power adapter), maybe a small PC monitor or television, emergency weather radio and cell phone charger. I have a jump pack that works for emergencies but the 2nd battery would also be a “just in case” for true emergencies when boondocking.

Laptop running at full tilt (and with a monitor at full brightness) would maybe be a max of 10A @ 12VDc which equals a run time of 8.8 hours. That would be plenty.

Also I’ve tried multiple household items off a DeWalt inverter and none of their power supplies mind the square wave output. Was surprised how tolerant most things are of square wave power…

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