Renogy DC to DC charger...interesting

[Oldwave]

When will Proust tested the Renology dc to dc he also got way lower out of it than it’s rating.

 

[Off Gridin' It]

I watched that video. I'm pretty sure the output was right on the money.

 

[Tomthumb62]

If you want to test without the truck charging through the 7 pin, you can pull the 30amp fuse. Long short, you should be getting at least 15amps just from the trailer connector.

This is good news! So you’re saying I can just run some wire from the 7 pin to my batteries and they’ll get charged at 15A? That sounds so much more simple and less expensive than installing a dc dc charger. Now if my bank is 12v lifepo, if I understand, the charge voltage from the 7 pin won’t be ideal for lithium but not damaging either, am I on the right track?

The only real downside I see to this way is only 15A vs 40 or higher.

And if one were to hookup both the 15A 7 pin and a 40A dc dc charger, you could theoretically get 55A, correct?

 

[HRTKD]

This is good news! So you’re saying I can just run some wire from the 7 pin to my batteries and they’ll get charged at 15A? That sounds so much more simple and less expensive than installing a dc dc charger. Now if my bank is 12v lifepo, if I understand, the charge voltage from the 7 pin won’t be ideal for lithium but not damaging either, am I on the right track?

The only real downside I see to this way is only 15A vs 40 or higher.

And if one were to hookup both the 15A 7 pin and a 40A dc dc charger, you could theoretically get 55A, correct?

The problem with a "naked" circuit is that it just keeps charging and charging and never stops until the BMS on the LiFePO4 battery gives the charge a middle finger and shuts it off. Most of use aren't charging to that point.

With regard to your second question, yes, you would get as much at 55 amps.

 

[grizzzman]

I own a Renolgy 40 amp DC to DC charger. In testing I found that at 14 volts input input amps was right at 50 amps and output was outputting 39+ amps. My truck has smart charging, At idle the input was between 12.7 to 12.9 input as amps was 50 and the output voltage of 14 volts at 33 amps.
My unit is set up as a jump starter with a total 20' of 4 AWG with parrot clamps.

 

[Rbertalotto]

Update on my original post here.....I just returned from a two month, 7700 mile cross country trip from Massachusetts to Arizona and back...Great trip BTW!.....I had reason to use the Renogy DC to DC charger a couple times while on the road. This time batteries (Two, 100aH Renogy Lithium in Parallel) were at 60-70% when getting underway. The Renogy DC to DC charger was outputting 35-38amps.....So I call this GOOD! My whole installed Li system worked great. Except one battery became unbalanced with 3.4/3.4.3.2/3.8 cell voltages. I called Renogy and the tech support was fantastic. They told me to disconnect that battery and charge it to 100% separatly. I had a Victron Blue Smart IP22 charger with me, so I did as suggested. All cells were now at 3.4. Reinstalled battery and as of now, couple months later, all is still well.
As a side note, I hit some VERY cold single digit weather on the trip and my DIY battery heating system worked fantastic!
Loving the performance of this new Li system!


You can view and read about all this here....

RV Lead Acid/AGM to LITHIUM | RVB Precision

A few years ago I installed a rather involved solar system in my Forest River RR19 Toy Hauler travel trailer. Back then, with a single Lithium battery costing over $1000 I decided to go the AGM (Absorb Glass Mat) route. You can read all about this project on another article here on my web...

rvbprecision.com

 

[HRTKD]

Thanks for the update. Sounds like a great trip.