More testing of RENOGY DC to DC Charger....Toyota

[Rbertalotto]

I have a Toyota Venza that I will be using to tow my trailer with RTT to various events where I will not be going off-road. V6 engine with 150A alternator.

I installed a 50A circuit breaker to the battery. Terminating with an Anderson plug. I used 8G wire I had for these short runs.



Last night I hooked up a few devices to my 100Ah battery box to draw it down to around 60%



I ran a 20' 4Ga extension cable from the Toyota battery to the RENOGY 40A DC to DC charger.

Started the car and immediately the amps to the battery jumped up to 39.6A, stayed there for about two minutes and then stabilized around 35A



Battery voltage when I started was 12.18V



While charging it started out at 14.2V for a minute or so, but quickly decreased to 13.16V.
I have absorption set at 14.4V and Float set at 13.2V.....



I timed it for 15 minutes......It took the battery from 56.8% to 65%......Didn't want to run the car any longer so discontinued the test. Hooked the battery up to portable , 120W solar panels to finish off the charge.

Seems good? Not sure what I should be expecting from this set up. Comments appreciated....

 

[Justin Cook]

Installation looks good; as an aside, though, I'd be careful about that off-brand 50A breaker, as those are known to have issues with either popping too early or too late or have sub-par connections inside that overheat or cause other issues. It's kind of a tossup... some of them perform as rated, but I've seen over a dozen mobile solar installations to date that were having issues because of using those. I pretty strongly recommend getting a Bussman unit in there; the matching style to the one you have would be the 285-series surface-mount. The "Blue Sea" series 285 is the same thing, it's just a Bussman 285 in Blue Sea retail packaging.

**EDIT: I'll also add that your 20' 4ga cable (so 40' round-trip) is giving you around 3.41% voltage drop, which is probably why you're seeing a lower voltage at the battery than you have the Renogy programmed for. Strongly recommend either cutting that distance in half (if possible) or bumping up to a 2ga to keep your voltage drop in the safe zone (2ga would keep your v drop at 2.15%, which is acceptable).

 

[Rbertalotto]

That extension cord is used between my 120w folding portable solar panels and the battery box. I have 100' of #2 welding cable sitting here waiting for a warm day to do the permanent install. It will be about 32 feet total (16/16).
I've personally used hundreds of these off brand circuit breakers as I owned a car stereo install center for years. Never heard of one of them failing. But I'll keep my eye on it. Thanks

 

[Justin Cook]

I've personally used hundreds of these off brand circuit breakers as I owned a car stereo install center for years. Never heard of one of them failing. But I'll keep my eye on it. Thanks

Ha, yeah that's where I started in DC electronics as well, and by the 10th time I had one fail (or fail to pop when it should, usually) I swore off them, and that's been reiterated in my years of high-current DC application experience.

 

[Chris-NC]

Nice write up on the install and test. I also visited your site to check out the build for your battery box. Nicely done! I'm in the process of doing this same type of project for my Jeep. I don't keep my fridge in it all the time, but once I hit the camping season it will remain in there more often than not. I have a couple of good AGM batteries and those exact battery boxes, so my plan is very similar. I'm interested in any additional testing you do with charging from the Renogy DC to DC charger. I was going to use the easy method and charge off the alternator, but I've done some testing and even though I have a good AGM starting battery, my fridge will run it down far enough where the alt isn't charging it back up enough. So now I'm planning to go with a separate battery/charging solution in the back of the Jeep for the fridge, device charging, etc.

 

[Rbertalotto]

Thanks for the kind words.....Appreciated!

I started "overlanding" in 1968 with a 1943 Army Jeep.....No frills at all. A few years, later I ,married and my wife and I wanted to REALLY Overland....We bought a International Scout 80A then a 800 and then a ScoutII...I installed two wet cell batteries with some kind of gizmo that ran off the alternators to keep both batteries charged. You had to keep a keen eye on the aux battery or the water would be boiled out of it.....A few years later a K20 Chevy with a PU truck camper came to live with us. A heavy duty relay was used to keep the aux battery charged. It toasted a couple alternators in the process....And it couldn't keep up with the demands that PU camper placed on the aux battery.
I've been away from Overlanding type camping as the last couple decades I've been motorcycle touring. Now I'm back and building a RTT trailer with that battery box you refer to. Tons of research on both overlanding and marine forums showed these DC to DC chargers were the only way to go. But until recently, they were stupid expensive. With RENOGY well under $175 for either 20A or 40A units, its a no brainer.

As far as testing, I've not had the time to wire the Toyota and the RAM yet.

Stay tuned....