Tapping 12V from the truck to charge Battle Borns

[Guest]

Tested the Renogy 20 amp DC DC charger today and before wiring it permanently into the Imagine. I temporarily wired it in and it provided 20.81 amps to the AIMS lithium battery that sat on the driveway. The total draw on the 7 pin battery connector from the truck was at 27 amps so I'm good with permanently wiring this into the rig. The EE's may want to provide feedback here where it appears the Renogy is pulling power from the truck rather than the truck pushing power to the Renogy charger. I've not seen 20 amps coming from the trucks 7 pin trailer connector prior to connecting the Renogy charger.

So far from this test, a light duty 20 AMP charger will function from the battery feed on my 7 pin connector. Now if you want more power, a separate dedicated cabling would need to be ran directly to the TV battery.

Jim

[howson]

Tested the Renogy 20 amp DC DC charger today and before wiring it permanently into the Imagine. I temporarily wired it in and it provided 20.81 amps to the AIMS lithium battery that sat on the driveway. The total draw on the 7 pin battery connector from the truck was at 27 amps so I'm good with permanently wiring this into the rig. The EE's may want to provide feedback here where it appears the Renogy is pulling power from the truck rather than the truck pushing power to the Renogy charger. I've not seen 20 amps coming from the trucks 7 pin trailer connector prior to connecting the Renogy charger.

So far from this test, a light duty 20 AMP charger will function from the battery feed on my 7 pin connector. Now if you want more power, a separate dedicated cabling would need to be ran directly to the TV battery.

Jim

That's fascinating, Jim, and quite a discovery. Obviously your test was done on a GM (duh!) so it will be quite interesting to learn if the same result comes from a Ford, Dodge, Toyota, etc.

[Guest]

That's fascinating, Jim, and quite a discovery. Obviously your test was done on a GM (duh!) so it will be quite interesting to learn if the same result comes from a Ford, Dodge, Toyota, etc.

Thanks Howard,

Now here is the catch. I looked up the wiring diagrams on the TV which shows this circuit is 35amps. When I looked at the fuse in the truck it was 30 amps so this is a bit strange. But it handled it so I will wire it in and through the 30 amp breaker that's on the frame of the imagine.

It was really nice to see this functioning as I hoped it would.

Jim

[ncitro]

Well I finally got the truck back from the body shop and was able to complete this project. Since I’m running a fifth wheel I really wanted the connection to be in the bed rather than down by the hitch, which made the whole thing way more difficult. I found some panel mounts for the smaller connectors, but none for the SB120. Finally found a guy on Etsy of all places in Australia who 3D printed some. I took a chance (and waited an eternity for them to get here), and I’m pretty happy with the results. Need to cut the weatherproof boot off the trailer end, but I think it’s worth it to have it tidy and tucked away when not towing.

[howson]

ncitro -- Adding the Renogy is by far one of the best upgrades I've done to compliment my Victron inverter and Battle Born battery setup. I'm confident you'll have the same experience--look forward to reading your review once you get to use it on the road.

[ncitro]

ncitro -- Adding the Renogy is by far one of the best upgrades I've done to compliment my Victron inverter and Battle Born battery setup. I'm confident you'll have the same experience--look forward to reading your review once you get to use it on the road.

Can’t wait, we’re hoping to maybe go to Yellowstone in late August, but will have to see how things go.

[ncitro]

howson Hey Howard yesterday was our first decently long trip since we put the charger in. Had the crock pot running with dinner in it so was a good test of the charger. We tripped the 60 amp breaker off the battery twice, didn’t reset it the second time as we were driving. I remembered when I ordered my parts a Covid was in the early stages and it was tough to get parts ordered. I didn’t end up with a blue sea breaker, but an off brand was all I could get. It looks identical and is listed as waterproof and ignition proof, but still you never know. I’m wondering if maybe the breaker is suspect or if maybe the extra length I have with a long bed and fifth wheel is pushing it over 60 amps on the input? I’d think the wiring would be plenty safe to 80 at #4 in open air, but curious what you think.

[howson]

howson Hey Howard yesterday was our first decently long trip since we put the charger in. Had the crock pot running with dinner in it so was a good test of the charger. We tripped the 60 amp breaker off the battery twice, didn’t reset it the second time as we were driving. I remembered when I ordered my parts a Covid was in the early stages and it was tough to get parts ordered. I didn’t end up with a blue sea breaker, but an off brand was all I could get. It looks identical and is listed as waterproof and ignition proof, but still you never know. I’m wondering if maybe the breaker is suspect or if maybe the extra length I have with a long bed and fifth wheel is pushing it over 60 amps on the input? I’d think the wiring would be plenty safe to 80 at #4 in open air, but curious what you think.

Hey Neil,

Let me make sure I'm understanding: the crock pot was running off the Victron 12/3000 inverter while you were driving. You have a Renogy 40A DC-DC Charger connected to the truck's battery through a 60A circuit breaker, right? Is the Renogy connected at the Victron, directly to the batteries, or some other configuration?

The 60A breaker is on the truck side of the Renogy (or the input side of the Renogy)--right?

What triggers the D+ signal on the Renogy in your setup?

The switches on the Renogy are set per my "Lessons Learned" in post 37 of this thread?


The Renogy adjusts it's output ~.7v above the battery SOC. Again, from post 37, Under load, the output of the Renogy is determined by the SOC (state of charge). For example, at one point my BB's were at 13.29v without any load. With the unit on and charging the voltage at the output was "only" 13.6vDC.

The 40A Renogy is rated for 500W, so assuming the input draw into the Renogy was more than 60A the voltage had to be <8.3v? (500W/60A=8.333v) That doesn't make sense...can't see that happening or you'd have other issues in the truck and likely would get an "idiot light" indicating a vehicle charge system fault. (I'm not an auto mechanic...so just taking an educated guess.) What's interesting is I typically see ~13.6v on the output of my Renogy and usually right at 40A. That's 544W. But even using 544W doesn't make much difference on the input side: 544W/60A=9.06v.

What I'd do if it was my setup would be to measure the voltage on the input side of the Renogy (at the Renogy). Compare to the voltage level at the truck's battery. If there's a drastic difference, there's a wiring issue. If the voltages are within acceptable loss tolerances (actual loss expectations depends on wire quality, connector quality, length of the wire, etc)...not sure. Could a wire be chaffing and shorting? You've got the recommended size breaker per the Renogy manual.

Hope this helps at least a bit...please post back with anything you find. There are a lot of smart folks on this forum that may have an input that makes us go "Aha!".

Howard

[ncitro]

Yeah when I get to our next stop I’ll do some testing. 60A breaker is on the input side, DIP switches are set the same as yours. No warnings lights in the truck, and I agree if the voltage was that low I’d see them.

Crock pot was on via the inverter. Batteries started off full, and I had the solar running too. I could watch the BMV and see the current bounce as crock pot cycled on and off. I think I recall the voltage in the 13.6 range, and when I switch on the up fitter I’ve the current go up by 40 amps almost exactly. Then after a while I checked the BMV again and saw the SOC was down in the low 90’s. When we stopped I popped the hood and saw the breaker was tripped.

I wonder if it’s an ambient temperature issue, or if the breaker might be defective.

[howson]

Yeah when I get to our next stop I’ll do some testing. 60A breaker is on the input side, DIP switches are set the same as yours. No warnings lights in the truck, and I agree if the voltage was that low I’d see them.

Crock pot was on via the inverter. Batteries started off full, and I had the solar running too. I could watch the BMV and see the current bounce as crock pot cycled on and off. I think I recall the voltage in the 13.6 range, and when I switch on the up fitter I’ve the current go up by 40 amps almost exactly. Then after a while I checked the BMV again and saw the SOC was down in the low 90’s. When we stopped I popped the hood and saw the breaker was tripped.

I wonder if it’s an ambient temperature issue, or if the breaker might be defective.

I don't have definitive evidence for the following or why I do it (still need to do some testing), but this is how I engage the Renogy (with solar).

START TOWING

1) Before starting the truck I open Victron Connect and under the MPPT's Settings I turn off the Charger Enabled option. I get a warning about only doing this for maintenance which I choose to ignore.

2) Start the truck and wait for all the "start up" stuff to finish (indicated by the display panel showing the GPS map).

3) Turn on the truck's lights (which is the D+ signal going into the Renogy).

4) Turn on the Upfitter switch which enables the relay to pass voltage from the battery to the input side of the Renogy. I monitor the amperage on the BMV-712 in Victron Connect to ensure it's working as advertised.

5) I then go back into the MPPT's settings and switch the Charger Enabled setting back on.

BEFORE TURNING OFF ENGINE

1) Turn off the Upfitter switch to remove battery power from the input side of the Renogy.

2) Turn off the truck's lights, removing the D+ signal.

3) Turn off the truck.

I follow this sequence because there is sometimes an odd interaction between the MPPT and Renogy, but I haven't documented it or quantified, so again...can't defend what I'm doing right now.

Howard

[ncitro]

howson Interesting thought. I’ll try disabling the smart solar before I turn on the Renogy today.

Oh I didn’t mention this but my D+ is tied to the running lights as well.

[ncitro]

Well I tracked it down. The solid state relay seemed to be the culprit. I reset the breaker, and checked voltage out of the truck and got 14.6, but when I loaded it down with the charger it dropped to 2 and some change. Checked resistance of the cables and all was good there, so no shorts or opens anywhere. I pulled out the relay and wired directly to the breaker and it runs like a champ now. This obviously means I’m not running off of the upfitter switch, and anytime I connect the charging feed and turn on the lights it’ll start discharging the truck battery, even if the ignition is off.

I’m going to take the blame for this one, I didn’t install a heat sink, which I now realize is required to active the stated ratings. I’m get some new components ordered and installed when we get home, at least it is working for now.

[wygieman]

I don't have definitive evidence for the following or why I do it (still need to do some testing), but this is how I engage the Renogy (with solar).

START TOWING

1) Before starting the truck I open Victron Connect and under the MPPT's Settings I turn off the Charger Enabled option. I get a warning about only doing this for maintenance which I choose to ignore.

2) Start the truck and wait for all the "start up" stuff to finish (indicated by the display panel showing the GPS map).

3) Turn on the truck's lights (which is the D+ signal going into the Renogy).

4) Turn on the Upfitter switch which enables the relay to pass voltage from the battery to the input side of the Renogy. I monitor the amperage on the BMV-712 in Victron Connect to ensure it's working as advertised.

5) I then go back into the MPPT's settings and switch the Charger Enabled setting back on.

BEFORE TURNING OFF ENGINE

1) Turn off the Upfitter switch to remove battery power from the input side of the Renogy.

2) Turn off the truck's lights, removing the D+ signal.

3) Turn off the truck.

I follow this sequence because there is sometimes an odd interaction between the MPPT and Renogy, but I haven't documented it or quantified, so again...can't defend what I'm doing right now.

Howard

I am in the process of implementing the truck charging setup pretty much the way Howard has implemented it, 4 awg through a 60 amp breaker enabled by a relay powered with an upfitter switch. I have the truck almost done and am getting ready to go work on the trailer. When I look at Howard’s model, I can’t see any reason to wire the D+ switch to the lights as recommended. If I wire the D+ switch to the 4 awg wire from the truck, I get the same results I believe. The wire can’t be energized from the truck until the ignition is on just like the lights as the upfitter switch isn’t energized until the ignition is on. When I turn on the upfitter switch it energizes the power to the renogy including the D+. What added value comes from the extra work to wire the D+ to the lights? It seems completely redundant once I have the upfitter switch controlling the charging. What am I missing?

[ncitro]

I am in the process of implementing the truck charging setup pretty much the way Howard has implemented it, 4 awg through a 60 amp breaker enabled by a relay powered with an upfitter switch. I have the truck almost done and am getting ready to go work on the trailer. When I look at Howard’s model, I can’t see any reason to wire the D+ switch to the lights as recommended. If I wire the D+ switch to the 4 awg wire from the truck, I get the same results I believe. The wire can’t be energized from the truck until the ignition is on just like the lights as the upfitter switch isn’t energized until the ignition is on. When I turn on the upfitter switch it energizes the power to the renogy including the D+. What added value comes from the extra work to wire the D+ to the lights? It seems completely redundant once I have the upfitter switch controlling the charging. What am I missing?

I tried that and it did not work for me. I did also have the Renogy fail shortly after I tried that method. I got it exchanged with no issue, but I never retried that configuration so I am not sure if that was the problem with tying it to the charging wire. I pretty much always tow with the headlights on so it was not worth troubleshooting further at that point.

I would caution you, I know Howard has had no issues with his setup, but the 60 amp solid state relay I used to go from the truck batteries to the upfitter feed failed on me. To finish that trip I just tied it to the battery, knowing if my lights were on it would be running the charger. Once I got home I picked up a 200 amp solenoid and it has been good ever since. I know it is not as efficient, but that waste of power is on the truck side, and the alternator has power to spare so I figured it would be fine.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[howson]

I tried that and it did not work for me. I did also have the Renogy fail shortly after I tried that method. I got it exchanged with no issue, but I never retried that configuration so I am not sure if that was the problem with tying it to the charging wire. I pretty much always tow with the headlights on so it was not worth troubleshooting further at that point.

I would caution you, I know Howard has had no issues with his setup, but the 60 amp solid state relay I used to go from the truck batteries to the upfitter feed failed on me. To finish that trip I just tied it to the battery, knowing if my lights were on it would be running the charger. Once I got home I picked up a 200 amp solenoid and it has been good ever since. I know it is not as efficient, but that waste of power is on the truck side, and the alternator has power to spare so I figured it would be fine.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Neil,
Any chance the solid state relay (SSR) in your original setup didn't have a good heat dissipation setup? When I installed my SSR I put a conductive pad (made for the SSR) between it and the truck where the SSR is mounted. If you've ever installed a computer CPU, it's the same as putting the paste between the cooler fan and CPU.

Took me a bit, but I found the receipt in my email. Here's the "Thermal Interface Product" I was referencing--it is specifically designed to work with Sensata SSRs: