Renogy 20 amp DC to DC charger

[John1961]

After using my dc to dc charger my alternator smell hot ever time I drive my van. My van has a 180 amp alternator . Any help would be appreciated on why this is happening and what I can do to fix this.

 

[John Frum]

After using my dc to dc charger my alternator smell hot ever time I drive my van. My van has a 180 amp alternator . Any help would be appreciated on why this is happening and what I can do to fix this.

What gauge are the wires from the starter battery to the dc2dc charger?
How long are the wires?
Is the wire or fuse also getting hot?
Are there any other loads on the alternator that you can avoid?

 

[timselectric]

After using my dc to dc charger my alternator smell hot ever time I drive my van. My van has a 180 amp alternator . Any help would be appreciated on why this is happening and what I can do to fix this.

Are you charging lithium phosphate batteries?
And if so, is the DC to DC charger made for this?

 

[John1961]

Yes the kodiak power generator is lithium and I'm pretty sure I have the switches in the right position for that.

 

[John1961]

What gauge are the wires from the starter battery to the dc2dc charger?
How long are the wires?
Is the wire or fuse also getting hot?
Are there any other loads on the alternator that you can avoid?

The wire is 10 gauge and about 10 feet long. The fuse has not burned out. I have not checked to see if it gets hot. And no, nothing else is on other than the normal things in a van when driving.

 

[John Frum]

The wire is 10 gauge and about 10 feet long. The fuse has not burned out. I have not checked to see if it gets hot. And no, nothing else is on other than the normal things in a van when driving.

10 awg is a bit small.
The voltage drop for 20 feet round trip is ~4.5% we usually shoot for under 3%.
What is the fuse rating?

 

[John1961]

not sure on the rating I'll have to check that after I get off work.

 

[time2roll]

After using my dc to dc charger my alternator smell hot ever time I drive my van. My van has a 180 amp alternator . Any help would be appreciated on why this is happening and what I can do to fix this.

I recommend measuring the current the alternator is producing into the low battery.
How is the smell determined to be the alternator?

 

[John1961]

10 awg is a bit small.
The voltage drop for 20 feet round trip is ~4.5% we usually shoot for under 3%.
What is the fuse rating?

checked the fuse last night it is a 25 amp going from the DC to DC charger to the Kodiak generator. Which is what was recommended by Renogy the maker of the charger.

 

[John Frum]

checked the fuse last night it is a 25 amp going from the DC to DC charger to the Kodiak generator. Which is what was recommended by Renogy the maker of the charger.

Since you are using 10 awg wire that is just about as big as you can go.

 

[John1961]

I recommend measuring the current the alternator is producing into the low battery.
How is the smell determined to be the alternator?

Ill have to get a clamp on amp meter to measure the amps, probably pick one up when I go home this weekend.
It smell like brushes heating up. And when I disconnected the DC to DC charger for the past month and the smell went away.

 

[timselectric]

Ill have to get a clamp on amp meter to measure the amps, probably pick one up when I go home this weekend.
It smell like brushes heating up. And when I disconnected the DC to DC charger for the past month and the smell went away.

Make sure that the meter can measure DC amps.

 

[John Frum]

Ill have to get a clamp on amp meter to measure the amps, probably pick one up when I go home this weekend.
It smell like brushes heating up. And when I disconnected the DC to DC charger for the past month and the smell went away.

Is it this charger https://www.renogy.com/12v-20a-dc-to-dc-on-board-battery-charger/ ?
"LC Current Limit Wiring" -- https://www.renogy.com/content/RNG-DCC1212-20-BC/DCC1212-204060-Manual.pdf

 

[OTRwSolar]

10 ft. of 10 gauge wire (one-way) at 30a produces a 5% voltage drop under ideal conditions---too high IMO. Bad connections, crimps, etc. could drive this voltage drop even higher. If it were me, I would have used 6 gauge cable (2% voltage drop). Physically larger cable equals less voltage drop, equals less load on the alternator.

Excessively long cable runs and/or too small of cables can cause the input current on a DCC12 20a Renogy dc2dc charger to go as high as 30a (while still producing 20a of charge current). The 40a and 60a models can go as high as 60a and 90a, respectively.

A 180a alternator should have zero problems powering a DCC12 20a Renogy. As others have suggested, I'd verify all the loads on your alternator with a dc clamp-on ammeter. We regularly power a 40a Renogy dc2dc charger (with a full 40a charge load) with a 220a alternator for hours at a time with zero issues. Our 40a Renogy typically draws 43a via 25 ft. of 2 gauge cable. Renogy recommended 4 gauge which would have "worked", but it would have bumped our load on the alternator up to approx. 50a (vs. 43a with 2 gauge).

BTW, you mentioned using a 25a fuse. Was that on the input or output? Renogy recommends the DCC12 20a dc2dc charger's input be fused at 30a, the output at 25a.

 

[fratermus]

can cause the input current on a DCC12 20a Renogy dc2dc charger to go as high as 30a (while still producing 20a of charge current)

Underappreciated factor. People assume 20A out means 20A in also.

 

[John1961]

Are you charging lithium phosphate batteries?
And if so, is the DC to DC charger made for this?

Yes to both question. Using a Renogy 20 amp DC to DC charger.

 

[John1961]

10 ft. of 10 gauge wire (one-way) at 30a produces a 5% voltage drop under ideal conditions---too high IMO. Bad connections, crimps, etc. could drive this voltage drop even higher. If it were me, I would have used 6 gauge cable (2% voltage drop). Physically larger cable equals less voltage drop, equals less load on the alternator.

Excessively long cable runs and/or too small of cables can cause the input current on a DCC12 20a Renogy dc2dc charger to go as high as 30a (while still producing 20a of charge current). The 40a and 60a models can go as high as 60a and 90a, respectively.

A 180a alternator should have zero problems powering a DCC12 20a Renogy. As others have suggested, I'd verify all the loads on your alternator with a dc clamp-on ammeter. We regularly power a 40a Renogy dc2dc charger (with a full 40a charge load) with a 220a alternator for hours at a time with zero issues. Our 40a Renogy typically draws 43a via 25 ft. of 2 gauge cable. Renogy recommended 4 gauge which would have "worked", but it would have bumped our load on the alternator up to approx. 50a (vs. 43a with 2 gauge).

BTW, you mentioned using a 25a fuse. Was that on the input or output? Renogy recommends the DCC12 20a dc2dc charger's input be fused at 30a, the output at 25a.

I have a 25 on the output side of the DC to DC charger

 

[John1961]

I recommend measuring the current the alternator is producing into the low battery.
How is the smell determined to be the alternator?

It has a burnt brush smell every time I drove the van for very long, and after disconnecting the charger for the last month the smell has gone away.

 

[timselectric]

Lithium batteries have a very low internal resistance.
They can absorb a lot of power, quickly. At idle, your alternator can't cool itself enough. Depending on the rpms while driving, this can also be the case.
Not sure if this is the issue. But, it's a possibility.
It does sound like the alternator is overheating.

 

[Levo]

John, I have basically installed and wired my 40A dc-dc charger with 6AWG, but not yet commissioned it. Potential overheating of my (nominal 160A) alternator is why I am proceeding carefully. I like the idea of being able to switch on and off as required, so I looked at this idea (8:20 sec):

but running control wire from truck to trailer would require more disconnectable conductors, kind of a pain as the charger is in the trailer (per recommendations). Would be easier in a van or motorhome. Considering this option (or one like it):
https://www.amazon.ca/dp/B08JGH471B...d=38YXI8UALTJMJ&psc=1&ref_=lv_ov_lig_dp_it_im one channel for on/off and one to activate the 50% current limit function.
I think this will reduce heavy loads on the alternator for too long, only using the charger as needed, and when the alternator has enough RPM for cooling.
Also, I may install this (one or both) so I can monitor current from the cab:
https://www.amazon.ca/dp/B07PV5Y6J2...olid=38YXI8UALTJMJ&psc=1&ref_=lv_ov_lig_dp_it
Any feedback from others who have tried methods/products like this is welcome.

 

[OTRwSolar]

. . . installed and wired my 40A dc-dc charger with 6AWG, but not yet commissioned it. Potential overheating of my (nominal 160A) alternator is why I am proceeding carefully.

How long is your run of 6 gauge cable? Using Renogy's AWG recommendations at the max allowable cable run/length will net approx. 60a of input current (alternator load) with a 40a charge load with the 40a Renogy dc2dc charger. If you use one or two gauges larger (physical size) than what Renogy recommends you can drop the input current as low as 42-45a. Pretty substantial reduction.

 

[Levo]

How long is your run of 6 gauge cable? Using Renogy's AWG recommendations at the max allowable cable run/length will net approx. 60a of input current (alternator load) with a 40a charge load with the 40a Renogy dc2dc charger. If you use one or two gauges larger (physical size) than what Renogy recommends you can drop the input current as low as 42-45a. Pretty substantial reduction.

Well the input run from the truck is long (about 25'). Would like #4, but the wire gets to cost more than the charger! Charger to house battery is only 1'. If it proves inadequate, I may reconsider. If I have to go 50% current, I'm okay with that for now; still 20A charge.
Avoiding risk to the alternator trumps maximum charge until I can evaluate it in practice.

 

[OTRwSolar]

Well the input run from the truck is long (about 25'). Would like #4, but the wire gets to cost more than the charger! Charger to house battery is only 1'. If it proves inadequate, I may reconsider. If I have to go 50% current, I'm okay with that for now; still 20A charge.
Avoiding risk to the alternator trumps maximum charge until I can evaluate it in practice.

Renogy recommends 4-6 gauge up to 16 ft, 2-4 gauge up to 32 ft for the 40a dc2dc input. With 25 ft of 6 gauge you may be hitting the 60a input limit with some reduction in output charge current, too. Alternator voltage is a factor (higher voltage = less current). Have you had a chance to verify any current with a clamp-on ammeter? Based on your readings, the Renogy half-power mode may be a wise choice.

We used a ~25 ft (one-way) run of 2 gauge for our 40a Renogy dc2dc charger install (220a alternator). 40a of charge current results in only a 43.5a load on the alternator. Regularly pull max charge current (40a) from the Renogy for 2-3 hours at a time with no issues. We activate high idle if we're charging while parked.

For what it's worth, temcoindustrial.com has 50 ft of 4 gauge welding cable for $63. 50 ft of 2 gauge for $90.

 

[Levo]

Renogy recommends 4-6 gauge up to 16 ft, 2-4 gauge up to 32 ft for the 40a dc2dc input. With 25 ft of 6 gauge you may be hitting the 60a input limit with some reduction in output charge current, too. Alternator voltage is a factor (higher voltage = less current). Have you had a chance to verify any current with a clamp-on ammeter? Based on your readings, the Renogy half-power mode may be a wise choice.

We used a ~25 ft (one-way) run of 2 gauge for our 40a Renogy dc2dc charger install (220a alternator). 40a of charge current results in only a 43.5a load on the alternator. Regularly pull max charge current (40a) from the Renogy for 2-3 hours at a time with no issues. We activate high idle if we're charging while parked.

For what it's worth, temcoindustrial.com has 50 ft of 4 gauge welding cable for $63. 50 ft of 2 gauge for $90.

As stated, not even test run yet so no readings other than alternator current with usual truck demands when idling (60A with heater, blower, wipers all running). There should be enough "headroom" with the 160A alternator. As it is already wired up with #6 (which I had on hand) my plan is to try it out. If the draw is too much with the charger I'll halve the output. It may be enough with the 500w solar panels (40A MPPT controller). Then I'll make the decision on whether to opt for the extra work and expense.
Also, not planning to let it charge on idle, only while driving.
Thanks for the suggestion, but no Temco sales in Canada. Princess Auto has #4 welding cable on sale here for another week (similar price), so I'd better get my arse in gear and test the charger before the cost goes up! I'll post what happens.

 

[Levo]

Renogy recommends 4-6 gauge up to 16 ft, 2-4 gauge up to 32 ft for the 40a dc2dc input. With 25 ft of 6 gauge you may be hitting the 60a input limit with some reduction in output charge current, too. Alternator voltage is a factor (higher voltage = less current). Have you had a chance to verify any current with a clamp-on ammeter? Based on your readings, the Renogy half-power mode may be a wise choice.

We used a ~25 ft (one-way) run of 2 gauge for our 40a Renogy dc2dc charger install (220a alternator). 40a of charge current results in only a 43.5a load on the alternator. Regularly pull max charge current (40a) from the Renogy for 2-3 hours at a time with no issues. We activate high idle if we're charging while parked.

For what it's worth, temcoindustrial.com has 50 ft of 4 gauge welding cable for $63. 50 ft of 2 gauge for $90.

Okay my (idling) test results are in (25' of 6AWG):

Input (full power) 50A, output to battery 42A
Input (1/2 power) 24A, output to battery 21A

Alternator draw: 28A no load, 80A full power,

Voltage drop 14.8/13.8 on full power, 14.8/14.3 on half power

I realise these numbers do no compute exactly as the alternator output fluctuates a little even unloaded, but the highest it hit was 85A initially then settled down. The voltage drop is exactly as predicted in the tables for 6AWG (7% full power, 3.5% half power). I doubt I'll ever hit 60A input. I know Renogy suggests 4AWG for that distance for 40A, but also allows up 10% what they call "non-critical" voltage drop.

Anyway, I am confident that the alternator current draw is safe for the 160A rating. I installed a remote control switch so I can switch on and off and halve the current from the cab.

Final step is to install hall effect current meters when they arrive from Amazon (one on the #6 charger input wire, one on the alternator output). That way, I'll always know how much current flows. I can always halve current when running headlights, heater etc and switch off when idling (if necessary).

Thanks for the feedback; prompted me to do more thorough testing. I know #4 would be better, but I really did not want to rewire the damn thing!