Charge Controller Installation location

[Jonnygsx]

Getting ready to start the install of my solar system and I am trying to figure out the best mounting/wiring options. I have the Xantrex C35 charge controller. My trailer is a prowler with a large front propane cover.



While this cover is not weather tight it does greatly cut down on what things underneath are exposed to. Do you think it would be ok to mount the Xantrex controller up under that cover nearest the batteries? That way it wouldn't require a separate temperature monitor and it would also give me the shortest run cables to the batteries. Thoughts?

[Jonnygsx]

Ha funny I didnt even think to look at the manual for mounting instructions, was going to use it more for setting up the dials and switches. Anyways the manual says to mount it in a waterproof box if it might be exposed to water. Doesn't say anything about ensuring ventilation so i'm not going to worry about it. Thanks for all the advice everyone!

[BFL13]

Solar charge controllers can be sensitive to heating- mine are for sure. They need air cooling. They have internal temp comp which means the unit has to be in the same ambient as the batts. Some controllers get warm if run at max amps for a time.

IMO just keep it in out of the rain, out of the sun, and not in a small box where it will not get enough cooling air. Mine go in the front cargo bay of the 5er which is near the batts and has good ventilation.

The user's manual will be clear on installation so it gets air cooling. Do what it says.

I can see it/them in there if I ever want to look at the display information on the units. I don't need them inside, because I have the Trimetric inside where I can see that. Mine don't have remote displays.

[westend]

Jonnygsx wrote:

westend wrote:
Mounting options:

Carlon 8" x 4" Weatherproof box

Irrigation timer box (you can probably source just the enclosure at a local irrigation shop).

If you have an electrical salvage store near you (most major metro areas have a few), they will have a variety of enclosures for cheap. I bought a 14" x 18" NEMA rated enclosure with a clear polycarbonate lid and lock hasp for less than $10. It houses cable TV and Sat TV junctions in my sticks and bricks.

Now were getting somewhere westend! Great idea here, but the charger says that it gets very hot and to place it somewhere it won't be bumped cause it can cause burns.... this was a concern I had for mounting it inside while also close to the batteries hard to find a safe location. Do you think putting it in this box would be an issue with poor air circulation or melting of the box/fire hazard?

The plastic or spun fiber boxes are pretty durable. Don't know what you have for a charge controller but mine gets barely warm, I have it indoors in a cabinet. I guess a guy could leave a couple of knockouts/box entrances open for ventilation. If you have fears of fire, get an exterior friendly metal box, they are even cheaper.
Does your controller have an encapsulated circuit board?

[RJsfishin]

I know I have a lot more important things to think about than a battery temp sensor. But getting back to location, every controller display I have ever seen was mounted on the side panel as you enter the doorway, which can be seen standing outside w/ the door open, or standing inside. Thats where I mounted mine also. Hard to believe anyone would mount them in some places like has been mentioned on this forum, namely under any cover, closet, or any other out of sight place. And I don't care how far it is to the batteries, its location first, then you deal w/ distance to batts, which people make way too bigga deal of that too. But to each his own I guess.

[pianotuna]

Hi Jonny and BFL13,

About 1/4 of all the energy used for charging a lead acid battery is dissipated as heat. That raises the core temperature of the battery. Similarly, on discharge, the internal resistance of the battery causes the core to rise in temperature.

Every chart and all the data provided by battery makers is correct--at 25 C (77 f). As soon as the internal temperature deviates from that number, the charging voltage should be "tweaked" to have the most efficient charging possible.

The charge controller needs to be placed where it will not get wet, not where it might not get wet. If it will be where the sun can shine on the compartment it will happily reduce the charging voltage unless the battery temperature sensor is used.

[Jonnygsx]

westend wrote:
Mounting options:

Carlon 8" x 4" Weatherproof box

Irrigation timer box (you can probably source just the enclosure at a local irrigation shop).

If you have an electrical salvage store near you (most major metro areas have a few), they will have a variety of enclosures for cheap. I bought a 14" x 18" NEMA rated enclosure with a clear polycarbonate lid and lock hasp for less than $10. It houses cable TV and Sat TV junctions in my sticks and bricks.

Now were getting somewhere westend! Great idea here, but the charger says that it gets very hot and to place it somewhere it won't be bumped cause it can cause burns.... this was a concern I had for mounting it inside while also close to the batteries hard to find a safe location. Do you think putting it in this box would be an issue with poor air circulation or melting of the box/fire hazard?

[westend]

Mounting options:

Carlon 8" x 4" Weatherproof box

Irrigation timer box (you can probably source just the enclosure at a local irrigation shop).

If you have an electrical salvage store near you (most major metro areas have a few), they will have a variety of enclosures for cheap. I bought a 14" x 18" NEMA rated enclosure with a clear polycarbonate lid and lock hasp for less than $10. It houses cable TV and Sat TV junctions in my sticks and bricks.

[BFL13]

Temp comp is important in temp extremes, but my point here is most RVers don't RV in those temp extremes, so it is not much value for them.

[Jonnygsx]

I also don't live in a place where it's 127 or - 40 tuna. But I am not arguing the merits of temperature compensation. I completely agree it's needed. However I find it hard to believe the built in temperature compensation of my charge controller is not accurate enough when mounted right next to the battery to justify $40 for a probe to measure a few inches over. Also the battery sensor does not measure inside the battery it mounts on the outside.

[pianotuna]

Hi BFL13,

You don't live in a climate where it is 127 F, nor -40. Trust me, temperature compensation is worth a measly $35 bucks.

The sensor measures the temperature inside the battery and attempts to optimize the charging voltage. That is no bad thing.

If, and when, my converter dies, I'll look to replace it with one that has a battery temperature sensor probe.

At -30 C (-22 f) charge voltage ought to be 16.2 volts

At +50 C (122 f) charge voltage ought to be 13.2 volts

Gassing voltage at +50 is only 13.8 volts.

Right now it is about -20 C here--so charging voltage ought to be 14.04 and gassing is 17.86 volts. So it is safe for me to "trigger" boost mode on my PD converter. Otherwise the battery bank will slowly discharge.

[BFL13]

I think the whole temperature compensation thing is way over-blown for many RV applications such as the OP's. IMO it is just the fine tuning of something that is so rough and ready in the first place that fine tuning it becomes pointless.

I don't need any temperature compensation for the five month stretch off-grid we do using solar in the sunny half of the year. Can't see that anybody else needs it very much either! 🙂

[pianotuna]

Hi jonny,

No.

Jonnygsx wrote:
Well isnt the temperature of the batteries primarily going to be from the air that they are exposed to? I would think that having a charge controller a foot from your batteries they would be within a few degrees of each other at the most?

[EsoxLucius]

It is the temperature of the battery that matters, not ambient temperature. Come on, it's no more than $30 for a battery temperature sensor. Get one, your batteries will thank you.

[Jonnygsx]

EsoxLucius wrote:

Jonnygsx wrote:
While this cover is not weather tight it does greatly cut down on what things underneath are exposed to. Do you think it would be ok to mount the Xantrex controller up under that cover nearest the batteries? That way it wouldn't require a separate temperature monitor and it would also give me the shortest run cables to the batteries. Thoughts?

Yes, that would be an acceptable place for the controller if it will not get wet there. The controller should be as close to the batteries as possible. I think you are mistaken about not needing a battery temperature sensor just because the controller is near the batteries. It is the temperature of the batteries that is important not the temperature around the batteries.

Im just not sure how dry it is in there. There is no siding on the wall inside the cover but there is some kind of coating so its not bare wood in there, implying that it may get some moisture in there occasionally.

Well isnt the temperature of the batteries primarily going to be from the air that they are exposed to? I would think that having a charge controller a foot from your batteries they would be within a few degrees of each other at the most?