Where to Locate MPPT Solar Charge Controller

[MikeM]

I have read conflicting guidance on where the controller should be located, and the installation guide for the controller itself doesn't directly address it. I've seen a guide that says to locate it in the same compartment as the batteries so they are at the same temp. But my batteries are in my engine room, and I have read that the controller should not be in the engine room.

What do folks think?

Thanks, Mike


Mike Metts
KK 42-165
Virginia Beach, VA

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[Sealife]

Mike, I located mine in the back of the laundry closet on KK42. Close to the batteries and inline with the wiring chase on the port side aft pilothouse. Mine is an Outback flexmax 80 with a cooling fan. Mine also has a battery temp sensor...I dont think location is a big deal other than avoiding excessive wire runs or upsizing the wire accordingly for 3% or lss drop according to ABYC charts.

 

[Panacea123]

Located mine under the lower helm next to the main elec panel "morning star TS-MPPT-60 amp"
Wired direct to the panel as I have robust wires from there to batt bank 780 watts of solar. 900 amp/hr bank.
Plenty of space and ventilation, also have batt temp sensor, a must IMHO
Just avoid heat(no small enclosed spaces) and voltage drop due to long or undersized runs.

 

[DavidM]

Here is my advice and the reasons why:


An MPPT controller drops the higher voltage that the solar panels produce to the lower voltage that charging the batteries require. So if you keep the voltage drop in the wire from the solar panel to the controller to 3% then there will be plenty of voltage at the controller terminals to work. Use the Isc spec to base wire sizing on.


For the run from the controller to the batteries you need to minimize voltage drop, otherwise the batteries won't be getting the correct charging voltage. This usually means locating the controller near the batteries, but if you can't do that, then size the wire accordingly. I would shoot for no more than 2% voltage drop in that circuit. Use the total wattage of the solar panels divided by 12 for the amperage in that circuit to base the size on.


Everything electronic is affected negatively by heat. Engine rooms are hot. QED- don't install your controller in the engine room. If that is unavoidable, then I would downrate the controller's amperage capacity by 25%.


David

 

[MikeM]

I have read conflicting guidance on where the controller should be located, and the installation guide for the controller itself doesn't directly address it. I've seen a guide that says to locate it in the same compartment as the batteries so they are at the same temp. But my batteries are in my engine room, and I have read that the controller should not be in the engine room.

What do folks think?

Thanks, Mike


Mike Metts
KK 42-165
Virginia Beach, VA

Sent from my iPad using Trawler Forum

I was thinking about doing just that, but it wouldn't be easily accessible. It's a little tricky to get in there to do any work. Is there any need to have easy access to the controller? I'd be able to see it by opening the small locker door, but I couldn't access it easily?

I don't have temp monitor yet, but it sounds like I should get one.

Thanks, Mike


Mike Metts
KK 42-165
Virginia Beach, VA

Sent from my iPad using Trawler Forum

 

[MikeM]

Located mine under the lower helm next to the main elec panel "morning star TS-MPPT-60 amp"
Wired direct to the panel as I have robust wires from there to batt bank 780 watts of solar. 900 amp/hr bank.
Plenty of space and ventilation, also have batt temp sensor, a must IMHO
Just avoid heat(no small enclosed spaces) and voltage drop due to long or undersized runs.

Thanks!


Mike Metts
KK 42-165
Virginia Beach, VA

Sent from my iPad using Trawler Forum

 

[MikeM]

Here is my advice and the reasons why:


An MPPT controller drops the higher voltage that the solar panels produce to the lower voltage that charging the batteries require. So if you keep the voltage drop in the wire from the solar panel to the controller to 3% then there will be plenty of voltage at the controller terminals to work. Use the Isc spec to base wire sizing on.


For the run from the controller to the batteries you need to minimize voltage drop, otherwise the batteries won't be getting the correct charging voltage. This usually means locating the controller near the batteries, but if you can't do that, then size the wire accordingly. I would shoot for no more than 2% voltage drop in that circuit. Use the total wattage of the solar panels divided by 12 for the amperage in that circuit to base the size on.


Everything electronic is affected negatively by heat. Engine rooms are hot. QED- don't install your controller in the engine room. If that is unavoidable, then I would downrate the controller's amperage capacity by 25%.


David

Got it. Thanks David.


Mike Metts
KK 42-165
Virginia Beach, VA

Sent from my iPad using Trawler Forum

 

[101TUG]

my controller are in engine room, bad idea they going in alarm temps after engine running ...

Hugues

 

[CMS]

I have read conflicting guidance on where the controller should be located, and the installation guide for the controller itself doesn't directly address it.

This is because it "depends"..

If your controller does internal ambient temp sensing, for temp compensation, then it needs to be as close to the bank as is possible, and safe. In other words if the controller is not sensing the same or similar temp to the batteries, without an on-battery sensor it will never be entirely correct, then your batteries will be seeing too high or too low a voltage.

I've seen a guide that says to locate it in the same compartment as the batteries so they are at the same temp.

Unless it uses a remote on-battery temp sensor lead then yes this would be the most optimal location in regards to properly charging your batteries..

For example I had a customer install an local ambient sensed MPPT on his vessel. The controller was outside the engine room in the locker backing up to cold Maine ocean water. The controller was regularly at a much cooler temp than the batteries, often a 30F spread or more. The batteries were in the engine bay, a horrible location for batteries.. The controller was actually compensating charge voltage up, based on controller location, instead of down based on battery location. A battery that charges at 14.8V at 77F can not charge at 14.8V at 95F or 110F or 120F...

But my batteries are in my engine room, and I have read that the controller should not be in the engine room.

It's not just the controller. The bigger issue is that your batteries should not be in the engine room either so your problem really started out with "stupid builder tricks". Builders don't care about the longevity or health of your batteries but they do care about saving nickles. As a result far too many batteries are installed in engine spaces that regularly exceed 100F. I have measured engine rooms 8+ hours after running still exceeding 110F. This is just bad news for batteries.

What do folks think?

Purchase a controller with remote temp sensing and ideally remote voltage sensing such as the Morningstar TriStar MPPT series. Place it outside the engine room and run the temp and voltage sense leads to the battery bank..

As a bonus get the batteries out of the engine room into a more hospitable environment. With batteries in the engine room all charge sources should have on-battery temp sensing not just the solar..

 

[MikeM]

This is because it "depends"..

If your controller does internal ambient temp sensing, for temp compensation, then it needs to be as close to the bank as is possible, and safe. In other words if the controller is not sensing the same or similar temp to the batteries, without an on-battery sensor it will never be entirely correct, then your batteries will be seeing too high or too low a voltage.





Unless it uses a remote on-battery temp sensor lead then yes this would be the most optimal location in regards to properly charging your batteries..

For example I had a customer install an local ambient sensed MPPT on his vessel. The controller was outside the engine room in the locker backing up to cold Maine ocean water. The controller was regularly at a much cooler temp than the batteries, often a 30F spread or more. The batteries were in the engine bay, a horrible location for batteries.. The controller was actually compensating charge voltage up, based on controller location, instead of down based on battery location. A battery that charges at 14.8V at 77F can not charge at 14.8V at 95F or 110F or 120F...



It's not just the controller. The bigger issue is that your batteries should not be in the engine room either so your problem really started out with "stupid builder tricks". Builders don't care about the longevity or health of your batteries but they do care about saving nickles. As a result far too many batteries are installed in engine spaces that regularly exceed 100F. I have measured engine rooms 8+ hours after running still exceeding 110F. This is just bad news for batteries.



Purchase a controller with remote temp sensing and ideally remote voltage sensing such as the Morningstar TriStar MPPT series. Place it outside the engine room and run the temp and voltage sense leads to the battery bank..

As a bonus get the batteries out of the engine room into a more hospitable environment. With batteries in the engine room all charge sources should have on-battery temp sensing not just the solar..

I do have a Morningstar controller, but I will need to purchase the temp sensor. Thanks for the advice


Mike Metts
KK 42-165
Virginia Beach, VA

Sent from my iPad using Trawler Forum

 

[DavidM]

CMS:


Do the controllers with remote battery temperature sensing capability revert to internal sensing when the probe is not attached, or do they disable that feature?


David

 

[MikeM]

CMS:


Do the controllers with remote battery temperature sensing capability revert to internal sensing when the probe is not attached, or do they disable that feature?


David

The controller I have (Morningstar Prostar) does revert to internal sensing if there is no RTS.

 

[JDCAVE]

The controller I have (Morningstar Prostar) does revert to internal sensing if there is no RTS.

Mike: I put my controller in the AC bus-bar compartment, simply because 1) there was room and 2) it's close to the batteries.




Jim kk42 owner.
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[MikeM]

Mike: I put my controller in the AC bus-bar compartment, simply because 1) there was room and 2) it's close to the batteries.
View attachment 56160



Jim kk42 owner.
Sent from my iPad using Trawler Forum

Jim,

That's a nice looking space. I wish I had one on my 42. My AC bus bar compartment is in the world engine room and much tighter than yours.

I wound up putting mine behind our washer as another 42 owner on the forum suggested.

Mike

 

[JDCAVE]

Jim,

My AC bus bar compartment is in the world engine room....

Mike

World engine room?


Jim
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[MikeM]

World engine room?


Jim
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No idea where that word came from. It's just in my engine room.


Mike Metts
KK 42-165
Virginia Beach, VA

Sent from my iPad using Trawler Forum

 

[MikeM]

Mike: I put my controller in the AC bus-bar compartment, simply because 1) there was room and 2) it's close to the batteries.
View attachment 56160



Jim kk42 owner.
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Jim,

I'm curious. Where is that compartment?

Mike

 

[JDCAVE]

It's in the engine room on the bulkhead between the engine room and the guest stateroom. This is an earlier photo of the space. I've since use some of the space in the ACD compartment.mthe DC compartment is starboard of the ACD compartment.

DC compartment




Jim
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[MikeM]

It's in the engine room on the bulkhead between the engine room and the guest stateroom. This is an earlier photo of the space. I've since use some of the space in the ACD compartment.mthe DC compartment is starboard of the ACD compartment.
View attachment 56209
DC compartment
View attachment 56210



Jim
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OK. So my panel is in the same place, but I don't have quite as much room in it. Does yours seem to be working OK since it is essentially exposed to engine room temps?


Mike Metts
KK 42-165
Virginia Beach, VA

Sent from my iPad using Trawler Forum

 

[JDCAVE]

It seems to be just fine. Remember, your Prostar is good to very high temperatures if I recall. They are designed to be operated in extreme environments. I went a bit cheaper on the controller to control the cost of things, but my first choice was the Prostar. My engine room doesn't get that hot. Our climate is cooler than yours.


Jim
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[MikeM]

That's right. You are in the Pacific Northwest, if I recall correctly. Definitely cooler where you are.

 

[Martin J]

My 940 watt of panels lead down to my Midnite controller @48 volts then to 12volts and into the back of my distibution panel, The heavy panel supply cables run it the 40ft to the engine room. I have 10xT105 Plus batteries. I previously had temp problems in the E.R. with high temps 130Degrees F and far to hot when I bought the boat. With upgraded ventalation ( discussed on another thread) I have lowered my temps to 90-110F and improved battery performance. The excess ventalation has enabled the engines to ingest 90F air (Ambient) which has enhanced output hp from the engines and efficiency.
The boat is in the Caribbean, so always fighting high temps in the engine room.