jimb753 avatar image
jimb753 asked

MPPT Controller / Battery Location On Boat

I am using MPPT 100|30's. The installation instructions require the temperature at the batteries and controllers not be more than 5 deg C difference. Will using a Smart Battery Sense get around this requirement. The batteries are above deck and I would like to place the controllers below.

Smart Battery Sense
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Justin Cook avatar image
Justin Cook answered ·

Yes, as long as you set up a VE.Smart network and the Smart BatterySense(s) and the controllers are on the network, you'll be fine. Couple of considerations, though:

1. The Smart BatterySense Bluetooth range isn't fantastic. The new (blue) units are vastly improved, but you start throwing decking and framework and likely wire runs and whatever else between them and the device they're talking to (the MPPTs), and you may well run into communication issues between the two. One possible workaround for this is to install a VE.Direct to Bluetooth dongle on your MPPTs and install the dongle abovedeck, if you can feed the cable through the deck somewhere.

2. Keep in mind that your cable size coming out of the MPPT (to battery) needs to be sized according to the 30A potential output of the MPPT, and the further away from your battery the controller is, the lower gauge you'll need. If, say, your battery bank is 10 feet away from your controller (so 20' round trip), and assuming 12v nominal battery voltage, you'd need to use 6AWG minimum (though that'd leave you at around 3% voltage drop, which isn't great)... but if your batteries are 20' away (so 40' round trip), you'd need to use a minimum of 4AWG for a 2.56% voltage drop, or preferably a 2AWG for 1.6% voltage drop.

We always recommend putting the controller as close to the battery bank as possible so that you can capture as much of your daily yield as possible, not to mention saving yourself quite a bit of money on cabling. All that being said, with the sole caveat of BT range as mentioned above, yes, the SBS units will work for you.

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jimb753 avatar image jimb753 commented ·

Thank you for your quick response and good advice. The controllers will be mounted on the 1/2" thick fiberglass bulkhead that separates the battery and controllers so I am hoping bluetooth will be ok. It is about a 4' cable run from the controller to the batteries and I will use 6AWG. There is a 15' run from the PV's to the controllers which will probably be 10AWG.

I am now looking at what material I might use where the controllers will be mounted as inflammable surfaces are hard to come by on a boat. I considered aluminum but would prefer not to use metal. So it's back to searching this site for a solution.

Many thanks!!!

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Related Resources

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Smart Battery Sense Product Page

Smart Battery Sense Manual