How to insulate batteries from heat in engine room

[Pete7]

I suppose the first question is how hot are those batteries after a couple of hours of motoring?

Having fitted a Victron battery monitor which connects via bluetooth to the MPPT, I was a little surprised at the battery temperatures. Over Christmas with water at 8c and 3 hours of motoring the batteries were at 18c despite being bitterly cold.

Last week with water temperatures around 17-19c and 10 hours of motoring across a glassy flat sea I saw battery temperatures of 31c. Even worse they only cooled to 26c over night because the water temperature in the local harbour was so warm. This was repeated the second day, no wind so engine on and more warm batteries.

So like you I am concerned. The FLA batteries are in boxes aft of the engine which the extractor draws through. Current plan is to ditch the antiquated extractor and replace with a blower onto the battery boxes and then into the engine space. However, this will have to wait until the winter.

Pete

[macman4190]

Originally Posted by rslifkin

What about adding a heat extraction blower in the engine room to keep temperature down in the general space? You could duct it so that the incoming replacement air gets pulled through the battery box, keeping that coolest.

Doing this worked for me. Batteries went from very hot to the touch to being perfectly cool.

[Singularity]

Do you have a means to monitor battery temps? Smart gauge of any sort?


Otherwise, if you're into gadgets, there are a variety of <$20 wireless air temp (and humidity) monitors on Amazon tan can be used for experimenting and monitoring of temps inside the box (to get a better handle on effects of different interventions trialed)...that of course can be used elsewhere on the boat.

[Bill O]

Originally Posted by StoneCrab

I plan on water cooling the batteries by making up battery boxes with pex tubing surrounding the batteries. It will not be hard to pump water through the tubes, keeping the batteries at lake or ocean temperature without the noise.

An interesting idea. Think you would need a better heat exchanger than pex tube, but still a good idea.

[Seriously Slow]

When I realized my batteries that were in a well ventilated but fully enclosed box in my engine room were very warm to the touch I decided to try something.
I now have 2 bilge blowers, one drawing from the top of the compartment exhausting and one drawing outside air and pushing it into the battery box using blower hose. That air pushes out through the ventilation holes in the box to the engine compartment and then out through the upper blower. They could be thermostatically controlled but for now I just start the blowers when motoring. We have a diesel so no explosion concerns. The 2 fans are noisy but when we are motoring the engine is also noisy so we pretty much stay outside. I did cut a lot of noise by suspending the blowers from the top of the compartment instead of fastening them directly to the surface.
The batts. now stay cool or at least about the same temp as outdoors.

[friz]

[QUOTE=Stu Jackson;3210445]I'm an hvac engineer. Insulation in that example will do absolutely nothing other than just delaying the time it takes for the heat gets to the batteries.

Somewhat discouraging. Can you also comment on what affect lagging/insulation has on a stainless steel exhaust pipe. Sorry if I am drifting off topic but your comment piqued my interest.

[jamhass]

Originally Posted by friz

Somewhat discouraging. Can you also comment on what affect lagging/insulation has on a stainless steel exhaust pipe. Sorry if I am drifting off topic but your comment piqued my interest.

Keeps from burning you and nearby "stuff"

[Cheechako]

A solution looking for a problem....