Battery temp sensor attachment-how?

Okay, to close the loop here, this is what I ended up doing. Just going to leave the probe taped to the back side of one battery case. You all reassured me that placement isn't going to be critical.





Rigged up a quick and dirty cover, just to prevent anything accidentally falling across terminals. I just didn't feel comfortable leaving lugs exposed in a storage area that is frequently accessed. But I also didn't enjoy that large NOCO battery box blocking access and taking up so much space.



We're hitting the road in a few weeks, and as luck would have it, while I was working on the batteries I found that my landing gear gear box had broken. So glad to have found that before leaving home. The old one was plastic, and known to fail apparently, and the new one is aluminum. A story for another day.

There are 3 ways to attach the temp sensor. One will require an additional part

IF the sensor has a "lug" attach to the NEgative battery post (You can also use positive but for some reason they say neg in the destructions)

Double faced tape

Put a cargo strap around the batteries to keep them tight together and drop it in between them like you did in the old days. (What I recommend)

Hi BFL13,

The negative terminal may often be a different temperature than the positive one. The positive post is usually cooler.

I would get the material intended for use on chips that need to be cooled on computers. Put on a generous portion on the negative terminal and then cover over the probe with heavy duty "gaffer's tape".

My own sensors both have ring terminals.

bpounds wrote:
It's a probe, not a ring terminal. I'm not really inclined to change it.

I think I might change the gorilla tape to some aluminized duct tape. The stuff actually meant for ducts, not the gray stuff. I think that might insulate it a bit from the ambient.

Incidentally, my inside monitor does display the probe temp. It's in C°, but at least you get it.

It is just a rough instrument to tell the charger what to do with its charging voltage wrt to battery temp. If the batteries are outside in the cold and the charger is inside where it is warm, it will do a better job by having that probe out where the batts are.

Some folks fuss over "battery temp" which rises while being charged above ambient temp. If you are adjusting voltage wrt ambient, you might be over-voltage when the internal battery temp warms up.

IMO ignore that. It will drive you insane since you can't measure all that like in a lab, while out camping. Like time2roll says, don't get too far into the weeds with temp comp in mild ambients.

EG, if the batts want 14.8v at 25C, then that is the same as 15.2v at 5C. Assumes your charger can adjust its voltage accordingly.

A curiosity is how the TempAssure of a modern type Parallax converter is set to 60F as the "nominal" instead of 77F like the battery specs have it.

Solar controllers can be with on-controller temp adjust, or by remote to the battery temp sensors. Not much point to on- controller if the controller is inside and the batts outside.

Whatever your situation is, just having the sensor "with" the batts to pick up their ambient wherever they are, is "good enough for government work."

I would not over think it. If the temp is well below freezing you will get the adjustment you need and same for very high temperatures.

It's a probe, not a ring terminal. I'm not really inclined to change it.

I think I might change the gorilla tape to some aluminized duct tape. The stuff actually meant for ducts, not the gray stuff. I think that might insulate it a bit from the ambient.

Incidentally, my inside monitor does display the probe temp. It's in C°, but at least you get it.

If the sensor is not on the wire right by/with a ring terminal (put that on the neg post if it is--I don't know why the neg), then do exactly like you did--tape it to the side of a battery or jam it between two batts.

Unfortunately that only tells your charger what to do, but you can't read the temp. AGMs can heat up if kept on a higher voltage charge after they are full and should be dropped to a lower, Float voltage.

Each AGM can be a little different for how they act like that. Have an IR temp gun handy so you can measure the temp of the side of each battery if you feel it getting warm while the other batt still feels normal.

Go online and search for genuine SILVER HEAT SINK EPOXY on eBay The word epoxy means it is an adhesive.

Roughen the FLAT part of the battery post with 90 grit sandpaper. Make it bright. Ceramic epoxy is cheaper but with either you'll have to blob it on.

The thermistor has to remain in close proximity to the lead while it cures. Place a weight on the small harness. Allow overnight cure.

The thermistor MUST accurately sense the heat of the interior plates and could care less what the plastic jar is thinking.

The installation is permanent. Buy an extra thermistor if that makes you more comfortable.

I get my thermistors through DWYER. All made in the USA