Battery temperature sensor location

mcgivor

 This question has been debated with differing opions,  reason and rationale, below is an excerpt from a Schneider manual, so with one word answers, without need for reasons, just state Terminal or Side
I'm taking a pole of opinions,  thought it would be interesting what the outcome would be.

REMEMBER ONE WORD 

(1) Install the BTS sensor on the battery.

Method (a) involves mounting the sensor to the 

negative battery post which allows the internal 

battery temperature to be sensed providing the 

most accurate results. 

Method (b) attaches the sensor to the side of 

the battery using the self-adhesive backing 

which also provides good results in most 

situations.

Aguarancher

side

_OS_

Terminal

Estragon

Side

Horsefly

Terminal

I know you are not looking for a reason but...  The terminal has a direct, very heat-conductive connection to the battery itself, and so will accurately reflect the temperature of the battery. The plastic outside of a battery is not very heat-conductive, so whatever temperature it reads will not reflect as much the temperature of the battery, and will be more influenced by the ambient air.

BB.

For side of battery RBTS, take a piece of Styrofoam and hollow out a place for the sensor, then place over sensor/side of battery. Will read case temperature more accurately.

-Bill

Marc Kurth

Your question is incomplete, so I cannot answer How many batteries in what configuration and application and location?

Lumisol

Terminal for best heat transmission without a lot of mickey mousing stuff stuck on the side of a battery.
If you are forced to use it on a side, add a layer of thermal insulation like fiberglass or foam to keep the ambient temps from interfering.

westbranch

Side. nestled between 2 2v cells in the approx middle of bank

Vic

ONLY on the side of one battery in the center of the bank,   and only under a rigid foam sheet one,  or more inches thick.   With multiple strings of batteries  it becomes a bit problematic,   so would get rid of multi strings,   and then place BTS under one battery  center of the bank,  half way down the side,  under rigid foam on the single string of batteries.

Also,   would place ALL BTS/RTSes on the same battery,  under the same foam sheet  --  very easy.

Heat rises,   and resistance in  battery interconnect crimps and between interconnect lugs and battery terminals  will cause heating.   Both of these can cause errors in the "battery" temperature that the RTS mounted on a battery lug/terminal,   reports to chargers.

IMO,   Vic

Lumisol

Vic said:

ONLY on the side of one battery in the center of the bank,   and only under a rigid foam sheet one,  or more inches thick.   With multiple strings of batteries  it becomes a bit problematic,   so would get rid of multi strings,   and then place BTS under one battery  center of the bank,  half way down the side,  under rigid foam on the single string of batteries.

Also,   would place ALL BTS/RTSes on the same battery,  under the same foam sheet  --  very easy.

Heat rises,   and resistance in  battery interconnect crimps and between interconnect lugs and battery terminals  will cause heating.   Both of these can cause errors in the "battery" temperature that the RTS mounted on a battery lug/terminal,   reports to chargers.

IMO,   Vic

So you think the manufacturers knowingly and purposely make the RTS so it can be mounted on a terminal post to give false readings?
How would that benefit them?

Vic

Lumisol said:

Vic said:

ONLY on the side of one battery in the center of the bank,   and only under a rigid foam sheet one,  or more inches thick.   With multiple strings of batteries  it becomes a bit problematic,   so would get rid of multi strings,   and then place BTS under one battery  center of the bank,  half way down the side,  under rigid foam on the single string of batteries.

Also,   would place ALL BTS/RTSes on the same battery,  under the same foam sheet  --  very easy.

Heat rises,   and resistance in  battery interconnect crimps and between interconnect lugs and battery terminals  will cause heating.   Both of these can cause errors in the "battery" temperature that the RTS mounted on a battery lug/terminal,   reports to chargers.

IMO,   Vic

So you think the manufacturers knowingly and purposely make the RTS so it can be mounted on a terminal post to give false readings?
How would that benefit them?

You will need to ask those manufacturers.   Vic

Marc Kurth

As I said earlier, the "best" choice is strictly dependent on the actual application details and specifics.

You will likely discover that the more actual field experience a person has, the more they lean to toward side mount, sandwiched between batteries - when insulated properly. The reasons have already been described.

Post mounting is quick and easy to install. And in some cases, it can be better - but then.......

Marc

Lumisol

I don't want my batteries crowded together in the first place, so the side mount is a less viable choice if you want air flow between the cases as I do.
To each his own, that's why there are options. Some people don't have spaces between batteries and they tent to heat up each other faster so a side mount might work if you are short on space.

westbranch

Case in point:  the mounting rack for my 2/v cells allows for  at max a few mm distance between cells..  that is all..  and it is very hard to squeeze the BTS in between 2 cells.

Estragon

Since we've ignored the one word answer asked for, I'll add that my side choice considers that ambient can be really cold, and top mounting could be a problem. I'd rather a controller read a bit high on temp and compensate to a bit lower voltage most of the time, instead of boiling the things dry. It depends.

Marc Kurth

Yep. My projects drifting out on the arctic ocean are setup very differently than my projects on the equator - which are different than those sitting in metal box in Southern Desert areas vs. a climate controlled battery room, etc. etc.

There is not one correct answer if you want optimum results. So a one word answer is worthless. And yes, we have run tests on this in the field.

Marc

Lumisol

Estragon said:

Since we've ignored the one word answer asked for, I'll add that my side choice considers that ambient can be really cold, and top mounting could be a problem. I'd rather a controller read a bit high on temp and compensate to a bit lower voltage most of the time, instead of boiling the things dry. It depends.

I agree, but the same thing can be achieved with slightly different set points on the setup of the controller. It will do what you tell it to.
A lot depends on the space around the bank too, if it's just slightly larger than the bank itself and lined with wood and vinyl flooring over wood or if it's a large concrete room.
My bank is in the former.

garynappi

Marc (IMO) is spot on. I worked for years in an electronics reliability lab, and the conditions of operation are everything in temperature evaluation. Ambient air temperature, localized heat traps, room airflow,  forced air / convection cooling, charge / operational voltage, current draw, and localized hot spots all affect temperature, and derating.

No one answer covers it but If I were to place a sensor, I'd use an LED thermometer at peak usage time around all of the cells and from there determine a location for a sensor. If the cells were enclosed with forced air circulation I'd use a thermal probe and DVM, slow but it may be the best way available without a lab.

Anyway, I would "think" that the terminal would be a less than wonderful sensor location because the cable itself is a heat sink while cell innards have less opportunity to vent heat.

Oh, P.S. without a corrective action plan after determining that there is excessive temperature, knowing the results of testing is useless.

mryimmers

terminal

Solray

Terminal to find the best,most direct thermal link to the plates inside.
When I set up in a colder environment I tend to use boxes to house banks for better monitoring with less heat loss, in warmer environments I use boxes, but to mitigate heat gain.
I always use enclosures though but for different reasons in different climates.
Batteries that are too hot or too cold are not happy.
Whether I am installing at the north pole or on the equator, I set it up to maintain the battery enclosure at 70 to 74 degrees. Sometimes it's by heating and sometimes by cooling but the battery ambient temperature is always a controlled variable since it is so critical to the system life.