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Monitoring Battery Temperatures


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We have a bank of 5 off 110Ah sealed lead acid batteries on our narrowboat, and I am idly wondering about installing a gizmo or two to monitor  temperature on the batteries. To do it properly would need a sensor fixed (taped?) to the end of each battery - a sensor per battery - but does that give any real advantages over a sensor between each battery - it only saves one sensor after all! 

 

I guess what I might be trying to ask is is it even worth monitoring battery temps?

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Some alternator controllers monitor temperature to optimise the charge voltage, especially at low temperatures.

Monitoring just single battery is the norm. Fixing the sensor to a terminal, with appropriate insulation, is how its usually done, this best monitors the temperature inside the battery.

 

................Dave

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1 minute ago, ditchcrawler said:

What are you going to do with the information

 

Like a trainspotter you could write the numbers down in a little black book. The modern way is to make an Excel spreadsheet and plot pretty graphs ?

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24 minutes ago, ditchcrawler said:

What are you going to do with the information

 

I don't do anything with mine, I don't even know what figures it is showing.

 

All I (need to) know is that the information is fed back to the battery charger and that then adjusts the charge level to the optimun for that current battery temperature, if the temperature rises or falls then the battery charger, again, alters its output.

 

Is there something I should be doing with the information ?

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My Victron combi has a thermistor temperature sensor that is bolted on to a negative post of one of the batteries as @dmr describes. Since there is a metal connection to the lead plates inside, the post is close to battery temperature. The Victron does some clever automagic modification of charging voltages, depending on temperature, which is then applied to the whole bank.

The only advantage I can see of monitoring individual battery temperatures would be to spot if one is going bad. Since a duff battery typically just has a single cell that shorts out and starts to overheat, you might want sensors on more than one part of the battery. I don't know of any consumer priced thing for this. If you went in to industrial monitoring equipment, it would cost an arm, a leg and another arm too. It would be pretty simple to do with an Arduino, if you have, or are willing to take the time to learn the skills, which could log the result, display alarms, or whatever else you want to do with it. It is something that Lithium battery owners are more likely to be doing as the consequences of one of these batteries overheating, or getting seriously out of step with the rest, or being charged when too cold is all bad.

Jen

Edited by Jen-in-Wellies
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3 minutes ago, Jen-in-Wellies said:

Since a duff battery typically just has a single cell that shorts out and starts to overheat, you might want sensors on more than one part of the battery. I don't know of any consumer priced thing for this. If you went in to industrial monitoring equipment, it would cost an arm, a leg and another arm too.

 

For five batteries with six cells each it might be simpler to install a cheap thermal camera (is there such an animal??) with a reasonable view of the top of the cells. As nothing moves physically it shouldn't be that hard to process the video and extract max and average temp (relatively) and sound an alarm if the max is way higher than the average. Don't need to know what the actual temperature IS just that one part of the image is a lot brighter.

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10 minutes ago, 1st ade said:

 

For five batteries with six cells each it might be simpler to install a cheap thermal camera (is there such an animal??) with a reasonable view of the top of the cells. As nothing moves physically it shouldn't be that hard to process the video and extract max and average temp (relatively) and sound an alarm if the max is way higher than the average. Don't need to know what the actual temperature IS just that one part of the image is a lot brighter.

The year before last, I made an infrared camera very cheaply from a webcam. The light detector arrays are actually very good at picking up infra red heat radiation and cameras have a filter in the lens to remove the infrared so people don't get freaked out seeing bright shining eyeballs in faces! Remove the filter and you have a very cheap IR camera. I did this so my Mum could watch and record hedgehogs in her garden at night. HedgehogCam! Connect one of these to a a Raspberry Pi and write a program to look for a big change in the range of brightness seen, output to an alarm and you can do what you describe.

 

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Apart from using the information to optimise the charge the only other thing it is likely to tell you with lead acids (as Jen says, lithium is different) is that you will get warning of cell failure from the heat the short circuits cause.

 

Unless you charging equipment is easily manually adjustable, I see monitoring the temperature as a pointless operation. As far as cell shorts are concerned the need of an individual cell for more topping up than the rest will tell you as will running you hand over them at each  shut down. However, if you are monitoring charge state and charging current when cells start to short you find the charging current getting  is higher for longer and the state of charge will be getting lower in the morning than is normal. As keeping batteries well charged saves you buying new ones I would suggest regularly monitoring charge and voltage would be more cost-effective.

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9 hours ago, dmr said:

 

Like a trainspotter you could write the numbers down in a little black book. The modern way is to make an Excel spreadsheet and plot pretty graphs ?

 

 

I like that reply ?

 

I've often wondered why people on this site...do stuff like that ?

 

After all...in my opinion  ( warning... Bob's opinions may vary from description)... It's all about cruising along looking at beautiful scenery. 

 

Having said that...blokes always like to tinker and change/Invent stuff. Often when you view boats they have some daft but "essential" thing strapped onto them..the product of much boredom and winter blues.

 

A book full of graphs about how much sun the solar panels gathered on Christmas day...or some weird and wonderful combination of "must haves" strapped onto the alternator...

 

For me....I don't do anything other than change oil and filters and cruise through some of the most beautiful parts of England. My gadget-less boat won't be worth any less than the one with its own spreadsheet ???

 

 

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10 minutes ago, 1st ade said:

Hmm. Where's that old webcam gone...

Going massively off topic now. How to make a HedgehogCam. I put the modified webcam in a housing with an array of around twenty 5mm infrared LED's to light up the area. This was the maximum number of LED's I could use without overloading the current supply capability of the USB cable. Having a separate LED power supply would allow more IR scene illumination. Broke in to the USB to get access to the 5V and 0V lines for the LED's by soldering a USB plug and socket back to back. Used a 5m USB cable to connect HedgehogCam to a laptop indoors. The laptop had software that recorded when moving stuff was detected. Focussed the camera so that it was sharpest where the food bowl was located.

A video by an actual rocket scientist from ESA on how to modify a webcam and what sort of camera it is easiest to do this on.

 

Jen

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17 minutes ago, Jen-in-Wellies said:

Going massively off topic now. How to make a HedgehogCam. I put the modified webcam in a housing with an array of around twenty 5mm infrared LED's to light up the area. This was the maximum number of LED's I could use without overloading the current supply capability of the USB cable. Having a separate LED power supply would allow more IR scene illumination. Broke in to the USB to get access to the 5V and 0V lines for the LED's by soldering a USB plug and socket back to back. Used a 5m USB cable to connect HedgehogCam to a laptop indoors. The laptop had software that recorded when moving stuff was detected. Focussed the camera so that it was sharpest where the food bowl was located.

A video by an actual rocket scientist from ESA on how to modify a webcam and what sort of camera it is easiest to do this on.

 

Jen

 

Thanks Jen

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10 hours ago, dmr said:

 

Like a trainspotter you could write the numbers down in a little black book. The modern way is to make an Excel spreadsheet and plot pretty graphs ?

Do you have an altimeter on your boat as well?

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3 minutes ago, Bobbybass said:

Couldn't you just buy one for a tenner,?

No. More like £30 or £40 to buy at a minimum. At least it was a couple of years ago.

Edited by Jen-in-Wellies
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Thanks to all for replies.

 

I was idly thinking of cobbling together an Arduino based thing, as something to do on a rainy day. As you all suspected, I have no real need of it, and have no idea of what I'd do with the info, so all a bit pointless really. Mind you, that may not stop me having a play, even if only to prove that I can do it!!

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If you want to try something out of curiosity, these can be set to trigger an alarm, or just read temperature. Cheap. Couldn't get the link to work. The units work - bought some. You can now walk into the doctor's with all your necessary temperature readings on display, and save the doctor the trouble. 

 

 

1907718781_Tempgauge.PNG.c0103f1e32c1de320e0b4c47fd3566fb.PNG

 

 

Edited by Higgs
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16 minutes ago, Higgs said:

If you want to try something out of curiosity, these can be set to trigger an alarm, or just read temperature. Cheap. Couldn't get the link to work. The units work - bought some. You can now walk into the doctor's with all your necessary temperature readings on display, and save the doctor the trouble. 

 

 

 

 

In which part of your anatomy should the probe be inserted ?

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Just now, Alan de Enfield said:

 

 

In which part of your anatomy should the probe be inserted ?

 

With four temperature gauges, you're spoilt for choice. You can use Vaseline or sticky backed Velcro to aid. 

 

 

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If your batteries are getting HOT then I suggest your battery capacity is too small for the load or conversely the charger is running at too high a rate.

Either way you can test the temperature by placing a spare hand (sic) on or near the battery bank.

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