Low cost way to monitor your 12V Battery

[garrity]

you can see over time with these things a charge pattern occurring, and if you see more frequent charging spikes and/or the resting voltage betwixt charges is lower than previous graphs, that could be s sign.

if you see some random 12V errors popup on model 3 screen, that is also a good sign of a near future battery replacement.

My friends 2018 Model 3's 12 V gave out on him with no warning on the screen last month. This is what is motivating me to keep watch over the battery in my 3 and Bolt.

I'm looking at using one of these:


https://smile.amazon.com/LIHAN-Char...04866692&sprefix=12v+voltmeter,aps,351&sr=8-4

There's no graphing just shows the current voltage. Can one assume that if the voltage measured starts registering lower than 12 V that the battery is on its last legs?

 

[SageBrush]

you can see over time with these things a charge pattern occurring, and if you see more frequent charging spikes and/or the resting voltage betwixt charges is lower than previous graphs, that could be s sign.

The car wakes up and charges the 12v when it reaches ~ 12.6v so I would not rely on low voltages to signal time for replacement.

OTOH, IF the battery drain during sleep is constant through the months (a BIG IF), then more frequent charging episodes would imply a loss of capacity. Similarly, a reduction of time to recharge back up to ~ 13.1V would imply the same.

The best approach is have a baseline of a new battery. Then aging is more apparent.

 

[SageBrush]

There's no graphing just shows the current voltage.

The graphing is quite useful for our EVs. The device you mention has utility in an ICE because of the high load to start the engine.

 

[Tz00]

My friends 2018 Model 3's 12 V gave out on him with no warning on the screen last month.

Any idea what happened to the battery? What was the voltage on the battery when it was "dead"?

 

[garrity]

Any idea what happened to the battery? What was the voltage on the battery when it was "dead"?

Sorry, he didn't know what the voltage was, and had enough charge left to pop the frunk, but the screen would not stay on. Had to get his wife to pick up a new battery and drive 40 miles to him. He insists that he had no warning at all. Drove to work, parked overnight with sentry mode on, and then the next morning car wouldn't move. After putting in a new battery car worked normally.

My brother's Model 3 gave him a warning and 3 days later the battery went dead. So I guess i'm going to start graphing a little to avoid the friends problem just in case the warning system doesn't work well.

 

[Tz00]

There's no graphing just shows the current voltage. Can one assume that if the voltage measured starts registering lower than 12 V that the battery is on its last legs?

If the car is awake, looking at the voltage at any one instant is pointless, as the DC-DC converter is active and it is providing the voltage. In fact, you could remove the battery from the car with the car awake (as is the standard procedure), and you are still going to show a good voltage. The problem will occur, once the car goes to sleep, of course.

So you need to be able to monitor the voltage when the car is asleep, however, once the car goes to sleep, the 12V outlet (cigarette outlet) is shut off.

 

[garrity]

If the car is awake, looking at the voltage at any one instant is pointless,.

Drat. I was slowly coming to this conclusion.

Would putting a batteryminder 1510 with desulfanator on the 12v occasional help preserve the battery better than simply keeping the car plugged in?

https://smile.amazon.com/BatteryMIN...327324990001&ref_=sbx_be_s_sparkle_mcd_asin_1

 

[Sam1]

Why not just use scan my Tesla or tesLAX?

 

[Josephep]

So I had this little gadget on my combustion engine vehicle and , well, with all the talk about the 12V battery error message popping up, I thought to revisit this little doo-dad.



View attachment 579857





its this cat:

https://www.amazon.com/gp/product/B07WCW49YM/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1


it's mostly designed for combustion engine vehicles because it shows you cranking amps and things of that nature.

It uses Bluetooth Low Energy so you have to be in about ~30 feet ish to connect to the little guy. it will show you the state of the the battery and when the HV battery charges it, it will show you "charging" and you will see the graph showing you the charging current, it updates as you are connected to it.

View attachment 579854

things like "cranking test" will not be applicable since there is no starter motor, but maybe, as I think about this, since the HV contactors need voltage from the 12V to close them, maybe this would show up under that option? I will test this if I remember to do so.

anyway, my point to post this was to offer a low cost solution for those to keep track of their 12v charge directly from your phone without having to use tesla fi or those other apps.

there are a few of these on amazon and some may be cheaper. there also may be other alternatives, but i know this works and have had it on model 3 for a few weeks now. I use the ohmmu battery and it works nicely with it.

I got stuck last week because my 12V battery died. So did I hear correctly that this battery never charges?!?!

Question about this monitor. Do you leave it connected? And I guess you use it connecting via Bluetooth in conjunction with the Tesla App to monitor your vehicle?

Appreciate a reply

 

[jjrandorin]

I got stuck last week because my 12V battery died. So did I hear correctly that this battery never charges?!?!

The 12v battery charges all the time from the HV battery.

 

[garrity]

I got stuck last week because my 12V battery died. So did I hear correctly that this battery never charges?!?!

Question about this monitor. Do you leave it connected? And I guess you use it connecting via Bluetooth in conjunction with the Tesla App to monitor your vehicle?

Appreciate a reply

I leave it connected to the battery. You download an app from ancel and it connects via bluetooth that way you can monitor your battery. I used to look at it all the time, but to be honest don't look at it very often now. I just plug the battery into a battery tender and hopefully will be able to see when it takes a long time to charge . I have still the original battery from 2018 31k miles

 

[Watts_Up]

I got stuck last week because my 12V battery died. So did I hear correctly that this battery never charges?!?!

No, the 12 V battery get charged using a DC/DC inboard charger connected to the propulsion battery.

When parked, after a while, the battery voltage starts to decrease, and when it reaches around 12.5 V​

the inboard charger gets triggered and charges the battery for about two to three hours.​

This occurs about every 36 to 48 hours, depending of the age of the battery, ambiant temperature...​

​

See below a detail of the voltage graph that you can get from the App:​

So if you noticed that the inboard charger is running quite often,
this is an indication that the 12 V battery cannot keep the charge and needs to be replaced.

Note: When Sentry is on, or when you are driving, the inboard charger is running and delivers then a 13.5 V​

to act the same way as the alternator of an ICE car, so the 12 V battery don't get discharged.​

See below

 

[lUtriaNt]

Question about this monitor. Do you leave it connected? And I guess you use it connecting via Bluetooth in conjunction with the Tesla App to monitor your vehicle?

yes it draws a super teeny tiny amount of juice that you wont ever miss. since the 12V is charged by the traction battery, this is a moot point.
the module has a qr code on it that you can scan to download the app. ive used this on a prior car i had for a couple of years and have been using it on model 3 since march of 2020 when i got it. it was really helpful back when tesla updated the charging algorithm that made the aftermarket lithium 12 battery not be recognized properly, causing the 12v battery error to crop up. this gave me peace of mind knowing the battery was just fine and charging normally.

 

[cleverscreenam]

I purchased the Quicklynks battery monitor, same as the thread author. When trying to pair the device, android forces me to input a PIN before I can press OK, I've tried 0000 and 1234 and none are working to pair it. Did you have to put in a PIN to pair it? I tried this on 3 brand new phones, they all did the same thing.

 

[lUtriaNt]

never had to put a pin in mate...

 

[cleverscreenam]

Thank you for replying, lUtriaNt. Could you share the steps you took to connect the app to the battery monitor? The seller says don't pair it, just turn on location and location permission. I did those, and the bluetooth pair screen sees the battery monitor, but the app still says no devices found.

​

 

[jrmt23]

I have my radar detector to show me the 12v reading coming out of the outlet in the center console...i have my doubts of it's accuracy of the actual battery status since i regularly see it below 12v, and rarely do I ever see it hitting over 13v like my VW would when it was coasting and the alternator was charging the battery.

 

[lUtriaNt]

Thank you for replying, lUtriaNt. Could you share the steps you took to connect the app to the battery monitor? The seller says don't pair it, just turn on location and location permission. I did those, and the bluetooth pair screen sees the battery monitor, but the app still says no devices found.

​

literally all i did was connect the item to the battery, then scanned the qr code to get the app. installed the app. it asked for permissions as you stated and the phone connected with no issue.

these are a lot of clones like these all over amazon and such. maybe a newer version adds some "security" to the pairing process?

 

[medphys3]

I have my radar detector to show me the 12v reading coming out of the outlet in the center console...i have my doubts of it's accuracy of the actual battery status since i regularly see it below 12v, and rarely do I ever see it hitting over 13v like my VW would when it was coasting and the alternator was charging the battery.

View attachment 802095

I’m pretty sure that the 12v outlets are controlled by the computers in the car and do not represent the actual 12v battery voltage.

 

[medphys3]

I bought this for piece of mind. Hook it directly to the battery and set the alarm to go off at your desired voltage. Mine is set to alarm at 12.3v (I think). It beeps for maybe 2 or 3 seconds 70% of the time when opening the door from a deep sleep prior to the HV battery kicking in. I figure when it randomly starts beeping, I’ll change the battery.

Battery Monitor, DROK 10-100V Digital Battery Capacity Tester, Percentage Level Voltage Temperature Switch Meter Gauge 12V 24V 36V 48V LCD Display Marine RV Battery Power Indicator Panel https://www.amazon.com/dp/B07759SLYP/ref=cm_sw_r_cp_api_i_86JBY205ZG5K027JPH3A?_encoding=UTF8&psc=1