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?