EarthX ETX900 12V Lightweight Lithium Battery Tesla Model 3

[Motion122]

The stock battery is 45Ah, while that one is 15Ah, about 1/3rd the capacity.
Does the car throw any errors for this? Seems like it would quickly identify it as a very worn out battery given it will have to charge it much more often.

13 months update. No issues.

I actually went to the service center and asked to speak with one of the techs regarding why the OEM lead acid often fails prematurely. He said not sit in the vehicle with the HVAC on while the vehicle is supercharging or just charging for that matter. He also said the 12V battery only gets charged while the vehicle is driving.

 

[gearchruncher]

He said not sit in the vehicle with the HVAC on while the vehicle is supercharging or just charging for that matter. He also said the 12V battery only gets charged while the vehicle is driving.

Your tech knows nothing. It's trivial to put a voltmeter on the battery and see it charge all the time while it's not moving. If this was not true, the battery would be dead in about 5 days and you couldn't get into the car. It's also trivial to use a voltmeter and see that the battery has no idea if the HVAC is on, or if it's supercharging, or charging at all. Because none of those directly impact the 12V battery. The fact he didn't mention sentry at all tells you all you need to know about their knowledge of the power management systems in the car.

13 months update. No issues.

One battery in one car means nothing. Ohmmu is on V3/V4 because they kept thinking it was fixed and then when it went wider it had issues. Not every car seems to throw errors.
Here's an owner with an EarthX having an issue: Quite a number of error messages...

 

[Motion122]

Your tech knows nothing. It's trivial to put a voltmeter on the battery and see it charge all the time while it's not moving. If this was not true, the battery would be dead in about 5 days and you couldn't get into the car. It's also trivial to use a voltmeter and see that the battery has no idea if the HVAC is on, or if it's supercharging, or charging at all. Because none of those directly impact the 12V battery. The fact he didn't mention sentry at all tells you all you need to know about their knowledge of the power management systems in the car.


One battery in one car means nothing. Ohmmu is on V3/V4 because they kept thinking it was fixed and then when it went wider it had issues. Not every car seems to throw errors.
Here's an owner with an EarthX having an issue: Quite a number of error messages...

What I didn't mention was that tech also said to use a battery maintainer when vehicle is not being driven. I'll hit up another tech the next time I am there.

Just reporting my findings to date. Looks like he is drawing down the battery too much, similar to the errors with a low/defective OE lead acid battery.

 

[gearchruncher]

What I didn't mention was that tech also said to use a battery maintainer when vehicle is not being driven. I'll hit up another tech the next time I am there.

This just proves how uninformed this tech is. The whole reason lithium batteries cause errors is that the charger onboard is very complicated and advanced and can be messed up by batteries that behave just a little bit different in voltage or capacity.

Yet the tech thinks that injecting power into this battery from the outside is a good idea and won't cause issues.
Yet the tech thinks a Tesla should have a battery tender plugged in to the 12V batt anytime it isn't driven
Yet the tech tells you to unplug your car from the wall so it STOPS CHARGING. Because the car can't tend itself and doesn't have chargers onboard.

Stop listening to this tech. Sounds like they just moved from McLaren and have no idea how a modern EV works.

 

[Motion122]

This just proves how uninformed this tech is. The whole reason lithium batteries cause errors is that the charger onboard is very complicated and advanced and can be messed up by batteries that behave just a little bit different in voltage or capacity.

Yet the tech thinks that injecting power into this battery from the outside is a good idea and won't cause issues.
Yet the tech thinks a Tesla should have a battery tender plugged in to the 12V batt anytime it isn't driven
Yet the tech tells you to unplug your car from the wall so it STOPS CHARGING. Because the car can't tend itself and doesn't have chargers onboard.

Stop listening to this tech. Sounds like they just moved from McLaren and have no idea how a modern EV works.

Well, this "tech" said he went through Tesla factory training. lol Perhaps Tesla training to replace parts instead of pinpoint the cause of the problem.

 

[CKwik240]

Mine never discharges more than 8%, so Tesla definitely does not treat it like a deep cycle battery and uses it more like a starting battery.

This kind of brings up a question. Seems to me it would be a better choice to use a deep cycle battery of one were to stick with lead acid. EVs don't have a need for a large amount of cranking amps, and deep cycle batteries can handle larger discharges better. I live in CA, so I used to buy deep cycle batteries for all my cars as temps would never be low enough to need high cold cranking ratings. Not sure If want to dish out so much for a lithium battery. Only lithium battery I bought for a vehicle was a sport bike as it's a much larger percentage of the weight and it's located up higher where it affects the moment quite a bit. Even then, I only switched to it because I needed a new battery anyways.

 

[gearchruncher]

Tesla doesn't deep cycle the lead acid battery. It's a 30+Ah battery that they use maybe 10Ah of capacity of before they recharge it.

 

[CKwik240]

Tesla doesn't deep cycle the lead acid battery. It's a 30+Ah battery that they use maybe 10Ah of capacity of before they recharge it.

Sure. But deep cycle batteries can inherently handle a greater number of cycles. One could obtain a deep cycle with similar Ah and maximize cycles. Or even size it slightly smaller and get more cycles while reducing weight (this may require some bit of research to determine if it may cause issue with Tesla's monitoring algorithms). Deep cycles are a little heavier so there is some crossover point. This may require a bit more research to figure out the ideal range.

 

[gearchruncher]

I'd never hard that deep cycle batteries are ALWAYS better at number of cycles. Got a pointer to a degradation vs cycles vs DoD study for various LA structures? (since the only difference is the thickness of the lead plates).

 

[CKwik240]

I'd never hard that deep cycle batteries are ALWAYS better at number of cycles. Got a pointer to a degradation vs cycles vs DoD study for various LA structures? (since the only difference is the thickness of the lead plates).

BU-201: How does the Lead Acid Battery Work?

BU meta description needed...

batteryuniversity.com

There's a table that summarizes it down the page a bit. Basically, the thinner plates of a starter battery wear quicker. But they provide more surface area to allow for bursts of high current.

 

[gearchruncher]

There's a table that summarizes it down the page a bit. Basically, the thinner plates of a starter battery wear quicker.

130-150 cycles of 30% DoD? If that were true, Tesla 12V batteries would last less than a year, yet I have a 5 year old one in my car that is doing just fine.

 

[CKwik240]

130-150 cycles of 30% DoD? If that were true, Tesla 12V batteries would last less than a year, yet I have a 5 year old one in my car that is doing just fine.

Can't comment on that. Do you know if your use case actually causes a 30% discharge all the time?

The more important takeaway is the difference in overall battery life differences for this use case. Like I said before, it would seem to me a deep cycle battery would be a better overall fit from a technical standpoint. Whether weight and cost have a substantial influence is not known to me.

 

[Motion122]

130-150 cycles of 30% DoD? If that were true, Tesla 12V batteries would last less than a year, yet I have a 5 year old one in my car that is doing just fine.

A customer of mine had the original AGM battery in his 2008 BMW 135i for 14 years before I replaced it earlier this year if you can believe that! He says as soon he is home the battery maintainer is hooked up. From experience AGM is good for 7 in most German vehicles and lead acid around 5. The exception are VW Golf/GTI/Tiquan that will only last 2-3 and some Fords that don't fully charge the battery and kill the battery within the warranty period.

 

[gearchruncher]

I believe it because I sold a 2004 BMW with a 14 year battery on it that was still fine. Never once was on a maintainer.
My other BMW made it about 10 years, and half of that time the car was in Nevada and Arizona. Did have to replace it at that point.
Yet people complain that BMW requires a battery reset in the computer which is "stupid" or "greedy" even though this is what enables this long life.

 

[Motion122]

I believe it because I sold a 2004 BMW with a 14 year battery on it that was still fine. Never once was on a maintainer.
My other BMW made it about 10 years, and half of that time the car was in Nevada and Arizona. Did have to replace it at that point.
Yet people complain that BMW requires a battery reset in the computer which is "stupid" or "greedy" even though this is what enables this long life.

At least with Fords the charging algorithm can be manipulated to give the battery a full charge to extend the battery life. I wonder if Ford does that from the factory to sell more batteries! lol

 

[android04]

Can't comment on that. Do you know if your use case actually causes a 30% discharge all the time?

The more important takeaway is the difference in overall battery life differences for this use case. Like I said before, it would seem to me a deep cycle battery would be a better overall fit from a technical standpoint. Whether weight and cost have a substantial influence is not known to me.

I've had a battery monitor hooked up to my Model 3 lead acid for about a year and it never gets drained more than about 4 - 5%. My battery monitor has a shunt that goes on the negative terminal and therefore keeps track of voltage, current, and capacity. Even when I let my car sit unused for 3 days, I've never seen the battery drained more than 4 - 5%. So Tesla does not deep cycle the lead acid battery (at least in my case in the past year).

My battery is over 4.5 years old and 86,500 miles.

 

[gearchruncher]

I've had a battery monitor hooked up to my Model 3 lead acid for about a year and it never gets drained more than about 4 - 5%.

So you've only seen Tesla use ~1.5Ah/20Wh before they charge again? Given at least on a Model 3 they charge at 8A, it should only charge for about 12 minutes, and with a 10W draw on the battery it should charge about every two hours.

 

[Motion122]

I've had a battery monitor hooked up to my Model 3 lead acid for about a year and it never gets drained more than about 4 - 5%. My battery monitor has a shunt that goes on the negative terminal and therefore keeps track of voltage, current, and capacity. Even when I let my car sit unused for 3 days, I've never seen the battery drained more than 4 - 5%. So Tesla does not deep cycle the lead acid battery (at least in my case in the past year).

My battery is over 4.5 years old and 86,500 miles.

Probably a good idea to install one on my EarthX to monitor it as well. Where did you get the monitor?

 

[android04]

So you've only seen Tesla use ~1.5Ah/20Wh before they charge again? Given at least on a Model 3 they charge at 8A, it should only charge for about 12 minutes.

Yes. When I installed the shunt/monitor I fully charged my battery with a smart charger and set the monitor to read the full capacity as 45 Ah and 100%. And yes, usually see 43.xx or 44.xx as the capacity. Lowest I might have seen was 42.xx Ah. And yes, I usually see less than 8 A going to charge the battery when I first get in it and start driving if it was parked at home and I had Sentry Mode off, and it quickly tapers down.

Probably a good idea to install one on my EarthX to monitor it as well. Where did you get the monitor?

I got this one from Amazon, and had to bolt on a terminal clamp and post so it all bolts onto my Model 3 Amazon.com

You can see actual pictures and readings of my setup that I posted in February here How do people determine/measure power usage while awake topping of 12V battery?

 

[BigNick]

I believe it because I sold a 2004 BMW with a 14 year battery on it that was still fine. Never once was on a maintainer.
My other BMW made it about 10 years, and half of that time the car was in Nevada and Arizona. Did have to replace it at that point.
Yet people complain that BMW requires a battery reset in the computer which is "stupid" or "greedy" even though this is what enables this long life.

Aren't BMW batteries usually under the trunk floor? Keeping it out of the engine compartment heat zone probably contributes more to its long life than the computer.