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Made In China Model Y has 15.5 Lithium battery to replace 12V lead-acid

jcanoe

Active Member
Oct 2, 2020
4,333
4,498
Maryland
:rolleyes:

So you're saying a car doing nothing will be 10x more efficient with a lead-acid battery vs a li-ion? I don't know how you came-up with your assumptions, but they seem half-baked at best.

The lead-acid battery has an larger initial energy reservior. Other than that, energy consumption should be very similar.



This 12V LFP battery is designed/created by CATL and works at low temps.
My assumptions are fully baked.

If the current 12V lead-acid battery, with a rating of 45Ah, can power the Tesla Model Y's essential 12V systems for ~24 hour before needed to be recharged from the Tesla vehicle's main battery pack then a battery with ~7Ah capacity will need to be charged more frequently due to the lower capacity.

The current 12V lead-acid battery will charge approximately once every 24 hours for ~2 hours. The anticipated 12V lithium replacement battery, with only 1/6th the capacity, will need to be charged more often. I estimate the 12V lithium battery will need to be charged every 4 hours for 30 minutes.

Any time the Tesla Model Y vehicle is awake it is consuming 230W just because it is powered on. Adding some power used to charge the 12V lithium battery (estimated at 15V and 10A (150W)) the total power drain during each charging period will be ~380W. Do this 6 times a day for 30 minutes each time and this would consume 1.14kWh per day, 7.9kWh per week.

By comparison, if the current 12V lead-acid battery charges for 2 hours every 24 hours this would consume 380W X 2hrs = 720Wh, (37% less power) per day. (I know that, recently, when I left my 2020 LRMY parked, unlocked for a week that the battery only lost 1% of the charge. Maybe the Tesla Model Y enters a deep sleep mode when parked for an extended period where is consumes less power.
 
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Unclepaul

Member
Jan 15, 2020
265
388
SoCal
Believe there are lots of benefits to this new little battery. It weighs less, does not need to be replaced every two years, has better vehicle packaging due to much smaller size. It can have less capacity as Li batteries can be discharged down below 20% while Lead acid cannot tollerate more than 50%.

Tesla has finally broken away from it's dependance on legacy lead acid technology.
 

Two-rocks

New England IPA
Jan 18, 2021
277
340
gone
Some points on the charging efficiency talk above…

For a lead acid there is about a 15% loss in round trip watt hours. (85% efficiency)

Lithium is typically 99%.

Lead acid takes a very long time to top off or reach full capacity, thus the charging time is longer (and car awake time as well).

Lead acid batteries never should be cycled below 50% capacity (deep cycle) or life expectancy is exponentially reduced.

Lithium can be cycled lower and retain an acceptable cycle life.

All of this makes the lithium ‘house’ battery a better choice
 

mark95476

Active Member
Jun 21, 2020
2,067
1,589
Bay Area CA
Lead-acid batteries can use ~50% of their capacity. So a 45Ah rated lead-acid battery has 22.5Ah of usable energy.
Li-ion can use >95% of their capacity. So a 7Ah li-ion rated battery has ~7Ah of usable energy.
So 1/6 capacity is more like 1/3 capacity.

Your cars HV battery lost 1% SoC being idle for a week. It'd lose that same ~1% regardless of lead-acid or li-ion 12V battery.

Maybe we'll hear about people with the new S/X complaining about excessive power loss due to the new 12V battery. It'll be followed shortly by new China MYP owners complaining about excessive power loss due to their new 12V battery.

I doubt it, though.

My assumptions are fully baked.

If the current 12V lead-acid battery, with a rating of 45Ah, can power the Tesla Model Y's essential 12V systems for ~24 hour before needed to be recharged from the Tesla vehicle's main battery pack then a battery with ~7Ah capacity will need to be charged more frequently due to the lower capacity.

The current 12V lead-acid battery will charge approximately once every 24 hours for ~2 hours. The anticipated 12V lithium replacement battery, with only 1/6th the capacity, will need to be charged more often. I estimate the 12V lithium battery will need to be charged every 4 hours for 30 minutes.

Any time the Tesla Model Y vehicle is awake it is consuming 230W just because it is powered on. Adding some power used to charge the 12V lithium battery (estimated at 15V and 10A (150W)) the total power drain during each charging period will be ~380W. Do this 6 times a day for 30 minutes each time and this would consume 1.14kWh per day, 7.9kWh per week.

By comparison, if the current 12V lead-acid battery charges for 2 hours every 24 hours this would consume 380W X 2hrs = 720Wh, (37% less power) per day. (I know that, recently, when I left my 2020 LRMY parked, unlocked for a week that the battery only lost 1% of the charge. Maybe the Tesla Model Y enters a deep sleep mode when parked for an extended period where is consumes less power.
 

SageBrush

REJECT Fascism
May 7, 2015
12,892
17,217
New Mexico
Reported on twitter and starting to echo through the internet.

I'm stoked !
I have this notion that a fair bit of my vampire drain is related to the car waking up to top off the 12v. An LFP may have enough capacity (for the same volume as the PbA that preceded them), and a shallower voltage discharge curve to reduce if not eliminate these events.

Now, if only it comes to the USA before my delivery ... Fingers crossed
 

NHK X

Active Member
Nov 18, 2017
1,059
953
Texas
Also very excited about AMD Ryzen for processor and also with a discrete GPU. Same as what is in the refresh S and Y. Being someone who has a MCU1 X and paid for MCU2, any future proofing in this aspect is always appreciated.

In terms of lithium 12v, can’t wait. I’ve replaced my model X 3 times over 110k miles. I do wonder how they regulate temps or if they are using cells rated for cold weather. The service center where I live told me the drop in non branded lithium 12v people have been using has been failing pretty frequently.
 

SageBrush

REJECT Fascism
May 7, 2015
12,892
17,217
New Mexico
About the usable capacity of LFP Vs Pba 12v in the Tesla:

At least in my Model 3, the 12v was 33 Ah Pba with a total nominal capacity of 400 Wh
The new LFP are 100 Wh

So are first blush, the LFP will have to be recharged 4x more frequently, but there is a an important missing detail here: at what voltage do each chemistry initiative a charging event ? Back in the day, I attached a Bluetooth monitor to my PbA and saw recharging events at 12.5V. That is somewhere around 75% SoC, so after 50 Wh was discharged.

We'll have to wait and see whether the new LFP are discharged more than 50 Wh before a charging event is triggered.

The other variable here is the charging curves of each chemistry. Anybody know ?
 
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rrolsbe

Member
Feb 18, 2017
308
191
Albuquerque
About the usable capacity of LFP Vs Pba 12v in the Tesla:

At least in my Model 3, the 12v was 33 Ah Pba with a total nominal capacity of 400 Wh
The new LFP are 100 Wh

So are first blush, the LFP will have to be recharged 4x more frequently, but there is a an important missing detail here: at what voltage do each chemistry initiative a charging event ? Back in the day, I attached a Bluetooth monitor to my PbA and saw recharging events at 12.5V. That is somewhere around 75% SoC, so after 50 Wh was discharged.

We'll have to wait and see whether the new LFP are discharged more than 50 Wh before a charging event is triggered.

The other variable here is the charging curves of each chemistry. Anybody know ?
My 2018 RWD Model 3 has a 45AH battery so 12 X 45 = 540Wh. So with a depth of discharge of 25% ---540X0.25=135Wh. My car wakes up around every 17 hours and I measured around 7+Watts used while the car is sleeping (7X17=119Wh). So if I am thinking about this correctly the numbers make sense. BTW, should your 50Wh be 100Wh? I though all Model 3's had 45AH batteries?
 
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SageBrush

REJECT Fascism
May 7, 2015
12,892
17,217
New Mexico
My 2018 RWD Model 3 has a 45AH battery so 12 X 45 = 540Wh. So with a depth of discharge of 25% ---540X0.25=135Wh. My car wakes up around every 17 hours and I measured around 7+Watts used while the car is sleeping (7X17=119Wh). So if I am thinking about this correctly the numbers make sense. BTW, should your 50Wh be 100Wh? I though all Model 3's had 45AH batteries?

You may be right about the 2018 model (which I had also) being 45 Ah. I don't have the car to recheck.
Your math looks right to me -- thanks for the correction.

I don't know the voltage of the PbA when 'fully charged', or what SoC that implies. And of course all these calcs presume a new PbA
 

mattnis

Member
Apr 2, 2020
90
76
Chicago
Maybe; the battery cable connector is different on the refreshed Model S with the lithium battery. You can replace your current lead-acid battery with an OHMMU 12V Lithium Iron Phosphate (LFP) today for ~$400.
It's annoying that ohmmu is so expensive given that you can get a huge 100ah Lifepo4 battery for like $350. This tiny battery should cost half that.
 

s14roller

Member
Jul 10, 2021
57
37
USA
So if the current system charges the 12V battery, why does it seem like it fails so soon? On cars that I use a battery tender on (especially during winter) the batteries seem to last years (4 yrs +). I don’t recall the last time I even changed a battery.

On a separate note, is it pointless to throw it on a battery tender from time to time? Sounds like it’s already doing this internally
 

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