12V battery charging, voltage limits, capacity, etc.

[ATPMSD]

Did you actually read the thread? You are out in left field.

My facts about he 12v are a bit off (mixed myself up a bit), but the statements as the charging cycle and capacity of a lithium are correct. See video starting at the 5:40 mark (great video for anyone who has a lithium battery to watch end-to-end):

 

[ATPMSD]

My understanding is that the 12V is not needed (the car will allegedly run just fine without a 12V

I have been trying to find the source of this, but it seems to be a bit obscure. As I recall the genesis of this are posts of Tesla cars where a pull over immediately battery warning is shown followed by the car shutting down, or the car shuts down without warning. In these cases jumping the car did not work and the car had to be towed. The fix was only a new battery, so the conclusion was that a 12v battery is needed, even when the car Is awake. I suppose it could have been a battery short which the BMS detected, and then to protect the system it shutdown the car.

If anybody has a source either way I would be interested!

 

[AlanSubie4Life]

In these cases jumping the car did not work and the car had to be towed. The fix was only a new battery, so the conclusion was that a 12v battery is needed, even when the car Is awake.

Yeah a shorted battery would cause problems.

The claim is you just pull the negative terminal and start the car with the external 12V, then you are good to go (with no sleep function).

I agree it would be good to have confirmation but I think if you look around you’ll find someone confirmed. In the end one has to just try it oneself.

 

[inigoml]

Reviving this thread, I've looking for a drop-in replacement for Telsa 12V battery. First I was reviewing Ohmmu battery that is insanely expensive here in Europe due to shipping cost (and also in USA). So, I started investigating about some alternatives. None of them convinced me:

- LFP batteries could eventually have problems associated with BMS, as Ohmmu.
- LFP are not good for low temperatures. So, although was thinking about some kind of DYI LFP battery, I abandoned this idea because eventually I would have to deal with thermal management.
- I've been researching a bit with LTO batteries, both drop-in replacement and DYI. There is no many options in the market and all of them are quite expensive. Good part is that LTO has high discharge rate and a wide temperature operation range. Good for an ICE car. But since volumetric capacity is not quite high, most cells I've found are big or eventually I'd have plenty work in order to accommodate inside a battery box.
- I'm also exploring sodium batteries. These are cheap and have a decent temperature operational range.

I've found at Alibaba a sodium brand with a BMS able to charge up to 15.8V before cut-off and that has almost the same dimensions as Varta B32 (OEM Clarios), at least in length (238mm), a bit more more wide (133mm vs 128 for Varta but inside range, I guess) and 222mm height (Varta 227mm). 40Ah, 12.4V.

I'm not sure if I will buy it because shipping cost could eventually be very high. Keep you informed.

New Launched Car Starting Na-ion Wide Range Voltage Low Temperature 3000 Cycles 12.4v 40ah Sodium-ion Battery - Buy 12.4v 40ah Sodium-ion Battery,Na-ion Wide Range Voltage Battery,Low Temperature Sodium-ion Battery Product on Alibaba.com

New Launched Car Starting Na-ion Wide Range Voltage Low Temperature 3000 Cycles 12.4v 40ah Sodium-ion Battery - Buy 12.4v 40ah Sodium-ion Battery,Na-ion Wide Range Voltage Battery,Low Temperature Sodium-ion Battery Product on Alibaba.com

www.alibaba.com

 

[Sophias_dad]

Reviving this thread, I've looking for a drop-in replacement for Telsa 12V battery. First I was reviewing Ohmmu battery that is insanely expensive here in Europe due to shipping cost (and also in USA). So, I started investigating about some alternatives. None of them convinced me:

- LFP batteries could eventually have problems associated with BMS, as Ohmmu.
- LFP are not good for low temperatures. So, although was thinking about some kind of DYI LFP battery, I abandoned this idea because eventually I would have to deal with thermal management.
- I've been researching a bit with LTO batteries, both drop-in replacement and DYI. There is no many options in the market and all of them are quite expensive. Good part is that LTO has high discharge rate and a wide temperature operation range. Good for an ICE car. But since volumetric capacity is not quite high, most cells I've found are big or eventually I'd have plenty work in order to accommodate inside a battery box.
- I'm also exploring sodium batteries. These are cheap and have a decent temperature operational range.

I've found at Alibaba a sodium brand with a BMS able to charge up to 15.8V before cut-off and that has almost the same dimensions as Varta B32 (OEM Clarios), at least in length (238mm), a bit more more wide (133mm vs 128 for Varta but inside range, I guess) and 222mm height (Varta 227mm). 40Ah, 12.4V.

I'm not sure if I will buy it because shipping cost could eventually be very high. Keep you informed.

New Launched Car Starting Na-ion Wide Range Voltage Low Temperature 3000 Cycles 12.4v 40ah Sodium-ion Battery - Buy 12.4v 40ah Sodium-ion Battery,Na-ion Wide Range Voltage Battery,Low Temperature Sodium-ion Battery Product on Alibaba.com

New Launched Car Starting Na-ion Wide Range Voltage Low Temperature 3000 Cycles 12.4v 40ah Sodium-ion Battery - Buy 12.4v 40ah Sodium-ion Battery,Na-ion Wide Range Voltage Battery,Low Temperature Sodium-ion Battery Product on Alibaba.com

www.alibaba.com

I gotta say, trusting the BMS in an alibaba battery to not screw up and turn your expensive Tesla into smoldering slag is something I wouldn't entertain, and that's assuming your expensive Tesla isn't sitting in your expensive garage under your expensive house while you are sleeping.

 

[jjrandorin]

I gotta say, trusting the BMS in an alibaba battery to not screw up and turn your expensive Tesla into smoldering slag is something I wouldn't entertain, and that's assuming your expensive Tesla isn't sitting in your expensive garage under your expensive house while you are sleeping.

Not to mention that the alibaba link is still the same basic price of the Tesla lead acid battery, within probably $10.

 

[dfwatt]

I gotta say, trusting the BMS in an alibaba battery to not screw up and turn your expensive Tesla into smoldering slag is something I wouldn't entertain, and that's assuming your expensive Tesla isn't sitting in your expensive garage under your expensive house while you are sleeping.

Incredibly unlikely that a 12 volt malfunction would cause a main pack Cascade Fire. Also very unlikely that an lfp (12 volt) low voltage system would catch fire at all.

 

[Sophias_dad]

Incredibly unlikely that a 12 volt malfunction would cause a main pack Cascade Fire. Also very unlikely that an lfp (12 volt) low voltage system would catch fire at all.

A 12V sodium ion battery sounds pretty dicey to start(although it MIGHT be safer than lithium ion), and since it needs a BMS by definition it needs M'anagement which needs to be reliable. I'm not sure if a 12V battery fire would cascade into a main pack fire, but I'm pretty sure a 12V fire would still be a car-killer if it weren't caught quickly.

I also fail to see the motivation to change to some other battery type. The original lead-acid battery seems to be inexpensive and reliable.

 

[inigoml]

Incredibly unlikely that a 12 volt malfunction would cause a main pack Cascade Fire. Also very unlikely that an lfp (12 volt) low voltage system would catch fire at all.

Sodium, in fact. More improbable if not impossible. What it's possible is to get stuck.

 

[dfwatt]

Sodium, in fact. More improbable if not impossible. What it's possible is to get stuck.

Yes an outright 12 volt failure does strand the car. But that should never happen if you're on top of your alerts and doing a reset. Which literally takes now that I've done it quite a few times about 10 seconds. That's if you have a Bluetooth enabled battery.

 

[inigoml]

I also fail to see the motivation to change to some other battery type. The original lead-acid battery seems to be inexpensive and reliable.

Just for fun. If I finally test this battery, the first thing will be take a look inside.

What it's incredible nowadays is that lead batteries with all associated problems (low lifespan, low discharge, environment unfriendly, questionable economics) are still in the market with no signs to be replaced. There are economic alternatives in the market but almost nobody is looking for a massive replacement but Tesla since 2022 onward.

By the way, both Dali and JK BMS are widely available at Alibaba and they are high quality. Alibaba / Aliexpress has lot of quality items and tons of trash. You have to be careful and test before. And of course, not rely just in the advertisement. Usually a pair of questions to the dealer can give you an accurate idea of what you are buying.

 

[dfwatt]

Just for fun. If I finally test this battery, the first thing will be take a look inside.

What it's incredible nowadays is that lead batteries with all associated problems (low lifespan, low discharge, environment unfriendly, questionable economics) are still in the market with no signs to be replaced. There are economic alternatives in the market but almost nobody is looking for a massive replacement but Tesla since 2022 onward.

By the way, both Dali and JK BMS are widely available at Alibaba and they are high quality. Alibaba / Aliexpress has lot of quality items and tons of trash. You have to be careful and test before. And of course, not rely just in the advertisement. Usually a pair of questions to the dealer can give you an accurate idea of what you are buying.

There's all that and there is the toxicity and the extremely inefficient charging relative to lithium ion. Which means that every time the battery charges you're donating an extra 15% lost to the process. For me that's enough to offset the need for occasional resets in colder weather. Works without issue in warmer weather but it does not agree with the 12 volt subroutines on the car in Colder Weather and I do have to do a reset once in awhile. Still worth it for me given that that takes a grand total of 10 seconds. Last but not least since we're in Florida resets are relatively rare.

 

[inigoml]

There's all that and there is the toxicity and the extremely inefficient charging relative to lithium ion. Which means that every time the battery charges you're donating an extra 15% lost to the process. For me that's enough to offset the need for occasional resets in colder weather. Works without issue in warmer weather but it does not agree with the 12 volt subroutines on the car in Colder Weather and I do have to do a reset once in awhile. Still worth it for me given that that takes a grand total of 10 seconds. Last but not least since we're in Florida resets are relatively rare.

Living in Florida for sure temperature is not an issue.

However here in Spain and Madrid in particular we have cold winters. So, temperatures under 0C (-32F) are usual. My car does not rest outside, however all winters we have a family trip to the mountains (ski) and it's frequent to reach -15C (5F) and LFP is not an option in that conditions. LTO or Sodium are better to deal with such temperatures. And, of course, outside Spain (France, Germany, Switzerland) temperatures are much lower in winter. So this is why I looking for an alternative to Ohmmu batteries.

 

[Flybyglass]

Living in Florida for sure temperature is not an issue.

However here in Spain and Madrid in particular we have cold winters. So, temperatures under 0C (-32F) are usual. My car does not rest outside, however all winters we have a family trip to the mountains (ski) and it's frequent to reach -15C (5F) and LFP is not an option in that conditions. LTO or Sodium are better to deal with such temperatures. And, of course, outside Spain (France, Germany, Switzerland) temperatures are much lower in winter. So this is why I looking for an alternative to Ohmmu batteries.

FWIW Ohmmu batteries now have internal heating elements.

 

[dfwatt]

FWIW Ohmmu batteries now have internal heating elements.

How can you tell if your version 4 battery has the heating elements or whether it's just the earlier version 4

 

[Flybyglass]

How can you tell if your version 4 battery has the heating elements or whether it's just the earlier version 4

On outside will be a yellow sticker saying Self Heating Technology Inside. It works.