12V LiFePO4 Battery Project - Suggestions Wanted

[tmho]

I have a 2023 Toyota bZ4X which is an electric car. I am planning to build a 12V LiFePO4 battery (4 x cell with smart BMS) to replace the existing 12V Auxillary lead acid 20HR 45Ah battery.
Below are my questions and suggestions/comments are welcomed:

1. I guess this conversion will be feasible for my electric car and most other electric car. Am I correct?
2. I am going to use a smart BMS. Will this prevent the normal operations of the car and how to avoid them?
3. There are a lot of sources for LiFePO4 cells and smart BMS. Any suggestions on reliable sources and how should I choose?

 

[fill]

probably cheaper to buy an off the shelf 12v pack, even if exempt from trump taxes.

What smart bms features will you use? - beter to buy a specific LiFEPO4 bms than rely on custom configuration if thats the reasoning.
A real time $2 volt meter providing direct voltage of the battery would e a lot cheaper and far more reliable for a real time monitor, will you really use a bms app 3 months later?

 

[tmho]

probably cheaper to buy an off the shelf 12v pack, even if exempt from trump taxes.

What smart bms features will you use? - beter to buy a specific LiFEPO4 bms than rely on custom configuration if thats the reasoning.
A real time $2 volt meter providing direct voltage of the battery would e a lot cheaper and far more reliable for a real time monitor, will you really use a bms app 3 months later?

Thanks for your comments.

I like the smart bms because it can show me not only the voltage of the battery. I can see the voltages of all the cells, output current, charging current. With these, I can understand how my electric car will do to and need from the 12V battery. The smart bms will also balance the cells. From these, I wish that I could make the 12V LiFePO4 battery last longer. (Many electric car owners complaint the short life of the 12V batteries).

Yes, a smart bms is usually much more expensive than a regular bms. Just like the cellphones. Not all the smart phone users really make good use of all the smart phone features/functions. But I will sure make good use of the smart bms features.

 

[Papa]

LiFePO4 doesn't appreciate temps below freezing, so you'll also need a dedicated battery heater, if you expect to use the EV during winters.

 

[tmho]

LiFePO4 doesn't appreciate temps below freezing, so you'll also need a dedicated battery heater, if you expect to use the EV during winters.

Thanks for your information.
My location will be below freezing for about a month every year. I have not come across such a battery heater. Could you send me a link of it so that I can consider if I am able to add it to my battery or not?

 

[Chalo]

New LEV60F 3.2v 74ah Lifepo4 Power Cells

If you buy 6 they will ship in the original case. Otherwise we will repackage them safely into a custom box. They are Lithium Energy Japan cells model LEV60F. These cells are overstock and were originally intended for luxury vehicle 12v lifepo4 starter batteries. Cell Specifications Nominal...

batteryhookup.com

These are very good value, and they can crank your vehicle if that's necessary at some point. You'll need 4 (or 4 x n) of them to impersonate a lead acid 12V battery.

 

[tmho]

New LEV60F 3.2v 74ah Lifepo4 Power Cells

If you buy 6 they will ship in the original case. Otherwise we will repackage them safely into a custom box. They are Lithium Energy Japan cells model LEV60F. These cells are overstock and were originally intended for luxury vehicle 12v lifepo4 starter batteries. Cell Specifications Nominal...

batteryhookup.com

These are very good value, and they can crank your vehicle if that's necessary at some point. You'll need 4 (or 4 x n) of them to impersonate a lead acid 12V battery.

Chalo, thank you for recommending Battery Hookup to me.
That 74Ah is a little too big to fit into the space. I will the consider the 50Ah.

 

[amberwolf]

My location will be below freezing for about a month every year. I have not come across such a battery heater. Could you send me a link of it so that I can consider if I am able to add it to my battery or not?

There's a lot of different kinds. Normally they're used in places like yours that freeze for long periods, where parking areas have outlets for them to plug into, to keep even the lead-acid batteries from freezing.

If you haven't had that problem with your old battery, you might already have a heater that runs off your traction pack (as your traction pack probably also already has a heater built into it that runs either from it or from the charge port or both, so it doesn't freeze).

If you don't, these are two possible searches to find one that fits your vehicle and whatever power source you want to use:

car battery heater - Google Search

car battery warmer - Google Search

 

[tmho]

There's a lot of different kinds. Normally they're used in places like yours that freeze for long periods, where parking areas have outlets for them to plug into, to keep even the lead-acid batteries from freezing.

If you haven't had that problem with your old battery, you might already have a heater that runs off your traction pack (as your traction pack probably also already has a heater built into it that runs either from it or from the charge port or both, so it doesn't freeze).

If you don't, these are two possible searches to find one that fits your vehicle and whatever power source you want to use:

car battery heater - Google Search

car battery warmer - Google Search

Thanks for your information.
I am in the south western part of BC, Canada. It is not that cold in winter. It is just below zero for a few degrees for at most 1 month. And may be that is why I have not seen those battery warmer before. I will try it in case my battery does not function properly.

 

[j bjork]

Audi etron gt has a lifepo4 12v battery and no battery heating. But it has communication with the battery, so it very possible that it adjusts charging according to temperature.

 

[tmho]

Audi etron gt has a lifepo4 12v battery and no battery heating. But it has communication with the battery, so it very possible that it adjusts charging according to temperature.

With the smart bms, I can know if my car adjusts charging to the 12V battery according to the temperature. That is another reason I prefer a smart bms which is much more expensive.