LiFePO4 batteries for 12V AUX?

Well, I have not used that chemistry either. But what I can say is that it would definitely work, but have you thought of the safety gadgets to manage temperatures and all that? I mean what BMS are you going to embed on it, before using em as a 12V battery on any of the Prius?

My best bet would be to use it only as a support to jump start a Prius at the rear with the stock battery in place.

I have a combination of modules I had lying in the shop, to jump start a Prius, and even a regular car, whose battery was weak.

It would be expensive to have those safety systems incorporated on the battery you're referring to, considering the cost of designing, and actually having the BMS hardware. Might be another weight on the car though.

Let's wait for other PC memevers and see what they've to say.

PS: You got to think about the amperage also.

Dxta

 

In that case, a study of the battery circuitry on the motorcycles would be of importance then.
But remember they aren't hybrid motorcycles.
I'd prefer to use such LIpos for only jump starting the aux battery specifically at the rear.

 

LiFe batteries aren't all that new and have been in use for a very long time in the R/C industry. (Model Airplanes - possibly model cars, but iono - I fly, I don't drive) They were and still are utilized to power the electronics. However they never really did dominate the industry and if I had to guess it's because you needed a special charger. Nowadays that's not such a big deal anymore because all of us have Hobby Chargers that cycle/charge/balance multiple types of battery chemistry.

The hobby today is dominated by LIPO.

Sidenote to that: There is a thread on here somewhere where the guy is working on his disassembled Prius HV Battery. The chargers he had on the wall were the same as we're using in the R/C hobby. Thought that was kinda neat.

{edit} - I guess what I'm trying to say after all that is your going to be charging a completely different type of battery chemistry with something designed to charge Lead Acid. Probably not the smartest thing - see stories of house/car fires in the R/C Hobby Industry as a result of doing this.

 

As mentioned they require different charging. You are not going to be able to program the inverter in the Prius for the new battery chemistry.

 

if you were to try it, i wouldn't bury it, and i would have some diagnostics hooked up continually until i was comfortable one way or the other.
i would also carry a jump pack.

 

So......if these are actually available yet......what IS the price ?

Under normal conditions, an AGM battery vents ZERO gasses also. And unless you have an unusual usage pattern or a really harsh environment, they will last up to 7 years, sometimes more.

At his point, I think a lithium battery in your average motor vehicle is WAY overkill.
But then some people put 1000 watt stereo's in their cars too.

A good value......NO.
But if it makes you happy.................

 

I have DIY lawn movers with LiFePo4 batteries, and did consider also replacing Prius 12V battery with one too. But decided not to go with it as they cannot be charged when the temperature goes below freezing. In Finland that means I need either battery heating or separate winter battery. Also replacing working battery would never be economical.

There are 12V LiFe batteries with so closely matched cells that you do not need balancing. If big enough, they are safe also for ICE starter currents. I was considering a battery with integrated BMS though (with Bluetooth monitoring), as it would protect the battery also from under voltage. LiFe does not like it either, even it handles basically all abuse a lot better than LiIons.

Car charger could overcharge the LiFe batteries in very long drives, but effect on the battery life time would still be very small. With mostly short trips over charge would not happen.

Fuel efficiency would be a little bit better than with lead acids. LiFe is lighter and charging efficiency is better. I estimated that it would save me about 1 liter of gasoline per year, when driving about 20 tkm per year I belive (I have no evidence) that LiFe batteries would last twice as long as AGM lead acids in Prius, if properly handled (no complete discharge and no charging when too cold).

With motorcycles they are more popular because they last vibration better than any lead acid. And weight has bigger effect on handling of a smaller vehicle. The last thing is the sub freezing temperatures - not very many people like to drive bike in such temperatures

 

The 12 volt battery for the Prius does not need ICE starter currents. MG1 starts the engine from the large traction battery. The 12 volt battery just powers computers & accessories as well as closing the high voltage relay.

 

but way too much for an experiment.

 

I think that the Optima is over-priced (and over-hyped) too.
You should be able to get a good AGM for about half that and you won't have to worry about any compatibility issues either.

 

Something like this -
Super Natto
LiFePO4 Power Start
46B24R 12.8V nominal (14.6V max), 46Ah, 4.5mohm ?, 8.8 lbs (4Kg) 1-Yr Warranty
Battery Monitoring System (BMS) built in, Lifecycles = 2000, Temp = -30C - +80C
Emergency starting function with built-in emergency battery
46B24R 12V 46Ah 650CCA Lithium Iron Phosphate Battery LiFePO4 for Automotive Car
$362 (eBay item number 372073283537, China)

And who doesn't want to "Make your car full of speed and passion"?

 

I'd guess that the Super Natto's Ah rating is "lead acid equivalent". At least judging from weight, which indicates specific energy of 125 Wh/kg. Wikipedia says bare batteries are 90–110 Wh/kg. My guess would be that 24R is the true capacity, i.e. 24 Ah. With Prius that would not be an issue, but it is worth of knowing when you compare different models.

I am about to order Winston from EU/Czech (EV-Power | Lithium Battery 12V/40Ah (WB-LP12V40AH)). Just have to double check the height of the original battery, before pulling the trigger.

I'll be running it without any extra protection - it has never happened to me that I'd have dead lead acid battery. Why would it happen with LFP? I'll just monitor the voltage often in the beginning after getting the battery. If I see any issues (low state of charge), I'll get something like this: 12V ProMax Heavy-Duty Battery Protector | AW Direct and start charging it from grid on regular basis.

My current battery, original AGM from year 2012 and 180 tkm behind it, is showing low idle voltage (12.3V about 1h after charging, no load, and 11.9V when "car on without pressing break pedal").

 

I posted the Super Natto as an example of a possible drop in, easy to use LiFePO4 replacement.
I can only go by the marketing literature at this point.
Using a generic rating from Wikipedia to try to judge the manufacturer's rating and make assumptions is error prone, to say the least.

I also liked the idea of the built-in backup battery. If you leave your lights on or listen to the radio too long, you can still get the Prius going.
The Winston battery (WB-LP12V40AH) you linked to is interesting, but is only 40Ah and doesn't have standard Prius terminals so it isn't a drop-in.

 

I have seen some companies to advertise those (imaginary) lead acid equivalent amp hours. Those were motorcycle batteries. But I failed now to find any references. Those that I have seen did mention the true Ah rating somewhere, so it is worth of reading the specs

Backup battery is very nice design idea They should do such a design with super capacitors (for traditional ICE's)?

I agree that Winston is not drop in, but should be doable. Height of the Winston is a little more than original battery, so mechanical adjustment may be needed also. But the difference is small, so I am not really worried about that. Most important reason for me to choose them is the cold side - they are specified to work from -45 deg C, also for charging. My neighbor is using the same batteries for his DIY electric conversion, so I may be biased The balance at the shop is currently zero, so I'll have to wait for May or June before installing it.

 

As far as the numbering goes, I couldn't find the official JIS listing (Japanese Industrial Standard).
But from all the listings I could find, such as Panasonic, the JIS Type is 46B24R (replaces old NS60).
Ex. - Panasonic CAOS N-S46B24R-HV, 49Ah, 238L x 128W x 202H mm (Body Height)
The first two digits are roughly the capacity in Ah, 46Ah
The next three digits are the JIS Group Number, B24, which represents the size - 237L x 128W x 200/222H mm (Body/Terminals)
The last digit represents the orientation of the terminals, where R is plus on the left (with terminals viewed closest to you).

So the B24R refers to the physical size and terminal orientation, not the true capacity.

The -45C cold temperature for the Winston is impressive. Quite chilly. No sources in the US though and seems no availability anywhere. Prices get high with shipping, $300 to $350 from EU or China.
I noticed this though "The monolithic 12V batteries do not have any PCM (any electronics) inside. They consist of finely balanced cells with identical perfomace."
It doesn't have the BMS, protection board, or charge control built-in.
So you have to adapt the terminals and provide the protection and charge control boards yourself. More $$. Too much work for me.

 

Winston 40Ah LiFeYPo4 Installed

(car on, i.e. charging)

Now we just have to hope I remember to update this thread after the battery or the car fails, or I sell the car

It's not direct replacement, but not difficult either. Two and half changes were needed:

1. On plus side I just removed the original battery post adapter (gray part in the 1st picture). Then I had to choose between cutting plastic or using spacer. The problem was the black plastic thingy in the 2nd picture. I chose to use spacer as my neighbor had suitable aluminium block available. Final solution is in the 3rd picture.





2. For minus side I made a new cable, see the next picture.


2.5 Mounting is original but I had to use a little bit more force to install it.

Parts used:
Battery Wintson 40Ah 12V
M8 x 12 mm and 25 mm bolts (length estimated, I did not measure it)
8 mm^2 cable (about AWG 8), length about 20. The original cable was even thinner!
8mm cable shoes, 2 pieces
Shrink tube
Battery post spacer

The change is fully reversible. Without that requirement one could just cut the original battery posts, and drill a hole into them.

 

Please keep us informed!
My concern would be if the relatively low charging voltage of the my Gen III hatchback , which seems to be 14.4 +/- 0.1 volt, would be sufficient to fully charge the replacement the lithium replacement battery.