Featured Dr. Prius Packs Less Than A Year Away?

When there isn't a battery warmer, car systems should be applying a very low charge rate until the battery warms up.

Hybrids also don't drain the batteries completely. Pulling energy out of the battery on start up will begin warming up the pack.

 

12 volt electric blankets are a thing. Insulation alone might be enough.

 

If I ever go the LiFePO4 route, a battery warmer will be a must.

 

Here are several questions I didn't see the answer yet:
1. Need the SOC mapping between NiMh Battery and LiFePo, for 40% SOC NiMh Battery, the same voltage, what is the percent SOC for LiFePo? And how about 80% SOC NiMh Battery?
2. Then, under this SOC range, what's the expect life cycle of the LiFePo battery set?
3. NiMh Battery has metal case, but LiFePo battery combined two blades and use plastic case, then how are you going to dealing with the heat generated by battery charging and discharging? Please show more data about your Thermal Design ,and your Thermal test data.

 

When in Dr Prius going to make a linsight compatible pack?

 

Please Use DATA to elaborate your point of view.

It is not saying today's test result is good, then it is good. Testing on new battery is good doesn't mean testing on old battery will be good as well(I'm a RC airplane player, and I know how hot an old LIPO battery can be).

As I know, both NiMH and LiFePo has the similar charge/discharge efficiency, which is 90%, thus, the rest 10% becomes heat, and that's why Themal Design is critical, while most people just overlook it.

 

I'm living in Denver, Colorado and would like to work with you guys on developing a battery warmer for these Lithium Cells, can you PM me so we can discuss it further?

 

The now-going price for a Prius gen 3 is $2170.00, Prius Gen2, Gen3, CT200h Lithium upgrade battery pack - 14 blocks – NexPower Energy (projectlithium.com) This does look good. It appears this is his own design, and he has kept the price down.

 

@PriusCamper any rough idea on what the new tech coming in the November delivery is? I'm bummed I just picked up my kit with the October shipment but everything I've read says ~55mpg

How much better could this kit get?

 

100Lb propane tank heater/blanket/wraps can go for over $500. And that's 'production' price. don't know if solo jobs would necessarily be a bargain.
.

 

I don't think you would need that much heating capacity, now I'm going to prototype it because I'm curious. I'm working off the 2nd Gen Platform and per the Nexcell specs I see two significant temperature ranges.

1 Month Storage Temperature: -4(F) up to 113(F)
Recommended Storage Temperature: 59(F) up to 95(F)

I'm going to target a cell temp of 0(F) or higher with my goal. I've started out the experiment using a temp probe and I'm working out of Denver in the middle of this cold front rolling through. The last two nights we've seen lows of about 19 degrees. I had parked my car by 9PM or earlier both nights and my rear interior is still fully gutted from installing my lift earlier this year. The plan is to sound deaden then foam insulate the whole car but this will serve as a conservative baseline as there is really nothing protecting / insulating the battery from cold soak throughout the night.

Night 1: Low of 19(F), Lowest Battery Probe Reading, 38(F)
Night 2: Low of 19(F), Lowest Battery Probe Reading, 26(F)

The annual lowest temp for the last 15 years hovers between -10 and -15. Given my lack of vehicle interior, let alone my plans to insulate and build a flat load floor it seems like there is enough of a safety margin in the natural high/low cycles of the climate here to avoid a battery heater.

But regardless, I'll build a small something and we can make this fun. My build is going to have (4) UT1300s for the battery bank to power the camp site and I'm going to lean on those to power the battery heating systems, much in the way that several Lithium manufacturers just include the heaters in the batteries. (That approach has its own set of issues)

I will get my Nexcell kit installed and my initial thought is to establish a few RV water tank heaters on an external thermostat, tied to the 12v (or battery bank). I'm going to attach the tank heating pads to the battery housing in the hopes that it delivers the right amount of "warm ambient" conditions that keep the Lithium cells running at optimal levels as opposed to some other system where the heating element would be more directly attached to the cells and likely creating an inconsistent result.

 

For starters, anybody got an estimate of the thermal mass of these Project Lithium packs?

That would give a sense of how many watthours of sock-warming would be needed to bring them from x ℃ to y ℃ before starting the car.

 

Warming it up to what temperature (="y" in ChapmanF's lingo)?

 

There is a selection of 12V electric blankets for the car.
https://smile.amazon.com/s?k=12v+electric+blanket&sprefix=12v+electric+b%2Caps%2C98&ref=nb_sb_ss_pltr-ranker-10hours_1_14