DIY 12v lithium battery for Prius - step by step with pictures

I'd be an even bigger fan of Jehu's work if he wasn't so popular... Whenever he has stuff to sell it's sold out in like 3 minutes. But at least there's always more to learn from him!

 

Once setup for the builds and understanding what's needed to monitor the packs long term, there's endless opportunities available to use the equipment and build experience gained by starting small.

 

Anyone that is interested in building packs should be able to find without too much trouble Youtube Videos on how to make a simple spot welder.
PLEASE - BE CAREFUL - you may think (12 volts) + High Crank (AMP)s can't hurt you. But anyone who's accidentally shorted a 12 volt lead acid battery knows, it can melt steel.

 

Microwave ovens have good parts to build a spot welder with, but never tried it...

 

I haven't messed with the microwave power supply either. I've debated giving the (super simple) 12 volt spot welder a try, just haven't had time yet. I'm still trying to schedule a recycle plan for all the lead acid stuff I can't get to hold a charge any more and old oil filters etc etc etc.........

Know anyone that could use a slightly damaged right signal lamp for a 17-19 Prime Plus and maybe a 20 21 Prime LE?

 

Lead Acid batteries are easy... Call around to auto parts stores. I found one (Advance Auto Parts) and they give me $12 store credit for battery cores.

 

I want to know more about why they don't hold charge anymore - possibly reusing the lead and learn more about the hydrometer as related to charge level. Ya know the old school basics.
thin plates thick plates negative terminal corrosion sulfation whiskers what have you?

got a spell check error on sulfation - this resulted
Sulfation and How to Prevent it - Battery University

do a youtube search on how deep cycle batteries are recycled if interested.

 

That Battery University website is a great resource so often... And with all the different kinds of batteries in the world that you can aquire for next to nothing, those lead acid ones are the bottom of my list. Maybe it's time for a fresh start and you sense the wisdom in getting rid of 'em all and getting less heavy stuff to study & learn from?

 

I'll get rid of them when I can stop buying them. I've got all shapes and odd sizes, not just car batteries.
I even talked to a person about converting the lead acid in the golf cat to lithium since they only last 5 or 6 years and are about 2 grand to replace. one has four or five 8 volt deep cycles the other one is a 48 volt.
Thinking is those 8 volts are gonna cost more than the 12 volt cart batteries.
Motorcycle batteries are another pain, especially if they are left outside or in an unheated garage all winter. Sure I'd love to make lithium to replace the old lead acid... so many ideas, I gotta pick and choose.

And it's so nice to have lithium tool batteries, instead of the old Ni MH pack that went dead in a year or two. Although I still have the nickel strips I pulled of them.

 

Have you priced other automotive batteries lately.......good brand name AGM ones ??
I'm guessing not.

And that price is the result of the law of "supply and demand".
The demand for Prius parts, batteries included, is low. Therefore the price is high.
Or to put it another way, they charge that much because they CAN.

 

Fun project. However, last picture of first post - rubber coated wire going through stiff plastic hole isn't a good idea. If the rubber is softer than the plastic vibration will eventually cause the rubber to be cut away, exposing the metal underneath. Potentially a problem at the positive post. A grommet might help. Better yet would would be some sort of bolt through the top: fastening the cables onto the bottom of the bolt, and the car's connectors onto the top.

On a Gen 2 at least that location is notorious for flooding. I wouldn't want to put the battery as designed in there as the dirty accumulated water could slosh in through the holes. It really should be completely sealed and water tight. There is a prototype like that

https://projectlithium.com/products/the-ultimate-12v-battery-design-for-prius-prototype-beta-test

although I cannot tell from the picture if the top part is completely sealed to the bottom.

I do wonder what the inverter charging circuitry is going to do long term if the voltage of the LFP differs too much from the AGM.

 

When most economists talk about the law of supply and demand, it's stated the other way 'round: low demand is associated with a lower price.

What's going on here is probably a more complicated, multi-step story. Something like, the Prius does not use a common battery shared with lots of other cars, and the demand is not high enough to induce many manufacturers to compete on offering them, so the supply remains tight ... therefore the price is high.

 

Where do you GET this stuff.

That first part can only be true for items that fall into the "discretionary spending" category.......where lowering the price can stimulate more buying. Automotive parts in general do NOT fall in that category. If you need it, you NEED IT no matter what the price is.

And the second part IS what I said, isn't it ???

 

Also there is limited competition for what market there is. That brings in monopoly or duopoly pricing, which drives prices up. With regards to car parts this sometimes happens even when alternatives in theory exist. For instance, the inverter coolant pumps are available at lower prices from Dorman and others, but the poor reliability of these "alternatives" has been widely reported, so many people will buy the OEM part even though it is more expensive.

 

Don't forget the eye protection. The light from electrical arcs can easily burn a hole in your retina - those do not heal.

 

I got it from my econ prof, and the text we used was Lipsey and Steiner, sixth edition, so yeah, it was a while ago, but I don't think I've missed any bombshell updates to the "law of supply and demand".

Where you wrote "The demand for Prius parts, batteries included, is low. Therefore the price is high.", the real trouble might have been invoking "the law of supply and demand" but only mentioning demand. The "law" necessarily involves where both intersect.

A single demand curve viewed in isolation usually does have a downward-to-the-right shape. It shows lower quantity demanded at higher price, and higher quantity demanded at lower price. It's possible that's what you were thinking of. However, the quantity demanded at a given price on a given demand curve is not what's meant by "demand": an entire demand curve is a snapshot of one level of "demand", with lower "demand" being a similar curve further to the left, and higher "demand" a similar curve further to the right.

If you look at where those demand curves intersect a given supply curve, the one showing lower demand will intersect at a lower price, and the one showing higher demand will intersect at a higher price. When talking about "the law of supply and demand", that's what you're talking about.

So what you're talking about here is demand elasticity. A demand curve showing absolutely zero elasticity would be vertical, and the quantity demanded would be the same at any price.

The demand for Prius batteries probably isn't that inelastic. Yes, if you NEED one you NEED it, but probably a lot of the owners who preen about replacing it preventively every few years at $200 would do less of that if it were $800. The curve might be steeper than the curve for Milk Duds, but they both have the basic downward-right shape, and they both intersect a supply curve at higher price points if you shift them right, and at lower price points if you shift them left.

The thing is that "law of supply and demand, demand is low, therefore price is high" leaves out too much. The "law" does not tell you that low demand makes the price high. The price is high because the demand curve intersects the supply curve at a high price point. That's what that "law" tells you, and it also tells you that if the supply curve stays where it is, more demand would mean a higher price, and less demand a lower price.

The "law of supply and demand" doesn't tell you why the supply curve is where it is. Other factors in the suppliers' businesses are behind that. If they figure out a cheaper way to make batteries, their supply curve will shift to the right, or if their other lines of batteries for more common cars become relatively less profitable, and so on.

All of which only means that telling an economic story can require talking about more things than just "the law of supply and demand."

 

OP brave man, personally I don't feel like burn my Prius down along with house....
My OEM battery almost 8 years old, still going strong, reads 12.4V, no maintenance or trickle charger ever.
How long DIY lithium will last assuming it will never catch fire?

 

You must have missed the last part.

LiFePO4 Drill Test! Will it erupt in flames?