Adding battery capacity to the Prime

I haven't tried to add more capacity to a battery, but I don't see why it would be too difficult.

I say you have two options. One, change out or add more cells in parallel with the cells already in the vehicle. Then the car's BMS will take care of everything else. In theory it should consider the battery low from lower voltage, which means you can use your battery for longer before the car decides it's time to go into gas mode.

The other option is to make another battery and connect just the positive and negative to the bus in the Prius' battery compartment. You'd want to add your own contactor system, BMS, etc. but as long as the voltage is within the voltages for the Prius' own battery and you don't ground it or something similar, I don't see why it wouldn't work. Just don't set up your contactors to close with the Prius own contactors open. You could fry something. That's happened to Nissan Leaf owners that have done a DIY extra battery that they forgot to disconnect before shutting off the car.

 

Too short of drives cause water to condensate in the engine, which makes the oil acidic. I've seen this problem cause the oil to eat through the oil pan. This is a concern of mine as the distance to everything here is very close. It's about a mile to work and even in the summer it doesn't give the engine enough time to warm up past 100°F.

I do miss my Leaf a lot as it not only wasn't affected by short trips in the same way as an ICEV, but it also had instant heat in the winter. I'm definitely considering a Bolt as my next vehicle.

 

None of that conflicts with what I said.
Extremely short engine runs for the ONLY use of the ICE is certainly not good.
But doing that once in a while between longer runs certainly is NOT something to obsess about.
And it certainly is NOT the "worst thing you can do to an engine".

 

Ok.

But what is the worse thing you can do to an engine?

Probably drive it off into an active volcano?

 

Unfortunately, those who have successfully added battery capacity in the past have had to hack the bms, an extremely difficult task

 

Isn't there a control in the car that lets you choose hybrid mode?

That way you can just start the engine while you still have time for it to warm up.

Maybe it's a pain to have to do that?

I don't see a way around that through automation until the car always knows the driver's destination.

Either way that strikes me as a cleaner, cheaper solution than enlarging the battery.

 

Who and why? For the regular hybrid Prius converted to a plug-in, yes. From what I understand, that's because the hybrid Prius runs in a narrow battery capacity range and the car wants to drive in like a hybrid turning on the engine when it deams necessary. For an example, you charge it up to full and turn on the car, then it wants to run the engine to burn off the extra capacity. And once it's down in the "normal" capacity range it will want to kick on the engine most of the time and keep the battery charged up at around half. Hacking the canbus is necessary in that situation.

But adding capacity to a plug-in hybrid that is designed to use a larger battery capacity range and drive around in an all EV mode would be easier I would think.

 

Trying to "enlarge" the hybrid battery in a conventional hybrid or a plug-in makes little to no sense on any level.
Except maybe for what the owner might learn by trying to do it.
And that little bit of education will be VERY expensive.......assuming that the person doing it survives.

 

That could depend on whether you have a free supply of lithium ion cells or not. One guy added more range to his Nissan Leaf with laptop batteries of laptops that were being thrown away. He did have to test every single cell for exact capacity before trying to do it, but it worked.

On the other hand, if tinkering with our cars is no longer feasible, I don't care what kind of car I get next then. The DIY'er is a dying breed. There's way more satisfaction, IMO, to put your own turbo on a car and go faster, than to buy a car with a turbo already installed. Same with batter capacity. Sure, anyone (with the money) can go buy a Tesla and get 300 miles of range. But that's just his money talking, not his skills. Rich people have fast cars and EV's with long ranges. Big deal. But do any of them have automatic tire chains? Rerouted the exhaust so it melts the ice that builds up in the fender wells? Added adjustable car ride height for all driving needs? Sat at a dyno and adjusted the timing to perfection?

I've tinkered and got as much as 60 miles per gallon in an old 1984 VW that cost me $600, rebuilt my own engines and tuned both the fuel and ignitions maps. I've added my own controls and gauges to my tastes. I've also replaced modules on my Prius' HV battery. I can brag about doing that.

 

it has appeared sporadically over the years, but you maybe right, might just be pure hybrids.
still, a lot of people have asked, like this thread, but no one has ever accomplished it to my knowledge.
there must be a reason.

 

It annoys and worries me, too, if the ICE has to run for only a few minutes in a trip, but it's OK if you have regular long (at least 10–15-mile) HV trips as well.

 

No car is perfect.

The perfect car would be and plug-in diesel hybrid with a manual transmission and solar panels that fold out on top to 6kW size and that seats 6 people with its front bench seat, and FWD with automatic tire chains. I can't seem to find any though.

 

give it a try sometime. Than tell us you still think is easy / easier than onboard grid charging a regular prius, unless you're thinking adding a plug to a regular prius involves more than just grid charging the traction pack without ever discharging it back to it's normal working voltages.

Interesting adding li ion laptop cells to leaf LTO pack. Is that person still posting? car still working? how long did li ion cells last same for the cars oem LTO's. The list of question goes on, but typically never get any answers. So the initial post of "It works" is a poor way to determine how well it works, or if it really works at all.

 

Nope. After the first fail he never posted again. The failure was from not disconnecting the second battery before turning off the car. The second battery was therefore connected to the bus which fried some sort of discharge resistor.

You can get to the failure at about 4:15 into the video. But other than that it seemed to have worked.

 

seems to have worked is much more informative and very much less definitive than the statement "but it works / worked" Ya Know?

 

So in his two tests things worked as hoped for. No warning lights, no DTC's, he got more range, nothing caught fire or started smoking. Everything went as planned. (Except, of course, his mistake of not having the secondary battery disconnect before, or at the same time, that the primary battery did.)

But are two tests enough to confirm it works? Maybe, maybe not.

 

My money is on the maybe not - in reference to the statement " It works"
There are way more safeties involved in producing add on battery capacity to a prius that actually works as opposed to something that seemed to have work for such and such a time span.
If that is not a consideration for a leaf, oh well, more power to the leaf community.

 

Might I say two things.

One, there are many other examples in both the Leaf and Prius communities that show adding capacity is possible. For an example, the LiFePO4 Nexcell battery upgrade for Prii is proof that you can even change battery chemistry, get more capacity and all without throwing codes.

Two, electricity isn't Voodoo. The main things are not shocking yourself or causing a fire. It's not that much different than modifying an ICE. The BMS wants to see certain voltages, which is perfectly possible to get with the right second battery, or bigger primary battery. Correct voltages, BMS happy, it should just work.

As I said before, and I'm pretty sure of this, is that the reason lots have had to hack the canbus on their Prius when adding more capacity is that a standard Prius is not trying to drive like a plug-in hybrid. But if your car already is a plug-in hybrid, add double the capacity and you'll get double the range. There's no reason why it wouldn't work except not wiring it correctly or something similar.