Currently Available Prius PHEV Mods?

Sadly in many areas a hybrid pays the same extra fee as a PHEV negating any payback on the system.

 

Hey all,
So I just bought my first Prius (2004 model) in August, and I've been doing some thinking and research on this topic. I right away purchased a Prolong Charger (haven't bought the discharger yet), and when I was installing it I went ahead and took the cover off of the traction/NiMH battery pack and studied it a while. As someone mentioned previously, there are 14 wire connections in there besides the 2 primaries.

One thought that I've been considering is simply taking a second NiMH pack and essentially using jumpers to connect all 16 wires to the same position in the second pack. This way you shouldn't have to modify anything else, because you'd have the same chemistry and everything, you'd just be doubling the amp/hour capacity. Additionally, I believe you should be able to use a Prolong Charger to bulk charge the pack, but you'd want to stop short of the balancing charge for regular use. I suppose you could even use a 120volt relay along with some sort of voltage sensing circuit to turn off the Prolong Charger when it reached the desired voltage.
The drawback to this is that you're still using the relatively expensive NiMH batteries.

I'd be interested in this as well.

 

If it were just a matter of delivering power, you would only need 2 wires. Given that they have 16 wires, those additional 14 wires do something. One thing I can think of is that the ECU monitors each bank individually. You can't have two Bank 1's, Bank 2's, etc. The ECU will get confused really quickly with 2 Bank 1's sending different signals.

 

Yeah, those additional wires just monitor the voltage every 12 cells (2 modules) throughout the pack.
In the picture below; where the green circles are there are jumpers connecting the modules in series, and where the blue circles are there are jumpers, as well as one of the additional wires connected to the jumper(wish I had gotten a pic of the connections). Another thing this pic reminds me of is the temp sensor (green wire laying on top of the pack). If the second pack has its own cooling system, I don't think you should have to worry about that. [note also that the white thing around the orange wire, to the left of the blue circles, is the current flow sensor]

So, the below sketch/diagram shows how they're hooked up, and if you add the second battery as shown it should all act as 1 battery.

 

sounds good, please let us know how you make out!

maybe pick up a salvage gen 2 or 3 pack? even 4 might work

 

Wow!
This is an interesting thread. A mild plug in conversion has long been a want to do project. Over the years I have removed many plug in conversions. It's not an easy project and most of the commercial products have faded away.

That's the holy grail of conversions. In 2020 there are now many lithium batteries available in junkyards.

You are not alone in your quest for a lithium battery conversion.

Here's a discussion of a Gen 0 conversion using 5 LiFePO4 cells to 12 NiMh cells.
Antiscab's NWH10 Prius plugin Lithium conversion - AEVA Forums

The Honda guys at Insightcentral.net are working on LTO conversions.
LTO "Lithium" battery conversion thread | Honda Insight Forum

 

Does being able to plug it in really help that much? All it gets you is a fully charged battery when you start a drive. If you never stop anywhere there's a place to top it off before you go back home, I don't see much point except for people who love to squeeze out every last MPG they can.

I was interested in a plug in mod, until driving the Prius for a while and experiencing how it operates. If the battery had a lot more capacity and it ran more often in electric mode in city driving it'd be worth it to be able to start the day every day with a full battery.

This town is on an overall bit of a slope so there are routes from the higher side to the lower side it's possible to drive without using a drop of gas. Of course it takes some gas to get up to the high side. No free lunch.

 

it depends on your situation. for me, i'm at 97% ev miles

 

As a practical cost saving approach the answer is no. In 2020 it's far easier to buy a OEM plug in.

As a challenge to do more with less it's a fun DIY project.

 

I wouldn't try and marry the two chemistries. Get rid of the nickel completely and replace it with lithium.

I have a bunch of lithium iron batteries. I might be trying this. If I used six cells per block the cell voltage would stay between
2.4 to 3.57. the problem is 3 volts is pretty much dead although they can handle 2.4 without damage. 3.35 resting is full . These cells are quite happily able to deliver a high amount of amperage at 3.25 volts. So I would have 84 cells. Each at 3.25 would be 273v plenty high enough to keep the Prius thinking the battery is full. I think the Prius likes to stay around 230 when cruising. So it'll probably try and keep my battery cells at 2.738 volts which represents a very near dead lithium iron cell. at that level of charge whenever I slammed on the gas pedal it could be damaging the lithium.

Well now I'm really disappointed because I've got a crap ton of these and two Priuses with bad batteries. So my idea would work to turn it into a plug-in hybrid that only went 35 miles an hour and had a really crappy range because I promise you I am not going to put the 1000lbs of batteries in the back of my Prius that it would require to get any reasonable range. I would only be trying to keep it a hybrid with a small enough battery that I wouldn't bother trying to plug in.

In order to do this right a five cell per block would have to be used with a different lithium chemistry. Remember that you can't just assemble any regular lithium pack and expect it to put out the 100 plus amps without being damaged. A battery that's physically small enough to take the place of the nickel would need to be of the lto or Lithium polymer chemistries. And the lto's voltage is quite different and lower so I think the Lithium polymer would be right and in fact there's already somebody doing it so there's no need for me to try and figure it out. You can find out more about the commercially available product by clicking this link.
Toyota hybrid battery upgrade pack– NexPower Energy

 

I am doing this at the moment as a work around after blowing up my traction battery .... long story but you can read some of it here Rainbow Prius Hybrid Powered by Lithium! | Page 23 | PriusChat

5 x LiFeP04 cells is the right voltage to feed into the voltage sensing wires in the original traction battery. In my case, the original NiMh modules are toast and can't hold a voltage, so the 5 x LFP cells provide the required voltage for the Prius system to consider things are ok.
If you decided to go with this 2 battery type set up, you will need to run a cable from the LFP negative to the traction battery side of the Prius negative contactor and for safety reasons, cables at the appropriate number of cells to the isolating fuse and and back to the next cell in the LFP series string so the safety feature of the battery isolator switch/fuse is still in the system. It might also be prudent to add a 12v 350 amp Gigavac contactor in the cable from the LFP positive to the Prius positive contactor along with a suitable Mega Fuse and holder so the big battery can be isolated if needed. The Gigavac could be wired to the same wiring as the Prius positive contactor, or to a separate rocker switch so the 12v supply to the Gigavac can be switch off to isolate one battery from the other.

In my case, I'm using 70 of the 40Ah LFP cells that were part of the Engineer extended range battery that lives in the spare wheel area. Keep in mind, you need a good cell balancing system that can move at least 5 amps between cells if you are going to use LFP or LTO cells as a traction battery, the p*ssy little balancers in the drop in 12v batteries and electric push bike batteries will not do the job, they move 0.5 amps at best, not enough to do the fast balancing required to prevent some cells being over charged on regen.

A word of warning about this bit from Travis Sanders post :
A battery that's physically small enough to take the place of the nickel would need to be of the lto or Lithium polymer chemistries. And the lto's voltage is quite different and lower so I think the Lithium polymer would be right

LTO cells for sure, but I wouldn't tempt fate by using lithium polymer cells, they are the ones that explode in flames if the voltage goes outside their safe operating range. The people who use these cell in model planes etc actually put them in a Kevlar pouch when charging them because of their tenancy to bust into flames. Unlike LFP and LTO cells that do not make oxygen inside the cell when things go wrong, all the other lithium chemistries do and that is how they can explode in flames, the flammable vapours within the cell are already in a rich mix of oxygen, all ready to go bang if a spark ignites them ....
Check out a video on You Tube, my first Tesla fire, RIP Daisy, a vivid display of just what can happen when you mess with the wrong chemistry cells without a suitable cooling and safety system also connected.

T1 Terry