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Mr C's 2001 Prius revival

Posted: Fri, 29 Jul 2011, 07:34
by Mr Camouflage
Wednesday I took a day off work and went and bought a dead NHW11 Prius at an insurance auction.

The car had been written off due to a what I shall call a "thermal incident" with the HV battery.
Not exactly a fire, but hot enough to melt some stuff. There were some melted plastic shopping bags and a windscreen sunshade all fused together in the boot. The vent pipe was also meted. I haven't had the battery cover off to inspect the damage yet.

Overall the car appears to be in good condition. I'm hoping to repair the battery pack, or replace it with a new battery pack, and hope that there isn't any damage to the rest of the electronics.

I'll have a better look at it on the weekend.

I had wanted to build a hybrid out of a an AWD car like a Laser TX-3 4WD (ICE front wheel drive, Electric rear wheel drive), which is why I joined up ages ago, but haven't had the time or the money (and probably the knowhow). Also the Prius cost me about the same as a suitable TX-3, and its already a hybrid.

Now time to sell off some of those old ICE project cars that I thought I'd get around to, but never did, and put the funds to good use.

P.S. I know its not a true EV, but hope its ok to ask for help here, since there doesn't seem to be a decent Aussie Mk1 Prius forum that I can find.

Pics to follow on the weekend.


Mr C's 2001 Prius revival

Posted: Fri, 29 Jul 2011, 20:03
by Simon
Hi Mr Camouflage
I thought that the Prius at auction was a 99 model (NHW10 aka MK1)..
The NHW11 looks very similar but has a different battery type and voltage.
Be interesting to see some photos of your battery pack when you start working on it.
Do you have plans to make it into a Plugin hybrid or keep it stock?
I need to update my Prius thread as I got another 99 Prius and got that going a few days ago.

Mr C's 2001 Prius revival

Posted: Sat, 30 Jul 2011, 08:51
by Mr Camouflage
Image

Maybe it was a different auction? (Edit: Simon, just realised you are also in Perth, must have been the same auction then.) Mine is an Aus delivered 2001 W11. I find the major external differences are the wheels (polished alloys on the W11) and the front bumper (Black strip on the W10, none on the W11).

Plans, not really sure what options are available at the moment. I've only been reading about them for a few days.

I was hoping that I could replace the damaged cells or the entire pack and drive it as stock for now.

Plug in hybrid would be good, but I read that the engine will always want to charge the battery periodically.

Seems like its too complicated a car to convert to full EV, and it wouldn't have the range I require.

Mr C's 2001 Prius revival

Posted: Mon, 01 Aug 2011, 08:53
by Mr Camouflage
Here's the damage Image

Image

Seems to have been a small fire with the upholstery around the HV battery box that mustn't have lasted too long, as the damage is localised to that corner.

This is what it was like when I got it. Someone had already started to remove the battery, but stopped for some reason (Maybe the insurance co had toyota look at it to determine a repair cost???)

I've removed the back seats and other junk from the trunk. Now I need to remove the battery and find someone to fix it, or attempt it myself. I decided not to remove the battery on the weekend, since I don't have any HV insulation gloves - anyone know where I could find some in Perth?

Mr C's 2001 Prius revival

Posted: Sat, 12 May 2012, 07:05
by antiscab
how did you go with this?

Mr C's 2001 Prius revival

Posted: Mon, 21 May 2012, 00:42
by Mr Camouflage
Replaced the damaged cell pair in the battery, and other associated parts that were heat damaged. Drove it out to Cannington a few weeks ago (was tipping down with rain) for its written off inspection. Was getting 6.4L/100Km on the economy display.

Passed the inspection ok. Needs to have its roadworthy inspection now, but I have to put new tyres on it before then. Some are quite bald.

Throws the occasional error on the dash, but they always seem to go away. It will need a new battery in the near future as the current one charges and discharges fairly quick.

Will start to look at battery options once its rego'd. Although, I haven't really made up my mind whether to keep it or sell it. I guess that all depends on how reliable it will be.


Mr C's 2001 Prius revival

Posted: Mon, 21 May 2012, 21:30
by Nevilleh
Quite interesting. You could probably make up a new battery using Headway 38120 Li cells. I think you can buy them for about 10 or 11 dollars US each if you try hard and you'd need enough to make up the required voltage. I know later Prius's have about 276 volts, so you'd need 85 of them but I have a feeling the early ones used a bit higher voltage so you might need 100. They are about 9 AHr, so you'd get 50% better range than the old NiMH cells of about 6AHr. A lot lighter too!

Mr C's 2001 Prius revival

Posted: Tue, 22 May 2012, 07:04
by Mr Camouflage
Not sure how the battery management computer would like different chemistry cells?

The usual swap is to use later model (better) prius cells in the gen 1 battery case, or buy a new battery pack from toyota (which still uses the older style cells).

Mr C's 2001 Prius revival

Posted: Tue, 22 May 2012, 12:40
by Nevilleh
I think (not 100% sure) that the bms is connected to groups of 6 cells ie 6 x 1.2 = 7.2v modules. You could emulate this by connecting it to pairs of Li cells. Be interesting to find out more about it. I wonder if anyone knows the details?

Mr C's 2001 Prius revival

Posted: Tue, 22 May 2012, 18:42
by coulomb
Nevilleh wrote: I think (not 100% sure) that the bms is connected to groups of 6 cells ie 6 x 1.2 = 7.2v modules.
No, it's pairs of groups of 6, i.e. groups of 12 cells, with nominal voltage 14.4 V, but more typically at full charge around 17 V.
You could emulate this by connecting it to pairs of Li cells. Be interesting to find out more about it. I wonder if anyone knows the details?

Yes, Matt (Antiscab) does, and is doing it here:

viewtopic.php?title=antiscabs-nwh10-pri ... ion&t=3075

He connects 5 Li cells to where 12 NiNH used to be. So that's a typical voltage at full charge of 17/5 = 3.4 VPC. Even at a more normal cell voltage of 3.3 V, that's 3.3 x 5 = 16.5 V, which looks like 1.375 V per NiMH cell. This is a very healthy voltage, so the Prius system sees this as a high SOC, so it favours electric-only or electric-mostly drive, which is what you want until the Li is much more discharged. Near dead flat on NiMH is (I think) around 1.2 VPC, so that's 2.88 V per LiPO4 cell, and you wouldn't want the Li to go much under that, and the Prius hybrid ECU will ensure that.

So it's a pretty good match. Matt has also found a cheap charger to go with it, making it a plug-in hybrid. I think quite a few people will be watching Matt's project to see how well it works.

A big question in my mind is whether you can get away without a single-cell level BMS; the Prius ECU provides a 5-cell level BMS. You would also want to discourage the Prius from attempting to do an equalise charge; that would possibly overcharge the LiFePO4 cells. Although 1.6 V per NiMH comes to 3.84 V per LiFePO4, so Headways could get away with that if well balanced.

Mr C's 2001 Prius revival

Posted: Tue, 22 May 2012, 19:06
by Nevilleh
Ah, might've known someone would be doing it already!
I'll just sit quiet then Image

Edit: Just a note that I have tried TS cells in scooters in groups of four ie charging them at 14.4v and they get horribly out of balance after only a few cycles. They are not matched in any way, just initially charged to 4.0v each to sort of top balance them. I think they need cell level bms definitely.

Mr C's 2001 Prius revival

Posted: Wed, 09 Jan 2013, 05:03
by Mr Camouflage
Have been thinking about selling this. I dont have the spare time anymore, and finding another traction battery from a wrecked prius to swap in has proved difficult.

Would have passed the pits, except for the dash warning light comes on the second time you start the engine. Have been reluctant to spend the $2000 odd for a replacement battery without knowing for sure what the issue is.

If only I could divise some way to disconnect the 12V battery for 2 seconds when you turn the car off, it would reset the warning and pass the pits, and I could use it for what I bought it for - to get to the train station and back 5 times a week. I can build circuits well enough, just cant design them Image

Maybe some sort of timer relay. Wonder if they make those? google will know.....

Mr C's 2001 Prius revival

Posted: Wed, 09 Jan 2013, 12:25
by Nevilleh
There is an outfit in Auckland that "fixes" old Prius's by sticking a 12V lead-acid battery in the boot powering an inverter that supplies the Prius battery enough to make the thing think all is well. That is, it starts the petrol engine quite happily, but you can't go any distance on battery alone. I believe they are doing a roaring trade as NZ is full of old, defunct Prius things. If this is of interest I could find out who they are for you.

Mr C's 2001 Prius revival

Posted: Thu, 10 Jan 2013, 06:53
by Mr Camouflage
Yeah, I've read about that. Its called a power jockey: http://thebatteryclinic.co.nz/power-joc ... -extender/

I dont think it would help a dying battery, as in my case the battery ECU will still report error codes and the Engine error light would still be displayed, and it still would not pass inspection.

I've worked out what sort of circuit/relay I need to use. It would work like so:

When car is off, relay is closed so -ve 12V battery terminal is grounded.
When car is turned to acc, or on, the circuit is powered (by the ignition acc lead). The relay remains closed.
When ignition is turned past acc to off, the circuit detects the loss of 12v from the trigger signal and opens the relay.
After a period of 2 seconds it closes the relay and 12V earth is restored.

This would reset the error codes every time the car is turned off so it would pass inspection.

Come to think of it I think the error light that is displayed it not a check engine light at all, but a general systems error warning. I was looking at the car last night and this just occurred to me.

Might need to check the regulations and see if there is a loop hole I can get it through.









Mr C's 2001 Prius revival

Posted: Thu, 10 Jan 2013, 11:04
by Nevilleh
I would've thought the error codes would be generated by low battery volts - how else can the ECU tell the battery state? - so having that "life extender" would prevent any errors being produced, at least by a low battery. But I know nothing about the Prius except it's ugly and expensive! Image

Mr C's 2001 Prius revival

Posted: Fri, 11 Jan 2013, 01:02
by Mr Camouflage
The Battery ECU is inside the battery and measures voltages of individual pairs cells. If one or more pairs get too different to the other pairs it generates an error and sends it off to the display computer or engine ecu or some such. (Think its only about .5 volt difference).

The power jockey is an external gizmo that only helps with the total voltage/current available.

These damn things will display a system warning if you forget to screw the petrol cap on tight. Image

Mr C's 2001 Prius revival

Posted: Fri, 11 Jan 2013, 02:11
by Simon
You could always take out the speedo display and disable the actual warning light itself.. Image

Mr C's 2001 Prius revival

Posted: Fri, 11 Jan 2013, 08:38
by Mr Camouflage
..and the video display in the center of the dash, but I think they would notice. Image

Mr C's 2001 Prius revival

Posted: Fri, 11 Jan 2013, 12:53
by Nevilleh
Do you get battery errors even when the thing is just turned on and not moving? ie the cell imbalances exist even under no load? If so, then there is tech term for that - bu@#%#ed!

Mr C's 2001 Prius revival

Posted: Thu, 17 Jan 2013, 11:31
by Mr Camouflage
Yeah, well thats what happens when the battery catches fire.