Cowardlyducks Prius - mods/conversion to Plugin/Solar PEHV

Cowardlyduck said:
Yeah, I think I would be better off using a DC-DC then as the Prius pack fully charged is 268V.

Anyway, first I'm gonna do the solar setup, and that will mean I need the DC-DC for that to work. Then (probably next year) ill tackle the pack.

Cheers

So are you going to plug a DC-DC from the solar panels to the battery pack? Wont you need a controller of some sort?

Cheers Kiwi
 
kiwiev said:
So are you going to plug a DC-DC from the solar panels to the battery pack? Wont you need a controller of some sort?
You don't always need a solar controller. I discovered this with the solar setup on my recumbent.
It's less efficient to use a DC-DC, but the cheapest Solar MPPT I can find that also go up to the 268V I need start at around $700.

On the other hand I just did some quick searching and found a 12V to 250V DC-DC that would probably handle as much solar as I can fit on the roof if I cool it.
http://www.ebay.com.au/itm/DC-12V-2...Converter-Step-Up-Power-Supply-/281867623223?
This one's only $17. I've used something similar on my bike for a while without issue.

Ideally I will find something that can do up to 270V DC output.

Cheers
 
The problem is the DC to DC dont have a charge curve they will give full Amps I researched this for my home solar to charge cars, anyone else have any ideas I would love to know.

Cheers Kiwi
 
kiwiev said:
The problem is the DC to DC dont have a charge curve they will give full Amps I researched this for my home solar to charge carsi
Ah, yes good point, however with only about 100-200W (guessing) worth of max available solar space on the roof of the Prius, it actually isn't a problem.

From what I've been able to find out, the second gen Prius sends up to 100A regen braking current to the battery. Thermal limits kick in sometimes limiting it to around 50A.
I reckon I would struggle to even reach 1A at 260V (260W of panels).

Much like my Recumbent, the solar setup will be more about long term trickle charging, and I fully recognise the minimal energy it will capture.

Cheers
 
Just found a great source of info for my Solar conversion:
http://www.aprs.org/APRS-SPHEV.html
SPHEV-roofAx.JPG

I looked at a few, but this guy's set-up comes closest to what I'll be attempting.

Another one wired the solar to the switched side of the battery so it couldn't charge the cells unless the ignition was on for fear of over charging them.
I don't want to have to do that and definitely want it to charge while left sitting in the sun. I'm thinking it should not be a problem if I correctly match the DC output voltage to the max charge of the NiMh cells, but unsure what holding them at max charge might do to them.

Does NiMh get hot if held at full voltage (1.6V per cell)?

Cheers
 
For the little ones (up to about 8Ah, I think) I've worked with, yes, they do--and as soon as the reach the point at which they begin heating, their voltage drops, which is what causes the heat (energy has to go somewhere).

So once the voltage drops, then the current flow into them increases, heating them even further, which can cause a runaway condition, and fire (or even explode the cells if they begin venting faster than the cell's vents can handle).

This is why it is generally a bad idea to parallel NiCd or NiMH, because whichever cells get full first will then start sucking power from the other paralleled cells, and heat much more than they would otherwise, with probably bad results, depending on number of parallel cells, capacity, charge state of those cells, pack construction, etc.


It is also why typical consumer-level NiCd / NiMH chargers have at least one (sometimes both) of two methods of charge shutoff: delta-V, detecting the drop in voltage, and delta-T, detecting the spike in temperature. Either one will trigger charger cutoff.


That's all for consumer-level stuff, RC stuff, etc., ebike packs, and so on; what I have my experience with.

I had a pack that while it didn't catch fire, it overheated severely when the thermistor the Tenergy charger depended on to determine end-of-charge (it didnt' do delta-V, apparently), had an intermittent connection that in this case worked during charge start when it tests that thermistor, but failed somewere during charge itself, so that when the cells heated, the charger never stopped trying to charge them. If I had had them enclosed in a box with no airflow, it's quite possible there *would* have been a fire. As it was, the pack was severely damaged. :(


I have no idea how the BMS in the car deals with all this, or if indeed it even ever charges the cells up that high in the first place; it may deliberately never give them a charge long enough to let them reach that topped-off state, just so the car doesn't have to deal with the heating problem, and potential fires from failure of the system to cutoff charge when it gets hot.

There are a few threads around here (and DIY Electric Car) about the packs in those cars and how they work, if you look around.
 
Thanks AW, appreciate the insights. I do need to branch out more, but I've made ES my online home, so can be a little arduous.

I had no idea about full charge state of NiMh doing that, but once I read that, it immediately made some past experiences I've had with NiMh make sense.

Anyway, I gave it some more thought, and there are a few solutions to that problem.
1 - Don't set the solar charger to max NiMh voltage...maybe 1.4 or 1.5V per cell would be ok?
2 - Charge a secondary (lithium) pack which then charges the NiMh once the car is turned on.

I might actually employ both solutions in order as I won't have the funds to build a secondary pack initially.

Cheers
 
Cowardlyduck said:
1 - Don't set the solar charger to max NiMh voltage...maybe 1.4 or 1.5V per cell would be ok?
The problem is just like with any other cell type as it ages: not every cell will be at the same voltage or state of charge, and some cells will have less capacity and reach the delta-V point before the whole pack reaches the cutoff point, and then when those drop the whole pack voltage drops by that much, leaving room for more cells to then reach their delta-V point, which then drop, etc. And so the cells will continue to flow current and heat, which might be normal, but if the solar charger doesn't know to stop once a certain temperature has been reached, there is a risk of fire or cell damage.

I don't know that this will happen, but it could...



2 - Charge a secondary (lithium) pack which then charges the NiMh once the car is turned on.

I think that as long as the car's BMS is involved in monitoring and/or cutting off charge from whatever source you use, then it is probably safe to do.

It's just that if you don't have a way of monitoring cell temperatures and cutting off charge current, that you then have a risk of fire.


Again, I don't even know if the car's pack ever even is charged to the point of delta-V as a whole (though as it ages it's nearly certain that the scenario above of some cells reaching delta-V point would eventually happen, it is likely this is provided for in the BMS).
 
I think that's why there are a few Prius around with Lithium only packs for that reason.

The other think is you check if any engineering needs to be done with sticking solar panels on, solar-online do a flexi roll type panel maybe worth a look.

I can do a 3KwH 56 volt pack for USD $900 plus shipping you could charge off. Easy to charge of two 24 volt panels with solar controller.


Cheers Kiwi
 
amberwolf said:
The problem is just like with any other cell type as it ages: not every cell will be at the same voltage or state of charge, and some cells will have less capacity and reach the delta-V point before the whole pack reaches the cutoff point, and then when those drop the whole pack voltage drops by that much, leaving room for more cells to then reach their delta-V point, which then drop, etc. And so the cells will continue to flow current and heat, which might be normal, but if the solar charger doesn't know to stop once a certain temperature has been reached, there is a risk of fire or cell damage.

I don't know that this will happen, but it could...
This makes sense. If that's the case, maybe my first stage will be to add Solar to the switched side only, then once I get the secondary battery, let the solar charge that.


amberwolf said:
I think that as long as the car's BMS is involved in monitoring and/or cutting off charge from whatever source you use, then it is probably safe to do.

It's just that if you don't have a way of monitoring cell temperatures and cutting off charge current, that you then have a risk of fire.


Again, I don't even know if the car's pack ever even is charged to the point of delta-V as a whole (though as it ages it's nearly certain that the scenario above of some cells reaching delta-V point would eventually happen, it is likely this is provided for in the BMS).
Have a look at the video I posted on the last page. The DC-DC is the limiting factor here really, and I don't see me using a super high current DC-DC anyway, so this shouldn't be a problem.

kiwiev said:
I think that's why there are a few Prius around with Lithium only packs for that reason.

The other think is you check if any engineering needs to be done with sticking solar panels on, solar-online do a flexi roll type panel maybe worth a look.

I can do a 3KwH 56 volt pack for USD $900 plus shipping you could charge off. Easy to charge of two 24 volt panels with solar controller.
This makes some sense. Before I bother linking a secondary pack to the NiMh, I will have to check if the NiMh is still worth keeping at all. If not, then I will have to rip it out and replace with the Lithium.
For now though, I can actually drive on the NiMh for at least 1KM, maybe more if I take it real easy. That's not bad considering the as new quoted stats for the NiMh battery are about 2KM.

Either way though, 3KwH for $900 sounds great, and likely what I'll end up doing.

I have to stop thinking about and planing these mods though as I really can't do any of them for a while anyway.

Cheers
 
I made a shitty little car charger not long ago, but mine isn't mobile at all.

https://www.youtube.com/watch?v=TRnkC41b-Hc
 
Hi guy's,

So instead of starting a new thread for everyone to subscribe to, I'll just convert this one into my mod/conversion thread.

Here's some shots of the car and how it looks now:
DSC_3481.jpg

DSC_3482.jpg


The other day saw me do some work to the front end of the car.
I started removing the fog lamp from the left side as it wasn't working. I thought it was damaged beyond repair, but discovered afterwards it was just a blown bulb. The mount is too damaged anyway, so I just won't bother having a fog lamp on that side.
DSC_3474.jpg


Next I by repaired the crack in the front bumper. I just used epoxy as I don't care how it looks too much:
DSC_3473.jpg

DSC_3475.jpg


After that, I had to address the fog lamp on the other side. It has a small hole in the centre which was allowing water ingress, but not letting it out. The lamp still works, so I just drilled a hole in the bottom to let water out. It took a loooong time and 4 broken drill bits, but eventually I got there after rigging it up to drill itself while I worked on other stuff...who would have thought glass could be that hard to drill.
DSC_3468.jpg


Lastly, I made a grill block. We recently had a state election, so after the voting had finished, I went round and collected a few election signs. The coreflute is ideal material for this kind of thing. I cut it to shape, painted it black and zip tied it into position. :)
DSC_3471.jpg

DSC_3472.jpg

DSC_3483.jpg

DSC_3480.jpg

The reduced drag was immediately noticeable. Coasting down a local hill where I normally tops out at 85kph, the car was still accelerating at 90kph before I had to touch the brakes.
So far, the engine cooling fan still hasn't even turned on in ambient temps of up to 25C, and some very spirited driving. If it starts coming on too much I can easily drill some holes in the coreflute, but given the short trips this car primarily makes, I don't see temps being a big issue.

Aside from that, I've also installed a tyre pressure monitoring system, and have a dashcam on the way.

Next I plan to install a small solar panel in the rear window for keeping the 12V battery topped up. Prius's use a DC-DC from the high voltage battery to charge the 12V SLA battery so reducing that load will free up more capacity for driving. :)

Cheers
 
Awesome work you should look under the car and see if you can seal up some gaps to reduce drag more. Also if your tires need replacing look at low drag skinny tires.

Cheers Kiwi
 
kiwiev said:
Awesome work you should look under the car and see if you can seal up some gaps to reduce drag more. Also if your tires need replacing look at low drag skinny tires.

Cheers Kiwi
Thanks mate! That's a good suggestion to look under as well. The tires are nearly new, so I've just upped the pressure to 38PSI for now to help with rolling resistance.

I need to get some more tools before I can do much more. I don't have any jack stands or anything, but looking around currently for cheapish options to get started.

Cheers
 
I'm liking my Prius. In any other 13 year old car with this many kms you would think the ECU was busted showing fuel usage this low in the city.

DSC_3958.jpg

DSC_3955.jpg


Still no further mods beyond the front grill block, and I'm not sure I'm going to bother. Everything I'm ready suggests the same amount of money invested in those mods would be far better off being put towards just buying a more updated Prius down the track that includes those same features stock, so that's where I'm leaning.
I might still chuck a small solar panel on it for the 12V battery, but not going to bother with any major changes at this point.

Cheers
 
Just gonna contrast and compare. My honda Insight mk1 with preheater, grid charger + grill block gets 88mpg imperial (UK) and its currently 15 years old. had to check the conversion on google. 5 l/100km is 56.4962 mpg imperial. This is careful driving though 56mph where ever possible.

average lifetime for the car is 68.3 mpg for 183,000 miles.

but the mk1 is not a practical family car but its pretty damn good for my 25mile each way commute. Totally agree with the solar for the 12v as the dcdc on the Honda does the same thing.

I am on the cusp of deciding what the next family car should be, we have a 2l old golf estate diesel which is very convenient but I wish there were decent alternatives, there are no estate electrics I know of, and if they started making them it would be years before I could afford a second hand one. A Prius as a compromise is not bad since there are so many of them that a second hand one is easy and relatively cheap. I like the plus model but they are never as cheap second hand.
 
Well...my Prius HV battery died the other week. :cry:
It had been going well for over a year, but recently started charging up and discharging quite fast.
Then the other day, I floored it in reverse up a hill while the engine was cold...yes, stupid I know...and it seems to have killed the battery.
I've got the standard red triangle of death, and multiple engine check lights...checked the codes and cell block 13 and 14 are 'weak'. Took it to a Toyota dealer to be sure and they confirmed the same thing. :(

Anyway, I don't really want to stuff around doing a custom pack for this car at this stage as I've got too many other projects, and from what I've read it's just not worth the hassle, time and money compared to just getting something newer...I would really like a Gen 3 Prius or a Prius C at some stage, so don't want to sink too much money into this thing.

So instead I've managed to find an entire replacement battery from a wrecked 2008 Prius with 117000kms on it. Picked it up for $1000 delivered which is an extremely good deal from what I've seen. It was delivered today, but I probably won't be installing it any time soon as I'm currently recovering from surgery.

As soon as I can though I will attempt the swap out myself, and then I will have 28 7.2V NiMh battery modules I can play with from the old battery. :)
I'm already planning on using a bunch to power my new JP spot welder.
I should also be able to use a few for some LED lighting around my shed...and the rest will probably be bad anyway.

Cheers
 
Hillhater said:
You know those earlier Prius and Camry hybrid battery packs were notorius for corroded terminal links between cells causing apparent electrical death.
Have you checked for obvious bad connections ?
No I haven't, and I probably should have, but considering it's over 13 years old with nearly 300000km on it, I don't think it would last much longer anyway.

I checked the new pack today and it does have some corrosion on the terminal links which I fixed up with some Corrosion X. I also checked each cell block and they are all 7.45-7.55V which is a good sign it's a good pack.

Even if it's corrosion on the old pack that caused the failure, I can still make use of a good chunk of it and should be able sell any extra cells I don't end up using.

Cheers
 
Cowardlyduck said:
So instead I've managed to find an entire replacement battery from a wrecked 2008 Prius with 117000kms on it. Picked it up for $1000 delivered which is an extremely good deal from what I've seen. It was delivered today, but I probably won't be installing it any time soon as I'm currently recovering from surgery.
FYI they now make kits that allow you to replace just the cells in the Prius pack.
 
billvon said:
FYI they now make kits that allow you to replace just the cells in the Prius pack.
Thanks. Yes, I looked at doing this to begin with, however decided against it because of the high km and age of the pack as mentioned above.

What often happens with older packs like this is replacing a few cells that are weak will work for a few months or maybe a year, but then the next weakest cells go, and so on...basically until all the cells are replaced, which is the same as getting a whole new battery anyway.

Cheers
 
Just finished the job and have my new (used) battery in the Prius. After remembering to re-insert the orange plug and clearing the ECU codes it seems to be working and the engine already gave it a bit of a charge.

I watched this video a few times before attempting the battery swap. I would probably have gotten stuck or taken a lot longer than I did if I hadn't seen this guy doing it first. As it was it took me the better part of 3 hours.
[youtube]4YWu-sA3UyU[/youtube]

Only time will tell if it's a dud or not, but so far so good. :)

Cheers
 
Hey CD, I seem to be facing the same dilemma you did with a similarish budget. Was the replacement pack worth and what kind of range can you get out of it?
 
Lurkin said:
Hey CD, I seem to be facing the same dilemma you did with a similarish budget. Was the replacement pack worth and what kind of range can you get out of it?
Still going strong.
The replacement pack was from a wreck in Sydney that had 117000km on it. I paid $1000 for it delivered after talking the guy down from over $1500. I would not expect a deal this good to be easy to find, and depending on the kms, I would have been prepared to pay up to $1500 for a replacement battery. Keep in mind it's about $2500-3000 for a brand new pack from Japan, installed.
As far as performance goes....it works. :)
I mean, it's hard to tell how good/bad it is, but it doesn't drop capacity anywhere near as fast as my previous pack was when it was dying. I can drive around in slow traffic, down hills, on the flat and round car parks all without the engine turning on, so it's doing its job as expected.

I was also recently able to sell most of my old pack in pieces to a local guy for $400 so that just sweetened the deal even more. I hung onto 4 of the best modules in case I have further issues down the track, and I threw out 2- or 3 of the worst modules and he took the remaining 20odd and the original battery housing. I was prepared to sell all the old working cells individually for $30-40 each, but when this guy just wanted the whole lot I couldn't refuse.

Cheers
 
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