Phev Insight

[retepsnikrep]

I've moved this post from the BMS thread as it's more appropriate here, i think

Offering up the cells to the Hindu god of electric conversions (Ideas for the name gratefully accepted )

Seems to fit as planned 5 rows of 10 cells, like the proverbial glove in the back of the Insight in the spare wheel well.

Have to lose the spare wheel or carry it elsewhere, but now carry a can of the get you home rubber gloop, never mind, also lose the weight of the spare which is a few kg so not all bad I realise the spare wheel is part of the accident protection strength at the back of the car, and vulnerability to a rear prang is increased but the cells are massively strong in a block, not sure if that's good or bad. I can add some more expanding foam later to the remaing gaps in the wheel well when I have an idea about the stable working temp for the cells.

Interesting with NIMH battery fitted, suspension with Matiz rear springs is fine with the extra 70kgs of li-fepo4 in the back. Measured from floor through centre of rear wheel to joint at top of wheel cover cowling 655mm. Still about 25kg to take out later when old battery is removed.

http://www.solarvan.co.uk/bms/WheelWell.jpg

http://www.solarvan.co.uk/bms/CellsInSitu.jpg

http://www.solarvan.co.uk/bms/UnderBatComp.jpg

To level up the bottom of the wheel well and provide a flat base for the cells I have cut a piece of lightweight plastic foamalux 3mm sheet to size and I will use expanding builders foam underneath to fill the voids and provide support to the sheet on top. I though about pouring plastic resin in the back so it could find it's own level with gravity, but that's a bit too permanent at least the foam can be removed reasonably easily and it's a lot lighter!

There is enough clearance for the cells underneath the IMU compartment and the whole lot will be covered with a sheet of 3mm clear lexan anyway to allow viewing and insulate the top teminals. They will be strapped into 5 or 10 cells blocks and then held down insitu with appropriate bolts.

I thought long and hard about trying to put the new cells into the battery compartment in place of the nimh pack, but there is just not enough room. Plus you then have to find a way of mounting the various components that attach to the oem pack. As I have a spare empty battery case I will simply use that in the original position to allow mounting of all the original components and extend the relevant BMC cables and power cables to reach the new pack.

I also think the weight distribution is a bit better with the new layout as that will help to counteract the weight of a single driver and all the cells on the right of the car, all the cells are nice and low as well for a lower CG

I've been looking at the voltage specs and am hoping I will be able to get away with simply tying the bcm subpack monitor leads onto the appropriate point in the new pack, basically every 5 cells. The total unloaded pack voltage is about 167v which also looks good. Be interesting to see the voltage sag under the 100A max drain later.

The other good thing about the choosen layout is I can assemble, test and install the pack before I even open the battery compartment which should mean I can be off the road for the minimum amount of time later.

I wanted to retain the rear luggage space but the depth will be reduced slightly by about 2", as I have a spare liner I will cut it in half around half way down and slide one part inside the other until reqd depth obtained, then glue it together. A small space sacrifce but should still look fine if done carefully.

Peter

[Mike Dabrowski 2000]

Hi Peter, great progress.
Let me lend a few bits from my experience with batteries in the spare tire bin.
The first thing I tried was using some builders foam. It just is not tough enough to offer much support, it turned to dust in a few days.

After trying several other things, I used a piece of good old 5/8" plywood that was fitted to the spare tire well, and nothing underneath. It is stiff enough to bridge the gaps without sagging from the battery weight.

Providing a secure way to hold things down if you ever hit a speed bump or pothole is something I should have done, as I have had the batteries become airborn a few times, and that could crack the cases.
Maybe a central recessed screw into the spare tire hold down threaded insert would keep the base anchored to the bottom?

Clear lexan on top should prevent a short to the bottom of the IMA box, but will somewhat restrict any cooling/ventilation air that you may need to keep the batteries cool. As you know, this IMA bottom area is how the air exhausted from the battery pack gets back into the cabin area.
At 100A of assist, I expect you will see some self heating of the cells, and the center ones will not have a good way to dissipate the heat.

We cut the ribs out of an old Insight battery case with a carpenters saw when I was trying to fit in some Prius cells:
http://www.99mpg.com/workshops/mikessat ... case.jpg,0
This makes a nice open box that you may be able to mount your master battery controller and some other electronics in, to retain as much of the remaining storage space as possible.
Keep at it, I am anxious to see how the extra capacity will bump up your MPG and range when you turn on PIMA and tune it for first IMA assist at 120MPG.

As far as riding without the spare, a suggestion from one hypermiler who did not want to carry the weight of the spare was, carry a AAA card, and you don't need the spare.Not sure if you have a similar organization in the UK.

[Dgate]

Re: the builders foam...the last time I bought any in the states (last year) it was lousy stuff, nothing like whats on sale here in the UK.
Re: the spare or lack of,what about the "spare in the can" which is being offered on many cars at the moment,the Smart included.

DGate

[JimIsbell]

As to the accident protection of the spare tire, I offer this:

Three days ago I was rear ended while waiting for the light to change. It was hard enough that my wife suffered a mild whiplash and as I got out of the car to inspect the damage I was fully expecting to see balled up tin foil where my rear panels were. Instead I saw NOTHING. There was no damage. NOT A SCRATCH. The car is tough. If I got hit hard enough from behind to need the spare as protection, I am afraid that the tire would not be much help

[retepsnikrep]

Thanks for the advice guys, the builders foam we have here seems to be pretty good, i've used it before for a few things so I am going to try that first with a piece of ply/plastic on top. The cells are very evenly distributed in the wheel well so the weight on any one area is basically the weight of one cell, about 1.5kg. I may well include a low profile fan in the lexane cell cover to draw heat from the pack. The IR of the whole Lifepo4 pack is about 50milliohms according to the cell labels when I have been testing nimh subpacks they have been about 22-25 milliohms each so the IR of a whole standard Insight pack is a factor of 20 higher. The new cells may not generate as much heat as you think. Lithium is much more effcient from a puekert point of view as well.

Securing them is vital. They will be strapped into blocks of 5 cells I think then the Lexane will fit over the top and be bolted with threaded rod through the floor of the wheel well. The Wheel securing bolt point might be useful I havent decided yet There will be four main power cables to the pack got to try and keep those short as possible. I have another idea which I will explore today


I'm already in the RAC recovery service and have a can of tyre gunk. If I do any long distance trips I'll take the spare securlely fastened down on the back shelf. I might make a small hole in the ipu cover a put a captive bolt inside it to take the spare wheel fastening thingy or use the 4 tie down points and the cargo net.

[IamIan]

Originally Posted by retepsnikrep

when I have been testing nimh subpacks they have been about 22-25 milliohms each so the IR of a whole standard Insight pack is a factor of 20 higher.

Interesting???

And very different from the tests I have read about the Insight whole NiMH Pack.

My own testing is not done yet.

[Mike Dabrowski 2000]

Peter,
I should have known that you would have considered all of those factors.
I will be watching your progress, and who knows, I may be able to "get the lead out" of my Insight and replace it with Lithium once I finish up the 60+ MIMA systems. I would move the lead to the E-wheel for my VAN.

I wonder if one could use the well well voids under the batteries as an air path for cooling air instead of filling them with foam, possibily with a 1/8" thick perforated aluminum to bridge the gaps?

Too many projects, not enough time or money.

[retepsnikrep]

1) PCB's are enroute from China

2) Got another cheap small display to try and this is the dogs Boll**ks. RCA Video input.

Native 640*480 resolution to match Video Chip on Master, very sweet and crisp display just like a tom tom type thing. Sticky pad or velcro to dash.

http://www.solarvan.co.uk/bms/FinalDisplay.jpg

http://www.solarvan.co.uk/bms/DashLcd.jpg

Banding is a photo artefact. No distortion on this, it looks great.

Has a spare video input so may put a small nightvision/infrared/camera into battery compartment to watch data leds flashing or hot spots etc etc.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0078827165

Back to connecting/laying out batteries now.

In my quest to achieve the lowest interconnect resistance I've been looking closely at my new cells. The terminals are held in place by a large nut and the centre conductor of the terminal is either level, proud or recessed depening on how tight it has been fitted or individual variations among cells. (One of my cells had a cross threaded nut but I can't take it of as I have no way of holding the other side of the terminal) This causes an issue straight away, and means there are gaps on the intercell bus bars contact point with the cell terminals. Anyway i've used a power file to level all the terminals so they are perfectly flat and clean giving maximum contact area. I'm also using 6mm studding inserted into the cell terminals to the maximum depth to give more available torque for the terminal nuts. More pressure less resistance

Quick diagram of Insight cell installation plan. Cells go in the spare wheel well. I've included an insulating divider to split the pack into two slightly less dangerous halves

www.solarvan.co.uk/bms/CellFinalLayout.jpg

[retepsnikrep]

Battery mounting.

I've been looking at the spare wheel well and I quite like the idea of welding/bolting right angled aluminium bracket down both sides so that it provides a ledge each side for a purpose built tray to sit on. I know a man handy with alloy welding so I may ask him about making two battery trays which take 25 cells each and can be dropped in and then pushed along the alloy runners under IPU compartment and bolted down.

So installation is 8 bolts, 4 per battery tray.

Drop first pack in, slide it along runners under ipu and bolt down, drop second pack in and bolt straight down. Does that sound OK? Batteries will be strapped to the trays with 10x300kg breaking strain nylon banding per 25 cells.

Safety is critical and the cells must remain in place even during/after a rollover type accident ending on the roof

I've already strapped the cells into 2x25 cell blocks and I salvaged the ptc strip from 4 bad subpacks and have used two bits joined together per block of 25 cells just to utilise the BCM temp monitoring function as well. the strip runs through the middle of the 25 cell blocks.

[JimIsbell]

I have a little experience with this sort of thing. In yachting the batteries must be secured against a 360 degree roll by insurance decree. The batteries in boats are MUCH heavier than the ones we use in our cars. I have 4 batteries in my boat that total 280 pounds.

In my boat I have them secured by 2x4s fastened to either side of the battery box. In this case, instead of depending on bolts through the bottom of the aluminum tire well, you might consider a wood brace from side to side of the well fastened thru the sides. It wouldnt have to be a 2x4 as these batteries are not that heavy. I have used a 2x4 with a coat hanger to lift the engine out of an MG, so it would be overkill in this case.