CHARGING.

The first charge is the time when you get to know your cells and how they behave, unless you use a BMS (battery management system) I don't.
After bottom balancing all 73 cells to 2.7 volts per cell, I charged as a whole pack in series using  my Zivan 3kw charger, monitoring all the cells with a digital volt meter. All the cells aventually got to around 3. 4 volts each pretty evenly, but then I started to notice around 6 cells climbing in voltage ahead of the rest. So I now watched these closely untill the first cell hit 3.5 volts, at this point I made a note of the pack voltage 249.5 volts, This will be my charge cut off point also the amp hours put into the pack read 126.4, I was told that these 100ah cells were new spec with extra capacity and the numbers prove it. 
Now with the cells bottom ballanced and a known pack voltage when the weakest cell hits 3.5 volts when charging I have my first lines of defence to stop me killing the battery pack prematurely.
 I will have the charger reprogramed to end charge at 249.5 volts, also my JLD404 meter is wired to the charger enable control and can terminate charge at a given amp hour or voltage of my choice, on top of that I've put a secondary programmable volt meter inline with the charger which can also turn the charger off at a pre-set voltage.
Hopefully with the charger shutting off automatically at the correct end voltage, with 2 secondary back up meters turning the charger off in the event of the charger malfunctioning I should be safe from over charging the battery pack.
On discharging the pack when driving, the Soliton controller can be programmed for minimum pack voltage with no load and also minimum pack voltage under load so this gives me warning of the pack getting low. Also and probably the best way of monitoring the state of charge or range in miles left is the ability to count amp hours in and out of the pack, pretty much like a fuel gauge. theJLD404 meter does this job nicely.

So, my safe usable capacity is 80% of the 126.4 AH that went into the cells that's 99AH.

DRIVING WITH LITHIUM.

wow!
The Sinopoly cells have transformed the car, I've gone from 5 miles range with the lead batteries to anywhere between 60 and 80 miles depending on type of driving.
the performance is better than I hoped for, still being careful gaining confidence in the batteries but when you put your foot down it's well? NUTS!
The cells are behaving perfectly, I've charged about 5 times now and the same cells  I'm still running around with the volt meter checking individual cells, also I've monitored individual cells under load and when the pack is close to my safe empty state the sag under load is only 3volts per cell 
     

The lead is out!

I finally took the big step and ordered 73, 100AH sinopoly lithium cells.
They arrived 6 weeks later all the way from china.
First impressions all the cells were packaged in quality steel framed wood case's, well protected for the journey they made.
opened up the case's to find quality looking cells.

 Started installing the cells in the car, 25 in the front and 48 in the rear box.
I decided after much reading and absorbing lots of advice to bottom balance all the cells.

Basically this means discharge all the cells to the point where they are all empty  at 2.7 volts.
Easier said than done! I decided to drive the car very carefully monitoring the cells to bring the voltage down a bit before discharging individual cells as they were all sitting at about 3.294volts.

After about 20 miles of stop start nervous driving, continually checking all the cell voltages I got them all to around 3 volts, after awhile you find a few cells going lower than the rest so you can just keep an eye on those cells with a volt meter. near the end of the driving I hooked the volt meter up to the weakest cell and monitored it while driving. During the drive no cell sagged lower than 2.9 volts. that was as low as I was going, so next step is to drain each cell individually to 2.7 volts.

After looking on youtube at various types of bottom balancers I made up a box with a JLD volt meter which has controllable relay outputs, a 20amp power resistor, along with power supply and cooling fan.
As you see from the photo below I connected my gismo to each cell in turn discharging 20 amps, the first lap around the 73 cells was 20 minutes each. the volt meter was set to turn the load on above 2.702volts and off when a cell hit 2.6volts.
At the end of the first lap sure enough they all bounced back up a bit, so around again for 5 minutes each cell.
 To cut along story short, 3 days later I had every cell within 2.702v to 2.705v resting overnight. good enough job done.

 

 

After the successful bottom balance it was time for the first charge, but I was having to many thoughts about spanners etc dropping on the cells and shorting! So I purchased some 5mm macralon sheet, cut it to size to fit over all the cells.
 To allow for voltage monitoring I drilled a small hole above each cell terminal as per photo below.
A lot happier now, should help to stop any silly accidents

 

 

 

 

 

 

 

I've been testing the car for the past month or more ironing out small problems and finally  have got to the point where all is running perfectly other than only 5 miles range due to cheap second hand lead acid batteries, this will be addressed once the car is road legal.

Booked in for  an MOT and the car went through with no problems.

After asking, the garage that did the MOT very kindly provided me with a letter stating the car was now fully electric and considered by them to be road worthy, this I needed for the tax office along with photo's Mot, insurance recietes etc to enable me to get my FREE road tax disc.

All went well at the tax office the TT is now road legal.
Next step will be to upgrade to lithium batteries, to enable a usable realistic range.

It lives!

I've been busy with all the high voltage cables and control contactors etc, also the dc to dc converter that powers all the normal 12 volt car system by converting the main battery pack down to 12volts.
I managed to connect the original electronic throttle to the Soliton controller along with all the other inputs it requires.
After a little thought, mainly being about the cost of lithium batteries, I decided to get hold of some cheap lead acid batteries to test the car with, just to prove to myself everything will work OK and also correct any problems I may encounter, then I'll take the plunge with the lithium and will be able to concentrate on looking after the batteries.
luckily I found 12, Yuasa 90ah second hand batteries on eBay in what appears to be good condition.
I finished installing the batteries and cables Saturday morning to give me 144 volts nominal.
 I jacked the drive wheels off the floor for safety just in case it turned into a run away, I then connected my laptop to the soliton controller, powered up and input the basic settings,

The fuse and safety contactor on the front battery pack

 DC to DC converter and high voltage cables to controller

 Front of car without headlights and grill etc  

Rear battery box showing fuse  + and - safety contactors

Rear battery box lid removed

clear plastic cover over fuse and contactors

 
Lockable Emergency stop installed just above ignition switch controls 12volt + and -  to coils on battery pack contactors.

The big moment?
Main battery pack contactors on, Ignition on, second gear selected, foot on accelerator,
BIG SMILE it works, the wheels are turning.
I spent the rest of Saturday and Sunday driving up and down the lane to my house with a big grin.

Lots more to do to make it road legal then MOT.
Then the lithium battery pack.

Finally I have my soliton 1 controller, I hope it will perform as well as it looks.

I've made a frame work with some aluminium box section to mount the controller.

I managed to construct the battery box in the back seat area, I just need to get some batteries to fill it but Im still not sure which way to go with the battery pack. eg, 100 AH cells for about 192v or go lower voltage with higher AH cells, its all about physical size of cells and the room available.

Ignore the piece of wood I will be comiing up with a lid keeper upper.

The other milestone I managed was to install the charger plug in the fuel filler cap, this was a big smile moment, I wonder if I will ever use it? (I WILL) 

I am now getting to the part where it all starts to come together,

I hope! thats the wiring of the contoller etc.

Motor now installed in car, fabricated bracket so motor would hang off of existing engine mounts.

When I finally got the motor installed I could not resist jacking wheels off floor and trying the motor with a 12 volt battery, Wow, it works even in reverse, so far so good.

I have fitted a vacuum pump for the brakes along with a small vacuum tank, controlled by a switch to maintain correct negative pressure.
This system replaces the vacuum created by the original ICE for the brake servo assist.
Also to the left of the vacuum tank you can see the electric power steering pump I've plumbed in to replace the pump normally driven by the ICE

Since fitting the motor into the TT I have selected and ordered a soliton 1 controller, this is probably big time over kill for the performance I require but its probably the best all round DC controller out there, rated up to 340v and a 1000 amps and programable from most PC's.
Gives me lots of options.

Batteries are my main concern in ths conversion, I want a minmum of 50 miles range with performance comparable to an average car,but not the original tt performance.
After reading much about battery types I've come to accept that lithium is the way to go, although very exspensive they are less than half the weight with more power than lead acid. I have seen many EV conversions on varrious websites etc that have used lead acid battery packs and have had poor range / performance.

After some thought I decided the best place for the batteries, or at least most of the batteries is where the rear seat is, as it is actually not usable just like most sports cars, also this position is reasonably centred between the front and rear wheels to spread the load and hopfully avoid that overloaded look when all the weight is at one end or the other.

Decided not to cut the floor out as in this position theres a lot of structural fabrication and could compromise the strength of the car, so I created a flat surface using aluminium box section, to which I plan to fit a suitibly sized box 1000mm x 550mm x 300mm high. this will give me maximum available space in this area.
Hopfully I will create a removable lid and upholster to blend with the TT's interior, thats the plan anyway.
Having a gym at the end of your garden has its uses, I decided to simulate the battery weight to see how the car will sit loaded up, the total weight of batteries will be roughly 230kg so that means around 160kg will sit where the rear seat is and the remainder either at the front or the rear so this is what I did.

 The TT looked fine with the weight in this position but when I put the remaining 70kg in the rear the TT looked low at the back or, um? high at the front.
 It became plain to see, the remaining 70kg had to go at the front not the rear, that meant constructing a battery box in front of the motor under the bonnet, this was a pain to achieve the space where I wanted it but I got there in the end using 20mm steel box section and 2mm aluminium plate. See below,

My next phase will be installing controller and sourcing battery pack.

Motor delivered in one piece all the way from Bulgaria, Kostov 11" 192 volt

Adaptor plate made, cut by hand with a hacksaw! 4.000" hole bored to suit motor spigot. Holes drilled to pick up motor and gearbox fixin holes. No clutch in this conversion hopfully will only need a maximum of 2 gears, maybe 1. Clutchless gear change should be easy without engine compression.

Spent an afternoon at work in my own time borrowing a lathe to make adaptor coupling to join motor shaft to gearbox input shaft, I used middle part of original clutch and an off the self taperlock as per photos, quite pleased with coupling as have not used a lathe for about 15 years.

Clocked adaptor plate to gearbox input shaft untill running spot on true within 0.0005" doweled in 3 places.

Finally connected motor to gearbox ready to install into car.

Offered up drive shaft to see if there was clearance between motor outer case and drive shaft cv joint, as you can see only just, but only just is all I need (result)