Thursday, 12 June 2014

Finally fit the front pads and flush the whole brake fluid chamber

Ok so I finally found the time last night to fit the front brake pads and bleed the whole brake fluid system through completely with brand new fluid, Although it feels a little better this morning I won’t be able to test the brakes properly until the front pads have bedded in properly (a week of my short commutes)

I am hopeful that now I have new discs on the rear and new pads all round that I will notice a significant difference, However I still think I am going to need to add an additional vacuum chamber to make the vacuum brake system work properly (already bought one) and I may well need to wire a bounce-less switch setup to the relay controlling it possibly with a capacitor resistor arrangement to provide an adjustable pulse of vacuum pump time.

The current 2 relay setup (one to provide current to the vac pump, the other to protect the vacuum sensor/switch from having too much current drawn through it) is just not working reliably enough to say the brakes are “working” satisfactorily.

Wednesday, 4 June 2014

Brake Disc’s and Pads arrived

Disc’s and Pads turned up on Tuesday 27th May 2014 when I arrived home I immediately grabbed them and began fitting.

The brake performance has been s#!t to say the least ever since I have had the car I am hoping this is going to help significantly, did both rear discs and pads on Tuesday evening.

Will try and do the front pads this weekend in between digging a pond (the work just never ends!) after speaking to a friend at work who knows his cars (fossil fuel cars anyhow) I described the colour of my brake fluid and he has suggested it is shot and needs replacing completely so I may well drain the lot and replace that as well at the same time, plus I am beginning to think that I will probably need an additional vacuum chamber as well as I think the pump is just not enough with such a small brake vac chamber as the Honda Beat has, I have seen Mike on diyelectriccar’s RX8 and he is using a nice looking 3 spheres chamber that seems to work well, will probably try and source something similar.

Ordered new rear brake discs and pads all round

Well it was about time for the 5-6 months I have been driving the EV the brakes have been more than a little wanting.

I have already dismantled and serviced any jammed callipers and when I did this the pads did not seem overly worn, however since then it has become apparent (now the rear brake pads are at least applying pressure to the disc) that the rear discs are shot.

I could get them skimmed but in an effort to get the job done quickly and easily I have elected to just buy new as the rear ones are nearly half the price of the fronts and the fronts are still in fairly good condition.

I also bought new Ultimax pads for the whole car at the same time, I may keep the knackered discs just to see if I could setup my newly acquired CNC to skim the disc’s as this skill could come in very handy.

Thursday, 22 May 2014

Brighton Mini Maker Fair comes around again!

Heck that was another year already! Well not quite but the BMMF have contacted me again to submit an application to exhibit at the BMMF 2014 in September.
I really enjoyed it last year (despite nearly losing my voice) so it was a no brainer to apply again, Plus this year I have the car finished and running so I will actually be able to show the car itself as well as my 3D printer, last year despite my efforts the car was just shy of being ready.
And in fact this year it is in a much better place with all the safety’s in place and the charger fitted and working with the J1772 plug adaptor fitted in the “ex” petrol filler cap and all 4 new alloy wheels with better sized (smaller) tyres fitted, it looks the nuts :-)
Photos coming very soon.

Fitting some smaller tyres

This weekend (17th May 2014) I finally got around to fitting some smaller tyres on the two front alloys and got them back on the car (they have been sitting in the barn since I bought them and realised that although the rears were fine I would need smaller tyres to avoid the rubbing.
I have replaced the stock 13 & 14 inch alloys with larger 15 inch BBS style deep dish alloys, they were needed urgently after I first got the car on the road as I had a major lack of grip due to the massive torque now available!
I had put the original 13 inch wheels back in place after I realised my first tyre choice was just too large for the front wheel arches and have been driving the car like this for several months waiting for my local part worn tyre fitter to come up with the goods.
The car looks fantastic now with its set of 4 matching BBS style deep dish 15 inch wheels, photos coming very soon (always best to get the photos done in summer)
Even with these smaller tyres there is still a very small amount of rubbing on full lock when turning right, full lock left seems not to have the issue so I will investigate where exactly the rubbing is and see if I can do anything more about it later, but for day to day use it is now fine with the matching BBS alloys.

LVC-HVC Wiring

Ok so the LVC/HVC cut off boards have two white plugs at the top of each board (one board for each parallel bank in the traction pack)

They are labelled as shown in the image below

Online manual for these boards below



http://www.methtek.com/docs/MethTek_LVC_HVC_Parallel_Manual.htm

Only found this manual recently (thanks again Steve)

I “just” need to connect all the HVC/LVC board connections in a chain connect the HVC part to the charger and connect the 6 solder connections at the top (can’t quite see them in the photo above) in line with the throttle cable, between the Throttle Position Sensor (TPS) and the Soliton Jr’s Throttle input.

So this bank holiday weekend 3rd/4th/5th May 2014 I spent several hours joining all the 3 packs HVC/LVC loom cables together, I have soldered them all up as I have not got any inline 6 way connectors handy although if I need to remove the pack again (I sincerely hope not any time soon) I would have to cut these cables, so I do need to buy some inline 6 way connectors for this purpose.
As the front 3rd of the Traction Pack is a good 2 meters further forward than the other two boxes I had to run a long 6 way cable under the car to join the front battery box HVC/LVC loom, I threaded this 6 way through another second hand inner tube and fastened this under the car using many zip-ties.


Once the HVC/LVC loom was complete I wired the Throttle and Controller as shown in the picture above (to the solder terminals hidden behind the white plugs at the top) this is so the LVC cut off can cut the throttle.

It is very difficult to test the LVC in the real world without running the pack to near flat, I did test the board on the bench with a variable PSU attached to fake a cell voltage and sure enough when the cell voltage drops to 3.00v the Throttle signal line drops to 0v (cutting the throttle)

I then set about connecting the HVC to the chargers BMS pin, I ran 4 wires out of the charger box, 5v, Gnd, BMS & EOC. After much fiddling about testing this I discovered that it only seems to work if I leave the BMS & EOC pins connected together (otherwise the charger never starts at all) and then connect the HVC “sig” line to these via a low value resistor (I was advised to add a resistor inline to avoid the Methtek boards drawing to much current) I am not sure the resistor is even necessary but I put one in just in case I ended up having to use two 51 Ohm resistors wired in parallel as that was all I had to hand that worked it seemed if the resistor was even 100 Ohms the signal would just not get through or was not detected on the far side of the current limiting resistor.

So to summarise:-

1) Connected 5v from the control board in the EMW charger and fed this directly into the HVC 5v pin.
2) Connected Gnd from the control board in the EMW charger and fed this directly into the HVC Gnd pin.
3) Connected the BMS/EOC pins from the control board in the EMW charger together.
4) Connected the HVC “Sig” line on the Methtek board (HVC/LVC chain) to the BMS/EOC via two 51 Ohm resistors in parallel.
5) Connected the “Throttle” 3 Pin soldered connections to the throttle.
6) Connected the “Controller” 3 Pin soldered connections to the controller.


I have just realised after writing this up (This is why it is a very good idea to write things up) that I have not fed the LVC part of the HVC.LVC chain with 5V or Gnd!  As this would be active when the car is running (unlike the HVC part which is only active when the car is charging) I would need to source this 5V & Gnd from the Soliton controller! (Update After speaking with Steve the + 5v & Gnd

Shit I had better check this when I get home tonight as I may very well not have a functional LVC!
Anyway I did test the HVC side of the HVC/LVC cut out extensively in the car by using a variable resistor to work out what value of current limiting resistor I would need, and testing it by starting a charge and then shorting the HVC “Sig” line to ground to see if the charger stopped and sure enough if I connected it directly it worked.


My initial guess of a 1K resistor did not work so I put in the variable and dropped the resistance until it started working, checked the resistance and it was way low I eventually settled on the two 51 Ohms in parallel which should give around 25 Ohms resistance and burn around ½ watt power (2 x ¼ watt resistors) I could be completely wrong here as my electronics is still decidedly rusty!

Back on the road at last.

It has been a long couple of months but at last my EV is back up and running, this time with and HVC/LVC harness in place!
LVC is already wired in line with the throttle albeit to only the 2 rear battery boxes I will be wiring the 3rd and final (for now) battery box in tonight which will give me a proper low voltage cut out at 3.0v on the nose on any of the cells in any of the 3 battery boxes, basically if any of the cells hits 3.0v the throttle is cut, I have not tested this in place as yet but I have tested the board on the bench with a variable PSU as a test cell and sure enough the LVC “Sig” line drops to 0v when the cell pin goes below 3.0v.
Once the HVC/LVC loom is complete (Tonight) I will be wiring the HVC side of it into the BMS pin on the charger in an attempt to get the HVC working as well although this would only cut out as a last ditch safety measure as it cuts at 4.4v not 4.2v.
So I still need to upgrade the firmware on my charger to allow a CV cut out of 4.2v (currently limited to 3.99v) and also to put in some physical isolation of the chargers case from the chassis of the car, this is because when the charger is plugged in and running the chassis has some voltage on it, I would not call it live but I think the stray voltage might be either leakage from the bridge rectifier, or possibly inducted from the large toroid.
I also need to investigate a low voltage safety in the charger software as according to Steve the charger should error if it detects an abnormally low voltage and cause you to check to see if any dead cells are present, charging dead cells could result in a thermal runaway event (Yeah don’t I know it!)
And to top this lot I still need to implement the fuel gauge and the heater/demister.