Wednesday, 3 December 2014

Replacing the LVC/HVC loom

I have been meaning to get around to replacing the LVC/HVC loom with decent ODBC II cables to allow for the removal of the Traction Pack without the need to unwrap and separate 18 spade terminal connections (6 per box) and then re wrap them on reconnect with insulating tape.
Seeing as this would require the complete removal of the entire Traction Pack and cracking the lids (Silicone sealed against damp) I had been putting it off until I had another reason to do it, Well here it came, I was around the mother in laws the other day and when I went to leave the car switched on as normal but when I put my foot on the pedal “nothing” not a dickybird no movement what so ever from the motor, suspected low 12V at first but a laptop conformed the problem was not with the controller at all as far as it was concerned it was all systems go! So this left only one possible explanation, The LVC/HVC loom was preventing throttle.
So I either had another dead cell or there was a fault on the loom and considering the recent damp spell I was suspecting damp in the loom.
Taking a little risk I removed the loom and connected the throttle directly to enable me to drive home (which worked) and the next day (which was a Sunday luckily) I set about the complete removal of the traction pack.
I had previously purchased the required ODBC II cables (4 of them, Three short 1 meter and one long 3 meter) to allow the complete LVC/HVC replacement loom, The huge advantage of the ODBC II cables is the waterproof plugs and sockets that are designed for automotive use and so do not suffer from damp or dirt getting into the connections and causing failures.
After removing all the lids I found that yet again despite my efforts with silicone the front Battery box has been compromised with a little water nothing major but not good all the same, So I took a heat gun to it on low to dry it our properly and after fitting the ODBC LVC/HVC loom cable did a full silicone seal to try once more to protect against water, However I think the under tray is vital now to see if that will stop water getting into this front box.
Strangely and despite there being no rubber grommets at all on the rear boxes they were both dry as a bone so obviously the front is where the water issues are causing problems, let’s hope the new waterproof LVC/HVC cable loom does the trick (Plus the imminent front under tray) 

The Beat goes in for brush and bearing replacement

I finally got the Beat booked in for brush and bearing replacement and I also asked Brent to fit a protective aluminium tray on the underside of the car to protect against water and dirt ingress into the motor area (I had previously thought that water and dirt were the primary cause of the early brush and bearing failure but on second thoughts I feel that the most likely cause is the lack if RPM monitoring/limiting)
And after getting the Beat back from Brent with its new brushes and bearings and a shiny new aluminium under tray (1.2mm) Brent informed me that he had taken most of the time cleaning up the dirt and grit from the motor so that he could fit the new bearing so I now feel that the tray is money well spent.
However Brent did not get time to do the front tray to protect the front battery box from water ingress in the same way and I now feel that this is also a requirement (I will book it in soon for the front tray).

250 Cells tested nearly half way there!

Testing continued over the next couple of weeks until I reached the half way mark and the fog began to close in.
Now I live in a low lying area prone to flooding and we get some awesome fog this time of year, Coupled with the fact that I have just had the roof of my workshop replaced and part of this job meant the old fascia boards being removed and not replaced has resulted in the workshop getting a little more condensation that it used to.
No biggie I thought and began to plan for some replacement plastic fascia boards, However the Antec 480P PSU I had been using to power my BC168 was and old reused ex PC PSU and had a fair amount of dust in it, The addition of a little condensate soaked into this dust meant that one Saturday morning when I went out to begin another productive days cell testing I switched on the PSU to hear a crackling sound, Rapidly switched off checked the connections and tried again, as soon as I switched back on BANG! Shit there goes another PSU and after disassembling and looking for the fault I decided it was simpler to replace.
So I put in an order for as brand new 450W Antec which arrived the other day, speaking of arrivals I have a box of silicone cell separators sitting in my hallway that arrived a few weeks ago now and I will be using these soon to start constructing the Traction Pack proper.

Silicone sheet delivery imminent!

I had also ordered the silicone separators from a company called Silex they have cut them to size for me for very little extra cost, let’s hope it is all good when it arrives, I went for plain white 1.5mm 40shore (the shore rating I have discovered is the hardness of the silicone sheet) I checked with a sales rep that 40 shore was approximately the same as a standard baking sheet and was assured that it was, I also checked with them that it was 100% insulating with no impurities that would compromise it’s electrical insulating capability again I was assured it was, I only checked this as I discovered on their website that they sell conductive silicone! Which in my mind was like being able to by insulating copper or dry liquid!
So fingers crossed I may be in a position to start laying out the blocks of cells for a sizing for the Ali battery boxes I need to get made, I am planning on keeping them all under the bonnet this time as there is plenty of room and the weight should nicely compensate for the lack of engine and gearbox and laying the cells out so that they are lying flat in blocks of 30 top to bottom (so 30 high) the space under the bonnet appears to give room for 5 blocks of 30 wide so that would be 150 cells and seeing as I need to get 350 under the bonnet with possible room to upgrade to 400 cells (to give me a 300v nominal rather than 260v nominal as advised by Steve, So room for an additional 50 cells), That would be 2 full rows (of 150 cells) and a row with 100 cells at either the front or back, Each of these rows will be separate boxes of cells bolted to a frame exactly as the previous EV but all in one place, The boxes will be linked in series as before and as before I will need to run cables for LVC/HVC and balance leads although this time I am going to use ODBII Cables as they are much better in the damp that JST connectors (which are shit for EV use!) I may also have an issue sourcing more of the methods LVC/HVC boards as Steve tells me that he has stopped making them and Steve has no stock AFAIK bummer, these are really good boards.
Still I have just started collaborating on a BMS with Simon Rafferty who UI met at the BMMF this year and is famed in DIY EV circles for being the inspiration behind the EMW high voltage charger design, so maybe this will fit the bill, watch this space ;-)

Brushes and bearing arrived in double quick time!

Despite my partner moaning about the cost of shipping from Bulgaria I was astonished to find the brushes and bearings arrived in double quick time on Friday 7th in fact I had only just sent an email to Kostov asking for a tracking number and they arrived! Which is odd because Kostov had given me the impression that the brushes would need preparing and that they may have them ready for sending by the 5th or 6th, So I had sent an email asking (politely) what sort of preparation brushes required to which I got a big fat silence! Followed by the parts arrival on my doorstep on the 7th! I wonder if this may be a “lost in translation” issue. Anyway due to me not knowing exactly when the parts would be here and assuming they would be sent over land (not air freight) I mistakenly assumed they would be a while and did not book my mechanic to get the Honda in for fitting of said brushes and bearings, the upshot of this is that he 18th is the earliest he can do it much to my partners dismay!

Testing, Testing 1,2 – 350 Cells!

I have been testing EIG’s constantly every spare minute (outside of my normal working day and working around my kids and partner) and what with the Halloween and Guy Fawkes Night celebrations and a dose of flu. I think I have managed pretty well to get to around 95 cells by the third weekend however this weekend I could just not bring myself to drag my sorry ass out of bed early enough to get stuck in so by the time I had managed to get to it I was already way behind schedule to achieve my “Required” 30 cells in one weekend target. So to quicken things up I decided to try the 40 amp 2S discharge and graph again (WHAAAAAT! I hear you cry) yes I know the last time I tried this I blew up the Powerlab 8 but it is well within the power rating of the Powerlab 8 and seeing as I have just tested over 90 cells without a single hitch with this new Powerlab 8 I am confident that the problem must have been with the previous one being faulty. So with everything crossed and my nose twitching for the first sign of any unusual smells I cautiously setup the 2S test and to my relief it all worked perfectly I carried on testing 2S all day to catch up to my 30 cell target and now have around 125 EIG’s tested and awaiting assembly into a sweet traction pack.

Tuesday, 28 October 2014

EIG Cell Testing continued

So seeing as the EV was out of action and my mechanic had pushed back the start of the RX8 build due to his business partner upping sticks and declaring he wanted to sell up and move on, I got busy with the testing of the new EIG cells, and this time I was going to make sure that there was no chance of failure.
So I bought a brand new 12V battery to compliment the better of my two existing 12v lead acid batteries and dumped the older/weaker one just in case this had anything to do with the failure (although Steve assures me that the Powerlab will compensate for any weakness in the Pb cells and simply fail the test rather than going bang so I still feel the last power lab must have been faulty) and I also replaced all the 12v battery terminal connections with brand new bright and shiny connectors again just in case a bad connection had caused any sort of spiking.
Voltage spikes are the most likely cause of electrolytic failure so I am taking no chances, also I reduced my test cell to a single 20Ah EIG cell rather than 2 in series even though the powerlab should be well able to handle 2S of these cells (we had already done the power calculations to check we were not pushing it beyond the 1344W limit and again if we did try to it should just fail the test not explode!) I was not willing to take any chances this time and am going to stick to single cell tests despite the huge amount of time this will eat.
So to get the ball rolling proper I configured my BC168 balance charger to charge at 6S (8A) so I could top up 6 EIG’s at once and once I had the first six charged the ball really started to roll, it turns out that a single cell test takes around 28 minutes @ 40A to discharge and it takes the BC168 around 3 hours to charge 6 cells so all in all a pretty good balance I can charge 6 whilst I am discharging 6 (albeit one at a time) and then rotate.
So pushing hard to keep this turnaround going I managed to get 30 cells done in 1 weekend that is 1/10th of the entire pack so assuming I only get weekends to do it (I will be doing some in evenings) it would take me 10 weekends to complete the job.