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by 4Springs
Sun, 31 May 2020, 19:28
Forum: General EV Discussion
Topic: EV subsidies - When will Australia learn?
Replies: 8
Views: 123

Re: EV subsidies - When will Australia learn?

The Tasmanian Government has taken the approach of subsidising the infrastructure. As a result, we are getting about 15 new DC fast chargers this year, up from 2 total in the state before that. This is in a state of 500 k people. 17 DC fast chargers mean that the entire state is covered. If you're o...
by 4Springs
Mon, 13 Apr 2020, 18:39
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

That Brillo scourer material is quite abrasive (if that's what it is). No, not scourer. This stuff is more dense, thinner and softer. I've spent the past couple of days dismantling and re-assembling battery modules. Re-polishing all the connections and doing up the roughly 300 fiddly little bolts a...
by 4Springs
Sat, 11 Apr 2020, 04:53
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

Here's what I'm doing now, following the advice gained here (mostly from Chris). IMG_0474.JPG Steel springs now have Kaptan tape on the side that touches the cell tabs (which are either aluminium or plated copper). IMG_0468.JPG More Kaptan tape, covering the corners of the cells to stop them making ...
by 4Springs
Sat, 11 Apr 2020, 04:41
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

Back to work again for the weekend and I found out some more info. I checked the current flowing from between random points on the ends of the cells. In most cases it was negligible - so little that just measuring the voltage with the multimeter made that voltage drop over a few seconds. I tried one...
by 4Springs
Tue, 07 Apr 2020, 14:30
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

Ok, here we go. IMG_0454.JPG IMG_0453.JPG IMG_0455.JPG IMG_0456.JPG I reckon this quite possibly my problem! I tested a few cells, and some display this feature more easily than others. On this one, which is one of the ones that got hot, it was very easy to find a place that would give me a voltage....
by 4Springs
Tue, 07 Apr 2020, 12:01
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

Can you tell me how many cells are leaking? So far there are 8 out of the 65 that I've checked that have some damage. 2 are leaking outside of the pouch and have burn marks. 4 have burn marks but no external leakage 2 have signs of leaking within the pouch but no burn marks. The aluminium next to t...
by 4Springs
Tue, 07 Apr 2020, 08:40
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

I'd coat it in Kapton tape, or at least some kind of contact adhesive, and make sure that you put a layer of something with a bit of give, like thin EPA or double-sided tape. Ideally you would glue the cells in position, but if you want the option of pulling them apart again, these would be the lea...
by 4Springs
Tue, 07 Apr 2020, 08:15
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

Yes I certainly wouldn't be packaging pouch cells against bare metal, especially not where it might rub. The pouch itself is a composite of aluminium and polymer, but the polymer is vanishingly thin - and effectively peppered with microscopic pinholes. Any moisture or humidity that works its way in...
by 4Springs
Tue, 07 Apr 2020, 06:33
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

I run the cells for at least 10 cycles at 1C from 4.2v to 3.0v and at least 4 cycles at 2C. This was when I was checking the capacity. After that I have used for energy storage for a battery tester but at very low C rates. The battery tester cycles NiMH prius cells. It is mainly used for recovering...
by 4Springs
Mon, 06 Apr 2020, 19:36
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

Did you do a check for stray voltages between (+) and chassis? If you do spot something, it's worth checking the current with a decent ammeter (don't forget to swap the cables back once you're done!). Should be well under 30 mA. I've just thought of something. The cells butt up against an aluminium...
by 4Springs
Mon, 06 Apr 2020, 19:19
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

The road is a brutal environment for cells. They really need to be well protected, snug, and unable to rub of fret against anything. Or reside in tension - eventually something gives way, and the opportunities for cascading problems start to pile up. Likely there was a leakage current to chassis? D...
by 4Springs
Mon, 06 Apr 2020, 18:18
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

I have had a pack of these cells assembled for over a year and didn't have any leak and they still seem to be working fine. I can not explain why you are having such a high failure rate. Is there any chance you could have pulled the tabs while tightening the bolts and damaged the inside? Assembled,...
by 4Springs
Sat, 04 Apr 2020, 17:37
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

So what happened? Why have these cells gone bad? With this fastening system the top and bottom cells in each pile of 10 have quite an angle on the tabs. The first failure I saw was one of these. But since then I've found others that were not the furthest ones, but ones in the middle where the tabs a...
by 4Springs
Sat, 04 Apr 2020, 14:30
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

What a week! On Monday I didn't drive the Brumby to work because I had a failed BMS celltop board. Today I'm wondering whether I even have a battery at all... I opened up the rear battery box today. Both to look at some of those warm cells identified by the graphs above, but also to look for more el...
by 4Springs
Thu, 02 Apr 2020, 18:12
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

jonescg wrote:
Thu, 02 Apr 2020, 18:04
Yeah, aluminium and anything other than aluminium will set up a galvanic reaction, and iron is a good candidate as it's further down the reactivity table.
Doesn't a galvanic reaction require a liquid? Electrolyte leaks aside, these connections should always be warm and dry.
by 4Springs
Thu, 02 Apr 2020, 18:06
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

I did some banana cleaning today. The aluminium tabs are somewhat corroded - they will need to be polished up. The copper tabs have lost some of their (nickel?) coating as well. I found another cell that suffered some damage. This is the one underneath the leaky one. Several spots around the anode. ...
by 4Springs
Thu, 02 Apr 2020, 18:01
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

I had no idea this clamping system used steel - at the very least use nickel plated steel, or just plain old aluminium if you have enough Alminox to throw around. Hmm... Would you like to elaborate? I've looked up Alminox, and it appears to be a compound to help aluminium surfaces make good electri...
by 4Springs
Wed, 01 Apr 2020, 17:19
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

I discharged the battery down to a minimum cell voltage of 3.1 V the other day. Took me 160 km to do it. Then I charged up to a maximum cell voltage of 4.1 V. The next day I found the BMS reporting "Fault 1". This means that it wasn't hearing anything from the celltop boards. The first cell up the l...
by 4Springs
Fri, 27 Mar 2020, 18:31
Forum: Renewable Energy and Storage (Non-EV)
Topic: AVASS cells 2nd lot
Replies: 52
Views: 5485

Re: AVASS cells 2nd lot

For those that have manufactured custom links from rigid conductors, what materials and cross section dimensions do you recommend? Here are mine. You've reminded me that I haven't updated the thread describing my build for a while. IMG_20191004_172325964.jpg I used flattened copper pipe. I got it a...
by 4Springs
Fri, 27 Mar 2020, 16:00
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

This is what i did on my board but i found that when the bypass is running it warms up the board and that causes the sensor to detect a higher temperature. I placed the sensor very close to the contact and far away from. The hot parts of the bypass circuitry but it still detects a few degrees highe...
by 4Springs
Thu, 26 Mar 2020, 17:19
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

How did you attached the temperature sensors? When I did some testing for the first time I found that if the contact overheats the tab conducts the heat to the cell quite efficiently. The temperature sensors are on the celltop circuit boards - surface mount component very close to the negative term...
by 4Springs
Wed, 25 Mar 2020, 18:54
Forum: Batteries, charging, management and monitoring
Topic: Low cost BMS
Replies: 441
Views: 63736

Re: Low cost BMS

Do the nodes turn off or go into some low power mode to avoid discharging the battery when not being used? At 40% that means you generally bypass at about 0.24A? After doing the balancing yesterday I am starting to think that maybe 5A is an overkill. I have also dropped the max current to about 3A....
by 4Springs
Wed, 25 Mar 2020, 18:35
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

I'm not completely convinced that the Brumby has the full power that it used to. Neither is my wife, Zara, who took it into Launceston the other day. Mind you, we haven't driven it for a couple of months, and we've been driving our new Kona in the meantime. So perhaps we are just spoiled! One potent...
by 4Springs
Wed, 25 Mar 2020, 17:41
Forum: Members Machines
Topic: 4Springs' Brumby
Replies: 297
Views: 48800

Re: 4Springs' Brumby

are you trying to drive on the pre-charge resistor only? Ah, I know what it is like to drive on the pre-charge resistor. This happens every time I forget to click around to 'Start' on the key. It goes 'eh', and just moves enough to tell me that it tried. This was giving me more than that, but not n...
by 4Springs
Wed, 25 Mar 2020, 16:12
Forum: Members Machines
Topic: Francisco's Electric Pajero
Replies: 145
Views: 17925

Re: Francisco's Electric Pajero

What voltage is considered 100% capacity? In other words, at what voltage does the cell voltage rise rapidly yet only a small current going into the cell. LFP and LYP cells will voltage balance quickly below fully charged but that has nothing to do with the state of charge being balanced. The only ...