Guru
Joined: 15/07/2006
Location: AustraliaPosts: 640
| Posted: 02:40pm 22 Feb 2014 |
The testing of Relativities double layer (posted back on 11 August 2013) did not work. In a very short time the cell voltages were pulled out of balance.
It was discovered that they had a fault. It was later found that one of the key components were substituted for a different component and so they did not work. They had to go back to be changed.
We now have them back, and tested on my test setup. All looked good, so set about potting.
I then fitted a double layer to my EV Hilux again. They were fitted Friday afternoon 7/2/14.
After leaving for a few days (weekend) with the Zivan charger switched on and holding pack voltage, the cells reached 3.52v on the top and 3.48v on the bottom by Sunday 9/2/14 afternoon at 6.20pm (18.20 on the screen).
The most separation is at the top end of charge and so I have pictures of the screen at this point. 2 days later 11/2/14 the cells have separated some. The next day 12/2/14 they are separated some more. The next day 13/2/14 separated more again.
The next day I got the photo at pack voltage 182v, showing a greater separation in cell voltage. Just over an hour later you can see voltage difference is closer. Pack voltage is still the same. If the pack could be left long enough it would get them much closer. 6.20am is when I am off to work (teaching).
The next day, 15/2/14, at peak pack voltage 3.50am it was 3.63v -3.46v (170mv). By 6.15pm (18.15 on the screen) Relativities had brought the voltages back to 3.58v -3.46v (120mv). As you can see, the large pack does not balance very quick. The number in brackets to the right of the cell voltage is the cell number, so cell 1 is the highest and cell 20/19 is the lowest. The power from cell 1 has to go through several Relativities to get to cell 19 or 20. Relativities is holding them though, every morning the cells have been around the 170mv different. They are not separating any more.
Trev @ drivebynature.com