Guru
Joined: 15/07/2006
Location: AustraliaPosts: 676
| Posted: 11:30am 15 Feb 2012 |
Gordon sent me an update on Relativities Active Balancing testing.
Quite some time ago I sent 8 cells x 90ah to Gordon to connect up to his 24v wind & solar system for the purpose of testing the Relativities. In a recent post I said, must be near 3 years now. Gordon assures me it is just over 2yrs, like 2 yrs and 3 months.
Gordon says
Here are some pics, of the drawdown curves, and the recharging curves. We used over 2kWh from the battery. Check out the kWh discharge, 2.13kWh, and the kWh used to recharge, 2.10kWh. These are circled in red. Pretty close to the same energy. A tribute to the performance of the Lithium chemistry. The dark red trace is battery current. Charging above centre, and discharging below, with a +/- 20A scaling. The green circles show the normal absorption time, as well as in the second pic, the battery was equalized. This is a fully automated system, with no user intervention.
The cells do separate slightly in voltage at the extreme voltages, but the equalizers can be seen to be bringing the differences down. This is the blue trace. It had been about a month since the last equalization had occurred. The multi coloured traces are the superimposed individual cell voltages. The recordings are at 10sec intervals. The normal scaling is 3-4V, that is 3v at the bottom and 4v at the top of the black window. This is a narrow range, so the working voltage range of the battery is from about 3.45 to 3.2 cell Volts, and the battery is considered charged at a cell volts of 3.65. The centre of the screen is 3.5V, or equivalent to 28V on the battery. As you know, this 8cell Lithium pack is in parallel with my 24Vnom lead acid battery.
Trev @ drivebynature.com