Thursday 17 July 2008

Greensaver battery inter cell balance - After Discharge

To satisfy Tuarns (and my) curiosity, I discharged the battery to 11.5v at 20A, let the battery rest, then measured the individual cell voltages. Following are the results.


Average = 2.097083
Standard Deviation = 0.003079
Range is from 2.0919 to 2.1004 difference = .0085 volts (0.406%)

Again the battery seems to be well balanced.

Wednesday 16 July 2008

Thanks Dom

Actually I am waiting to get the engine mount back from the sand blasters and painters, bit it looks good hanging there. :)

Tuesday 8 July 2008

Greensaver inter cell balance

Greensaver have been very helpful in providing technical details regarding their batteries.
They provided the following diagram of the top of the cell including the interconnecting links.

I drilled 5 holes in the top of the battery according to their diagram and measured the voltage of the 6 individual cells. The battery is measured at full charge. This battery has been (unfortunately) over discharged about 35 times and is only about 1/2 new capacity. A battery that has been cycled like this should exhibit significant imbalance between cells if the cells are not almost identical.

The results below are measured with a meter (not pictured) with 4 decimal places:

Cell : Voltage

1: 2.2402v
2: 2.2456v
3: 2.2452v
4: 2.2541v
5: 2.2490v
6: 2.2458v

Average cell voltage is 2.2466 volts. This is 100% charged including some surface change.

The standard deviation is .004616

The range is from 2.2402 to 2.2541. A difference of 0.0139v (13.9mv) or 0.6205%

I am not an expert in battery chemistry but this seems to be quite good.

Comments welcome.

Brake Vacuum Pump and Manifold complete

The brake vacuum pump and associated fittings are installed.

The pump is quite quiet. At higher vacuum the vibration is less.

From left to right:

1. T goes to brake booster and to the vacuum tank. (Aluminium drink bottle from Katmandu)
2. T and vacuum cutoff swithch
3. T and vacuum gauge
4. One way valve
5. Vacuum pump.

I bought the brass fittings (5/16") from ENZED