Bob has some accurate figures on this I believe its between 25% and 28%.
It also depends on your cell, plate area and design.
I tested several types of cells this year with different concentrations.
Fo example one cell I tested between 1% and 20% concentration. It was a sealed cell with small holes in the plates so it was self leveling (not a pure bob one)
With the lower concentrations it was slow to start but after a few hours it heat up and get more efficient. With the higher concentrations it would produce lots of gas instantly...slowly heat up resulting in more amps being drawn and over cooking the cell. To control this we used a pwm device to limit maximum power.
The above applies to straight DC brute forse only. Its my belief that using the ideas Bob has shared with us that the heat may not present it self to be a problem.
If a cell gets too hot you may boil it producing a lot of water vapour.
Another consideration is plate area. You need to have enough plate area. The more you have the less problems you will have with heat building up at higher concentrations. Many of the chaep nasty cells on the market just heat up too much through lack of plate area.
Hope this helps
MarkStatistics: Posted by MarkinAustralia — Sun Aug 12, 2007 6:39 am
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