On 14-04-05 01:16 PM, Instrument Resources of America wrote:
Speaking of batteries. I don't know how many of you buy batteries (cells) at Harbor Freight Tools, but be aware that they sell several different cells with different chemistries. Alkaline, which I've bought lots of and had no problems, and some VERY INEXPENSIVE cells, that I've been told by another customer standing in line with me the following. That they were the decades old ZnMgO chemistry,
There are a few types of button cells, The so called ZInc-Air cells are used in Hearing aids where the battery runs down in a few days of use no mater what. They have a seal that you pull off to activate them, and then you start the limited life.
They have the advantage of producing 1.35 volts just like the now banned Mercury batteries. There is a version made for photographers who use equipment that depends on the fixed voltage.
Alkaline are common, the in circuit voltage declines in use. Silver Oxide are longer lasting but more expensive, and have a relatively constant 1.55V output.
If you have cells in series, there will always be one cell that that "runs out" first. When it does, the rest in the series will "charge" it. Very few chemistries or constructions are suitable for this, and generally instead, the water within the electrolyte hydrolyses to hydrogen and oxygen. The gas produced naturally expands until some portion of the case fails. This is a long-winded explanation that says, if you assemble a 90V cell, use the chemistry they did back then with the type of cells they used back then, or design your experiment to deal with potential explosion and/or fire.
One potential offset to this is that as most cells wear out they build up a good amount of internal resistance. this limits the available current. YMMV
This however does reinforce the rule that you should never mix batteries on a series combination as that does create the risk of one wearing down when the rest of the group are still very lively and running with little internal resistance.
-- Charles MacDonald Stittsville Ontario [email protected] Just Beyond the Fringe http://Charles.MacDonald.org/tubes No Microsoft Products were used in sending this e-mail. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/5341B0B7.7080802%40zeusprune.ca. For more options, visit https://groups.google.com/d/optout.
