Date: Mon, 05 Jan 2004 05:35:02 GMT From: Derrick 'dman' Hudson <dmannopsam13.dyndns.org> Subject: Re: battery electrolyte level test - how to ?
On Mon, 05 Jan 2004 04:26:47 +0000, tom wrote: > 1. how can I measure the levels of each cell ? Use a hydrometer (I think that's the name of it). My dad has one. It looks like an eye-dropper with 4 colored balls in it. You stick it in the cell, after taking off the vent cover, and draw up enough fluid to more than cover the balls. > 2. what am I measuring - voltage? sulphiric acidness ? Density of the liquid. This directly relates to the ratio of acid vs. water, which directly relates to the amount of charge the cell is capable of producing. > 3. when I get a result: whats good ? whats bad ? If all 4 balls float (on all 6 cells), then you have a good fully charged battery. If half of the balls float, you have a half-charged battery (could just be drained, or could be incapable of holding a charge). If the balls float on some cells and not others, then the cells they float on are good and the others are not functioning correctly (might just need fluid). > 4. how do I know if i need to top up with sulphuric acid ? I don't know the answer to this one, sorry. I have heard of topping off with distilled water, though. That needs to be done if water that used to be there has evaporated. A visual inspection to see if the water-acid mixture is high enough to cover the lead terminals. I think the acid, under normal operation anyways, is produced by the reversal of the chemical reaction which is caused by an input of current, rather than a draw, which occurs when the alternator provides a higher voltage, with sufficient current, across the batteries terminals than the battery itself produces. > BYW: my dead bettery is currently charging, now its 7.59 volts; A single lead-acid cell can produce 2 volts. This is chemistry. A car battery has 6 cells, so that in series 12 volts can be produced. My dad is an Electrical Engineer and, naturally, enjoys understanding the principles behind various electrical devices. He explained the above (about voltage per cell) to me when my digital voltmeter read 24 volts on a friend's battery I brought home to recharge. It turned out that the 9v battery powering my meter was producing about 4.5 volts. I suspect the meter uses the battery's voltage as a reference, and when that reference was half of what it should have been the battery being measured was reported as double. Replacing the battery in my meter solved the anomaly. HTH, -D -- Love is not affectionate feeling, but a steady wish for the loved person's ultimate good as far as it can be obtained. --C.S. Lewis www: http://dman13.dyndns.org/~dman/ jabber: dmannopsam13.dyndns.org
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