Hi All, What type of guage can I hook up to my battery to monitor the "condition" of the battery ? Thanks Richard
Battery
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Depends on your needs. In my case, I wanted to be able to "spot check" the battery to know when it needs recharging. From Radio Shack, I bought a 15vdc panel meter, a momentary contact switch, and a project box to mount them in. Two leads attach to the battery and to the meter through the switch. By pressing and holding the switch, I can compare the voltage reading to published voltage levels, such as at the link below. AGM batteries read slightly higher than the values shown in that chart. One thing I'd like to improve upon would be the range of the meter. With my AGM battery, the monitoring range is something like 12 to 12.9 volts. With a 15 volt meter, that means a very narrow range on the display to monitor. If I could find one, I'd like to use a meter with a range of say 10 - 15 volts, or even narrower if possible. Jack
Depends on your needs. In my case, I wanted to be able to "spot check" the battery to know when it needs recharging. From Radio Shack, I bought a 15vdc panel meter, a momentary contact switch, and a project box to mount them in. Two leads attach to the battery and to the meter through the switch. By pressing and holding the switch, I can compare the voltage reading to published voltage levels, such as at the link below. AGM batteries read slightly higher than the values shown in that chart. One thing I'd like to improve upon would be the range of the meter. With my AGM battery, the monitoring range is something like 12 to 12.9 volts. With a 15 volt meter, that means a very narrow range on the display to monitor. If I could find one, I'd like to use a meter with a range of say 10 - 15 volts, or even narrower if possible. Jack
If you want to check individual batteries
in a bank, set a digital voltmeter to a selector switch with conections to each battery. A digital volt meter is easier to read than an analog thus you can obtain a more precise reading
in a bank, set a digital voltmeter to a selector switch with conections to each battery. A digital volt meter is easier to read than an analog thus you can obtain a more precise reading
If you want to know exactly
whats going on with your battery state of charge, try this. http://www.xantrex.com/web/id/237/p/1/pt/5/product.asp
whats going on with your battery state of charge, try this. http://www.xantrex.com/web/id/237/p/1/pt/5/product.asp
Good idea!
Benny - Sometime after my previous post, I too thought of the digital multimeter. It would show the exact voltage whereas an analog meter is a bit harder to read. And they have gotten pretty cheap to purchase. Jack
Benny - Sometime after my previous post, I too thought of the digital multimeter. It would show the exact voltage whereas an analog meter is a bit harder to read. And they have gotten pretty cheap to purchase. Jack
If you have a newer GPS…
It has a voltmeter as one of the display readouts (a good time to figure out how to change what’s displayed on the GPS anyway). Keep in mind, the readout will depend on your battery switch setting.
It has a voltmeter as one of the display readouts (a good time to figure out how to change what’s displayed on the GPS anyway). Keep in mind, the readout will depend on your battery switch setting.
When I my analog portable volt meter,
I get a slightly different voltage (a volt higher) reading than the digital portable volt meter. My other digital agrees with the digital reading. Can anyone shed some light here? Do the digital units have a different system to sense voltage?
I get a slightly different voltage (a volt higher) reading than the digital portable volt meter. My other digital agrees with the digital reading. Can anyone shed some light here? Do the digital units have a different system to sense voltage?
Consider an AC/DC clamp meter !
I have long hesitated whether to jump into this discussion or not. First of all, I am not a card-carrying battery expert. Secondly, my approach to battery monitoring is neither traditional nor cheap. However, over the past 5 years or so, it has given us invaluable peace of mind. In 12 volt battery banks, with individual 12 volt batteries linked in parallel by short, heavy-gauge copper leads, there is really not much to be learned about individual battery condition by voltage measurement, unless one first disconnects the batteries, thereby altering the entire circuit. Just imagine that the plus terminals and the minus terminals are each interconnected by heavy copper bars. In that situation one would not expect to measure any voltage difference between both ends of the same bar. Moreover, one expects to measure the same voltage difference between any point on the positive bar relative to any point on the negative bar. If the bars are massive enough this holds true even if a fair amount of current is being drawn and one of the batteries is not doing its job well. Now imagine using a "current clamp" type meter and measuring the current along each bar, in between the different batteries. With four batteries in parallel and a 6 Amp (e.g. freezer) load connected between one end of each bar, each of the batteries should be contributing roughly 1.5 Amp. As we clamp in between the various batteries (on either the positive or negative bar) we will thus find readings of approx. 1.5, 3.0, 4.5 and 6.0 Amp respectively. If instead we find 1.8, 2.4, 4.2 and 6.0 Amps, it will be instantly clear that the second battery is contributing less than half of it's share. After verifying that the terminals are clean and make good contact, we now know that the second battery is bad and should be removed. All of this is diagnosed within minutes and without disconnecting any leads at all! That same current clamp meter will also tell whether your batteries are absorbing the proper amount of charge within the proper amount of time. It will also tell whether your alternator is putting out enough current and whether most of the return current runs through the negative alternator terminal or through the engine bracket. Finally, it will be able to tell you whether your nonfunctioning bilge pump is shorting out or the circuit is interrupted, and so on and so forth. Good AC/DC current clamp meters will set you back approx. 50-100 bucks. That is, if you are happy with a resolution of several hundred milliamps in DC mode. Because we do leave our vessel alone for long periods of time and I need to instantly detect small current "leaks", e.g. because a gas sensor was left on or because of a faulty connection, I spent nearly $ 250 for a Prova CM-1 (no longer available, but replaced by newer Prova models) with 20 mA DC resolution 4 years ago and believe that I have saved many times that amount in prevented trouble with batteries and other equipment. Have fun! Flying Dutchman
I have long hesitated whether to jump into this discussion or not. First of all, I am not a card-carrying battery expert. Secondly, my approach to battery monitoring is neither traditional nor cheap. However, over the past 5 years or so, it has given us invaluable peace of mind. In 12 volt battery banks, with individual 12 volt batteries linked in parallel by short, heavy-gauge copper leads, there is really not much to be learned about individual battery condition by voltage measurement, unless one first disconnects the batteries, thereby altering the entire circuit. Just imagine that the plus terminals and the minus terminals are each interconnected by heavy copper bars. In that situation one would not expect to measure any voltage difference between both ends of the same bar. Moreover, one expects to measure the same voltage difference between any point on the positive bar relative to any point on the negative bar. If the bars are massive enough this holds true even if a fair amount of current is being drawn and one of the batteries is not doing its job well. Now imagine using a "current clamp" type meter and measuring the current along each bar, in between the different batteries. With four batteries in parallel and a 6 Amp (e.g. freezer) load connected between one end of each bar, each of the batteries should be contributing roughly 1.5 Amp. As we clamp in between the various batteries (on either the positive or negative bar) we will thus find readings of approx. 1.5, 3.0, 4.5 and 6.0 Amp respectively. If instead we find 1.8, 2.4, 4.2 and 6.0 Amps, it will be instantly clear that the second battery is contributing less than half of it's share. After verifying that the terminals are clean and make good contact, we now know that the second battery is bad and should be removed. All of this is diagnosed within minutes and without disconnecting any leads at all! That same current clamp meter will also tell whether your batteries are absorbing the proper amount of charge within the proper amount of time. It will also tell whether your alternator is putting out enough current and whether most of the return current runs through the negative alternator terminal or through the engine bracket. Finally, it will be able to tell you whether your nonfunctioning bilge pump is shorting out or the circuit is interrupted, and so on and so forth. Good AC/DC current clamp meters will set you back approx. 50-100 bucks. That is, if you are happy with a resolution of several hundred milliamps in DC mode. Because we do leave our vessel alone for long periods of time and I need to instantly detect small current "leaks", e.g. because a gas sensor was left on or because of a faulty connection, I spent nearly $ 250 for a Prova CM-1 (no longer available, but replaced by newer Prova models) with 20 mA DC resolution 4 years ago and believe that I have saved many times that amount in prevented trouble with batteries and other equipment. Have fun! Flying Dutchman
Fred, most analog meters are spec'd at
at 3-4% of Full Scale. That means if you are using a 0-50 VDC scale, your meter could be off 1.5 - 2 V; if in a 0-25 VDC scale it could be .75 - 1 V off. Many digital meters are more accurate than that; usually in the 1% range. In addition, ripple on a DC voltage can affect the readings but how they vary depends on how they compensate, filter, etc. the sensed voltage.
at 3-4% of Full Scale. That means if you are using a 0-50 VDC scale, your meter could be off 1.5 - 2 V; if in a 0-25 VDC scale it could be .75 - 1 V off. Many digital meters are more accurate than that; usually in the 1% range. In addition, ripple on a DC voltage can affect the readings but how they vary depends on how they compensate, filter, etc. the sensed voltage.
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