voltmeter: if i keep it hooked up, will it drain the battery?
02-09-2002, 09:55 AM
#1
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voltmeter: if i keep it hooked up, will it drain the battery?
right now i have a relay that supplies the power from the battery when it senses the accesory power. that way the meter turns off when my car is off, is this necessary? can i keep the voltmeter hooked the the battery directly? or will it drain it slowly/
02-09-2002, 02:10 PM
#3
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Re: well.. i once left ...
If your voltmeter is of the 'moving needle' type, then it will not drain your battery even after a long vacation.
If your meter has an LCD display on it, then there are electronics that need to be powered inside the unit - still not any more than an alarm system.
If your meter has an LED display, the current drain will be greater than others, but possibly still OK.
Find out what the current (amperes) requirement of your meter is and repost.
If your meter has an LCD display on it, then there are electronics that need to be powered inside the unit - still not any more than an alarm system.
If your meter has an LED display, the current drain will be greater than others, but possibly still OK.
Find out what the current (amperes) requirement of your meter is and repost.
02-09-2002, 08:04 PM
#4
for overnight and short periods of time, it's not a problem, but if you leave the car alone for more than a few days or weeks at a time (i.e. businessmen that travel and stuff like that).. that will kill your battery.
I would recommend leaving the relay on it.
it's easy enough to leave it hooked into an accessory wire such as your head unit or something else that only comes on with the ignition...
I would recommend leaving the relay on it.
it's easy enough to leave it hooked into an accessory wire such as your head unit or something else that only comes on with the ignition...
02-10-2002, 12:48 AM
#5
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Just wire up your voltmeter to your ignition line. Do NOT wire it to accessories because whilst cranking, you will not see a reading since all accessories are cut off whilst your key is in the "start" position.
This is crucial because you especially get a good indication of your battery's condition when cranking (which should usually sink to no lower than 10.2V).
This is crucial because you especially get a good indication of your battery's condition when cranking (which should usually sink to no lower than 10.2V).
02-15-2002, 12:10 PM
#6
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Most modern voltmeters have a resistance in the Mega ohm or more. V=IR. so the drain from a volt meter will be 10^-5 Amps. The normal parasitic drain is usually 80 mA, so the addition of the voltmeter is nill compared to what's normal.
If you are driving the voltmeter from the car battery, then you have to add in the current draw of powering the meter.
If you are driving the voltmeter from the car battery, then you have to add in the current draw of powering the meter.
02-15-2002, 03:38 PM
#7
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Originally posted by OnTheRoad
Most modern voltmeters have a resistance in the Mega ohm or more. V=IR. so the drain from a volt meter will be 10^-5 Amps. The normal parasitic drain is usually 80 mA, so the addition of the voltmeter is nill compared to what's normal.
If you are driving the voltmeter from the car battery, then you have to add in the current draw of powering the meter.
Most modern voltmeters have a resistance in the Mega ohm or more. V=IR. so the drain from a volt meter will be 10^-5 Amps. The normal parasitic drain is usually 80 mA, so the addition of the voltmeter is nill compared to what's normal.
If you are driving the voltmeter from the car battery, then you have to add in the current draw of powering the meter.
02-19-2002, 05:48 PM
#8
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Posts: 231
I've not seen an LED volt meter for 20 years. Even the $20 RadioShack one 4 years ago is a liquid crystal. Takes botton cells, so must be low drain. But no auto turn off, replace batteries every year, depending on how offen I forget to turn it off. The ~15 year old Fluke takes a 9V and is a LCD. Replace the battery every two to three years (as auto turn off).
02-19-2002, 06:37 PM
#9
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Originally posted by OnTheRoad
I've not seen an LED volt meter for 20 years. Even the $20 RadioShack one 4 years ago is a liquid crystal. Takes botton cells, so must be low drain. But no auto turn off, replace batteries every year, depending on how offen I forget to turn it off. The ~15 year old Fluke takes a 9V and is a LCD. Replace the battery every two to three years (as auto turn off).
I've not seen an LED volt meter for 20 years. Even the $20 RadioShack one 4 years ago is a liquid crystal. Takes botton cells, so must be low drain. But no auto turn off, replace batteries every year, depending on how offen I forget to turn it off. The ~15 year old Fluke takes a 9V and is a LCD. Replace the battery every two to three years (as auto turn off).
And as for not having seen an LED voltmeter, I can't say I have seen one prefabricated either. Which is why I designed my own and did something useful with that hopeless coin tray 3#-)
02-19-2002, 06:56 PM
#10
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Originally posted by OnTheRoad
I've not seen an LED volt meter for 20 years. Even the $20 RadioShack one 4 years ago is a liquid crystal. Takes botton cells, so must be low drain. But no auto turn off, replace batteries every year, depending on how offen I forget to turn it off. The ~15 year old Fluke takes a 9V and is a LCD. Replace the battery every two to three years (as auto turn off).
I've not seen an LED volt meter for 20 years. Even the $20 RadioShack one 4 years ago is a liquid crystal. Takes botton cells, so must be low drain. But no auto turn off, replace batteries every year, depending on how offen I forget to turn it off. The ~15 year old Fluke takes a 9V and is a LCD. Replace the battery every two to three years (as auto turn off).
And as for not having seen an LED voltmeter, I can't say I have seen one prefabricated either. Which is why I designed my own and did something useful with that hopeless coin tray 3#-)
02-19-2002, 08:46 PM
#11
02-19-2002, 09:21 PM
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02-20-2002, 11:27 AM
#14
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For the volt meter located on the link
http://www.mpja.com/allpict.asp?dept=52 , they will need a voltage regulator for the 9V supply. A $4 fix from RadioShack will do. If the 12V to the reg. is supplied only when the key is turn on, the load will be nil when off. The ad. states that the voltage of the power source can not be monitored, so it can't be directly connected the the battery.
http://www.mpja.com/allpict.asp?dept=52 , they will need a voltage regulator for the 9V supply. A $4 fix from RadioShack will do. If the 12V to the reg. is supplied only when the key is turn on, the load will be nil when off. The ad. states that the voltage of the power source can not be monitored, so it can't be directly connected the the battery.
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