attempting to use a simple led voltage meter

[emaayan]

hi..
my regular current meter is in the shop, so i thought i'd use this: http://www.dfrobot.com/index.php?route=product/product&path=70&product_id=454#.UE5Nr43iYRB , but since my battery is 48 volts, i used a voltage divider (20000/20000) , so while the actuall voltage is around 53, when i connect the divider, my regular lab voltage/current meter shows 26 volts, however when i connect the led voltage meter, it shows 4.4, suspiciously this is just below it's range of 4.5-30 volts. so i guess it means something. i've tried different wires, i also have 2 led voltage meters and i get the same result.

 

[OlderThanDirt]

You need to factor in the current drawn by the meter through your voltage divider. It looks like about 2.5mA will cause the voltage drop you're seeing. If the current into the meter is indeed 2.5 mA, I'd suggest a 5K/10K voltage divider to apply about half of the 53V battery voltage to the meter. If you want an exact 1:2 ratio, use a potentiometer to trim the voltage.

 

[emaayan]

i need to be carefull not to apply to lower resistor or they burn..

 

[shock]

You need to get a meter that handles 12-120DCV and be done with it. They are out there, I own 3.

 

[emaayan]

i got myself a 10k:5k and still i get the same result, i've measured the current being drawn and it's 4.35 ma. i've tested it with a 9volt battery which does show the correct value, and the current being drawn is 10 ma.

 

[wesnewell]

Get the right meter.
http://www.ebay.com/itm/Waterproof-Digital-Voltmeter-DC-15V-To-120V-Red-Led-Voltage-Digital-Panel-Meter-/170846310527

 

[emaayan]

but i already got that, http://www.aliexpress.com/snapshot/201203773.html a week or so ago,and on top of that i have speedict (which i sent for replacement) , i just wanted something in the mean time, cause i had this voltage meter laying around.