Dody eBay volt meters

[averhamdave]

Following a comment from someone on here I bought two of these digital volt meters.

Waterproof Digital Voltmeter DC 15V To 120V Red Led Voltage Digital Panel Meter | eBay

Plan was to fit one to a large leisure battery I run a Lipo charger off, the other would be fitted to a bike I also run lipos on and where I thought I could just keep an eye on total voltage as a secondary check to other monitoring equipment I use.

Anyway they came today and I tested them both on a 3S lipo that is at between 12.48 and 12.52 volts - checked with two calibrated test meters.

One of these things indicates a voltage of 10.7v, the other 25.4v, LOL

 

[Deleted member 4366]

I've just been to check mine against my multimeter on a battery I charged a few weeks ago. Both the Ebay meter and my multimeter showed 41.2v, which is what I'd expect (voltage-wise).

Try it on a higher voltage because 12.5v is below it's minimum of 15v, so you should expect that.

 

[jazper53]

With all the talk of batteries, multimeters etc, I decided to upgrade my tatty analogue meter with a digital one from amazon, has all the features continuity buzzer back light,, save and hold readout feature etc. So I decided to check my battery(LiFePO4 36vx9ah), the readout was 39.6v and my analogue meter indicates about 41v The battery was charged about a week ago. I have been reading from other thread that the optimum reading should be about 42v and wonder whether 39.6 is to low or maybe my new digital meter could be wrong which i doubt, as it seems pretty accurate with other test readings.

 

[Deleted member 4366]

Measure the charger voltage. It's value should be written on it, then you know if your meter's right. LiFePO4 chargers can be as high as 45v, but the battery quite quickly settles down to a much lower voltage, while as LiNiCoMn ones are charged to about 41.7v, which the battery tends to hold.

 

[jazper53]

Thx for the tip, just checked the charger which states 43.8v output, digital read out was 40.7 so I am relieved and disappointed at the same time. The meter seems to be out by 3.1v

ps. Have just opened up the back of the multimeter and noticed a variable resistor plugged into the circuit board I wonder if that is a +/- for the read out, if so I may be able adjust to the chargers output

 

[colonel]

I purchased the same meter to monitor the standard battery while utilising a booster battery. When it arrived I thought I would check it utilising a 3S lipo. It gave all sorts of readings from 20-35v and I too thought I had received a dud. Then I noticed it was not 0-120v as I had thought but 20?-120v. Having now wired it into the main battery circuit it gives me perfect, repeatable readings. The only issue I have is being able to read it in sunlight - can anyone recommend some form of anti-glare filter?

 

[averhamdave]

Ah, despite my advancing years I have still not learned to read manuals or small print!

The one that reads 10.7 reads 10.7 on all 3S and 4S packs and just displays three "dashes" on all 6S packs so have concluded it doesn't work.

The other that was reading 25.4 on a 3S pack is surprisingly very accurate when checked against known voltages on several 6S packs.

Given that one was for a leisure battery (which it isn't designed to do) and the other for one of my bikes I'm still OK - particularly given the price.

Thanks wise ones

 

[D C]

The only issue I have is being able to read it in sunlight - can anyone recommend some form of anti-glare filter?

Red transparent plastic helps a lot if it has red characters.
Mine seems to be accurate.

 

[colonel]

Just checked mine for accuracy and found it consistantly reads 0.3v under. It is consistant and on the "right" side to be I guess, so can live with this. I have some red model "solarfilm" so will give that a try - thanks for the tip.