cheapest watt meter yet?

[dnmun]

i just saw this ad another thread. this has to be the cheapest and for most controllers should work fine. but 14AWG silicone flexy type wires.

http://www.ebay.com/itm/New-Digital-60V-100A-Battery-Balance-LCD-Voltage-Power-Analyzer-Watt-Meter-/170982183517?pt=US_Radio_Control_Control_Line&hash=item27cf55125d

i had bot several for $23.74 from another source because they have the trimpots inside the case so you can remote the shunt and be able to calibrate the shunt after it is moved.

they are really low low current and i was even able to repair mine after shorting out my 48V15Ah ping through it. i have two turnigy meters i cannot make work any more.

no led inside so they don't use as much power as the turnigy watt meter but you can calibrate these after you get them and you cannot calibrate the turnigy meters.

 

[Ykick]

How's it handle slight over voltage, 62V?

 

[dogman dan]

Looks worth a try, I just bought one for cheaper than repairing my CA. I'll still get a shunt for my CA soon, but a third wattmeter for my dirt bike is something I kind of needed.

Thanks for the link!

 

[1000w]

I've just bought one.
Cheers for the link.

 

[wineboyrider]

Looks good

 

[dnmun]

the leads are just 14AWG so it is made for lower current discharges. but for high currents over say 30A then it would be best to add another wire to the shunt leads imo.

but i liked jeremie's idea of the remote shunt and if you solder the shunt in a new location then the resistance will change and you have to recalibrate the meter. this little cheapie still has the trimpots to adjust the calibration. the turnigy wattmeter does not so it is hard to calibrate that wattmeter.

also i found that the turnigy readings were 15% off my voltmeter readings.

the lack of the led backlight means it doesn't use much power so you can leave it on for long periods with no impact on the battery.

the turnigy uses an 8 pin SOIC chip for the voltage regulator to get to the 3.3V for the display and uprocessor.

this meter uses a linear shunt voltage regulator to regulate the voltage from the input so it may be possible to raise the input voltage a little by changing the resistor in that linear network so it will be able to handle the larger voltage drop. but i think the display has been shown to be limited to 70V.

i damaged the first one i got by shorting my battery through it, but it ran for a few hours afterwards. eventually it died.

i opened it up and found that the 2k surface mount resistor to the 431 voltage reference had burned up so i replaced it with a 1.6k leaded resistor soldered on top of the traces. that resistor got so hot i replaced it with a 3k ohm leaded resistor and it doesn't get hot as before and the thing works fine now.

i could not repair either of the turnigy meters i killed.

as with all shunt based watt meters, you do not and should not run the current through the red wire. run the current from the battery directly to the controller, and then the positive voltage of the battery can be carried to the watt meter on a small wire. just enuff to provide circuit current for the watt meter.

the black leads of the watt meter have to be in the ground leads from the battery though in order to measure current. so if you wanna upgrade you could swap out the 14AWG wires for 12G or larger if you wanna run up to the 100a current limit.

if you do the remote shunt thing that jeremy introduced, then you would only need large wires where the shunt was located and then bring the kelvin probe voltages back up to the meter on small wires just like the voltage. so no need to run the large wires up to the dashboard for the meter.

also it may be possible to take the shunt kelvin voltages from the controller shunt just as justin does it for the cycle analyst. then tweak the trimpot to bring the current reading into calibration after the leads are installed in the controller across the shunt.

 

[dogman dan]

Bypass the red wire, and you only have the black wires to replace with 12g wire. Works for me.

 

[mxer]

Worth a a shot, Thanks Op

 

[RLD70]

This watt meter is nearly the same as the Watts Up meter I have but a hell of a lot cheaper. And speaking of Watts Up, one LCD line decided to go blank the other day and never did come back on so chances are a new watt meter is in the cards for me and this one looks like its going to be the one. Plus I could buy 3 of these for the price of Watts Up which is 49.99.

 

[dnmun]

my display just went blank too. i had pushed it a little over 60V to about 61 i think, but later the display did not work.

i had already lost the 2k shunt resistor on the 431 in the power input section that sets the voltage output on the linear regulator.

i thought that was because i had shorted it out on my battery. maybe not, maybe they so i will look at this one and see if it has the same problem.

 

[kfong]

I just pick one up as well, cheap enough to justify it as a spare. Sounds easy to mod as well.

 

[DVDRW]

I ordered one about year ago. Compared with CA. Not acurate at all.
When CA reach 10ah then this reached ~11,5ah. Tried calibrate but no luck. Its seems that error is not linear. :?
When you calibrate W right then ah is way off and so on.
Sadly no backlight. On cold weather below 5°C very dim and slow.
I hope that this accuracy problem is fixed now. Waiting your accuracy test.
63v (18s Lifepo4) was no problem.
But for that price its a good toy.

 

[dnmun]

i had to calibrate mine using the ammeter in my digital voltmeter and it was not linear as you said. also the factory settings are as much as 10% off, but the turnigy wattmeter was also as much as 10-15% off too. but i could not calibrate it.

 

[dogman dan]

Got mine, and it's off just a bit on voltage. No substitute for a CA, but cheaper than a third CA for me. It will be good enough to tell when power use is above normal enough to require a slow down on the ride home.

 

[dnmun]

you can take the end off and adjust the voltage. the upper trimpot is voltage.

they use just about the same power as a cellog 8. about 7mA.

with the otmar hack to take power from all 8 cells, and with the opto transistor for the alarm output, the cellog can turn off the display so it uses minimal power but still be running so it would use less than the cheap wattmeter, and still be able to alarm or switch the opto on the alarm output that goes to the led on the dashboard.

 

[dogman dan]

Thanks for the tip, I dialed mine in for 44v use.

 

[OldHarley]

as with all shunt based watt meters, you do not and should not run the current through the red wire. run the current from the battery directly to the controller, and then the positive voltage of the battery can be carried to the watt meter on a small wire. just enuff to provide circuit current for the watt meter.

OK, why would you say this? The meter was designed with a 14 ga. red and black wire on the source side and a 14 ga. red and black wire on the load side.

Why was it done this way if not to run current thru the meter on the red wire? There are no instructions that say "CAUTION, do not use the red wires furnished, these are only for show and should not be used in any event!"

In fact, the instructions say "Acts like a wire, so doesn't affect the models performance."

If you run a small wire to the meter to power the battery side as suggested, you will end up with a potentially dangerous energized wire on the load side unless you open up the box and terminate the wire inside. Maybe this is what you mean, but that goes in the face of the design of the meter.

 

[dnmun]

well you proved something

 

[dogman dan]

Now I'm confused, is there a shunt inside this thing? Can I mod it so I handlebar mount it without a huge wire to the bars and back to the battery in my panniers?

 

[friendly1uk]

It says balancer, but I see no proof of this?

$3 more gets 3 buttons, a useless servo tester, and some balancing leads
http://www.ebay.com/itm/130731639478?ru=http%3A%2F%2Fwww.ebay.com%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D130731639478%26_rdc%3D1

I would like to see the cheaper one's display. It claims a few functions that I'm not sure it does.
Edit: Found a pic. I don't see how it does peak data as it claims. It has no mode switch or place on the display. They appear to be exaggerating it's abilities with these balance and peak recording claims.

 

[OldHarley]

Yup, on the cheap one the bottom right window continuously cycles thru Ah - Amp hours, Ap - peak Amps, Wp - peak Watts and Vm - minimum voltage.

The one in dnmun's link at the top is what I bought and does everything it says. Although it is possibly a downside, you have to unplug it from the source to reset the values noted above.

Thanks for the link!

OH

 

[dnmun]

It says balancer, but I see no proof of this?

$3 more gets 3 buttons, a useless servo tester, and some balancing leads
http://www.ebay.com/itm/130731639478?ru=http%3A%2F%2Fwww.ebay.com%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D130731639478%26_rdc%3D1

I would like to see the cheaper one's display. It claims a few functions that I'm not sure it does.
Edit: Found a pic. I don't see how it does peak data as it claims. It has no mode switch or place on the display. They appear to be exaggerating it's abilities with these balance and peak recording claims.

the RC servo tester is useful for the people who would normally use that meter. it allows them to test the motor on their plane or scale model car to see if the motor works right and to exercise the motor without it being in the model and controlled by the radio. they usually have only a few cells in their battery so that is enuff balance leads for them to use.

 

[1000w]

Mine arrived yesterday, well packaged and in a reasonable time. Just powered it up on a 4S lipo with no load and it came to life.

 

[Patriot4]

Received mine. After working to connect plugs for 2 hours I first hooked it up to the battery pack, fired up, cool. Finished the harness to hook to the bike. Decided to use it to test charging the battery. I hooked it first to the charger, set at max 50.3 volts, fired up, but the display was dim, then connected to the battery. Was about to ramp up the charge amp amperage when the display went dimmer and died.

Dead

I am suscpecting either I got bad unit or I when 1st connected it to charger and if it has high AC ripple, exceeding 60 volts, without the battery load to absorbed the ripple, the power supply died.

in any case I ordered another one today.

 

[dnmun]

yes, they go fast at 60V. it can be repaired though. not simple so unless you are a little experienced you can wait to fix it when you know more.