Shorted Battery With Multimeter

Catalyzt

Well-Known Member
Region
USA
Okay, feeling pretty stupid, here. The Hilltopper battery or controller died on my kit bike 10 days ago, so I was testing the battery per instructions.

Here's what the service guy at Clean Republic Told me to do:


1) Please make sure the red and black wires are plugged into the multimeter as shown in the product photo on Amazon (red plugged into the hole above VΩmA and black in the hole above 10ADC).

2) Turn the dial to the left so that it is set to the blue dot labeled "20" - AKA DC 20. The screen should now show a read out of zeroes, or possibly a very low voltage.

3) Plug your charger into the wall.

4) Take the red probe and insert it into the inside of the charger barrel pin. Now place the black probe on the outside of the barrel pin. The two should be situated as in the photo below. Be sure to keep the probes as far from one another as possible to avoid any shorting of the charger.

5) Record the full reading off your multimeter. If it is working properly, it should be putting out around 42.4 volts or so.

6) Now move onto the battery. Be sure the battery is on by pressing in the red button on top.

7) Set the battery on its side, so you can access the connection points on the bottom where the battery is seated on the kit dock.

8) Place the red probe into the slot labeled "+" and the black into the slot labeled "-".

9) Note the reading on the multimeter.

10) Press the red button on your battery in order to keep the battery from slowly draining!

I did that-- and no joy-- even though step 2 made me very nervous: Doesn't the black lead always go in the COM port, which is colored black? I checked the manual, checked online, every instruction I could find told me that was where the black lead ALWAYS goes. The 10ADC port was for the RED lead in every instruction I could find. The 10ADC port is COLORED red, so it seems logical that's where the red lead goes, and I thought that was the safest place to start if current might be over 200 milliamps.

So I tried that, and I tested the multimeter, and it gave me a fine reading from a nine volt battery with the black lead in COM and the red lead in 10ADC, and 10ADC should be safer anyway, even if it's unfused, right?

Using the same settings and with the leads plugged in the same way-- Black COM / Red 10ADC-- I followed the rest of the instructions, with the dial turned to 20 V at approximately 10:00 position, put the red lead into the positive slot on the battery and the black lead into the negative and... ZAP! Big spark, smell of burning metal, burnt lead.

What did I do?! It's a pretty small battery, 36 volt 5.4 amp.

I have a feeling I made a $300 - $550 mistake...
 

chunk

Active Member
Region
USA
If you are checking voltage, your leads should be in the volt jacks, not the 10ADC. The dial scale should be set at to the DCV scale above the expected voltage, on my meters, that would be 200 VDC. ADC is for checking current not voltage. Can't say what smoked, maybe in the meter. How did you determine that the battery has gone belly up? I think you might still be okay except for the meter. Voltage and Amperes are not measured the same way. amps in series, voltage in parallel. Measure the battery voltage again, I suspect all will be okay. Fingers crossed.
 

indianajo

Well-Known Member
Measuring volts on the 10 A scale can blow the fuse in the meter. Open the back and see if you did so. Usually 5x20 mm fuses, for sale @ newark, digikey, mouser, one of those big electronic chain stores if you live in a city >10 mlllion.
 

harryS

Well-Known Member
Here's what the service guy at Clean Republic Told me to do:

1) Please make sure the red and black wires are plugged into the multimeter as shown in the product photo on Amazon (red plugged into the hole above VΩmA and black in the hole above 10ADC).
Black has to be plugged into COM for all voltage measurements,.Your freelancing put the black lead at COM, but the red lead on the 10ADC. That's for measuring current. When you did the 9V battery, you were measuring a dead short across it, and the current reading must had a 9 in it, making you think it was 9 volts, but it was really 8-9 amps.

WHenb you tested the battery, the 10A fuse in the meter should have popped. However, the meter should still work in the voltage mode.

Red on VΩmA
Black on COM
Measure your 9 V battery. If it works, meter can stll get voltage.

Most cheap meters have a 20V DC and a 200V DC range. You have to use 200 to measure a 36V battery unless it's a fancy autoranging meter.
 

Catalyzt

Well-Known Member
Region
USA
You guys are the greatest! Thanks so much for all this.

Harry, I'm gonna try with the 9 volt as you say. Will report back.