How to test battery w/ multimeter

[trek7000]

Hi All,

I have a Clyte 408 rear motor, Clyte 36-72V 20A start anywhere controller and LIFEpo4 48V 12aH battery .. i've had this setup for 3 years now and its worked flawlessly... took the bike out of the garage today, charged battery up and plugged it all in.. turn on.. throttle light comes on... but no movement when engaging throttle... now its time to troubleshoot...

My question is... im no electrician.. but I want to test that my 48v battery is working properly... how do I use the multimeter to test that im getting 48v's? My meter has all these settings.. DCV "20V", "200V", "500V" .. which one do I use to test my battery? if any of them will even work ...

Thanks!
Kevin

 

[dak664]

Generally the highest voltage setting will display volts, the next highest tenths of a volt, the next hundredths of a volt, etc. For a three and a half digit meter the maximum value is 1999 volts, 199.9 volts, 19.99 volts, etc. Most digital voltmeters won't be damaged by trying to measure <200 volts on the 200 millivolt scale (it would blow the fuse or meter on an analog VOM). But measure >200 volts only on the highest range, internally that uses components and board traces that can handle the voltage without arcing.

If you are measuring the battery pack voltage stay away from the ammeter ranges, switching across them will blow the fuse. NEVER connect to the 10 amp socket without double checking your connections to verify the current will be limited to <10 amps. That socket is typically a direct short between the probes with no fuse.

 

[dogman dan]

So set the thing on 200volts. Red wire on the positive wire of the battery, Black on the negative. If you get it backwards, nothing bad will happen, you just get a negative reading, or if analog, it will just peg on the bottom of the scale.

Start checking connectors too, sometimes they bend around on the back side of the plug, till they have only one wire left unbroken. If lucky, you just need new connectors fromthe battery to the controller.

 

[GrayKard]

took the bike out of the garage today, charged battery up and plugged it all in.. turn on.. throttle light comes on... but no movement when engaging throttle... now its time to troubleshoot...

How long was the battery sitting partial charged/discharged? Some Lifepo4 packs will have a drain from the BMS that will pull one group of cells down if not regularly recharged during storage.

Gary

 

[trek7000]

Thanks for the replies... Gary... your right.. my battery sat all winter without being recharged.. I didn't know I had to keep it charged so now im kickin' myself. Just sent it back in for repair... we'll see how it goes. Hopefully its not pooched!

Kevin