How to determine battery % charge off-bike

[Luto]

A multimeter is invaluable. Many Chinese kits use blue and brown, rather than red and black. If on the wong poles you'll see a - minus before the numbers. Very useful!

So much better than putting your tongue on a 9V to see if it works.

 

[ExFire]

Did you turn on the key first?

Step Thru batteries not correctly/clearly marked for + and -.

I finally got an accurate meter reading of my Step-Thru battery.
The correct reading is only gotten when the meter probes are in the end connections, with the red(positive) lead in the end-most contact ( ...the one nearest the long/pointed end of the battery), and the black(negative) lead in the contact at the other end-most of the 5 contacts.

The reading is only available with the key turned "ON". The "off" or "unlocked" positions of the key give no reading!

In short, the battery has + and - indicators (molded into the black end-cap)in the WRONG positions, seeming to indicate contacts that are 1 contact removed from either end of the row.

 

[bigcanoe]

What should it read to maintain 75%?

 

[Sierratim]

What should it read to maintain 75%?

It depends of course on your battery's nominal voltage. Take a look at the chart in @jaizon post #2 above for expected voltage levels at 75% charge for the most common battery voltages.

 

[bigcanoe]

Yea, makes sense, thank you! Mine is a 48V.