Testing a Battery - by a novice

I tried to post this on "Technical Section" but I was disbarred from doing so.

With the very technical (most of the time) discussion going on about Lithium Batteries at a level that is completely beyond my understanding, I was wondering if there are SIMPLE rules for running a test on a Lithium Battery to discover where it might be in its life, regardless of its age.

I have a Multimeter (I believe it's called a 'Galvanometer type') which measures:

OHMS (X1 - X1OK)

DC.mA (.o3 - 600)

AC.V (6(17dB), 30(31dB), 60, 300, 600up)

DC.V 3 - 300

DC.mV (60 - 1200)

There are 3 'sockets' for placing the red/black probes:

- COM, +v.ohms symbol, AC1200V

 

I have tested my 2 Lithium Batteries after they have been fully charged (checking for any 'false green lights') and they both read 42V (or as near as my feeble eyesight can make out on the tiny scales). That is so despite the fact that one battery is 17 months old) and the other is only 7 months old).

I should say that the older battery has covered about 700 miles and the younger one about 300 miles.

Apart from riding them to the red light are the results I am getting from the above readings telling me anything useful?

Incidentally, the last time they were out performing service they each achieved 19 - 20 miles (eZee Sprint + 88Kg unfit rider - hilly route 0 - 10%) before they became too feeble on hills (like 3%) to be tolerated (red light on from time to time).

Is my 'equipment' sophisticated enough to be useful in undertaking further bench tests for significant results?

Peter

I'm afraid not Peter, the voltage gives very little indication of a battery's real condition. The best test from a user point of view is range comparison from what was achieved when new after running in the battery on a given route. This gives an accurate indication of the capacity left. End of life is whatever is convenient to the individual user. I do lots of short journeys so can use a battery right down to less than a third of the capacity/range, but for many, half capacity/range is the limit of usefulness.

.

A very rough guide to a batteries condition could be obtained by using a lamp to discharge the battery to a safe voltage (eg. 32V) and measuring the time taken to reach this voltage. The most convenient load is probably 3 identical 12V bulbs in series, 6W bulbs (car tail lights) will draw around 0.5A so the approximate capacity in Ah is twice the number of hours taken for (3 x 12V 6W bulbs) to discharge a full battery to 32V. It is important to not to allow the voltage to fall below 32V so this method does require vigilance.

battery testing

 

Hi

ibelieve that one way of testing a battery which has been fully chatged

would be to test the battery under load if you see a voltage drop which

is some where in the regon of 32 volts or less then i would believe that

it may be on the way out.you could cunnect a volt meter to the battery

and do a test run to see how low the voltage drops

 

best regards