wet cell battery test

All you need is a hydrometer and a thermometer.

Monitor the SG of the acid electrlyte and the temperature and that will tell you all about the condition of each cell used in the battery.

John.

There is also some sort of testing coil available, which will "short circuit" the battery for a very short time. A gauge on the coil will show you the condition in red / yellow / green, which is an indication of the condition of your battery. Be careful with this coil, as it can get very hot and can damage your batteries.

Yes, that is a voltage under load test.

Measuring the acid specific gravity is far more accurate and shows up weak cells easily.

John.

The specific gravity tells you what state the cell is in at that very moment, but it does not tell you what the capacity of that cell is (and more important: the battery). When a battery has just been disconnected from a charger (after using the forklift, disconnecting a normal charger) the specific gravity can be within the "green" range, but it is possible that it does not have enough capacity to get the engine started.

Errrrm nor does a voltage under load tester tell you what the battery capacity is...

What the SG does tell you is the state of charge of the cell, and so it does tell you the battery capacity. I think you must be thinking of a cheap hydrometer with a red, green and orange scale, I am referring to a decent measuring hydrometer.

Another good reason for using the SG of the acid is that most batteries do not allow individual cell connections to be made, so if you were to use a voltage drop under load on a 12 volt battery it may well indicate a good charge but one of the cells could be weak and due to expire soon.

John.

You're right, but our guest was looking for some simple fool-proof tool (I think to adequately test batteries there is none) to test these batteries. I worked in the past with the floater-type hydrometers, indeed on one side with these colourzones, on the other side with the actual values. We used a combination of these tools, so for weekly testing the hydrometer, and once every month or two months this tester. We considered the big advantage of these things that there was no need to open up the battery's cells, so no danger of people being exposed to this acid.

Yes, you're right of course, I forgot the bit about it needing to be 'idiot proof' and for use on the shop floor...

So your voltage drop instrument would be the preferred solution.

John.

John,

What would the thermometer tell you?

Thank you in advance . . .

Cornelius

The thermometer is used to measure the electrolyte temperature, so that you can correct the hydrometer's reading...

The hydrometer's scale will be for a temperature such as 20*C so any change from this will need a correction factor applied.

John.

A refractometer can be used to test the charge level of batteries. As well as the antifreeze and concentration levels of other fluids.

yes, expect Specific gravity and acid level you can monitor/ record battery with a simple instrument. It costs about US$. 1000, if can effort. It is possible to monitor Spg, electrolyte level, temperature along with "Impedance, charge/ discharge voltages, In/ Out Ah, times etc but much costlier instruments. visit "megger" web site for information on such instruments.

guest, are you saying you are an idiot?. All lead acid batts/cells degrade from new - all you need to know is are the units still serviceable- this is easily checked by inner resistance test of the batt/s against the new figure- check batt volts at rest as against run- any doubt remove caps & test SG- finally use high discharge test to see if batt can deliver amps.