ZTS tester (%) Vs. Charger (Exact Volts) - Which one is better?

[p1fiend]

Hi Guys,

I currently use the MRC Super Brain 960 (http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXRST9) to test all my batteries. I do this by simply touching the provided alligator clips (which come from the charging port off the 960) to the + and - terminals of the battery.

I check the volts on all my cells when new, and periodically check the volts of the batteries in my EDCs.

New SF 123s will always read between 3.25-3.27 volts, exhausted ones lower and so forth.

Looking at the ZTS tester which many people here recommend, I see it only gives a percentage of the capacity of cell.

Which is more accurate? It would seem that the exact volt reading would be better than 20% increments. Any reason to by a ZTS when I can currently test all my cells with my charger?

 

[Mr Happy]

An exact volt reading is just that -- an exact volt reading.

An exact volt reading is not necessarily a good indication of the state of charge and/or capacity of a cell. With a CR123 it can be quite a poor indication. The ZTS tester is likely to give a better indication of how much useful capacity is available in a cell than a straight voltage reading will do (some half empty cells may still give a high voltage reading).

Note that the ZTS tester only has 20% increments because estimating the remaining capacity of a cell is not an exact science. The only true way to do it is to drain the cell through a measuring device, which of course is not a helpful test method if you actually want to use the cell afterwards.

 

[michelkenny]

Getting a voltage reading with no load with lithium primaries is useless. It will stay the same until it is almost dead. The ZTS puts a load on the battery so that is a better measurement.

 

[p1fiend]

Getting a voltage reading with no load with lithium primaries is useless. It will stay the same until it is almost dead. The ZTS puts a load on the battery so that is a better measurement.

Not true. Before I load my P2D I'll verify the voltage of the new battery is 3.25-3.27, and after some use the volts indeed do drop. The battery will be dead (meaning it will not power up the P2D) around 2.78 volts.

A big question I have been meaning to ask in a seperate thread is about the minimum input voltage, or start-up voltage, required by a light. Although it would most certainly vary from light to light, knowing the exact minimum required volts and the exact volts of the battery in hand would be able to tell you how soon that battery should be swapped with a fresh one. Ex - If the battery from my P2D is 2.80 volts, I know it will be useless in the light pretty soon.

Seems like a big advantage (if you know the exact volts of the battery) and quite important. :candle:

 

[Mr Happy]

Not true.

It seems you have much to teach us, O wise guru of battery lore.

Please impart to us your great knowledge on the subject in which we are so lacking.

 

[p1fiend]

It seems you have much to teach us, O wise guru of battery lore.

Please impart to us your great knowledge on the subject in which we are so lacking.

Not true

My orginal claim of not true was in reference to the statement, "It will stay the same until it is almost dead". As I stated, the exact voltage of the battery from a P2D will change from fresh to dead as I have experienced

I'm just :thinking: here because the voltage reading does seem to be helpful, but I'm not sure what I'm missing because it doesn't seem to be a major concern here.

Just looking for some help...

 

[Mr Happy]

If you have a sample of cells of the same brand and of similar freshness from the same manufacturing batch, and if you measure their voltage after a long enough period of resting, you may find some consistency between the voltage measurement and the remaining capacity.

However, there are other variables such as age and history of cells before use, manufacturing variances and tolerances, different brands, different intended uses of the cells (photo vs flashlight), different storage conditions, and various other factors that will make the exact correlation between voltage and remaining capacity (or immediate cell performance) much more difficult to predict than you estimate from your limited testing.

I could easily give you two cells, both of which measure the same 3.0 V, one of which would light a bulb brightly and the other of which would fail to light the same bulb at all. You haven't encountered that situation yet, but if you did the ZTS tester would have no trouble telling the difference.

 

[MorePower]

Not true

My orginal claim of not true was in reference to the statement, "It will stay the same until it is almost dead". As I stated, the exact voltage of the battery from a P2D will change from fresh to dead as I have experienced

I'm just :thinking: here because the voltage reading does seem to be helpful, but I'm not sure what I'm missing because it doesn't seem to be a major concern here.

Just looking for some help...

OCV of a lithium primary cell is simply not a good indicator of how much capacity is remaining. Knowing, for instance, that a 3.25V OCV is unused, and that 2.78V is "dead" only tells you what's going on at those 2 points. Also, differences in additives and materials used in different brands means that you can have 2 partially used cells with the same OCV, but that are not at the same depth of discharge.

Remember, too, that OCV of a partially discharged cell can recover to some extent the longer it sits unused, so after 2 or 3 days, a freshly dead cell at 2.78V may read 2.85V, 2.9V, or higher, but won't be able to support the current draw necessary to start a light.

 

[N162E]

OCV of a lithium primary cell is simply not a good indicator of how much capacity is remaining. Knowing, for instance, that a 3.25V OCV is unused, and that 2.78V is "dead" only tells you what's going on at those 2 points. Also, differences in additives and materials used in different brands means that you can have 2 partially used cells with the same OCV, but that are not at the same depth of discharge.

Remember, too, that OCV of a partially discharged cell can recover to some extent the longer it sits unused, so after 2 or 3 days, a freshly dead cell at 2.78V may read 2.85V, 2.9V, or higher, but won't be able to support the current draw necessary to start a light.

OCV ???

 

[Burgess]

OCV = " Open Circuit Voltage "


That is, a battery with No Load applied.

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