Do you "need" a DMM/batt checker for primaries?

[lovenhim]

Hello everyone. I see that a DMM or a battery checker system is pretty much a must have with a rechargeable setup but is it needed for primarary batteries like a CR123? Also a DMM can check a voltage reading but that does not tell you how much life is in the battery, so are battery checkers worth it....or just carry backup cells?

 

[PeaceOfMind]

For rechargeables such as li-ion, there is a direct correlation between battery voltage and remaining charge, so a DMM is can be used to get an estimate on remaining charge for those cells. I do NOT believe this is the case with a lot of primary chemistries (mainly thinking of Lithium Primary here).

You definitely don't need a DMM to run primaries.

That being said, a DMM is a useful tool that can do neat things such as diagnose flashlight problems or give you current draw readings for a light.

 

[lovenhim]

OK thanks for that. Now I see many use and own a Fluke meter which I know is the best out there. However, I do not have a need for such a meter, so are there any quality in-expensive units that are worth having? I know nothing else is a Fluke but those are beyond my needs, so how about a newbie/beginner quality DMM?

 

[ptolemy]

OK thanks for that. Now I see many use and own a Fluke meter which I know is the best out there. However, I do not have a need for such a meter, so are there any quality in-expensive units that are worth having? I know nothing else is a Fluke but those are beyond my needs, so how about a newbie/beginner quality DMM?

i own equus 3320 and i paidn about $15 for it

for basic stuff it will work just fine

 

[lovenhim]

Thank you for the help.

 

[march.brown]

Hello everyone. I see that a DMM or a battery checker system is pretty much a must have with a rechargeable setup but is it needed for primarary batteries like a CR123? Also a DMM can check a voltage reading but that does not tell you how much life is in the battery, so are battery checkers worth it....or just carry backup cells?

There are battery testers on Ebay for well under £2 including postage ... These are great for primary cells and will show you how good or bad the cells are ... Most of my batteries are rechargeables but I still have some primaries and these testers are ideal ... If one of the cells in a torch or a radio is bad , it will show you.
.

 

[lovenhim]

I know that people seem to like this model http://www.batteryjunction.com/zts-mbt.html

now is this one worth anything or is it junk?
http://www.batteryjunction.com/tunbachformo.html

I know I can go with a DMM as well

 

[pae77]

I bought a cheap "E*Cell DT9205A" DMM on DX and it seems to be working fine for my needs which is mostly checking the voltage of my rechargeable Li-Ion cells. Has a nice big display and came with a working battery installed. In fact it looks exactly like the "cheap" DMM pictured in the "How to Use a DMM" guide on this site. It cost about $13.00 shipped. I haven't had a chance to calibrate it yet but it when checking 10440 cells, it reliably reads .01 volts lower than the voltage report on my LF2XT.

 

[kramer5150]

Hello everyone. I see that a DMM or a battery checker system is pretty much a must have with a rechargeable setup but is it needed for primarary batteries like a CR123? Also a DMM can check a voltage reading but that does not tell you how much life is in the battery, so are battery checkers worth it....or just carry backup cells?

The purpose of the DMM is not really to try and measure how much life is left in the cell. Its primary function is to show how depleted 2 cells are relative to each other for use in multi-cell lights. If you have 8 cells, measure them and pair up the like voltage readings. This becomes more critical with high C applications.

Yes I consider it a must have. For all battery and cell types. NiMH cells can be just as explosive, and alkaline batteries can be even more prone to leaks if cells are improperly mixed.

I have never used a battery tester. I would just go with an inexpensive DMM... A DMM is just one of those things to have around the house, it will get more use than you expect.

 

[BigBluefish]

I have been using a ZTS tester to match my primary cells in my 2-cell lights. I've been surprised to find quite a bit of difference between the capacities of "new" cells, so I'm glad I have it.

I recently got some rechargeables, and a DMM to test them coming off the charger.

Now, I'm wondering if I should be using the DMM instead of the ZTS tester for cell matching. Or will the ZTS give me enough infor about capacity to keep the primary cells safely matched?

 

[HKJ]

I have been using a ZTS tester to match my primary cells in my 2-cell lights. I've been surprised to find quite a bit of difference between the capacities of "new" cells, so I'm glad I have it.

I recently got some rechargeables, and a DMM to test them coming off the charger.

Now, I'm wondering if I should be using the DMM instead of the ZTS tester for cell matching. Or will the ZTS give me enough infor about capacity to keep the primary cells safely matched?

A DMM alone only works for LiIon batteries, for all other chemistries it is best to use a battery tester or use a resistor in parallel with the DMM.

 

[kramer5150]

A DMM alone only works for LiIon batteries, for all other chemistries it is best to use a battery tester or use a resistor in parallel with the DMM.

So the idea behind parallel resistor DMM testing, is to place a load on the cell and then test for V?

What R value works best for CR123 primaries and NiMH cells?
Does resistor type make a difference?

thanks!! Learned something new today :thumbsup:

 

[HKJ]

So the idea behind parallel resistor DMM testing, is to place a load on the cell and then test for V?

Exactly.

What R value works best for CR123 primaries and NiMH cells?
Does resistor type make a difference?

thanks!! Learned something new today :thumbsup:

Something in the range 1 to 10 ohm for 1.5 volt batteries and 3 to 10 ohm for CR123 and preferable a power resistor or it might go up in smoke!
You need to do this kind of measurement fast (i.e. read the voltage within 10 seconds after connecting the resistor) not wait for a stable reading on a alkaline battery.
There are some photos of the method in my DMM guide.

A battery tester works the same way, it applies a load and measures the voltage, then uses a table to translate voltage to capacity %.

 

[Nil Einne]

You can get cheap battery testers on eBay with LCDs that shown the volts BTW. Cheapest price I've seen is US$3.69 including shipping for BIN. Can't vary the load of course. There seem to be two common types, one black, one blue both same price (the black one on eBay doesn't say it's LCD in the title but the picture clearly shows it is and it's available from the same seller). The black one is also available on DX so you can see some discussion there.

These aren't designed for li-ion sellers. They have two terminals one a sort of holding mechanism designed for AA, AAA etc cells the other one with two metal contact terminals designed for 9V. The black one at least doesn't fit 18650 batteries in the holding mechanism without modding it (you could use wires too of course. One report suggests a 12-13ohm resistor which should be okay for 18650 although you probably don't want to leave it on for too long in case it's not really rated for that high watts. The 9V has a ~500 ohm resistor which you could use with a wire for a lower load if you ever want that.

No idea about the blue one although it claims it's suitable for lithium 3V primaries (i.e. CR123) but from the pictures suggests you use the 9V terminals.

Also don't know how the accuracy of these tend to be. If you already have or have access to a multimeter and want something portable for testing or whatever then it may be an okay since even if it's not accurate provided it's resonably precise you can do mental corrections.