Bridges Loc: Memphis, Charleston SC, now Nazareth PA

I have several battery testers: Micronta, Eveready, Sunbeam, Sears, etc. What I want though is one that will test the battery under a load. I hate it when I go through a pile of batteries, bag the ones that test totally charged and then try to use them in a flash unit or CD player to find they will only last for 15 min. or with flash, only about 25 - 40 shots! I guess I could add a resistor between the battery and tester but would anyone know what the average resistance would be for a flash unit using 4 AA batteries?

BebuLamar

Some recommend to use a 6 ohms resistor and measure the voltage. The voltage should be above 1.46V when using the resistor as load. For me the battery is good if I simply measure the voltage without any load and the voltage is higher than 1.5V. The resistance for a flash probably about 4 ohm when the capacitor is empty.

larryepage Loc: North Texas area

The instantaneous current drawn by an electronic flash unit while the capacitor is recharging is key limited only by the internal resistance of the batteries supplying it. This current is larger than can be safely maintained for the time required to read the battery's condition. The likelihood is that the voltage is also going to drop significantly during that time. Your battery tester is probably already using a parallel load resistor to simulate real operating conditions, just at a much lower current level.

The problem comes about because modern rechargeable batteries (NiCd or Li Ion) maintain nearly full output until just before they are completely discharged...the old tester technology is just not capable of determining the amount of charge remaining.

To get around all this complexity, I simply store my charged batteries separately from my used ones. My goal is also to recharge used batteries as quickly as possible and store them in the 'charged' bag, trying to avoid an inventory of depleted batteries.

TriX Loc: Raleigh, NC

You can use a resistor in parallel with the meter, but I don’t have a clue what the current looks like as the capacitor in the flash charges - it’s not constant - there’s a relatively high inrush current which tapers off as the capacitor charges, unlike a fixed value resistor. Like Bebulamar, for alkaline, I just measure the voltage with an accurate DVM, not a battery tester, and a new cell typically measures 1.548 -1.565 volts and they become unusable at about 1.3v or so. With rechargeables (I use Eneloops), I just put everything I’m going to use in the smart charger before an important shoot (and I always have a couple of sets of spares).

Bridges Loc: Memphis, Charleston SC, now Nazareth PA

Thank you. Sounds like just what I needed to know!

Bridges Loc: Memphis, Charleston SC, now Nazareth PA

Thanks for the info.!

Bridges Loc: Memphis, Charleston SC, now Nazareth PA

Thanks!

aphelps Loc: Central Ohio

Open circuit voltage or even resistor load ed voltage can be misleading. The best way to evaluate is by using a charger/discharger that measures mAh in both the discharge and recharge cycle. As that value decreases over time you will have a better idea of replacement.

dsmeltz Loc: Philadelphia

When I saw the title, I thought it might be a job posting. I was looking for a new career for my retirement. Oh well.

charleswendt

I use a pulse load ZTS Multi Battery tester that I purchased from Amazon. does a good job testing the batteries, I also use it to match batteries.

birdman12 Loc: Pinopolis, SC

I have a Micronta Battery Tester that tests 1.5, 6,9,15 and 22.5 volt batteries including 1.5 button batteries, applying a proper load to each battery tested depending on the voltage setting. I have used it for many years.
Barry

charleswendt

Thanks I will look that up and add it to my collection

sabfish

I have the ZTS pulse load tester as well. It will accurately test alkaline batteries and imposes a load, as its name suggests. I am not sure whether it will give accurate tests on rechargeable batteries.

charleswendt

I find the ZTS pretty accurate on rechargeables. That is about all use it on.

chrissybabe Loc: New Zealand

I test alkaline cells by measuring the voltage. If they are up around 1.52-1.53v then they are probably okay. If down to 1.49 then out they go. Voltages like 1.506 usually means they have probably been used a bit and not worth trusting. In this case they get relegated to use in torches.
Rechargeable batteries are charged, placed in series with some sort of load, and voltage across the load measured until the battery voltage drops depending on chemistry to a certain minimum value. From this you can calculate the average mA draw and compare it with the rated value of the cell. Do this up to 3-5 times to get an average. If the average is reasonable consistent and isn't too far from capacity then cell is probably okay. Worth repeating after a week to make sure the cell has held charge for a while. This is how you can tell whether a cell (lithium anyway) is either at its rated capacity of say 3000maH, or as often happens with some Chinese sourced (read manufactured) cells where the capacity might only turn out to be 1200maH. If you are handy with your hands you can make up a holder to fit camera batteries into for testing. Any battery not close to the rated capacity should be replaced.