Bulk Batteries

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Batman

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#1841712 9-Aug-2017 11:28

1-day Philips batteries are useless. They have no charge in them. Don't even power clocks for more than a few months, or children toys for more than a week.

richms

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#1841848 9-Aug-2017 13:45

I've seen heavy duty Philips ones come up for sale before. They are useless. No idea why they even bother making them.

Alkalines start off at about 1.7v and seem to be floating at 1.4 when I pull them from remotes because I'm sick of having to aim it.

Richard rich.ms

Batman

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#1841850 9-Aug-2017 13:52

One can tell how much capacity is in a battery using a multimeter?

nolanz

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#1841858 9-Aug-2017 14:10

I have made a few purchases of Duracell Industrial batteries worth a look at

http://www.duracellbatteries.co.nz

richms

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#1841904 9-Aug-2017 15:20

Batman:
One can tell how much capacity is in a battery using a multimeter?

No. Not even a reliable indication of charge level since as batteries age their internal resistance goes up as capacity drops. Not a huge drop in terminal voltage until right near the end. Dave Jones on the eevblog channel did heaps of videos on it when dealing with that scammy batterizer thing that was Kickstartered claiming to make batteries last longer.

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#1845270 11-Aug-2017 15:30

True, but you can determine the internal resistance by measuring current and voltage drop through a known load and therefore know if it's a weak battery though?

SepticSceptic

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#1846858 15-Aug-2017 09:03

kryptonjohn:

True, but you can determine the internal resistance by measuring current and voltage drop through a known load and therefore know if it's a weak battery though?

I use the 10A range on a DMM, and just use the probes directly across the battery.

Only long enough for the reading to stabilise.

A fresh AA Alkaline (Varta) will read about 7.5A. When flat, and barely moves an analog clock, then it's around 0.8A.

Always use the same DMM, as readings will vary between DMM's.

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#1846875 15-Aug-2017 09:23

Cheers Seppo, I'll try that. So at 1.6V (that's what some new alkalines I checked show) you can at least tell the DMM plus battery has only 0.2 ohm.

SepticSceptic

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#1846895 15-Aug-2017 09:42

i should dig out my old analog VM, and see if the readings are similar.

DMM have such a high input impedance ( 1meg ohm upwards) ( load), that even a flat battery will still show 1.3-1.4v,, as there is no resistance to load the battery down.

Analog VM's have a lot lower impedance (20Kohm) that it should show a difference in the volts scale. But I doubt it.

Probably a better way would be a single cell batter holder, with a 10ohm resistor across the holder terminals, and then measure the voltage directly across the battery.

That will draw 150mA - a reasonable current to get a good voltage reading

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