Inexpensive battery tester

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I can’t believe the BB has become such a shrill shilling machi…

That actually looks useful, thanks!


Use the old fashioned one, it’s cheaper and it works!


My younger brother once did the same thing, only he used his braces. :boom:

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I had a “show off” brother too, boy he kept me busy out-doing his shenanigans!


Traditionally, multimeters didn’t use batteries, either. The old analog kind only needed a battery for measuring resistance.

A multimeter is handy to have, generally, and it’s not like they can only be had for a hundred dollars, like my first two digital multimeters (1984 and 1996). I’ve had lots of chance to buy a low end one for ten dollars in recent years, and I gather places that have "Harbor Freight’ often find them cheaper, maybe free with a coupon.

That said, a distinct “battery tester” can be useful, if done right. Does this thing load the battery under test? Lots of batteries will show a decent voltage, but not be useful in use. If the battery tester loads the battery, so there is some level of current draw, that better reflects whether the battery is still good. But that isn’t specified in this brief review.


Please do the world a favor and teach your kids to use a real meter:

It does a lot more, and it’s even cheaper!


See my post, it way way cheaper and it does a freaking hell’a lot of stuff too!

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You’ll get no argument from me, I still test 9V batteries that way. :smile:


The meter can be modded with ease.

A simple way is adding a “LOAD” button and a resistor. (Or more buttons and resistors, for different loads.) A slightly more complex way is the same button(s), but with a FET or a BJT transistor connected as a constant current sink.

An even more complex way would use a microcontroller, which would automatically run a set of measurements on the battery and report its characteristics; for rechargeable cells it could even measure the discharge characteristics, and/or run several measured charge/discharge cycles with varying loads and assess the cell’s health.


That’s exactly what this guy does:

But it’s slower than the 15 minute quick chargers, so I don’t use it as much as I should.


Not entirely. Apparently does not give you the charge.discharge curves.

I have an idea of a battery charger with batteries equipped with either QR-code or a NFC tag so they could communicate with the charger, and so the charger (or even eeprom in the battery’s tag) can keep track of the cell’s real performance. Could be handy for e.g. drone batteries, so the degraded ones can be moved to a less demanding service (e.g. cellphone power bank) before they endanger an expensive hardware.

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You can get the same charger for around $2 delivered from aliiexpress. My general rule of thumb is that once a piece of precision electronics equipment gets more expensive than a soda from the vending machine, it had better be made in Germany. (Preferably not by VW.)

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Chinese are learning fast. Quite a lot from them is not awful crap anymore. (Quite a lot still is, though. Caveat emptor.)

Also, VW is not as bad. I’d gladly buy something that cheats on tests as long as it is not my own tests and are imposed to my equipment by some third party.

My problem with VW is the cost of servicing and spare parts; that is why I tend to avoid them.

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I happened to get one of these a couple of weeks ago and can confirm it’s utility. Simple little device but it works great.

[quote=“shaddack, post:14, topic:67050, full:true”]

Chinese are learning fast. Quite a lot from them is not awful crap anymore. (Quite a lot still is, though. Caveat emptor.)[/quote]

I agree with this; I’m old enough to remember the same evolution with Japanese products. My point I guess is that I prefer to pay Chinese prices for Chinese goods, and that is often half the cost of buying the same product from US stores.

The VW comment was meant to be a joke. I actually like VW, and hope they don’t get fined or sued out of existence.

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