XH-M240 Battery Capacity Tester mAh mWh for 18650 Lithium Battery

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G0OSE
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XH-M240 Battery Capacity Tester mAh mWh for 18650 Lithium Battery

Found this on BG, is slightly cheaper on ebay – Not strictly a charger….seems to get good reviews and it may be of use to some on here for a project – so I posted it Smile Apparently it can be used to power things too.
I lust ordered one to play with for £5.82.
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Edited by: G0OSE on 06/11/2020 - 11:32
RobinVC
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Kind of a weird design choice to put the discharge resistor next to the cell (its not too low a value so discharge current won’t be high -> less heat… but still). Btw before placing a cell in, place a small strip of fabric or tape or something to pull the cell out. I have a few of those carriers for 3s packs and they keep the cells in there quite firmly.

Other than that, seems like a fun thing to play with Big Smile Let us know if it ends up being something worthwhile.

G0OSE
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Ok, so this arrived. It’s not a power supply too. My mistake.
The left battery powers it up – I thought the socket was for an output, but it’s an input Facepalm
You have to set the voltage to discharge to – any ideas what I should set that to? presumably this has to be exact to get a true reading of capacity.

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RobinVC wrote:
Kind of a weird design choice to put the discharge resistor next to the cell (its not too low a value so discharge current won't be high -> less heat... but still). …

Heat in the resistor is proportional to power, which is voltage times current.

So its like setting an up to 10W heater next to the cell being tested. But its not really a bad design as far as I can see, looks like some sort of discharge tester which straight uses an 8Ω load resistor attached next to the battery. At most the resistor will dissipate slightly above 2W, and so it shouldn't get nowhere near blazing hot. 

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The human mind, and its programming, is at the forefront of a particular battle of The Light vs evil dark forces. Nearly every human being on this beautiful planet “Earth” has some sort of negative mind programming in its mind. And you better take care of your mind programming, or someone else will in this wicked world.

G0OSE
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Barkuti wrote:

RobinVC wrote:
Kind of a weird design choice to put the discharge resistor next to the cell (its not too low a value so discharge current won’t be high -> less heat… but still). …

Heat in the resistor is proportional to power, which is voltage times current.


So its like setting an up to 10W heater next to the cell being tested. But its not really a bad design as far as I can see, looks like some sort of discharge tester which straight uses an 8Ω load resistor attached next to the battery. At most the resistor will dissipate slightly above 2W, and so it shouldn’t get nowhere near blazing hot. 


Thanks Barkuti – but what voltage should I set the discharger to cut off? it looks like you have to set that manually or it could over discharge? So what V 3.5v? 3.7v?
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G0OSE, most common discharge cut-off value for cylindrical cells of the big manufacturers right now is 2.5V; the actual specified value is in whatever cell's datasheet. Tester Henrik (Mooch too, usually) uses 2.8V as cut-off in his tests, this probably has to do with habit and testing standardisation.

Thu, 06/11/2020 - 20:04

Please avoid fully quoting lenghty posts, namely with nested quotes. Trim quotes down to the essential. Helps with neatness and legibility. Thanks.

The human mind, and its programming, is at the forefront of a particular battle of The Light vs evil dark forces. Nearly every human being on this beautiful planet “Earth” has some sort of negative mind programming in its mind. And you better take care of your mind programming, or someone else will in this wicked world.

G0OSE
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Barkuti wrote:

G0OSE, most common discharge cut-off value for cylindrical cells of the big manufacturers right now is 2.5V; the actual specified value is in whatever cell’s datasheet. Tester Henrik (Mooch too) uses 2.8V as cut-off in his tests, this probably has to do with habit and testing standardisation.


Thanks for that Big Smile I suppose best practice would be to discharge a ‘known’ good quality cell and set it to a ‘set’ voltage – test a few down to the same V and see how it tallies up to the claim on wrapper. If it is miles out, maybe drop the voltage by 0.1v and retry.