Conflicting readings from BT-3100 & a SM8124A (advice please)

[Luddite]

HI

I have been happy with my Opus BT-3100 v2.2 charger but wanted a dedicated (portable) resistance tester
I yesterday received the SM8124A which according to reviews is quite good.

However I noticed the readings are way off between the two devices so I need help please.

Using "quicktest" on a reclaimed 18650 the unit returned 77 yet the the SM8124A returned 32
This is happening on all the ones I am testing, roughly twice the amount between them.

Is there an easy way to find out which unit is accurate please

Ta

 

[Pommie]

Numbers without units make no sense. 77 what, 32 what?

Mike.

 

[Luddite]

It says in the o/p " but wanted a dedicated (portable) resistance tester "
that's what the figures are "Resistance (thats what the sm8124A does)

Numbers without units make no sense. 77 what, 32 what?

Mike.

 

[Nigel Goodwin]

It says in the o/p " but wanted a dedicated (portable) resistance tester "
that's what the figures are "Resistance (thats what the sm8124A does)

Perhaps you should have mentioned 'internal resistance', as that's what it's supposedly measuring. Just saying 'resistance' makes no sense.

I would imagine that the actual value you get depends entirely on how it does the reading, and what it applies - so I wouldn't expect comparisons between different meters to have any value.

 

[KeepItSimpleStupid]

It's a number that you can relate to battery health. Something that's dedicated, probably is gtting the right answer.

Do the measurement, then add some small resistance and do it again, See what delta R is.

 

[rjenkinsgb]

Is there an easy way to find out which unit is accurate please

It looks like the SM8124A can be rather variable on manufacturing quality; there is a thread on accuracy and problems here:

SM8124 Battery Impedance Meter - Page 1

SM8124 Battery Impedance Meter - Page 1

www.eevblog.com

Basically, clean the board and add switch lubricant to get more consistent operation.

It also says in that thread that the impedance test is done at 1KHz. That could presumably give different readings to a low frequency stepped current test.
I have no idea how the Opus test works in detail, though I have one myself.