Author Topic: Brymen BM235 Low internal battery gives false readings?  (Read 946 times)

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Offline MacMeter

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Brymen BM235 Low internal battery gives false readings?
« on: April 03, 2018, 11:15:55 pm »
I own the EEVBlog version of this Bremen BM235 meter, and just read HKM’s review, here:

https://lygte-info.dk/review/DMMBrymen%20BM235%20UK.html

I wasn’t aware of this low battery voltage reading “issue”. Pardon me if this has been discussed, I do monitor most of the BM235 threads and have never seen this brought up.

From his misc. notes:
“Reading is stable until about 1.8V where it increase significantly (5.000V -> 5.206V)”

From final conclusion notes:
“It has one problem and that is the behavior when the battery is nearly empty, a good DMM must never show wrong value!”

Just curious has this been confirmed? Thanks.
 

Offline EEVblog

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Re: Brymen BM235 Low internal battery gives false readings?
« Reply #1 on: April 03, 2018, 11:52:12 pm »
1.8V total battery voltage?
That's 0.9V per cell, you can't expect any meter to work at that voltage. The low battery warning comes on at 2.5V and effectively means "replace the batteries before taking critical readings". That's the same with every meter. That fact that it still works so far under the low battery cutout voltage is testament to the good design margin.
Should it cut out completely? Yeah, ideally, but few meters on the market do that that I am aware of.
 

Offline MacMeter

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Re: Brymen BM235 Low internal battery gives false readings?
« Reply #2 on: April 04, 2018, 12:14:27 am »
1.8V total battery voltage?
That's 0.9V per cell, you can't expect any meter to work at that voltage. The low battery warning comes on at 2.5V and effectively means "replace the batteries before taking critical readings". That's the same with every meter. That fact that it still works so far under the low battery cutout voltage is testament to the good design margin.
Should it cut out completely? Yeah, ideally, but few meters on the market do that that I am aware of.

Thanks for the confirmation Dave. I’ll respect the low battery warning. Maybe forum member HKM will read this and amend that part of his review with your feedback.
 

Offline Whales

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Re: Brymen BM235 Low internal battery gives false readings?
« Reply #3 on: April 04, 2018, 12:43:35 am »
One of my cheap meters didn't have a low battery warning.  You only noticed when the readings started looking strange.

That meter is now in metrological heaven.

Online HKJ

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Re: Brymen BM235 Low internal battery gives false readings?
« Reply #4 on: April 04, 2018, 04:19:51 am »
Thanks for the confirmation Dave. I’ll respect the low battery warning. Maybe forum member HKM will read this and amend that part of his review with your feedback.

The warning is correct, a good design will disable the meter before it shows wrong readings.
 


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