Brymen BM 235 Startup issues

[derree]

Hi everybody!

I am a hamradio and general electronics enthusiast and quite happy with my Brymen BM 235, at least until 2 weeks ago.

I always used rechargeable AAA batteries (eneloops) in all of my multimeters, never had a problem. The BM 235
seems to stay stuck in the startup process, means when I switch from "off" to a function, the LCD shows all segments as black (which is normal for about half a second), but the device never pulls through to the selected function. The display stays in the state of all segments black.

I suspected the eneloops to cause this, as they by default have a voltage of 1,2V, whereas alkalines have a voltage of 1,5V, which I suspected to make problems during a phase of higher power requirements during startup of the multimeter.

It seems to be better, but now and then the BM 235 shows this behavior.

Has anybody an idea what could cause this problem?

all have a nice day! 
Derree

[Specmaster]

A simple way to test your theory is to replace the eneloops with conventional alkalines and see how it behaves. I think you might well be right as a rechargeable has a maximum voltage of 1.2V whereas a alkaline is around 1.6V so with a new set of batteries you are already .8V lower and I believe that the alkaline is capable of supplying a larger starting current.

[wraper]

I think you might well be right as a rechargeable has a maximum voltage of 1.2V whereas a alkaline is around 1.6V

BS, freshly charged NiMH has around 1.45V voltage but fresh alkaline around 1.55V. Nonetheless even at 1.2V per battery meter must work fine unless it's faulty.

[wraper]

[Specmaster]

I think you might well be right as a rechargeable has a maximum voltage of 1.2V whereas a alkaline is around 1.6V

BS, freshly charged NiMH has around 1.45V voltage but fresh alkaline around 1.55V. Nonetheless even at 1.2V per battery meter must work fine unless it's faulty.

Just taken a new AAA alkaline from a sealed pack and it measures 1.595080V so it is much nearer to 1.6V than it is 1.5V, also the maH capacity of alkaline is higher than a eneloop, typically 1,200maH alkaline as opposed to 800maH of a eneloop. Reference is from Wikipedia                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               

[derree]

Hi!

Thank you both very much for your replies.

I have changed the batteries from eneloops to fresh alkalines, and I will observe the behaviour of the multimeter.

I have measured the voltage of other fresh charged aaa eneloops and fresh energizer aaa batteries.

Results:

eneloops      about 1,3V
alkalines      about 1,56V

I have also measured the voltage of other freshly charged NiMH aaa, which also gave me about 1,3V.

I also think, that the meter should work fine with a voltage as low as 1,2V, so I assume there is something wrong with my brymen.

Thank you all for your help, and I wish you a happy new year btw! 
Derree

[Specmaster]

I think you will find that the 1.2V might well be very suspect with regard to the meter working correctly, in particular with regard to its starting up from cold so to speak because the data sheet https://brymen.eu/shop/bm235/ clearly states that the meter displays "Low Battery" warning at around 2.5V so if your batteries are reading 1.2V each, then you are already 0.1 Volt lower.

Personally I always use alkaline batteries in my meters.

[Helix70]

Might need some batterisers!

[Specmaster]

Might need some batterisers!

[wraper]

I have also measured the voltage of other freshly charged NiMH aaa, which also gave me about 1,3V.

Then it was not just charged but stayed some time after charting.

[wraper]

Sounds more like problem with rotary switch.

[NoisyBoy]

I would guess the meter is defective.  I have yet seen any electronics not accepting rechargeable batteries, that is assuming your rechargeables are freshly charged.

[derree]

Hello everybody,

The meter works perfectly with the alkalines, and starts to produce the mentioned behaviour when used with the eneloops. I am thinking that the eneloops start to fail after one year of usage. Time to get some new rechargeables!

[Specmaster]

Thanks for letting us all know, I know that I have never had much success with rechargeable batteries of any make, as mentioned earlier, they seem to struggle to deliver peak currents when required.

[wraper]

I have never had much success with rechargeable batteries of any make, as mentioned earlier, they seem to struggle to deliver peak currents when required.

Nonsense. NiMH have several times lower internal resistance than alkaline and thus can deal with much higher loads. Look at that graph above in my post. Try drawing a few amps from alkaline. At 1A they are virtually useless, even at 0.5 A they still suck a lot.

Typical alkaline discharge curve.

[wraper]

Also if meter struggles at 1.3V per battery, it means that more than half of Alkaline capacity will go to waste.

[GLouie]

I'm using white Eneloops in my Dave-branded BM235 and am not having any problems, even after some months.

I use Eneloops whenever possible due to repeated leakage problems with all alkalines.

[bc888]

Same as Glouis. I use the BM235 meter infrequently as I have a Tek 850 that stays on the desk ready to grab, same set of eneloops(white) for a couple months in the bm235, meter still working as of 2 days back. Which doesn't tell anyone what the batteries are currently measuring of course and therin lies the question.

[Specmaster]

Rechargeable batteries when new are completely different kettle of fish to rechargeable batteries that are not so new clearly as the OP has already reported, the meter is performing perfectly on alkaline batteries.

I have tried to use rechargeable batteries myself on a many occasions and it has been my experience that once they are a few months old, they do not seem to be as effective as they were and then at that stage alkaline just seem to be a better bet all round and in general more cost effective as the rechargeables are that much more expensive to begin with.

I have tried many makes and capacities and the end result is the same, a few charging cycles and the performance drops off, maybe I've unlucky and have brought batteries that had been shelf sitting too long I don't know.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

[wraper]

Rechargeable batteries when new are completely different kettle of fish to rechargeable batteries that are not so new clearly as the OP has already reported, the meter is performing perfectly on alkaline batteries.

I have tried to use rechargeable batteries myself on a many occasions and it has been my experience that once they are a few months old, they do not seem to be as effective as they were and then at that stage alkaline just seem to be a better bet all round and in general more cost effective as the rechargeables are that much more expensive to begin with.

I have tried many makes and capacities and the end result is the same, a few charging cycles and the performance drops off, maybe I've unlucky and have brought batteries that had been shelf sitting too long I don't know.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     

Regular NiMH have extremely high self discharge rate. After a half a hear they will be empty on their own, without any load. Eneloop does not have this issue. Also unless you do something ridiculous to them, they'll last hundreds of recharge cycles without any noticeable degradation. BTW just buy white IKEA LADDA, they are Eneloop pro in disguise for a fraction of the price.
https://www.ikea.com/gb/en/p/ladda-rechargeable-battery-70303876/
https://www.ikea.com/gb/en/p/ladda-rechargeable-battery-90303880/
Also they don't leak. Alkalines leaking twice in my Keysight U1272A and back cover replacement was enough to decide never buying them again.

once they are a few months old, they do not seem to be as effective as they were

That's some first class nonsense BTW. They easily last for more than a decade if treated properly.

[Specmaster]

@wraper Next time I go to Ikea I'll grab some AA's and give them a try then and see how I get on with them.

[Miti]

The BM 235
seems to stay stuck in the startup process, means when I switch from "off" to a function, the LCD shows all segments as black (which is normal for about half a second), but the device never pulls through to the selected function. The display stays in the state of all segments black.

I suspected the eneloops to cause this, as they by default have a voltage of 1,2V, whereas alkalines have a voltage of 1,5V, which I suspected to make problems during a phase of higher power requirements during startup of the multimeter.

A phase of higher power during startup? Why would that be? I don't expect that instrument to draw more than 10-15mA, unless it is defective.
A short inrush current to charge some capacitors, if at all, shouldn't be a problem either.

I have an old Protek HC81 that does exactly that if I push a button right after the power on, during the display test phase. It stays there with all the segments turned on, until I release that button.

Can you try the same thing with the alkaline batteries? Just push any button during the display test and see if you can duplicate your issue.
You may have some dirty button contacts, or some moisture.

[derree]

The BM 235
seems to stay stuck in the startup process, means when I switch from "off" to a function, the LCD shows all segments as black (which is normal for about half a second), but the device never pulls through to the selected function. The display stays in the state of all segments black.

I suspected the eneloops to cause this, as they by default have a voltage of 1,2V, whereas alkalines have a voltage of 1,5V, which I suspected to make problems during a phase of higher power requirements during startup of the multimeter.

A phase of higher power during startup? Why would that be? I don't expect that instrument to draw more than 10-15mA, unless it is defective.
A short inrush current to charge some capacitors, if at all, shouldn't be a problem either.

I have an old Protek HC81 that does exactly that if I push a button right after the power on, during the display test phase. It stays there with all the segments turned on, until I release that button.

Can you try the same thing with the alkaline batteries? Just push any button during the display test and see if you can duplicate your issue.
You may have some dirty button contacts, or some moisture.

Hi,

I already tried that, pressing some of the buttons during startup with both, alkalines and eneloops. Same result: 2 times of 10, the meter with eneloops is stuck in the boot process, with alkalines the meter pulls through every single time.

I have to correct myself, the eneloops are older than a year, it was my second batch bought in September 2017, so we are talking about 2 years now. My fault!

[Specmaster]

Any idea how many times they were recharged during that time? So far my experience has shown with batteries that have been recharged 2 or 3 times and then not used for while fail next time they are charged with error codes on the battery charger. Whereas alkaline batteries are quite happy with periods of non-use Ni-MH arent.

[wraper]

2 or 3 times and then not used for while fail next time they are charged with error codes on the battery charger

Sounds like your charger is (probably faulty) crap. It's your charger what fails, not batteries  .