eneloop rechargeable batteries

[Nathaniel]

This is not a photographic question but relates to eneloop batteries which we all seem to be using now.

I use a wrist type blood pressure monitor to keep a routine check on my self, apart from period monitoring with my GP. I recently bought a set of AAA eneloop batteries and although they are full of charge, I find that the blood pressure monitor does not function when I replace the duracell batteries in the monitor. Any reason why eneloop rechargeable batteries do not work with my BP monitor?

Many thanks

Nathaniel

[George Bear]

Re: eneloop rechargeable batteries

Might be the voltage.

[Paulstw]

Re: eneloop rechargeable batteries

Could be the type of battery Nat. Eneloop rechargeable are Nickel–metal hydride batteries and standard charge are Alkaline. I dunno just clutching at straws I think.

[CountDavid]

Re: eneloop rechargeable batteries

Hi Nat - as George says voltage may be an issue. Typically rechargeable batteries run a lower voltage than "normal" batteries. I would check the instruction manual for the monitor to see what voltage it requires and if alkaline is specified.

David

[Nathaniel]

Re: eneloop rechargeable batteries

Thanks George,Paul and David for your prompt replies. Unfortunately I don't have the instructions for my BP monitor as I have lost it whilst downsizing and moving. At the moment I find that I have to keep on replacing my "normal" batteries (two every time), when I find I get the "low" battery signal on my BP monitor. Just as a matter of note, I might say that even when I get the "low battery" signal on my BP monitor, I find that the alkaline and other batteries have reasonable charge as indicated by my battery checker- a separate device I have got AND they work fine on say my TV, DVD and similar handsets. I have not tried the rechargeables on my handsets yet.

[mikep]

Re: eneloop rechargeable batteries

Does the monitor still work with new Duracells... And do the eneloops work in another device? If so, the above comments are correct. Process of elimination!

Mike

[Nathaniel]

Re: eneloop rechargeable batteries

Mike, the BP works fine with new Duracells or other normal heavy duty batteries. I check these on my battery checker and they show the green symbol. But as soon as the batteries go to the yellow symbol on my battery checker, the BP monitor works slowly and shows the "low battery" symbol. However these "low" batteries work fine on my other devices like the TV handsets, clocks and similar. The only problem I have got with these new AAA duracell batteries is that I find that I have to keep on replacing them for fresh ones, and also accumulating a bag full of semi discharged duracell batteries which are of the wrong size apart from my TV/DVD and other remote handsets, which accept AAA batteries.

I therefore wonder whether there are other rechargeable batteries which will give the correct voltage for my BP monitor to function, without my changing batteries almost every month and piling up semi discharged AAA batteries.

Needless to say, the BP monitor is one of my "life savers" since my stroke.

[CountDavid]

Re: eneloop rechargeable batteries

Unfortunately I don't have the instructions for my BP monitor as I have lost it....

Nat - you might find a copy to read on the internet - worth a quick search

David

[S_J_P]

Re: eneloop rechargeable batteries

Nat, it's almost certainly voltage issues. Dry-cells start at 1.5v whereas rechargeable operate at 1.2v and some equipment is sensitive to this difference.

However (there's always a however isn't there?) it's not that simple! Normal dry-cells may start at 1.5V but this falls pretty rapidly as they discharge whereas a 1.2v rechargeable will maintain 1.2v until it's almost depleted, this may be the reason the BP Monitor is showing low-battery when your battery tester is still showing them to be good, it is very intolerant of even a small voltage drop.

Your best bet is to stick with dry-cells I think!

[Nathaniel]

Re: eneloop rechargeable batteries

Thanks David and Steve. I think it is the dry cells that I should use in my monitor. I did run up to the hardware store and manged to get 8 AAA Panasonic batteries for £2.99 (BOF scheme) and checked my BP and it was reading 122/82 with pulse at 69. So I am a happy bunny today. Furthermore my BP is keeping a constant, steady reading. So I will close this thread with the caveat that not all rechargeables are compatibile with electronic devices. There is a place for dry cells as well- which is on the expensive side for me.

[Oggie]

Re: eneloop rechargeable batteries

Generally Eneloops will work harder as when you start to draw a current from them, the voltage will hold up better than single use cells, but if the unit draws very small current it just may see the voltage as low. It surprises me though. Most modern electrics is pretty tolerant.

[Nathaniel]

Re: eneloop rechargeable batteries

It is a big disappointment to me that the AAA eneloop batteries I bought specially for use with my BP monitor does not work with it but I have to now put up with the dry cells; unless of course I buy another BP monitor which will function with rechargeable batteries.

[Longshot]

Re: eneloop rechargeable batteries

Your BP monitor what make ? My wife is diabetic type 1, she uses a Accu-Chek blood monitor, yes different to yours I know but they supply that free ! Hope it helps.
Graham

[Nathaniel]

Re: eneloop rechargeable batteries

Graham, Mine is a Braun which I bought myself. Thanks for the information. I will check this out.

[the black fox]

Re: eneloop rechargeable batteries

s_J_p got it spot on nat ,its the voltage drop ,your device is obviously made to only work at a certain voltage .without much tolerance .standard batteries are usually stated to be 1.5 volts but will often measure up to 1.7 or even 1.8 volts when tested on a voltmeter ,where as most rechargeables will only measure 1.2 volts when fully charged .

the best rechargeables i ever found were vaporex they are hard to find but give good results ,we used to use them in metal detectors and found they actually increased the depth of the signals ,unlike any other batteries made and tested up to that point in time (about 5 years ago)

as an aside you often get good deals on duracells in large packets at B & Q ,worth a look theres one opposite sainsburys