battery voltage question

[peanut]

like a lot of detectors ,my Garrett Euroace can use either AA alkaline or NiMH rechargable batteries. Although I have now used both types I did'nt really pay much attention to how long each set of batteries lasted.
My question is this , which  batteries should last the longest .?

 The 1.2volt NiMH batteries generally charge up to 1.35- 1.38 volts
wheras the 1.5volt  Alkaline batteries generally have surprise surprise ...about 1.5 volts each, therefore ....

Total voltage of 4x rechargables is about 5.4 volts
Total of 4x Alkalines is about 6 volts

Now I know that the detector power supply board will probably have a 5volt rectifier to fix and stabilise the supply to about 5 volts so the difference shouldn't make any difference to detector performance but presumably  as far as the battery longetivity situation ,the critical thing is the speed of battery voltage decay time for each of the battry types.?

Most of you will probably have switched over to the Aviva video thread by now   but for those of you that are still with me .... which set of batteries will decay the fastest to the point where there is insufficient voltage to run the detector. ?

answers on the end of an AA battery  please  to peanut

ps next rally I think we should have a prize for the deepest hole dug. What do you thing Griffon ?

[Tafflaff (Rob)]

Simples , Its nothing to do with the voltage. What you need to be concerned about is the Mah  (Milli Amp Hours)

The AA rechargables I use are 2900 maH   thats as high as they get.

[ysbytymike]

No expert here Peanut but its the 'mA' is what you want to look out for. The higher the number the longer they retain their working life.
I always use rechargables rated at 2900mA, which I think currently, is the highest they go to although I bought them some time ago and this
might be higher now.

[balaclava]

there is a graph in the back of my minelab user guide that explains it. ill see if i can find it i think it is rechargables hold there voltage constant for longer but are used up faster if that makes any sence 

[Nick]

I've got some 3000 MaH batteries which I shall be trying out on a new Pi detector today.

I understand that although they don't last as long, they produce a more consistent voltage over a given period, which Pi detectors need to operate to their full potential.

[Chef Geoff]

The AA rechargables I use are 2900 maH   thats as high as they get.

WRONG
http://www.amazon.co.uk/Rechargeable-Ni-MH-Batteries-Card-1-2v/dp/B000PC20X8

If you are going out for a whole days detecting then you should be charging your batteries for each session, which means Ni-MH batteries are better as they have no memory build up. If you follow this regime it also means that any battery over 2000Mi-MH will do as they will last the day.

[ysbytymike]

The AA rechargables I use are 2900 maH   thats as high as they get.

WRONG
http://www.amazon.co.uk/Rechargeable-Ni-MH-Batteries-Card-1-2v/dp/B000PC20X8

If you are going out for a whole days detecting then you should be charging your batteries for each session, which means Ni-MH batteries are better as they have no memory build up. If you follow this regime it also means that any battery over 2000Mi-MH will do as they will last the day.

I know that Geoff. Just trying to keep it simple   I did mention that its been some time since I'd bought any and that they might be higher now.. mentioning advantages of Ni-MH is a good point.
One of the first things I do on returning home is to put batteries on charge. Old habit I guess. Checklist of essentials is good idea regardless of how often you do things.


http://en.wikipedia.org/wiki/Nickel–metal_hydride_battery


 

[peanut]

As a budding togger I have switched to using mostly Enelopes . They are amazing batteries. They arrive fully charged and do not deterioate even if left unused for months. Toggers swear by them.
The problem with Alkalines is although they are convenient on the odd occasion when you haven't got the time to recharge I don't think old stock hold their charge very well.

In terms of voltage and Mah , as I understand it .. no matter if you connect dozens of batteries together to get a huge  Mah rating they still don't work once the voltage drops sufficiently that the rectifier isn't driven adequately.  Voltage is what drives the circuitry not Mah

[ysbytymike]

As has been mentioned Peanut. A decent fully charged set of batts should do a full days detecting no probs. 
Where you might have a problem if your running cells in sequence is, if one of the cells is duff and goes down, that would break the sequence and no matter how many cells you have connected they will not work. Check your batts from time to time. Make a mental note of how long each cell takes to charge. If a cell charges much quicker or slower that the rest then throw it in the recycling bin straight away. That way you eliminate problems before they cause failure.

[Chef Geoff]

Good advice Mike. Peanut, it doesn't matter how many batteries you join together your Mah won't go up any higher that the lowest Mah battery, "links in a chain". Mah just refers to the amount of charge and therefore length of use from a single charge, and yes you are right in saying  all modern machines are rectified.

[rjm]

The AA rechargables I use are 2900 maH   thats as high as they get.

WRONG
http://www.amazon.co.uk/Rechargeable-Ni-MH-Batteries-Card-1-2v/dp/B000PC20X8

If you are going out for a whole days detecting then you should be charging your batteries for each session, which means Ni-MH batteries are better as they have no memory build up. If you follow this regime it also means that any battery over 2000Mi-MH will do as they will last the day.

I think you may be wrong.  These are even more powerful......


http://www.ebay.co.uk/itm/New-4-x-3800Mah-AA-Rechargeable-rechargable-batteries-/110741584570?pt=UK_ConsumerElectronics_Batteries_SM&hash=item19c8b67aba

[Tafflaff (Rob)]

The AA rechargables I use are 2900 maH   thats as high as they get.

WRONG
http://www.amazon.co.uk/Rechargeable-Ni-MH-Batteries-Card-1-2v/dp/B000PC20X8

If you are going out for a whole days detecting then you should be charging your batteries for each session, which means Ni-MH batteries are better as they have no memory build up. If you follow this regime it also means that any battery over 2000Mi-MH will do as they will last the day.

I think you may be wrong.  These are even more powerful......


http://www.ebay.co.uk/itm/New-4-x-3800Mah-AA-Rechargeable-rechargable-batteries-/110741584570?pt=UK_ConsumerElectronics_Batteries_SM&hash=item19c8b67aba

awww wow , I know what I'm replacing mine with!

[legio11augustus]

believe it or not a dead battery tested with a meter can show full voltage , its the amperes that matter

[Nick]

Always have an eye for a bargain, so I bought some batteries from the link in RJM's post (3800 MaH).

They sent me 4600 Mah Ni-Mh batteries. I'm not complaining, thanks for the link Bob.
£7.99 for 4 and free delvery 

[CZFisher-man]

Always have an eye for a bargain, so I bought some batteries from the link in RJM's post (3800 MaH).

They sent me 4600 Mah Ni-Mh batteries. I'm not complaining, thanks for the link Bob.
£7.99 for 4 and free delvery 

Hope they are good quality, as I read just read this:
http://forum.bidorbuy.co.za/forum-community-watch/14582-fake-sony-aa-4600mah-batteries-again-others-beware.html