Battery Modification Question

[Skippy]

The battery in his Whites is under the elbow cup. Removing the weight will upset the balance. Using decent rechargeables should be fine, don't get hung up on the capacity. The manual says it runs for 20 hours (on alkaline) so 1900 or 2500 mAh is really not important. The discharge current will be less than 100mA, so that Eneloop vs Alkaline graph posted earlier is not relevant, as it's a hard discharge one (500mA, 2 hours)

[Sacchetti]

Hi,
a good circuit to avoid sulphation I found in Elektor magazine n.9 of 2001.
I found it very useful also for moto and car battery.

Hi!
There is not necessity lo limit the current because the circuit get what it need to work.
It is important instead to have the same voltage, in this case 12V.
Remember when you have a PB Gel full charged do you have 14,4V.
The maximum voltage I seen with 8 new alkaline battery is instead 13,2V, but it depends also from brand and model.
You must be sure these 1,2V volt added do not damage your MD.
Do you have a schematic? Which is brand and model?

After this check if is possible to use it without problem then you can evaluate 1,3Ah or 2Ah model.
More Ah has the problem relative to the weight.
Less Ah has the problem relative to the time of working, it is reduced.
Therefore you must check which is the current absorbtion of your MD.
Normally, PI technology absorb more current if compared to IB technology.
These are generic indications, it is better also to measure the current absorbed from you MD.
Remember when it sound it is bigger.
The same if your MD has light in LCD, when you turn on it your MD get more current.

Personally, I do not like PB Gel battery because if you do not use them continuosly then you can meet problems relative to its sulfation.
You can found in internet some schematic circuits to solve this problem.
Normally they send high frequency electronic pulses.
A good one circuit was showed from elektor magazine in the past years but I do not remember in which month/year but I can search it if you are interested.

[sinclairuser]

The Eneloop rechargeables your son gave you, what are they in milliamps?

3rd gen ( HR-3UTGB 1900mah(AA)), they were brand new in packets, but since the 4th gen was introduced in april 2013 they must have been new old stock.

[Funfinder]

@ Ham
Such 12vdc gel cell (lead?) is not worth the whole trouble, especially no extra body battery pack.

If you have already a set of 8 NiMH or Eneloops ("Ready To Use") accus compare them with
usual batteries concerning the detectors depth - test your detector with them to see the results.
Usually those rechargables have 1,2v so the detector in total receives 9,6v instead of 12v.
Normally this will not reduce depth or volume etc.


If you're really experienced with such stuff you also can use a Li-Po accu with 3 cells in series,
it will provide 11,1v which is even better seen from the voltage, milliAmps and weight.

[Sacchetti]

@ Ham
Such 12vdc gel cell (lead?) is not worth the whole trouble, especially no extra body battery pack.

If you have already a set of 8 NiMH or Eneloops ("Ready To Use") accus compare them with
usual batteries concerning the detectors depth - test your detector with them to see the results.
Usually those rechargables have 1,2v so the detector in total receives 9,6v instead of 12v.
Normally this will not reduce depth or volume etc.


If you're really experienced with such stuff you also can use a Li-Po accu with 3 cells in series,
it will provide 11,1v which is even better seen from the voltage, milliAmps and weight.

Hi Funfinder!
I do not have the schematic of this detector but if it does not have a low dropout regulator I think can be a problem using a set of 8 NiMH cells.

At page 6 of user manual is explained that exist a NiMH battery pack, not to use them directly as replacement of alkaline.

[Funfinder]

hi,
Simply test it, you can't do any harm to the detector if you're checking
out the depth with a set of NiMH accus instead those alkalines.

It would be the same as if the usual batteries are no longer fully charged but still working yet.


And per instance the Garrett Euro Ace also works fine with just 4,8v instead of 6v.


If you don't want to buy NiMH cells first, you also can replace 2 of the usual 1,5v cells
with some battery-dummies made of pressed alu-foil so you will have 9v instead of 12v.

If the detector still works fine it will work the same good with 8x 1,2 NiMH cells.