What is it?

Quite a while back (long before the first system became available) we had ideas of making a system using these types of batteries but the prohibitive price, for us cheapskates anyway, made it uneconomical. We couldn't really justify the huge sale price as with the GPM we wanted something that was affordable to all. Anyway just recently we decided to look into it a little more. We have trialled a system using a straight Video Cam 7.2V 6000mA battery and it works well without the need for a regulator. To give an example of our preliminary tests, a mate (Outback) tried it on a GPM and with a very small modification it ran the detector for 3.5 hours and only went down to 7.8V. These batteries charge to around 8.2 - 8.4V Ideal for the GPM and as you can see very little reduction from full after 3.5 hours. We also found that the difference from 8 - 8.4V (as DAE) is quite small. The total cost so far has been around $90 with a 12V/240V charger included. A little mod has to be done and that's why we are experimenting more. The reason for the mod is some Lithium batteries will shut down immediately on the start-up of the detector due to the sudden current surge.

Once we have it going I will let you know.


Keep watching this space.

Thanks Doug on the compliment. Yes the major problem with Lithium batteries designed for low current items such as videocams and the such is that when used with a detector that immediately pulls a high current (although with our detectors the initial 1ms can be 1.5A) the safety circuit (as described in my article about Reeds Lithium) will immediately switch out the batteries to prevent any over current like a short circuit. Basically the safety circuit presumes that is what is happening. My mate who has experimented with this battery is also using a switch. At the moment there is no way out because of the above, you have to use the battery to turn on the detector. I am surprised that Coiltek's battery needs that as I am sure they would be regulating the unit but that obviously does not help as the cam batteries are obviously manufactured for low on current surge.

The battery AZNuggetBob mentioned on ebay I looked at but was unable to see the physical parameters such as Voltage and Current capacity. If you want to experiment buy a battery with these specs: 7.2V 6000+mA. Remember the rule of thumb is for every 1000mA (1A) our detectors will run for just over an hour.

Have fun...

Hi NuggetBob, Firstly I would suggest that you do not play with lithium batteries at all if you are considering doing so (I mean internally), You can pull them out of a pack WITH the circuit (safety) in place and attached!!! and put in a different package. NEVER solder directly to the batteries and use the wires from the out put of the safety circuit to do any other connections.

Now with that out of the way, Standard Lithium Ion batteries are prone to shelf life and start from manufacture, the new Lithium Polymer batteries however (as far as I understand) do not suffer from this effect. Also the rate of degeneration is better. This is why I suspect the 5 year warranty. Later to aid the DIY I will post the circuit and description for my regulator. Now running a 7.2V Lithium with 2000/2100 there is no problem with running direct (except for the battery switch off as explained before) The initial voltage level will be 8.2 - 8.4V and will drop down to around 6.4V when depleted. By then your battery will generally have switched off. So no harm to the detector to speak of. 2200 and GP's will not be able to run a straight 7.2V battery because of the high charged-up voltage level.

The best way to lower the voltage is by using diodes in series to obtain the voltage level required, but of course this means the level will drop to a lower voltage quicker unless you can switch out diodes as battery level decreases.....

Catch ya later

AZNuggetBob wrote:

Do you think anyone would be interested in a post about hip mounting?? I solved several problems with hip mounting a few years ago on my 2000 and used the same setup on my 2100. Nuggetbob

Most definitely Bob, you can either post in General Discussion or even as an article in DIY or Prospecting tips, Up to you. I even would be interested....