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This is the new (well kind of been around for a while now), Lithium Battery system from Reeds Prospecting Supplies. It comes in a very nice metal box unlike the old ugly diecast box of the past but has it changed much? Well to RPS credit yes it has. They obviously got hold of someone that had a better understanding of electronics than the first one. Lets take a look at it in detail.

First thing you notice is that the layout is now done on a proper PCB rather than the wire system of the old one. Also it has now followed my system in that the PCB also contains an audio amp as well. The regulator has been upgraded to a LM2677 family of switching regulators. The numbers are rubbed off but the IC is a National 7 pin switching regulator and there are not that many with the same pin configuration. The basic circuit is below and this is straight from the datasheets, I do have the actual circuit but found it easier to put this one up:

The amplifier section is to the right of the photo above by the headphone socket. This also has the numbers taken off but the configuration is pretty much standard LM386 pattern. I drew the circuit out below:


I never fird the unit up on a detector as I didn't see the need. The battery pack is the same as the previous model and the extra advertised usuage time (from 8 -12+ hours) would be due to the efficiency of the regulator. Below are photo's of the circuit boards:

The overall impression is well done Bernd, just a pity that it comes with such a price tag. In the above photo you can see at the top on the left of the inductor is a blue trimpot, this you can make small adjustments to change your voltage. I never played with it to see the range but I imagine it can go around .5V. The system I was designing was similar to my own but instead of Li-Ion I am using Li-Polymer which have a higher rating and are reasonably cheap. I buy the packs (3sx4p) 11.1V 8000mAhr which with a standard regulator give me 11+ hours. If I was to use a similar design (Switching Regulator) I'd imagine the time would stretch at least a few hours more, considering the battery packs cost me US$80 and the chargers only US$40. These are sample prices and the chargers are balanced chargers which means all batteries are charged equally.

In summary the RPS system is very good and is a good choice for what is available around. If you are not running a variable system like mine then the other obvious choice is to go with Coiltek's cam-corder battery system. I have made these and if you go to my forum you can see the test I did on my own system. This is just by running the battery without any regulation straight into the detector so 8.4V and after running for 11 hours it had drop to 7.3V.

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