dignfool said:
Cold, windy, and wet! No digging today dang it!
Anyways.....I am in the process of rebuilding my rechargeable battery pack and noticed something. The rechargeable pack contains ten 1.2volt batteries. The backup "AA" pack holds eight 1.2volt batteries. Is there a regulator built into the rechargeable pack? If not it would appear I get more power from the rechargeable pack. I could use some input here. I'm just curious why one pack would supply 12volts while the other supplies 9.6volts. Also does this effect performance?
Higher voltage won't give a detector more performance. They use a voltage regulator to stabilize the output voltage to the circuit board. In other words, 10V versus 12V supplied to the regulator, the output isn't going to change. It'll stay at whatever the board wants. If it's 8V then that's what the board sees, no matter how much voltage you feed the regulator.
I've seen some try to increase the performance of the machine by feeding it more voltage. Unless they are using some odd home made detector or one from long ago perhaps that doesn't have a regulator in it, all they are doing is risking burning out the regulator. Not sure if the Sovereign is using a linear or a switching regulator, but if it's linear they get rid of excess voltage by converting it to heat, and if it gets too hot then it'll either burn out or shut down on a thermal overload switch (if the regulator has one). If they are lucking, when the thermal switch in the regulator cools down it'll reset and work again, but those kinds of safety features usually have a very limited life span of "trips" before they won't work anymore.
If you dig up some old threads searching for "Kered", he's ran 8AA rechargable nimhs in his 8AA holder and got long run times with it. The key for him was to charge the pack before use, as nimhs self drain (they have low self draining ones these days too), and to also use a higher capacity cell of about 2600ma or higher. Nimhs might start out at a lower voltage than regular AAs, but they hold their voltage higher and more steady as the cells drained compared to non-rechargeables. For me, in many devices I've found a 2600ma or higher cell often gives me much longer run times than non-rechargeable AAs. In my GT though I run a 3 cell lipo for weight/convience factors. Just about zero self discharge on the shelf and fast 1 hour charge times.
The extra 2 cells in the Minelab pack helps to keep the voltage high enough after they've sat for a while so that they'll still have some run time to them. Plus, the capacity of the cells isn't all that much at all (be it say around 1000ma on the GT pack), so with the extra two cells the voltage is boosted higher both while sitting on the shelf, and also while the pack is draining while be used. Otherwise the low battery alarm would kick in far sooner for either of those reasons. Wouldn't be too fun to charge the pack and then a week later it gets about 1 hour of run time first time you use it.
