Lith-ion battery

This might be a too technical question to ask but here goes, i see that a rechargable battery system for SD's are avail for quite a high price, has anyone made their own? i found that a Samsung camcorder runs a battery of 7.2 - 7.4 volts 2800mHa @ $16.00 and upwards, chargers 12 and 240 volt@$10.00 and upwards, i thought this is a lot cheaper than buying a so called profesional setup. The only other question i have is what is the mAh of the genuine Minelab batt, does anyone know?

Gooday JeffH,
Firstly you must realise a few things abouyt the camcorder batteries. The stated voltage (7.2-7.4), is the voltage that the battery is when it is almost flat. When it is fully charged, it will be 8.2-8.4v. If you are running a 2000, then it will possibly cope with this but if you are running a 2200d, then it does not like anything above 7.9v. In fact, my 2200d, when I connect 7.9v to it, may switch on or it may not switch on. I tested this and decided that it was not good for the detector to be MAXed out like this so I would advise not to do it. If you was to build your own, then you must build one that has a voltage drop of no more than .3v but also regulates it to 7.3v, across the regulator, ie 8.4v in -> 7.3v out, 7.4v in -> 7.1v out. You can build one of the Jaycar power supplies (which I did) but you have to run it with a 12v battery and that defeats the purpose as a long lasting 12v battery weighs quite a bit. It will give you constand 7.3v though. By the way 7.3v is the commonly agreed "sweet spot" for the SD detectors.
As far as the current draw, the 2200d (and I presume the 2000 and 2100 wouldn't be too disimallar) draw approx .75A with a 11"DD coil and about .85A (from memory) with a 14"DD coil. They do require an initial burst at startup which can overload a camcorder battery which would mean you need to place it back in the charger for resetting, but I've only had this happen 1 or 2 times to me.
Personnaly I would look for a well made bought one, ie Coiltek Pocket Rocket, Reeds Lucky Lark, Ismael Jones new wireless power supply just to mention a few of the better known ones. There are others that are listed on eBay that I would not particularly recommend. These would enhance your detector and it's abilities and the cost of one of these would be probably less than fixing your detector if you accidently did some damage from a home made power supply.
Cheers

Im jumping the gun a bit, as i dont have a SD2200 yet, next wk it'll be here, the previous owner has supplied a batt regulater as well as some gelcell batteries, i'll have to wait to see what type and how he's been using it but he has mentioned it was running on 7.2v

If you like, let me know when it arrives and what items you have with it and I'll let you know what I think you can do with what you have and what else you may need.

Interesting on ebay, the RC cars use a 7.2v battery up to 6800mHa, only $29.

Look with caution and don't forget what I mentioned before about the battery when it is fully charged, this battery will be around 8.2v and will probably (but not certainly) burn out your 2200d. The stated 7.2v is when the battery is almost flat. Smartest thing is to wait and see what comes with the detector first...

7.3V for the 2200 - all the way. You can even clip it the side of the detector cover. makes it easier to cover up with the 'custom-made' (plastic shopping bag) wet weather cover. My old mentors all used and recommended the 7.3v. The only other piece of advice was, switch the battery on and then the 2200. It runs as sweet as and after carrying the old original 2200 battery set up in a harnass, the 7.3v setup was heaven.

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Hi fencejumper - I was told that if the detector was turned on first and then the battery, it could overload it. Anyone got a definate answer? My major problem is the chargers (which arent cheap) keep playing up. Now into a second type and same issues. Despite the cost, they are shockers. Anyone got any ideas on a good charger to buy? Havent visted 'battery world' yet.