Hi All,
One thing I do when going out for just a short hunt is to use a lighter battery. The run time is shortened but when only going to hunt for a couple of hours, why lug the extra weight in the detector when another spare battery can be carried on the belt or in a pouch. Don't forget to include the shutdown circuitry if you build your own. This will protect your cells from destruction which can easily happen if the voltage drops below 2.75 per cell. Low voltage can easily render one or more cells worthless. If one cell fails, then the entire pack won't work correctly.
Now, the TDI battery is made up of 8 cells, two parallel packs of 4 cells in series. The 4 cells in series produce the initial 16.8V and by paralleling two packs, we get the higher current capability.
So, by now many of you have guessed that you can run on a single series pack of 4 cells which is obviously lighter than the standard factory 8 pack. The down side is the run time is shortened by more than 1/2. If you decide to build your own pack, then it is best to use quality Japanese or Korean cells such as Panasonic or one of the other key Japanese or Korean brands. Some of the cells you can buy on Ebay boast a high current capability but fall far short.
A good quality cell will have a 2600ma capability with top higher current ones having capabilities of a little over 3000ma. Many of the cheaper cells may boast a 4000ma rating but often have a real capability of a little over 2000ma.
A typical current draw of the TDI is 650+mah so 4 hours is absolute tops for most 4 packs. Usually, one can begin to notice more noise and some change in detection beginning at 2+ hours or so.
On one of my TDI's, I added a 12V regulator right after the switch. This stabilizes things, lowers the current draw a little which lengthens the run time a little. Right now, I don't remember the actual current draw, but I think it went down to closer to 500mah but did keep things quieter and more stable with no noticeable depth loss.
Reg
One thing I do when going out for just a short hunt is to use a lighter battery. The run time is shortened but when only going to hunt for a couple of hours, why lug the extra weight in the detector when another spare battery can be carried on the belt or in a pouch. Don't forget to include the shutdown circuitry if you build your own. This will protect your cells from destruction which can easily happen if the voltage drops below 2.75 per cell. Low voltage can easily render one or more cells worthless. If one cell fails, then the entire pack won't work correctly.
Now, the TDI battery is made up of 8 cells, two parallel packs of 4 cells in series. The 4 cells in series produce the initial 16.8V and by paralleling two packs, we get the higher current capability.
So, by now many of you have guessed that you can run on a single series pack of 4 cells which is obviously lighter than the standard factory 8 pack. The down side is the run time is shortened by more than 1/2. If you decide to build your own pack, then it is best to use quality Japanese or Korean cells such as Panasonic or one of the other key Japanese or Korean brands. Some of the cells you can buy on Ebay boast a high current capability but fall far short.
A good quality cell will have a 2600ma capability with top higher current ones having capabilities of a little over 3000ma. Many of the cheaper cells may boast a 4000ma rating but often have a real capability of a little over 2000ma.
A typical current draw of the TDI is 650+mah so 4 hours is absolute tops for most 4 packs. Usually, one can begin to notice more noise and some change in detection beginning at 2+ hours or so.
On one of my TDI's, I added a 12V regulator right after the switch. This stabilizes things, lowers the current draw a little which lengthens the run time a little. Right now, I don't remember the actual current draw, but I think it went down to closer to 500mah but did keep things quieter and more stable with no noticeable depth loss.
Reg
