[1] unit locking up when external power finishes recharging the internal battery.
Resolution: Last night I found out the JB3 will run from external DC power with no battery in the battery bays.
It's actually not from 'finishing the recharge'. External power seems to always be given the priority in terms of where the JB3 looks for power. All that's going on here is that recharging the internal battery has depleted the external one. Then you get the same thing that happens if you run off external power past the safe point.
The solution is to start with the external and internal in place. Then, at a safe point, pull the external (and switch over to internal). If you go internal first, the external will use all it's power recharging the internal and you'll lock up as described.
I wouldn't recommend running without the internal battery - it's your safeguard against power interruption (cord gets yanked). Just make sure it's charged first and you won't have the lockup problem as long as you pull the external in time.
check my last post here
http://www.taperssection.com/yabbse/index.php?board=25;action=display;threadid=9872 for some more details
The JB3 battery is only 1600 or 1700 mAh so you should be able to get better battery life from a 3000 pack. I've used 4 NiMh cells without a regulator to run successfully - other than the slight over-voltage issue right at the start (check that other thread) it works great. If it's really charged up and won't bring the JB3 to life, just run a halogen bulb on it for a minute to take it down to JB3 level voltage. btw, I just chopped a 9.6 pack into two pieces to do this.
You can definitely run a regulator with a 7.2v pack, but all you do is burn up the extra voltage as heat. It won't run any longer than running 4 of the same NiMh cells straight in. In fact, it may be slightly shorter because of the regulator.
Another thing I did was run one pack for the UA-5 and JB3 together. Just split the power between them - straight for the UA-5, car adapter for the JB3. I could run both devices for 3 hours on a 3000mAh pack (without the JB3 internal). So one strategy is to run both for the first hour or two and then unplug the JB3 for a total run time of 4-5 hours when combined with a single JB3 internal battery.
Both of the above are 'hot swappable' as long as you have the internal battery in place. The only time it will die is if you mess up and hot swap a weak battery in there. Remember, the JB3 always looks to the external first.
The JB3 is a power pig but it's not quite that bad. I measured 260 mA with peaks of 800 or so on disc writes. For battery life calculations you can consider it to be around 600 mA (which conveniently fits the almost 3 hour battery life of the internal).
Ever start writing a short post and then before you know it.... (I know this happens to you Brian!)