Yes, thanks for the recommendation for batteryspace. NiMH cells for sure. Going to get an extra set & also use them in a radio. Wondered whether the batteries were really good for "500 cycles" as claimed, and whether the smart charger was really smart enough not to kill them young.
Specifically, if the 'smart charger' detects negative delta V, has two settings 1 A and 2 A, and recommends changing between 1 A for batteries < 2000 mAh and 2 A for > 2000 mAh... will it have a problem detecting (a slower to change?) -dV for a 10000 mAh pack?
EDIT - OK so I've been inspired to google for answers - here's an interesting site - http://www.powerstream.com/NiMH.htm
. Says -dV is not reliable. Says charging efficiency is typically ~66%. (1.5 Ah of charging gets 1.0 Ah of charge). Also says if charging at <= C/10, don't have to worry about overcharging. So I'll get the 600 mA charger ( =C/17 for 10000 mAh D cells ), and charge for over 24 hrs or so w/o worrying about overcharging. Is this OK?
Edit 2 - I got over the fear and cracked open the water bottle battery case. There is a 4/3A x 4 battery pack in there. These are marked '2500 mAh' while at batteryspac*.com the new 4/3As are good for around 4000 mAh. So I'm not sure how many mAhs are actually there, but I'm sure that AAs will work well enough, given that NiMHs are happy giving current at least up to C/1. Connector looks like a 'Mini Tamiya' with female pins male housing. I've ordered two 4xAA holders and two connectors and 12 new NiMH AAs, already have a smart charger for AAs. I'll be ready for a much longer night ride than I can imagine doing.
Edit 3 - It's a nice light. '255 lumens' or whatever, it's more than enough for me. I haven't challenged the battery enough yet to know if it's good for the claimed 3 1/2 hrs.
Last edited by duffer1960; 10-15-09 at 12:43 PM.