Need some advice and help

[nw5951]

As the title really, as I'm a complete idiot when you start talking about volts/amps/draw and so on I thought I'd ask you lot as I know there are plenty of knowlegeable guys out there.
I'm running a lamp for night lamping its one of these
http://www.deben.com/lights_lamping/tracer_gunlights/mini.php
Deben tracer mini, in case the link doesn't work, runs on a 3ah 12v battery (35w bulb)and there lies the quandry...I need a new battery but as I'm always lamping on foot I'd like to try and save a bit of weight.
I can get a new battery but they weigh in at approx 1.2kg or there is a new Lithium poly battery but at the "deben" cost of £84 which as always for the UK is overpriced I reckon...The deben li-po is 5ah and they say runs the lamp for approx 1 hr 30 but i'm happy with an 1 hrs runtime anyways.
I've seen this
http://www.flyonthewall.uk.com/12v-....html?osCsid=86d0230339832d7b564683977a1fb912
Which if the description is to be believed is
Product Details

9v or 12v switchable high capacity rechargeable Lithium battery pack with charger.

6600 mAh can power a camera or receiver for up to 60 hrs.

Capacity: 6600mAh
Battery weight: 200g
Dimensions: 95 x 55 x 20 mm,
Lots of saved weight but being a complete numpty with electronics and so on thats where I need the advice...would this work firstly and secondly what do you think the runtime would be?...thanks for any replies much appreciated. Also the deben uses a bullet type connector so I presume I'd have to make one up for the new battery.

 

[BVH]

Seems to me based on the case size, a max of 6 ea., 18650 cylindrical cells would fit into it. The newest Panasonic 18650 cells are rated at 2.9 AH so a 3 Series, 2 Parallel setup would at a maximum, be only 5.8 AH. My guess would be that they are using 2.2 AH cells, yielding only 4.4 AH. Also, the seller indicates only a 15 increase in run time over the SLA battery. This does not make sense given their claim of 6.6 AH for the Lithium battery. I would guess it's really a 4.4 AH battery. All in all, probably not a bad replacement for your situation.

If they're using a smaller Lithium cell, well, then maybe it's possible but I still wonder at only 15 minutes of increased run time. 3 AH SLA vrs 6.6 AH Lithium should equate to at least 1.75 times or more runtime.