I have 2 Lenmar LISG480 7.4V- 6000mAh Lithium Ion batteries (www.lenmar.com
) which I used on my Leaf Aptus II 10 back. They will fit and work on any Leaf Aptus (but not pre-aptus Leaf digital backs).
These are great batteries, giving extremely long shooting time before having to recharge. I never exhausted either of these batteries in any one day of shooting, and I shoot a long day--it really gives you flexibility in planning your shoots and saves interruptions at inopportune times. These retail for anywhere from $50-70. I also have 2 Leaf 2350 mAh batteries which are older but still charge and last as good as ever which I will include with the larger batters--entire pack of 4 batteries as identified for $49.95. + shipping