I've just ordered a new R-44 (woohoo!) and have been researching powering options.
I had been thinking in terms of cheap n' simple SLA, but its many issues have led me to reject it. My local WallyWorld doesn't carry the infamous eponymous battery, so I was launched into an internet research project.
LiFePO4 (Lithium Iron Phosphate) is a new generation lithium battery technology that's safer than other lithium chemistries, has none of SLA's self-discharge or cycling issues, and is apparently environmentally very low-impact (as batteries go). A good overview article is found
here.
Batteryspace is carrying a good selection.
This puppy looks like it will run the R-44 for at least 6 hours, and possibly up to 14 hours! (I will explain my rationale for this later)
It is 6.8 Ah and about the same physical size as an SLA of the same capacity, but only weighs 2 lbs. It outputs 12.8 volts, which is a bonus over the WW battery at 9v. It's ~$96 right now, and its
special charger is ~$22 (so battery pack + charger around $118 as of may '09). While this is kinda spendy up front, the lifespan for LiFePO4 is supposedly an amazing 2000+ charge cycles. Over the long run, this theoretically makes the cost per recording-hour (or watt-hours or whatever unit) the cheapest of any battery type!
As for runtime, the R-44 specs state it draws 1.2A at 9-16v. It makes sense that it should draw slightly less current at higher voltage, slightly more at lower voltage, so it's hard to say exactly at what voltage it draws 1.2A. Using the mean of 12.5v, the R-44 power draw would be 15 watts, i.e.: 12.5v x 1.2A. However, in
this thread, mblindsey ran tests and got ~8.5 hours on a 5.4Ah, 9v WallyWorld battery (running 4 phantom pwered mics at 24/48). This indicates a power draw of only ~6watts! i.e.: (5.4 Ah x 9v) / 8.5 hrs.
At the higher power requirement this LiFePO4 pack calculates to give 5.8 hours runtime, i.e.: (6.8 Ah x 12.8v)/15w = 5.8
At the lower, but real life tested, power requirement, it should give around 14.5 hours! i.e.: (6.8 Ah x 12.8v)/6w = 14.5
BTW,
here is a page at Batteryspace which goes over the pertinent battery math.
A search here on TS turned up very little on this battery type. I'm intensely interested if any one has used them, your observations, and in whatever flaws you find in my thinking-through-it process. Critiques please!
Peace,
Sanaka
EDIT: While this is a fine battery, it is expensive and my thinking that 12v is better for running an R-44 was wrong. Please check this thread for info from Edirol.