Topic: LiFePO4 seems awesome - possible killer R-44 runtimes

[sanaka]

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.

[phanophish]

Depending on how the DC>DC power conversion is handled in the R-44 it is possible that the unit simply dumps the excess voltage as heat and the current draws would remain the same regardless of input voltage.  I have not seen a good analysis of the runtime difference (if any) between varying input voltages.

[bhadella]

That's a whole bunch of ching for just 6.8 ah.   Your can get 5.0 mah LION battery with charger and cables for under $20 new on ebay.  Seems like a no-brainer to me.

[flipp]

what kills it for me are 1) size (primary reason) and 2) cost (secondary and liable to fall in the future); other than those two reasons it looks like a viable option for field power

[sanaka]

phanophish: Good point, though that would be slightly lame if true. When my brain is less fried than currently I'll try to contemplate what the battery run time implications of that may be.

Your can get 5.0 mah LION battery with charger and cables for under $20 new on ebay.

Link? (And assuming you mean 5Ah not mah). That would certainly be something to consider, even if all amp-hours are not created equal. I was more comparing this (in my mind) to Tekkeon, against which it definitely wins, IMO.

flipp: Yes this is a bag-unfriendly/brick-like shape. I work out of a Pelican box so it would be fine for me. However, there's a variety of shapes for these at batteryspace, some flatter. And if you wanted to DIY your own battery pack, you could make almost any shape you wanted from individual cells.


The big attraction is the whole amortized-cost-per-recording-hour-over-life-of-the-battery thing, because this particular chemistry apparently outperforms all others in that regard. Am I making too much of this?

Peace,
Sanaka

[bhadella]

http://cgi.ebay.com/Initial-Universal-Portable-DVD-battery-Brand-New-Inpack_W0QQitemZ250413276938QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3a4dcb5f0a&_trksid=p3911.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

Typical run times have been in the 6 to 8 hour range with this style of battery (long enough that you may run out of card space before the battery  ).   

[bhadella]

If I had a dvd battery failure, I'd toss it and buy another $20 battery instead of putting so much into one battery that can fail.

[sanaka]

Whoa, even if the LiFePO4 is way more reliable, that's fairly amazing. Thanks!

[sunjan]

The big attraction is the whole amortized-cost-per-recording-hour-over-life-of-the-battery thing, because this particular chemistry apparently outperforms all others in that regard. Am I making too much of this?

Comparing new batteries, the energy density of LiFePO4 is actually lower than traditional Li-ion chemistry (but of course way better than SLA):
http://www.batteryuniversity.com/partone-3.htm
For those looking for the highest energy/cubic footprint quota, Li-ion is still king.

The financial benefit of LiFePO4 lies in the potential number of charging cycles, which is possibly 2-3 times that of Li-ion.

So if you have a Li-ion and a LiFePO4 battery with otherwise identical specs, go for LiFePO4 only if the price is not more than 2-3 times the Li-ion.

Personally, I jumped the gun on a 9.6V LiFePO4 that I intend to run with my CA-9100, but I haven't had a chance to try it yet:
http://taperssection.com/index.php/topic,115620.msg1546192.html#msg1546192

From http://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery#Advantages_and_disadvantages
Advantages and disadvantages

The LiFePO4 battery uses a lithium-ion-derived chemistry and shares many of its advantages and disadvantages with other lithium ion battery chemistries. The key advantages for LiFePO4 when compared with LiCoO2 are improved safety through higher resistance to thermal runaway, longer cycle and calendar life, higher current or peak-power rating, and use of iron and phosphate which have lower environmental impact than cobalt. Cost may be a major difference as well, but, that cannot be verified until the cells are more widely used in the marketplace[citation needed].

LFP batteries have some drawbacks:

   1. The specific energy (energy/volume) of a new LFP battery is somewhat lower than that of a new LiCoO2 battery. Battery manufacturers across the world are currently working to find ways to maximize the energy storage performance and reduce size & weight.[6]
   2. Brand new LFP's have been found to fail prematurely if they are "deep cycled" (discharged below 33% level) too early. A break-in period of 20 charging cycles is currently recommended by some distributors.[citation needed]
   3. Rapid charging will shorten lithium-ion battery (including LFP) life-span when compared to traditional trickle charging.[citation needed]

While LiFePO4 cells have lower voltage and energy density than normal, LiCoO2 Li-ion cells, this disadvantage is offset over time by the slower rate of capacity loss (aka greater calendar-life) of LiFePO4 when compared with other lithium-ion battery chemistries (such as LiCoO2 "cobalt" or LiMn2O4 "manganese spinel" based Lithium-ion polymer batteries or Lithium-ion batteries).[7][8] For example:

        * After one year of use, a LiFePO4 cell typically has approximately the same energy density as a normal, LiCoO2 Li-ion cell.
        * Beyond one year of use, a LiFePO4 cell is likely to have higher energy density than a normal, LiCoO2 Li-ion cell due to the differences in their respective calendar-lives.

[Gutbucket]

http://cgi.ebay.com/Initial-Universal-Portable-DVD-battery-Brand...

Typical run times have been in the 6 to 8 hour range with this style of battery (long enough that you may run out of card space before the battery  ).   

Store in the fridge at half charge to greatly extend capacity and lifespan. Info.

[edtyre]

http://cgi.ebay.com/Initial-Universal-Portable-DVD-battery-Brand-New-Inpack_W0QQitemZ250413276938QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3a4dcb5f0a&_trksid=p3911.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

Typical run times have been in the 6 to 8 hour range with this style of battery (long enough that you may run out of card space before the battery  ).   

Ran one of these the other night with my r-44, and got over 6 hours runtime, and only used one bar
out of 4. Not a bad deal for 12.99

[sanaka]

So if you have a Li-ion and a LiFePO4 battery with otherwise identical specs, go for LiFePO4 only if the price is not more than 2-3 times the Li-ion.

That seems like spot-on advice. And given that edtyre:

Ran one of these the other night with my r-44, and got over 6 hours runtime, and only used one bar out of 4. Not a bad deal for 12.99

I'd say, uh, yah, I'm off to ebay to part with $13 or $26. 

And the fridge is a great tip too. That article also made SLA not look so bad (except for weight as always).

Thanks all!

Peace,
Sanaka

[sanaka]

Actually I should ask edtyre: what exactly were you running on your R-44 the other night? All 4 with phantom?

Peace,
Sanaka

[edtyre]

Actually I should ask edtyre: what exactly were you running on your R-44 the other night? All 4 with phantom?

digi in and two analog w/p48

[sanaka]

Cool, thanks!