REFLECTOR: It's been really quiet this week

[Brian Michalk]

I've been flight testing.  It's a slow process for me, since my engine 
design while Franklin based, has EFI and EI.
I have been battling high CHT's even in the cooler weather, and am 
seeing positive results as the engine breaks in.

Specifically, I've been testing the forward CG limits, and have decided 
that my decision to move equipment as far forward as possible was a bad 
one.  I was intending to have Juanita be able to fly the airplane 
without ballast, but with my weight, I can't really carry much in the 
copilot seat.  I mounted a big Optima Red Top at a 15 inch arm 
location.  This weekend I relocated it temporarily to just forward of 
the whales tail, but for a permanent solution, I am looking at some of 
the really lightweight batteries that are out there, and am having a 
hard time making up my mind.

Option 1: some lightweight lead/acid battery
Option 2: an alternative chemistry

For option 1, John mentioned the Braille batteries.  I looked online, 
and people seem to think that Braille is stretching their performance 
numbers, but if Velocity is using them, then that's a pretty good 
endorsement.  There are also Odyssey batteries that look pretty good as 
well.

Option 2 for me would be the new LiFe (Lithium Iron) batteries that are 
used in some motorcycles, snowmobiles and jet skis. Those are all pretty 
high vibration environments, which was my first concern.  Next, they are 
really incredibly lightweight.
Now, when these batteries reach 13 volts, they are basically dead, with 
30% capacity remaining.  They are fully charged at 14.3 volts, and 
appear to take a charging voltage up to 15 volts.  For me, I'd need to 
convert my internal regulated alternator to external, and bump up the 
voltage to accommodate these new batteries.
Another down side is, like the LiPo batteries, these need to have the 
cells balanced.  There is a special connector that ensures all of the 
cells are charged to their proper voltage, but balancing a battery 
doesn't have to be performed for every charge.  I also think that rather 
than charging through the balancing port, a person could use a hobby 
grade balancer that places a load on cells to draw down their voltage, 
achieving the same goal.  Bulk charge through the terminals, then 
balance by discharging excess capacity.
And another downside is that they like to be stored at something like 
80% capacity.  This may be fine for our needs.  As long as they can 
start the plane, they can be charged at high currents, so within a few 
minutes after starting they would be at 100%.
Okay.  For one final upside:  The higher operating voltage will spin a 
prop faster, and will have smaller voltage drop in your cables.  I'm 
solid state switching, losing a couple of tenths of volts across each 
solid state relay.  This bump up in voltage would really be nice for my 
electric gyros, which are always complaining about low voltage until I 
bring up the engine RPM's.


    LFX19A4-BS12MSRP: $199.95

SHORAI LFX Lithium-ion Powersports battery,19AH 12V, "A" polarity, Case 
Type 4
Length 5.83"
Width 3.39"
Height 3.46"
Weight 2.32lbs
CCA 285amps

I would need two of those, which would put me at the lower end of my CCA 
requirements.
www.shoraipower.com


On 02/17/2014 08:29 AM, Reiff Lorenz wrote:
>
> The Reflector has been so quiet the past 5 days. I've been busy 
> traveling for work and tackling home renovation projects that I have 
> not been building much. (One of my trips was to Seattle, though, and I 
> stayed an extra day with Clay Chase to work on his kit, so I guess 
> that counts as building time; just not on my plane!)
>
> Hope everyone else is finding more time than I am to build or fly.
>
> *Reiff Lorenz, Dayton, OH*
>
> Velocity XL-RG, 53% complete
>
> Currently working on: March issue of Velocity News
>
>
>
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