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genie(at)swissmail.org
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 Posted: Sun Jun 15, 2014 9:06 am Post subject: LiFePo Battery by EarthX and Weight Reduction |
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As I have mentioned I have been suffering from starting problems with my
RV-6. In the AeroElectric list several people stated that the Odyssey PC
680 battery by Enersys is very well suited for light aircraft
applications. However, some contributor wrote that if I change battery I
should consider one of the new LiFePo batteries such as EarthX and thus
save 11 lb weight.
What could be wrong with saving 11 lb of weight? The centre of gravity
location. As the battery is placed on the floor in the cockpit just
behind the firewall I measured that its centre of gravity is 54" aft of
datum. On this basis I made a few calculations and figured that with one
pilot, full fuel and full luggage the centre of gravity remains within
limits.
Furthermore it should be taken into consideration that I removed the
ELT. Over here it is only mandatory when crossing a frontier (i.e. for
the duration of a millisecond or so during a flight). Besides, I
understand that the French authorities hate ELTs due to a history of
false alarms. As my ELT weighs 3.3 lb (without antenna or fasteners) and
was mounted in the baggage compartment which is 117" aft of datum I
calculate that by removing it this almost totally compensates for the
aftward movement of the centre of gravity by reduing battery weight by
11 lb.
Despite my requests to the aviation administration they will not allow
an increase of MTOW to more than 1600 lb (something which I have
previously written about in this list). Therefore a reduction in the
empty weight of my RV-6 by 14 lb would be welcome.
If any of you knows about LiFePo batteries such as those by EarthX or
about the consequences of reducing battery weight in an RV-6 please let
me know. If you desire I can send you the calculations on which I base
the above. Thanks.
George Nielsen
RV-6 PH-XGN
The Hague, the Netherlands
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jsflyrv(at)frontier.com
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| Posted: Sun Jun 15, 2014 9:20 am Post subject: LiFePo Battery by EarthX and Weight Reduction |
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No way would I put a Li Po in a airplane, ever see the fire one can make
if the are not charged correctly.
George Nielsen wrote:
| Quote: |
As I have mentioned I have been suffering from starting problems with
my RV-6. In the AeroElectric list several people stated that the
Odyssey PC 680 battery by Enersys is very well suited for light
aircraft applications. However, some contributor wrote that if I
change battery I should consider one of the new LiFePo batteries such
as EarthX and thus save 11 lb weight.
What could be wrong with saving 11 lb of weight? The centre of gravity
location. As the battery is placed on the floor in the cockpit just
behind the firewall I measured that its centre of gravity is 54" aft
of datum. On this basis I made a few calculations and figured that
with one pilot, full fuel and full luggage the centre of gravity
remains within limits.
Furthermore it should be taken into consideration that I removed the
ELT. Over here it is only mandatory when crossing a frontier (i.e. for
the duration of a millisecond or so during a flight). Besides, I
understand that the French authorities hate ELTs due to a history of
false alarms. As my ELT weighs 3.3 lb (without antenna or fasteners)
and was mounted in the baggage compartment which is 117" aft of datum
I calculate that by removing it this almost totally compensates for
the aftward movement of the centre of gravity by reduing battery
weight by 11 lb.
Despite my requests to the aviation administration they will not allow
an increase of MTOW to more than 1600 lb (something which I have
previously written about in this list). Therefore a reduction in the
empty weight of my RV-6 by 14 lb would be welcome.
If any of you knows about LiFePo batteries such as those by EarthX or
about the consequences of reducing battery weight in an RV-6 please
let me know. If you desire I can send you the calculations on which I
base the above. Thanks.
George Nielsen
RV-6 PH-XGN
The Hague, the Netherlands
-----
No virus found in this message.
Checked by AVG - www.avg.com
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ceengland7(at)gmail.com
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| Posted: Sun Jun 15, 2014 10:35 am Post subject: LiFePo Battery by EarthX and Weight Reduction |
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On 6/15/2014 12:05 PM, George Nielsen wrote:
| Quote: |
As I have mentioned I have been suffering from starting problems with
my RV-6. In the AeroElectric list several people stated that the
Odyssey PC 680 battery by Enersys is very well suited for light
aircraft applications. However, some contributor wrote that if I
change battery I should consider one of the new LiFePo batteries such
as EarthX and thus save 11 lb weight.
What could be wrong with saving 11 lb of weight? The centre of gravity
location. As the battery is placed on the floor in the cockpit just
behind the firewall I measured that its centre of gravity is 54" aft
of datum. On this basis I made a few calculations and figured that
with one pilot, full fuel and full luggage the centre of gravity
remains within limits.
Furthermore it should be taken into consideration that I removed the
ELT. Over here it is only mandatory when crossing a frontier (i.e. for
the duration of a millisecond or so during a flight). Besides, I
understand that the French authorities hate ELTs due to a history of
false alarms. As my ELT weighs 3.3 lb (without antenna or fasteners)
and was mounted in the baggage compartment which is 117" aft of datum
I calculate that by removing it this almost totally compensates for
the aftward movement of the centre of gravity by reduing battery
weight by 11 lb.
Despite my requests to the aviation administration they will not allow
an increase of MTOW to more than 1600 lb (something which I have
previously written about in this list). Therefore a reduction in the
empty weight of my RV-6 by 14 lb would be welcome.
If any of you knows about LiFePo batteries such as those by EarthX or
about the consequences of reducing battery weight in an RV-6 please
let me know. If you desire I can send you the calculations on which I
base the above. Thanks.
George Nielsen
RV-6 PH-XGN
The Hague, the Netherlands
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Well, they are really pricey...
There's a long thread on the VansAirForce.com forum, with several posts
from someone at the company. They seem to be trying to address a/c use
concerns, but I still can't tell from their info whether they are doing
all the needed charge/discharge management inside the battery case.
Even if you get comfortable with the charging/fire issues (which they
*might* be adequately addressing), you need to know whether the battery
you choose has the no-alternator capacity to keep your plane running
long enough for safe flight completion. Most of the various lithium
batteries were sized for starting capacity, not total energy. If you fly
day VFR & are running mags, running out of electrical power might not be
a big deal. IFR or night flight is another question. They do have a
total-energy comparison chart on their website now; you can see if it
gives you confidence.
If you do make the switch & you're willing to do a bit more work, you
can save another couple of pounds plus move your cg forward by moving
the battery & contactors to the firewall, like the newer planes (-7 & -9).
Having said all that... Any 18AH-22AH SLA type battery (PC680
lookalikes) in good condition should start a Lyc without any problem.
I'd have an automotive shop test your existing battery for capacity, &
if it checks good on the bench, you either have a charging problem in
the plane, or a high-resistance joint in the wiring path somewhere in
the path: battery positive>master contactor>starter
solenoid>starter>engine ground wire>battery negative. Quickest way to
just tell that you have a problem is to place the voltmeter leads
directly on the posts of the battery (not the clamps/bolts/etc, but the
posts). While monitoring voltage, hit the starter. Voltage should drop
from around 12+ volts to somewhere between 8 & 10 volts. If voltage goes
lower than 8, odds are good the battery is either bad or not fully
charged (or the starter itself has shorted windings, which is very
unlikely). If voltage stays above ~10.5, then you have high resistance
somewhere in the wiring path.
Hope that helps,
Charlie
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