Brian, The standard wiring has the alternator going to rectifier with
output going through a 30amp slow blow fuse to the alternator switch
with the no 1 fuel pump supplied before the switch. In my case I have
fitted a 30 amp switchable contact breaker in place of the alt switch
and done away with the fuse - all this with the blessing of inspector &
LAA. This should be proof against the scenario you mention and it would
seem to need two seperate failures, of battery and either alternator or
rectifier to stop the no 1 pump. The fuel pump is preceeded by a 5 amp
contacr breaker by the way, which seems to add to the safety of the
system.
Regards, David
On 2017-09-10 13:47, Brian Davies wrote:
> Hi David,
>
> I think the LAA are taking a very cautious approach to lithium batteries and
this will change with more service experience. It might be worth someone making
a case for the standard Mod to be revised based on your failure analysis,
however,
if an electrical fault causes the alternator fuse to blow and the lithium
battery BMS to disconnect the battery I think you will be in a glider with
a 914 but not so in a 912 so there is a slightly higher risk.
>
> Duncan's comment regarding lithium battery capacity is a good one. The sellers
do tend to focus on cranking capacity and tend to ignore total capacity
(endurance).
Buying a lithium replacement that has the same total capacity as the
lead acid is an expensive proposition so the tendency is to go for a smaller
capacity.
Probably not a good idea on an electrically dependant aircraft such as
a 914 model.
>
> Brian
>
> FROM: owner-europa-list-server@matronics.com
> [mailto:owner-europa-list-server@matronics.com] ON BEHALF OF
> davidjoyce@doctors.org.uk
> SENT: 10 September 2017 10:34
> TO: europa-list@matronics.com
> SUBJECT: RE: Europa-List: Battery
>
> Brian, A lot of years ago I found myself over horizon to horizon thick forest,
somewhere near the Czech border with all my electrical instruments showing no
signs of electricity and my assumption was that my 914 was running on the fuel
left in the carb bowls Fortunately my standard checking system found that both
master and alternator switches were off and order was restored before everything
went quiet (I had just returned my pee bottle to its place under my left
thigh support and in doing so had managed to catch the toggle switches with
my trouser bottom. I felt that I had to share this slightly embarrassing
incident
with the Europa community via Matronics in the spirit of the club, and Andy
Draper pointed out that if my wiring was as per manual the 914 would continue
as the first pump is driven directly from the alternator before its output gets
to the alternator switch. I have subsequently deliberately switched everything
off and found this to be true.
>
> Which makes me wonder about the exclusion of 914s from the Lithium battery
> approval.
Clearly if your battery blows up you won't be able to get started, but
on the face of it if it happens in flight you can still expect to get home,
(assuming
you can find the way!)
>
> Regards, David Joyce, GXSDJ
>
> On 2017-09-10 08:43, Brian Davies wrote:
>
>> For those of you operating under the LAA system there is a Standard Mod SM
>> 14337
that gives details of approved Lithium batteries. Just a note of caution
when using batteries with a Battery Management System (BMS) that automatically
disconnects the battery if over or under charged. The Rotax built in alternator
produces avionics damaging voltages when the battery is disconnected. An
overvolt
protection circuit should be fitted to guard against this.
>>
>> At the moment the Mod cannot be used for the 914 because it relies on a
>> working
electrical system. The range of batteries will be updated as more data becomes
available from the manufactures. What has already become clear is that not
all lithium batteries are suitable.
>>
>> Brian
>>
>> G-DDBD
>>
>> FROM: owner-europa-list-server@matronics.com
>> [mailto:owner-europa-list-server@matronics.com] ON BEHALF OF Greg Fuchs
>> SENT: 09 September 2017 20:30
>> TO: europa-list@matronics.com
>> SUBJECT: RE: Europa-List: Battery
>>
>> Paul,
>>
>> The ETX36C has been used successfully for years. The Rotax 914 charging
>> system
needs to be slightly modified to bring the charging voltage into the range
the lithium battery likes (Jim and Heather brought that to my attention). A
diode
on the 'C' terminal of the Ducati regulator is adequate to fool the regulator
into thinking the battery is at a slightly lower voltage than it actually
is and so it will up its charge voltage, placing the battery into proper
charging
range. I think its 13.9 to 14.6 volts per the data sheet, if memory serves.
>>
>> This lithium battery has cell protection. It has internal circuitry that can
remove the battery from the circuit due to too low or too high voltages (i.e.
when it is overcharged or drained). A happily charged battery will not
disconnect
---From the airframe. It is wise to have a good metal battery box for these
in the unlikely event of a thermal fiasco. A thin Fiberfrax layer can likely do
wonders too.
>>
>> The weight savings is amazing.. When you hold them in your hand, they feel
>> like
a fake toy battery, but they will spin the engine right up for sure.
>>
>> Greg
>>
>> -------------------------
>>
>> FROM: owner-europa-list-server@matronics.com
>> [mailto:owner-europa-list-server@matronics.com] ON BEHALF OF Paul McAllister
>> SENT: Friday, September 08, 2017 7:13 AM
>> TO: europa-list@matronics.com
>> SUBJECT: Europa-List: Battery
>>
>> Hi All,
>>
>> My trusty Odessey battery has died and gone to heaven (or wherever batteries
go).
>>
>> I am seeking peoples experience with the new style Lithium batteries, and in
particular what can be sourced in the US.
>>
>> Thanks, Paul
>>
>> [1]
>>
>> Virus-free. www.avg.com [1]
Links:
------
[1]
http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient
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