Today's Message Index:
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1. 05:17 AM - Recommended wire gauge for battery (Alec Myers)
2. 06:11 AM - Re: Recommended wire gauge for battery (Art Zemon)
3. 06:43 AM - Re: Recommended wire gauge for battery (Kelly McMullen)
4. 07:26 AM - Re: Recommended wire gauge for battery (user9253)
5. 02:30 PM - Re: Re: Recommended wire gauge for battery (Alec Myers)
6. 03:11 PM - Re: Internally Regulated Over Voltage Protection (BMC_Dave)
7. 05:42 PM - Re: Internally Regulated Over Voltage Protection (user9253)
Message 1
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| Subject: | Recommended wire gauge for battery |
Here is a question about what gauge of wire the list would recommend for extending
a battery installation on an aircraft.
Parameters are that a 24V battery needs to move from behind the baggage compartment
to the firewall, for balance purposes.
The aircraft has a Lycoming O320 engine. The battery is 24V 11AH and rated at cold
cranking amperage 200A. It needs to move about 5 from its present position.
I can re-site the ground terminal (to the airframe) to the new location, but Im
unwilling to move the battery and starter contactors, as an alternative Id prefer
to run a heavy 24V wire back to the original battery position where the contactors
are.
My certification engineer says hes willing to sign off the extended unswitched
and unfused power line as long as its properly grometted through the firewall
etc.
What gauge of wire should I be considering?
Anything other considerations Im missing?
Message 2
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| Subject: | Re: Recommended wire gauge for battery |
Alec,
I do understand wanting to keep the contactors in their existing positions,
aft of the baggage compartment. It is a paperwork hassle to move them. Even
still, I would reconsider that decision. You need BIG wire to carry the
current for the starter. In my airplane with an IO-360 and the battery on
the firewall, I used 4 and 6 gauge wire in the circuit from the battery
through the contactors to the starter. I'll bet that you already have
something BIG running from the contactor to the starter and you would want
something at least that large to run from the battery's new location back
to the contactor.
-- Art Z.
On Tue, Jan 15, 2019 at 7:33 AM Alec Myers <alec@alecmyers.com> wrote:
>
> Here is a question about what gauge of wire the list would recommend for
> extending a battery installation on an aircraft.
>
> Parameters are that a 24V battery needs to move from behind the baggage
> compartment to the firewall, for balance purposes.
> The aircraft has a Lycoming O320 engine. The battery is 24V 11AH and rate
d
> at cold cranking amperage 200A. It needs to move about 5=99 from it
s present
> position.
>
> I can re-site the ground terminal (to the airframe) to the new location,
> but I=99m unwilling to move the battery and starter contactors, as
an
> alternative I=99d prefer to run a heavy 24V wire back to the origin
al battery
> position where the contactors are.
>
> My certification engineer says he=99s willing to sign off the exten
ded
> unswitched and unfused power line as long as it=99s properly gromet
ted
> through the firewall etc.
>
> What gauge of wire should I be considering?
>
> Anything other considerations I=99m missing?
--
https://CheerfulCurmudgeon.com/
*"Be kind, for everyone you meet is fighting a hard battle."*
Message 3
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| Subject: | Re: Recommended wire gauge for battery |
If I understand correctly, you currently have battery box with master
contactor and the starter contactor both behind the baggage compartment.
That implies you are running a heavy cable for the starter and a
somewhat smaller cable for the main aircraft bus, both from behind the
baggage compartment. I don't understand why the starter contactor wasn't
placed on the firewall to begin with, but okay.
Presumably anything in the tail cone that is powered is getting power
from bus on the instrument panel. I don't see any advantage of keeping
the contactors in their current location. You can use existing wire,
just shortening the cable to what is needed from the battery box on the
firewall. No new cable needed, just cutting and crimping new connectors
on existing cable. Only other wires to move are the master switch wire
and the ignition switch wire, again just making them shorter.
While you could do the calculations to the W&B for the battery move, you
would be better off just re-weighing the plane.
O
> On Tue, Jan 15, 2019 at 7:33 AM Alec Myers <alec@alecmyers.com
> <mailto:alec@alecmyers.com>> wrote:
>
> <alec@alecmyers.com <mailto:alec@alecmyers.com>>
>
> Here is a question about what gauge of wire the list would recommend
> for extending a battery installation on an aircraft.
>
> Parameters are that a 24V battery needs to move from behind the
> baggage compartment to the firewall, for balance purposes.
> The aircraft has a Lycoming O320 engine. The battery is 24V 11AH and
> rated at cold cranking amperage 200A. It needs to move about 5 from
> its present position.
>
> I can re-site the ground terminal (to the airframe) to the new
> location, but Im unwilling to move the battery and starter
> contactors, as an alternative Id prefer to run a heavy 24V wire
> back to the original battery position where the contactors are.
>
> My certification engineer says hes willing to sign off the extended
> unswitched and unfused power line as long as its properly grometted
> through the firewall etc.
>
> What gauge of wire should I be considering?
>
> Anything other considerations Im missing?
>
>
> --
> https://CheerfulCurmudgeon.com/
>
> /"Be kind, for everyone you meet is fighting a hard battle."/
Message 4
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| Subject: | Re: Recommended wire gauge for battery |
The engine is on the front of the airplane, correct? As others have said, it is
best to move the contactors forward near the battery. Weight will be less and
safety will be increased. What is the reason for not moving the contactors, no
room, more work, regulator?
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=486988#486988
Message 5
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| Subject: | Re: Recommended wire gauge for battery |
I miswrote, and in fact the starter contactor is already on the firewall.
So I would have to move the battery contactor only, but thats not trivial in this
airplane. Also I would have to keep or install a heavy cable from the external
power relay back to the battery - the external power relay, connector (through
the fuselage side) and external power control relay are all colocated behind
the baggage compartment.
I was really wondering what gauge of wire people use for a 24v starter...
On Jan 15, 2019, at 10:26, user9253 <fransew@gmail.com> wrote:
The engine is on the front of the airplane, correct? As others have said, it is
best to move the contactors forward near the battery. Weight will be less and
safety will be increased. What is the reason for not moving the contactors, no
room, more work, regulator?
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=486988#486988
Message 6
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| Subject: | Re: Internally Regulated Over Voltage Protection |
Bueller
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=486999#486999
Message 7
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| Subject: | Re: Internally Regulated Over Voltage Protection |
Most of the battery charging current will come through the battery contactor.
Very little, if any will pass through the E-Bus diode. Another diode between
the battery and E-Bus is not desired because it will drop voltage. Not good if
the battery voltage is low.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=487001#487001
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