Fuses in general

I always use automotive type flat spade fuses on the battery itself...the
fuses and fuse holders are far more durable than round glass fuses.

I honestly have no idea where we come up with some of these ideas for
battery holders and hold down's...
nowhere in AC4313 or any aviation mechanics books will you ever see bungee
cords (these are for holding your lunch box on your Schwinn, Hose clamps
(these are for....you guessed it...hoses!), Tie wraps....these are for
wrapping up your Christmas tree lights after January 1st ...or duct tape,
Velcro, handcuffs....or??? I've even found packaging tape and pine 2x4's in
gliders...Keep in mind these are still aircraft we are talking about and
even if they weren't, even automobiles has simple but strong bolts and
brackets to anchor their batteries....just like normal aircraft do...it
doesn't take too much imagination to make a simple and secure battery anchor
using real nuts and bolts...and if it's done right it is as or simpler to
remove and replace the battery with a wingnut or an over-center latch and a
safety pin...
tim

Please visit the Wings & Wheels website at www.wingsandwheels.com


"brianDG303" wrote in message
...
First, a nit-pick; incandescent lamps are resistive and not inductive
and inrush isn't a common component. But low voltage lighting systems
with a core and coil transformer is exactly what will pop a fast fuse.

I would use Anderson Powerpole connectors and strap the batteries down
with good-sized nylon ties, you can get quite large ones if needed. Or
you could heat-shrink some parts of the hose clamp. Also, it sounds
like the battery connectors you are using leave the connections
exposed, if so an insulated connector is suggested. If using crimp
connectors use Panduit brand or maybe AMP and NEVER use the cheap ones
that you see everywhere.

Anderson powerpoles will allow two batteries to be connected, but it
will be + to + and - to - and that might be less entertaining. I guess
if the batteries are at the same voltage nothing would happen.
Anderson uses a small roll pin to join two connectors together, I
really don't like the pins and let a little glue wick between them
instead.

What's wrong with a short piece of bungee cord?

Batteries are heavy, hard objects that I would prefer not hit me in
the back of my head in heavy turbulence or worse, a crash landing. I
would never trust a bungee cord to restrain a few pounds of lead! I
use a 1" nylon strap (heavy duty) with a METAL BUCKLE (I have broken
too many plastic buckles to trust them in a critical application)
attached to some solid structure of the glider. Buckle is positioned
to keep it far away from the terminals (which are insulated too)

In my glider, the (2) 12 Ah batteries are sitting in a aluminum angle
(1.5") tray bolted to the structure. This way the tray absorbs most
of the g forces and the straps keep the batteries in the tray. By the
time the straps break or the tray tears loose, I probably no longer
have to worry about the batteries hitting my head.

I also use PowerPole connectors with fuses on each battery.
Connectors are double sided taped to the battery as a strain relief.

I also carry a auto cigarette adapter with a powerpole connector and
my cell charger so I can charge my cell if I get stuck somewhere.

On Dec 9, 3:15*pm, Todd wrote:
I use a 1" nylon strap (heavy duty) with a METAL
BUCKLE...

I've used a very similar setup with good results. The battery box I
built for my HP-11 was one of my very first sheetmetal projects, and I
tested it and the retention strap to about plus or minus 12g. That
means I could stand my 140 lb weight on it without yielding, and I
could safely apply the same force upwards to the strap.

However, one thing I didn't know at the time is that nylon is rather
sensitive to acids, and loses strength quickly when so contaminated.
Given that the S in SLA is for "sealed," under most circumstances
there's no chance of spillage. But the A does stand for "acid," so it
pays to keep an eye on the battery to make sure it doesn't leak, and
on the strap to make sure it isn't becoming brittle or discolored.

Thanks, Bob K.

On Dec 9, 2:28*pm, brianDG303 wrote:
First, a nit-pick; incandescent lamps are resistive and not inductive
and inrush isn't a common component.

Sorry wrong nit to pick. The resistance of an incandescent lamp
filament is temperature dependent. Anyone that has used lamps as
current control devices is well aware of this.

Andy

On Dec 10, 8:44*am, Andy wrote:

Sorry wrong nit to pick. *The resistance of an incandescent lamp
filament is temperature dependent. *Anyone that has used lamps as
current control devices is well aware of this.

I suppose I should have completed the information. The resistance is
low when the filament is cold. There is a large inrush current which
reduces as soon as the filament gets hot.

Anyone old enough to have used equipment with vacuum tubes (valves or
bottles) will remember how bright the heaters glowed when the
equipment was first turned on. The thermionic valve was a marvelous
device - heat, light, and RF out of one component .

Andy

OK Andy, I'll bite. Lighting loads are generally considered to be
resistive and not inductive. While not perhaps true in some examples,
for the subject of this thread I think the nit was picked correctly.
For example, if you connect 16 amps of lighting load to a 20 amp fast
fuse (or 'Quick Operating' magnetically enhanced circuit breaker) you
will have a reliable circuit. If you connect a 16 amp capacity core
and coil transformer to that same fuse, or if you connect 16 amps of
old style HID lighting with the reactive ballasts acting as inductors,
you will pop that fast fuse most of the time in an AC circuit. I think
that if in an AC circuit the contact closure is timed exactly as the
sine wave crosses the 0 volt line there is sometimes sufficient lag to
slow the inrush enough to keep the fuse from popping. That's my theory
anyway.

If you still don't buy what I am saying, I'm perfectly happy to
concede the point. However, the original post implied that motors and
incandescent light bulbs require slow-blow fuses. (Many) motors do and
incandescent light bulbs do not, so if you are designing an electrical
system and the only "Inductive" loads are incandescent it would be
fine to use a fast blow fuse in order to protect electronic gear.

I guess this brings up another point, if there is more than one fuse
certainly the battery fuse or CB could be a slow blow and the fuses at
the gear would want to be fast blow in most cases.

On Dec 10, 11:39*am, Andy wrote:
On Dec 10, 8:44*am, Andy wrote:

Sorry wrong nit to pick. *The resistance of an incandescent lamp
filament is temperature dependent. *Anyone that has used lamps as
current control devices is well aware of this.

I suppose I should have completed the information. *The resistance is
low when the filament is cold. *There is a large inrush current which
reduces as soon as the filament gets hot.


Andy

My glider has multiple batteries with a switch to change between them
during flight. To, hopefully, eliminate loss of logger data during the
brief interruption of power during the switching process there is a large
capacitor to ensure continuity of supply to selected instruments during
switching. Although there is a resistor to limit the inrush current to
the capacitor this type of circuit needs a slow-blow fuse. (Factory wired
in last two years.)

This looks like a major clue that changes everything. (Well, almost
everything.)

My ASG29 also has two main batteries and a dial switch on the panel
that selects which battery is providing power to all of the
instruments. I wonder if the transition from B1 to B2 is popping the
(fast-blow) fuse on the back of the B40. And it would explain why
there was a T500L250V fuse in the panel fuse holder; I understand that
the "T" means slow-blow ("T"imed?), where an "F" would indicate fast-
blow.

2NO

On 10 Dec, 22:53, brianDG303 wrote:
OK Andy, I'll bite. Lighting loads are generally considered to be
resistive and not inductive. While not perhaps true in some examples,
for the subject of this thread I think the nit was picked correctly.
For example, if you connect 16 amps of lighting load to a 20 amp fast
fuse (or 'Quick Operating' magnetically enhanced circuit breaker) you
will have a reliable circuit. If you connect a 16 amp capacity core
and coil transformer to that same fuse, or if you connect 16 amps of
old style HID lighting with the reactive ballasts acting as inductors,
you will pop that fast fuse most of the time in an AC circuit. I think
that if in an AC circuit the contact closure is timed exactly as the
sine wave crosses the 0 volt line there is sometimes sufficient lag to
slow the inrush enough to keep the fuse from popping. That's my theory
anyway.

If you still don't buy what I am saying, I'm perfectly happy to
concede the point. However, the original post implied that motors and
incandescent light bulbs require slow-blow fuses. (Many) motors do and
incandescent light bulbs do not, so if you are designing an electrical
system and the only "Inductive" loads are incandescent it would be
fine to use a fast blow fuse in order to protect electronic gear.

I guess this brings up another point, if there is more than one fuse
certainly the battery fuse or CB could be a slow blow and the fuses at
the gear would want to be fast blow in most cases.

On Dec 10, 11:39*am, Andy wrote:



On Dec 10, 8:44*am, Andy wrote:

Sorry wrong nit to pick. *The resistance of an incandescent lamp
filament is temperature dependent. *Anyone that has used lamps as
current control devices is well aware of this.

I suppose I should have completed the information. *The resistance is
low when the filament is cold. *There is a large inrush current which
reduces as soon as the filament gets hot.

I too vaguely recalled that the initial current in a cold
incandescent bulb might be rather high. I cant however
remember precisely. It is though easy to find out
if you have a bulb and a multimeter. Just measure the
resistance when the bulb is cold and check
the expected current with V = IR. Well I = V / R.

This article
http://en.allexperts.com/q/Physics-1...lamp-surge.htm
states that the initial current is 10 times the
running current for a domestic light bulb.
Bulbs used in gliders are likely to run cooler
so that they can be tougher to better resist
vibration, and so the initial vs final current
ratio will likely be lower.

The other aspect to this is of course that the bulb
does warm up very quickly and so even a fast blow fuse
may well be unable to respond quickly enough to
fail 'inappropriately'.

On Dec 11, 9:00*am, Tuno wrote:
I wonder if the transition from B1 to B2 is popping the
(fast-blow) fuse on the back of the B40.


I have the same factory standard rotary power switch and an unmodifed
B40 that is always left on and selected to external power. My B40
fuse has never blown. (There are no external capacitors in my glider
nor do I need any).


Andy