Today's Message Index:
----------------------
1. 05:48 AM - Re: Battery Voltage Under Load, no Charger (Robert L. Nuckolls, III)
2. 05:50 AM - Re: Battery Voltage Under Load, no Charger (Robert L. Nuckolls, III)
3. 09:13 AM - Re: Battery Voltage Under Load, no Charger (Sebastien)
4. 09:38 AM - To charge or not-to-charge, that is the question (Robert L. Nuckolls, III)
5. 09:41 AM - TRIM those replies (Robert L. Nuckolls, III)
6. 09:54 AM - WTB junker 2" instrument (Robert L. Nuckolls, III)
7. 10:10 AM - Re: TRIM those replies (John M Tipton)
8. 10:58 AM - Re: Battery Voltage Under Load, no Charger (farmrjohn)
9. 12:10 PM - Re: Re: Battery Voltage Under Load, no Charger (Robert L. Nuckolls, III)
10. 01:54 PM - Re: WTB junker 2" instrument (Sebastien)
Message 1
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| Subject: | Re: Battery Voltage Under Load, no Charger |
At 09:11 PM 1/24/2020, you wrote:
>
>My search skills are not the best. I've found that a 12 volt
>battery should indicate 12.8 volts on its own. What voltage should
>it indicate if it has loads applied to it, i.e. checking out
>electrical components without the engine running or a
>charger/external power applied?
It depends on a lot of variables. Size and condition
of battery, state of charge and size of loads. A fully
charged battery in good condition and lightly loaded
will start out at about 12.8 volts and move down
from there. Here's an exemplar discharge plot for
a 17 a.h. svla battery under various loads:
Emacs!
As the battery ages the initial discharge voltage falls
and the rate of decay increases illustrating an increase
in internal resistance and loss of capacity.
Bob . . .
Message 2
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| Subject: | Re: Battery Voltage Under Load, no Charger |
At 09:11 PM 1/24/2020, you wrote:
>
>My search skills are not the best. I've found that a 12 volt
>battery should indicate 12.8 volts on its own. What voltage should
>it indicate if it has loads applied to it, i.e. checking out
>electrical components without the engine running or a
>charger/external power applied?
It depends on a lot of variables. Size and condition
of battery, state of charge and size of loads. A fully
charged battery in good condition and lightly loaded
will start out at about 12.8 volts and move down
from there. Here's an exemplar discharge plot for
a 17 a.h. svla battery under various loads:
Emacs!
As the battery ages the initial discharge voltage falls
and the rate of decay increases illustrating an increase
in internal resistance and loss of capacity.
Bob . . .
Message 3
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| Subject: | Re: Battery Voltage Under Load, no Charger |
Do we have a consensus on how charged a battery must be before starting? Is
it ok to hand start the engine and charge a very discharged battery with
the alternator or is there some point at which a charger must be used? As
long as there is enough power left to close the master relay and get the
alternator going I've used the engine to charge the battery rather than a
charger.
On Sat, Jan 25, 2020, 08:54 Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 09:11 PM 1/24/2020, you wrote:
>
> faithvineyard@yahoo.com>
>
> My search skills are not the best. I've found that a 12 volt battery
> should indicate 12.8 volts on its own. What voltage should it indicate if
> it has loads applied to it, i.e. checking out electrical components without
> the engine running or a charger/external power applied?
>
>
> It depends on a lot of variables. Size and condition
> of battery, state of charge and size of loads. A fully
> charged battery in good condition and lightly loaded
> will start out at about 12.8 volts and move down
> from there. Here's an exemplar discharge plot for
> a 17 a.h. svla battery under various loads:
>
> [image: Emacs!]
>
>
> As the battery ages the initial discharge voltage falls
> and the rate of decay increases illustrating an increase
> in internal resistance and loss of capacity.
>
>
> Bob . . .
>
Message 4
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| Subject: | To charge or not-to-charge, that is the question |
At 11:10 AM 1/25/2020, you wrote:
>Do we have a consensus on how charged a battery must be before
>starting? Is it ok to hand start the engine and charge a very
>discharged battery with the alternator or is there some point at
>which a charger must be used? As long as there is enough power left
>to close the master relay and get the alternator going I've used the
>engine to charge the battery rather than a charger.
The IDEAL answer is, don't use the ship's
power sources to charge a depleted battery.
This is echoed in the AFM for virtually
all of the TC aircraft I've had contact
with. Not that it's a guaranteed formula
for system compromise . . . it's the SAFE
formula to avoid system compromise.
The REAL answer is, probably okay
but with reservations. Depending on the SIZE
of battery, SIZE of the alternator and battery
CONDITION, the battery recharge rate MIGHT be
hazardous to battery health. In extreme cases . . .
catastrophic. In the earliest days of
wet ni-cad batteries, numerous incidences
of thermal runaway culminating in a battery
fire were experienced. This condition prompted
the 'band-aid' battery temperature monitor
mandate in some aircraft
Emacs!
The PRACTICAL answer is, don't do it unless
you've got no other options. I've brought
airplanes home with crapped electrical
systems in what I call the J-3 mode. If
you're off home field and have no way
to gently charge the battery, then consider
propping the engine and coming home dark.
You DO know how to do that . . . right?
Consider charging the battery through
el-cheepo jumper cables from a car. The
$10 cable sets from Dollar General are
small gage wire . . . generally 8 or
even 10AWG. This small wire will limit
recharge rate. Leave connected to the
car with engine running for 10 minutes
or so, THEN start ship's engine and let
the alternator take over.
There is no one-size-fits-all, simple
answer beyond don't do it. But with some
careful implementation and skill, it
can be done with little if any risk.
Bob . . .
Message 5
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| Subject: | TRIM those replies |
When replying to a message you've just downloaded,
try to trim away stuff not relevant to your comment.
Some of my posts ARE lengthy but echoing the entire
posting when your question/comment is prompted by
a few lines makes your posting more difficult to
follow.
Also, when taking the thread off on a connected
tangent, consider changing the subject line to
reflect that new path for the discussion.
Bob . . .
Message 6
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| Subject: | WTB junker 2" instrument |
I'm looking to acquire a 2" instrument of any
genre' for the case so the type of instrument
and operating condition is irrelevant. Does
anyone have something laying around that
they could part with?
Bob . . .
Message 7
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| Subject: | Re: TRIM those replies |
Maybe using English too, rather than local dialects ~
Sent from my iPad
----x--O--x----
> On 25 Jan 2020, at 5:55 pm, Robert L. Nuckolls, III <nuckolls.bob@aeroelectric.com>
wrote:
>
>
> When replying to a message you've just downloaded,
> try to trim away stuff not relevant to your comment.
> Some of my posts ARE lengthy but echoing the entire
> posting when your question/comment is prompted by
> a few lines makes your posting more difficult to
> follow.
>
> Also, when taking the thread off on a connected
> tangent, consider changing the subject line to
> reflect that new path for the discussion.
>
>
> Bob . . .
>
>
>
Message 8
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| Subject: | Re: Battery Voltage Under Load, no Charger |
The situation that prompted my question is when I switched the battery on it indicated
12.8 volts. After I turned on the equipment I was working with (lights
and radios) I noticed the voltage holding steady at 12.3. Unfortunately I didn't
check the amps at that time. After I was done, I switched everything off
then started the engine normally and the voltage was up to 14.2 when I switched
on the alternator, amps were 6+.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=494455#494455
Message 9
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| Subject: | Re: Battery Voltage Under Load, no Charger |
At 12:56 PM 1/25/2020, you wrote:
>
>The situation that prompted my question is when I switched the
>battery on it indicated 12.8 volts. After I turned on the equipment
>I was working with (lights and radios) I noticed the voltage holding
>steady at 12.3. Unfortunately I didn't check the amps at that
>time. After I was done, I switched everything off then started the
>engine normally and the voltage was up to 14.2 when I switched on
>the alternator, amps were 6+.
Having no more details, it sounds like things are
fine.
Have you ever cap-checked this battery? What
kind, what size, how old?
Bob . . .
Message 10
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| Subject: | Re: WTB junker 2" instrument |
I think my ammeter died the other day and I think it's 2 inches. Rather
than replacing it I was just going to remove it completely from the system.
I'm planning on troubleshooting it next week, I'll let you know.
On Sat, Jan 25, 2020 at 9:59 AM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> nuckolls.bob@aeroelectric.com>
>
> I'm looking to acquire a 2" instrument of any
> genre' for the case so the type of instrument
> and operating condition is irrelevant. Does
> anyone have something laying around that
> they could part with?
>
>
> Bob . . .
>
>
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