Today's Message Index:
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1. 07:00 AM - resistance in solenoid (bobnoffs)
2. 07:54 AM - Re: resistance in solenoid (user9253)
3. 10:36 AM - Re: resistance in solenoid (Jeff Luckey)
4. 03:39 PM - Re: resistance in solenoid (bobnoffs)
5. 03:51 PM - Re: Re: resistance in solenoid (Alec Myers)
6. 03:52 PM - Re: Re: resistance in solenoid (Alec Myers)
7. 04:26 PM - Re: resistance in solenoid (Ceengland)
8. 04:37 PM - Re: resistance in solenoid (user9253)
9. 04:38 PM - Re: Re: resistance in solenoid (Jeff Luckey)
Message 1
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| Subject: | resistance in solenoid |
my voltage number is dropping in my eis. i have determined it is resistance in
my continuous solenoid for my battery. this solenoid is from acs and has only
100 hrs on it. i really dont want to redo those fat wires on the firewall to fit
a different solenoid but isn't 100 hrs a short lifespan? should a go for a
better solenoid?
bob noffs
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=516706#516706
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| Subject: | Re: resistance in solenoid |
Bob, does the engine crank and start okay? If so, then maybe the solenoid is
good. Once the engine is running, the aircraft electrical system is powered by
the alternator, not the battery. If the EIS is showing low voltage with the
engine running, suspect the charging system.
The best way to measure low values of resistance is with a voltmeter and
heavy load, not with an ohmmeter.
--------
Joe Gores
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http://forums.matronics.com/viewtopic.php?p=516707#516707
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| Subject: | Re: resistance in solenoid |
Bob,
Assuming you are using the standard and ubiquitous solenoid like the Cole H
ersee 24059, it should certainly last more than 100 hrs.=C2- More like 10
++ years.
JoeG is right on the nose with his advice.
Maybe you could post bus voltage with engine off and voltage with engine ru
nning.=C2- Also have you confirmed the EFIS numbers with a volt meter?
-Jeff
On Monday, December 1, 2025 at 10:25:38 AM PST, bobnoffs <icubob@gmail.
com> wrote:
my voltage number is dropping in my eis. i have determined it is resistance
in my continuous solenoid for my battery. this solenoid is from acs and ha
s only 100 hrs on it. i really dont want to redo those fat wires on the fir
ewall to fit a different solenoid but isn't 100 hrs a short lifespan? shoul
d a go for a better solenoid?
bob noffs
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=516706#516706
-
S -
WIKI -
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=C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Admin.
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| Subject: | Re: resistance in solenoid |
voltage at eis is 12.6 with engine off. it is 14.3 with engine running. i have
checked all numbers with eis voltage, handheld voltmeter and panel mounted voltmeter
i just bought and they are all aligned.. measured voltage is 13.2 at battery
side of solenoid and 12.6 on the load side, engine off. alternator is charging
fine and battery voltage is fine but after the solenoid it drops to 12.6.
all this is with an earthx, not lead acid.
i haven't actually measured resistance in the solenoid but it seems to be pointing
at that, what else could it be?
bob
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=516709#516709
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| Subject: | Re: resistance in solenoid |
>measured voltage is 13.2 at battery side of solenoid and 12.6 on the load side,
engine off.
13.2V anywhere with the engine off is extremely suspicious. 12.6 sounds correct
for a topped-off lead acid battery, but youd have to be pulling some major current
to drop 0.6V across a solenoid, and if you were pulling any major current
from the battery it wouldnt be anywhere near 12.6V still less 13.2V.
Id recheck the 13.2V carefully.
On Dec 1, 2025, at 6:38PM, bobnoffs <icubob@gmail.com> wrote:
voltage at eis is 12.6 with engine off. it is 14.3 with engine running. i have
checked all numbers with eis voltage, handheld voltmeter and panel mounted voltmeter
i just bought and they are all aligned.. measured voltage is 13.2 at battery
side of solenoid and 12.6 on the load side, engine off. alternator is charging
fine and battery voltage is fine but after the solenoid it drops to 12.6.
all this is with an earthx, not lead acid.
i haven't actually measured resistance in the solenoid but it seems to be pointing
at that, what else could it be?
bob
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=516709#516709
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| Subject: | Re: resistance in solenoid |
Sorry - just realized youre not using a lead-acid battery, so my voltage comments
dont apply.
On Dec 1, 2025, at 6:50PM, Alec Myers <alec@alecmyers.com> wrote:
> measured voltage is 13.2 at battery side of solenoid and 12.6 on the load side,
engine off.
13.2V anywhere with the engine off is extremely suspicious. 12.6 sounds correct
for a topped-off lead acid battery, but youd have to be pulling some major current
to drop 0.6V across a solenoid, and if you were pulling any major current
from the battery it wouldnt be anywhere near 12.6V still less 13.2V.
Id recheck the 13.2V carefully.
On Dec 1, 2025, at 6:38PM, bobnoffs <icubob@gmail.com> wrote:
voltage at eis is 12.6 with engine off. it is 14.3 with engine running. i have
checked all numbers with eis voltage, handheld voltmeter and panel mounted voltmeter
i just bought and they are all aligned.. measured voltage is 13.2 at battery
side of solenoid and 12.6 on the load side, engine off. alternator is charging
fine and battery voltage is fine but after the solenoid it drops to 12.6.
all this is with an earthx, not lead acid.
i haven't actually measured resistance in the solenoid but it seems to be pointing
at that, what else could it be?
bob
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=516709#516709
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| Subject: | Re: resistance in solenoid |
Bob, your system architecture and actual measurement points need to be specified.
If you're measuring Battery voltage on the source side of the master contactor,
observing system voltage on your EIS, and there's any sort of isolation diode
in the system somewhere, that would easily account for for the voltage difference.
To get an honest number, you need to measure on each side of the contactor
itself. Or, just measure across the two terminals & look for zero volts.
Charlie
--------
Charlie
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http://forums.matronics.com/viewtopic.php?p=516712#516712
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| Subject: | Re: resistance in solenoid |
Bob,
Measure the voltage again. But this time do NOT connect the black lead of the
handheld meter to ground. Instead, connect the meter black lead to the
contactor stud on the load side. And connect the red lead to the contactor stud
on the battery side. Connect meter leads directly to the contactor studs, not
to
the nuts or wire terminals. Turn on every electrical load possible and add extra
loads that make heat like a seat heater or automotive headlight.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=516713#516713
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| Subject: | Re: resistance in solenoid |
What we know:1. remote diagnosis is difficult at best ;)2. not having a sc
hematic makes that worse3. the resting voltage of an EarthX is about 13.2 V
Questions:1. have you put the voltmeter across the input and output studs o
f the solenoid?=C2- With what you are describing, engine off, that readin
g should be 0.6 volts (13.2 in - 12.6 out = 0.6 volts)
2. does cranking current flow thru this solenoid?
3. has cranking seemed "soft" lately?
3. is there an errant diode somewhere in the circuit - just a WAG, but 0.6
v is about the drop of a silicon diode - again, just making this up ;)
Things you could try:Starting with simple, no-disassembly-required tests1.
put the voltmeter across the input and output studs with everything off - w
hat's that voltage?2. turn on the master (but don't run the engine) - based
on your description, should read 0.6v3. start turning on high-current stuf
f like pitot heat, landing lights, etc - IF there is some weird resistance
thru the main contacts, the voltage drop should increase as you add load.
=C2- If you have an ammeter, write down amps, what equipment is turned on
, and voltage drop across solenoid.
You could have a high-resistance thru the contactor, but if starting is goo
d, it kinda rules that out.
Also, the resistance we are talking about would be well below 1 ohm and typ
ical multi-meters cannot accurately measure resistances that low.=C2- Jus
t as JoeG mentioned, you will have to use another technique to test that hy
pothesis.=C2- #3 in Things to Try might shed some light on this.
Happy (gremlin) Hunting,
-Jeff
On Monday, December 1, 2025 at 03:50:03 PM PST, bobnoffs <icubob@gmail.
com> wrote:
voltage at eis is 12.6 with engine off. it is 14.3 with engine running. i h
ave checked all numbers with eis voltage, handheld voltmeter and panel moun
ted voltmeter i just bought and they are all aligned.. measured voltage is
13.2 at battery side of solenoid and 12.6 on the load side, engine off.=C2
- alternator is charging fine and battery voltage is fine but after the s
olenoid it drops to 12.6. all this is with an earthx, not lead acid.
i haven't actually measured resistance in the solenoid but it seems to be
pointing at that, what else could it be?
bob
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=516709#516709
-
S -
WIKI -
-
=C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Admin.
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