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battery disconnect switch in car


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pv13 
Copper - Posts: 154
Copper spacespace
Joined: April 11, 2005
Location: United States
Posted: September 24, 2014 at 5:29 PM / IP Logged  
yellow_cake wrote:
If you go on youtube, search for parasitic battery drain by EricTheCarGuy, that video in my opi nion is very helpfu.
It is very helpful! I saw that video months ago, and it was the way I told my uncle to find the drain. But he seemed to opt for something different :). We've both been really busy recently, but I'm still trying to convince him to forget about the switch and focus on the drain. Thanks
davep. 
Gold - Posts: 639
Gold spacespace
Joined: May 27, 2011
Location: California, United States
Posted: September 26, 2014 at 8:47 PM / IP Logged  
I'm very familiar with 68-72 Chevelles. I've owned my 70 El Camino for 41 years, and worked on tons of these cars over the years. A few comments /observations.
50ma is a 1.2 amp hour per day draw. A group 75 battery has at minimum a 50amp hour capacity at that minimal rate of discharge. You should be able to crank the car weeks later with a 50ma draw. It isn't the tracker.
If you do the cut-off switch in the negative wire, changing to a gear reduction mini starter (I specify a 1996, 454 7.4L Silverado pick up for the one I use) will reduce the amp draw of the starter that #4 wire will be more than adequate to crank the "mini" starter even with the 8' or so of added circuit run.
What alternator / regulator is in the 72? 1972 was the last year for the 10si Delco with divorced regulator mounted on the fender. Sometimes the old mechanical regulators would stick on. But 40 years later the original regulator has probably been changed out to an electronic unit which doesn't suffer this maladie.
\
In 73 they introduced the 12si with the internal regulator. I've seen some late 72's with 12si alternators. Early 12si's were notorious for regulator failures that kept the alternator on without the engine running. This will drain the battery overnight, as rotor draw is about 5 amps.
A quick test for alternator remaining "on" after engine stop is to take a steel screwdriver and touch it to the shaft in the center of the pulley nut. If the screwdriver "sticks" with magnetism, the field is energized, and is the source of battery draw.
Check the alternator.
It's not the tracker.
It could be a weak battery.
Use a mini starter if you want to keep cable size smaller, and do the shut-off.
Regards
catback 
Silver - Posts: 703
Silver spacespace
Joined: August 13, 2002
Location: Canada
Posted: September 27, 2014 at 10:58 AM / IP Logged  
How hard is it to fix a battery drain when 8' of ground cable, a battery disconnect switch, AND a new mini-starter is the easier thing to do? sheesh battery disconnect switch in car - Page 3 -- posted image.
howie ll 
Pot Metal - Posts: 16,466
Pot Metal spacespace
Joined: January 09, 2007
Location: United Kingdom
Posted: September 27, 2014 at 11:24 AM / IP Logged  
About 20 minutes with a 12Volt test light?
(Keep it simple).
pv13 
Copper - Posts: 154
Copper spacespace
Joined: April 11, 2005
Location: United States
Posted: September 28, 2014 at 2:45 PM / IP Logged  
davep. wrote:
I'm very familiar with 68-72 Chevelles. I've owned my 70 El Camino for 41 years, and worked on tons of these cars over the years. A few comments /observations.
50ma is a 1.2 amp hour per day draw. A group 75 battery has at minimum a 50amp hour capacity at that minimal rate of discharge. You should be able to crank the car weeks later with a 50ma draw. It isn't the tracker.
If you do the cut-off switch in the negative wire, changing to a gear reduction mini starter (I specify a 1996, 454 7.4L Silverado pick up for the one I use) will reduce the amp draw of the starter that #4 wire will be more than adequate to crank the "mini" starter even with the 8' or so of added circuit run.
What alternator / regulator is in the 72? 1972 was the last year for the 10si Delco with divorced regulator mounted on the fender. Sometimes the old mechanical regulators would stick on. But 40 years later the original regulator has probably been changed out to an electronic unit which doesn't suffer this maladie.
\
In 73 they introduced the 12si with the internal regulator. I've seen some late 72's with 12si alternators. Early 12si's were notorious for regulator failures that kept the alternator on without the engine running. This will drain the battery overnight, as rotor draw is about 5 amps.
A quick test for alternator remaining "on" after engine stop is to take a steel screwdriver and touch it to the shaft in the center of the pulley nut. If the screwdriver "sticks" with magnetism, the field is energized, and is the source of battery draw.
Check the alternator.
It's not the tracker.
It could be a weak battery.
Use a mini starter if you want to keep cable size smaller, and do the shut-off.
Regards
He bought the alternator (with the external regulator in the fender) and battery at the same time. So I will definitely have him check out the alternator. I convinced him to focus on the drain, so the switch is no longer necessary. Thanks
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: September 28, 2014 at 6:40 PM / IP Logged  
Tho it sounds like this thread is over & solved...
pv13 wrote:
He bought the alternator (with the external regulator ...
So just the alternator, or the regulator as well?
Not that I think that's the problem - tho if it is it will be easy to find - but someone once said...
uncredited KIA wrote:
... when he has problems with the alternator or regulator, replace them with a modern alternator with integral regulator...
But it sounds like YOU have the right ideas. He needs to pull his finger out and do some basic checking.
If it's a laziness issue, as per catback - finding (or isolating) a drain is more work than installing a high current battery feed switch? (BTW - the attraction of reduction starters is irrelevant to polarities etc.)
If it's a thinking issue - good luck - but to isolate the battery and hence alarms & HU memories etc when the culprit was (supposedly) known... Surely you'd merely isolate the culprit? (In fact IMO if it is the tracker - remove it unless its for family to track the driver. Why have it otherwise?)
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: September 28, 2014 at 7:21 PM / IP Logged  
And since this thread seems over (I'm tempted to make this reply a new thread...)
A few days ago I dropped in on a competitive mate who I hadn't seen for several years.
I asked if he was using - or if The Regulators - were prescribing multipole switches like the FIA approved Battery Isolator Switch when "engine kill" and "battery isolation" functions were combined.
What horrified me is that remote +12V isolation is still acceptable.
What amused me (with horror) was the other 2 things my mate said:
- various (complex?) arrangements use relays; &
- scrutineers don't care how the thing(s) work as long as when they flip the switch, the battery is isolated and the engine dies.
So yet again we can have a "safety feature" that kills you in the field but that's ok since it passed (static) tests.   
Apologies, but I am simply amazed. We have devolved at least 30 years. What next - red EXIT signs in buildings (because that's logical? and ban laminated windscreens & airbag systems?
But I'll leave all that for the first victims to take action...
I was going to add that that is why I avoid Australian forums, however after seeing the wiring diagrams for the FIA approved switch (which all isolate the +12V batter terminal) I'm wondering if the rest of the world is turning stupid, or ignorant?
BTW - the IMO correct base diagram WRT heavy isolation wiring in the GND path ...battery disconnect switch in car - Page 3 -- posted image.
pv13 
Copper - Posts: 154
Copper spacespace
Joined: April 11, 2005
Location: United States
Posted: September 30, 2014 at 4:31 PM / IP Logged  
pv13 wrote:
davep. wrote:
I'm very familiar with 68-72 Chevelles. I've owned my 70 El Camino for 41 years, and worked on tons of these cars over the years. A few comments /observations.
50ma is a 1.2 amp hour per day draw. A group 75 battery has at minimum a 50amp hour capacity at that minimal rate of discharge. You should be able to crank the car weeks later with a 50ma draw. It isn't the tracker.
If you do the cut-off switch in the negative wire, changing to a gear reduction mini starter (I specify a 1996, 454 7.4L Silverado pick up for the one I use) will reduce the amp draw of the starter that #4 wire will be more than adequate to crank the "mini" starter even with the 8' or so of added circuit run.
What alternator / regulator is in the 72? 1972 was the last year for the 10si Delco with divorced regulator mounted on the fender. Sometimes the old mechanical regulators would stick on. But 40 years later the original regulator has probably been changed out to an electronic unit which doesn't suffer this maladie.
\
In 73 they introduced the 12si with the internal regulator. I've seen some late 72's with 12si alternators. Early 12si's were notorious for regulator failures that kept the alternator on without the engine running. This will drain the battery overnight, as rotor draw is about 5 amps.
A quick test for alternator remaining "on" after engine stop is to take a steel screwdriver and touch it to the shaft in the center of the pulley nut. If the screwdriver "sticks" with magnetism, the field is energized, and is the source of battery draw.
Check the alternator.
It's not the tracker.
It could be a weak battery.
Use a mini starter if you want to keep cable size smaller, and do the shut-off.
Regards
He bought the alternator (with the external regulator in the fender) and battery at the same time. So I will definitely have him check out the alternator. I convinced him to focus on the drain, so the switch is no longer necessary. Thanks
I took a steel screwdriver to the alternator like you said, and while there wasn't a strong magnetic connection, you could definitely feel the magnetic force between the two when the car had been sitting for two weeks.
Does this mean the alternator or external regulator is faulty? He had a problem with the drain before he replaced these parts.
I sent you a private message, as this is no longer about the battery disconnect switch.
Thanks.
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: September 30, 2014 at 4:49 PM / IP Logged  
Many alternators will have residual magnetism - that's why sometimes certain types start without the trickle/tickle D+/L feed.
A strong pull indicates rotor current (or permanent magnets).
A weak pull may exist with no rotor current.
And not all leakages go thru the rotor.
The magnet test is a simple test to indicate high rotor current or residual magnetism.
It is not a "current drain" test.
pv13 
Copper - Posts: 154
Copper spacespace
Joined: April 11, 2005
Location: United States
Posted: September 30, 2014 at 5:58 PM / IP Logged  
oldspark wrote:
Many alternators will have residual magnetism - that's why sometimes certain types start without the trickle/tickle D+/L feed.
A strong pull indicates rotor current (or permanent magnets).
A weak pull may exist with no rotor current.
And not all leakages go thru the rotor.
The magnet test is a simple test to indicate high rotor current or residual magnetism.
It is not a "current drain" test.
Okay thanks. Given that he had the same drain before he replaced the alternator,external regulator, and battery, it is probably something like residual magnetism. Thanks
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