What is the symptom of a dying or dead original battery master switch
- Thread starter 1911tex
- Start date
Marlin Prowell
E34 - Bellingham, WA
This is probably more than you want to know, but I found the pysystems.ca website a month or two ago, and it has hundreds of excellent videos and articles about marine electronics. Check the Resources section.
Jeff Cote is the owner, is extremely knowledgeable, and does all the videos.
His advice: hook the alternator directly to the battery. Don’t go through the battery switch at all. Then you can’t blow up the alternator by accidentally disconnecting the alternator from the battery.
I know. Heresy.
He explains his reasoning here. He says that Nigel Calder came up with the idea. The main concept is having both Switched and Unswitched distribution sections to your electrical system.
Jeff Cote is the owner, is extremely knowledgeable, and does all the videos.
His advice: hook the alternator directly to the battery. Don’t go through the battery switch at all. Then you can’t blow up the alternator by accidentally disconnecting the alternator from the battery.
I know. Heresy.
He explains his reasoning here. He says that Nigel Calder came up with the idea. The main concept is having both Switched and Unswitched distribution sections to your electrical system.
Another option to prevent alternator damage from a faulty batt-selector switch (or, user error on a functioning switch):
Sterling Power 12V or 24V - Alternator Protection Device
Sterling Power Alternator Protection Device
shop.marinehowto.com
1911tex
Sustaining Member
mbp: I just listened to Cote's video, thank you. He is horrified the way we wire our alternators. We wire them switched...i.e.; alternator to starter solenoid to master battery switch to battery bank. He recommended only wire unswtitched...i.e.; alternator directly to battery bank! Now I am trying to figure out how to rewire??
Sounds great, but nothing is free (especially when it entails re-wiring your existing system).
If you wire directly to the battery, you also must install proper fusing on that line (which is likely a smaller line and, thus, a smaller fuse than what you would have on your main battery cable fusing. That's if you have main battery cable fusing, which Ericson did not install from the factory.
Even if you wire & fuse directly to the battery, you've now created an always-hot line (with a LOT of amperage) between the battery compartment and the engine compartment. Most wiring schemes that do this also add an "alternator disconnect" switch to disable the hot line while working on your engine and/or alternator. So, it's not as clean and simple as it sounds at first. If you happen run your engine with the "alternator disconnect" switch off, you've created the same problem you were initially trying to solve--frying the alternator by having the switch that connects it to the battery turned off.
Like they say, you can try to idiot-proof something, but they never seem to stop inventing better idiots.
1911tex
Sustaining Member
Ken has a terrific point....Here is a video on the alternator protection device which seems like the better alternative:Another option to prevent alternator damage from a faulty batt-selector switch (or, user error on a functioning switch):
Sterling Power 12V or 24V - Alternator Protection Device
Sterling Power Alternator Protection Deviceshop.marinehowto.com
paul culver
Member III
If you're worrying about an old master switch its probably time for a new one. The modern Perkos are make-before-break types so ypu can switch between battery banks with the engine running. Switching to off while running is still taboo though.
1911tex
Sustaining Member
Does the "Alternator field disconnect" below, have the same function as "Alternator Protection Device":
www.hodgesmarine.com
Blue Sea 9002e E-Series Battery Switch Selector W/Alternator Field Disconnect
BLUE SEA 9002E BATTERY SWITCH E SELECTOR ...
www.hodgesmarine.com
The APD is also recommended for use with new-fangled batteries (LiFePO4) which have their own control systems that might abruptly disconnect from the alternator.
I think the sign of a failing switch is likely to be high resistance - which is a really really bad thing on a battery cable. --> heat --> melting insulation --> fire.
I think the sign of a failing switch is likely to be high resistance - which is a really really bad thing on a battery cable. --> heat --> melting insulation --> fire.
1911tex
Sustaining Member
OP Here...great news...when the master battery switch decided to die and the alternator/engine shut down along with the voltmeter which dropped to full discharge ......I had visions of bad diodes in the alternator, fried wires, ruined batteries, and woe is me!
Took the alternator to an alternator/starter shop to have the voltage output and internal voltage regulator checked...100% perfect!
Checked out the 4-0 +/- alternator/battery wires...no melted insulation..all perfect. Of course the master battery switch, the original instigator was history. I called Blue Seas tech (800-222-7617) and told them the story and added that I had recently installed fuses to both + battery posts and they were both blown.
Interesting...the tech said that was the smartest thing I could have done!!...most folks don't add marine fuses (or the correct fuses) to the house batteries. He said "THE BATTERY FUSES SAVED THE DAY" !!!
I also asked the tech about the "Alternator Field Disconnect" option in the Blue Seas e-series Master Battery Switch...was it like the Sterling Power Alternator Protection Device"? Tech said the AFD was not sacrificial and would reset if a problem occurred, and highly recommended.
I ordered the Blue Seas 9002e Batt Switch and another 2 Blue Seas fuses...
So happy now!!
Took the alternator to an alternator/starter shop to have the voltage output and internal voltage regulator checked...100% perfect!
Checked out the 4-0 +/- alternator/battery wires...no melted insulation..all perfect. Of course the master battery switch, the original instigator was history. I called Blue Seas tech (800-222-7617) and told them the story and added that I had recently installed fuses to both + battery posts and they were both blown.
Interesting...the tech said that was the smartest thing I could have done!!...most folks don't add marine fuses (or the correct fuses) to the house batteries. He said "THE BATTERY FUSES SAVED THE DAY" !!!
I also asked the tech about the "Alternator Field Disconnect" option in the Blue Seas e-series Master Battery Switch...was it like the Sterling Power Alternator Protection Device"? Tech said the AFD was not sacrificial and would reset if a problem occurred, and highly recommended.
I ordered the Blue Seas 9002e Batt Switch and another 2 Blue Seas fuses...
So happy now!!
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1911tex
Sustaining Member
Continuing Post #11:
Blue Seas also stated that a starter battery should not be fused; however the other house battery which may have an inverter will need a class T 5502 (#5120) 350amp fuse.
I know this is confusing...would highly recommend calling Blue Seas or contacting a local marine electrical professional for your own application.
Blue Seas also stated that a starter battery should not be fused; however the other house battery which may have an inverter will need a class T 5502 (#5120) 350amp fuse.
I know this is confusing...would highly recommend calling Blue Seas or contacting a local marine electrical professional for your own application.
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Nice save!
From Blue Seas, regarding the battery switch with AFD: https://www.bluesea.com/resources/91
If a battery switch is turned off while the alternator is producing current, the voltage will increase due to the sudden elimination of the load. This will burn the diodes out in the rectifier quickly. To prevent this, a battery switch with an alternator field disconnect (AFD) can be used. The AFD is a secondary, isolated, single pole switch within the battery switch, through which the alternator field current source wire from the voltage regulator is wired.
The AFD is constructed in such a way that the AFD switch does not close until slightly after the main switch contacts have closed and it opens slightly before the main switch contacts open. This insures that there will always be a path for the alternator's output current when the alternator is producing power. The field disconnect will only work on alternators with an external regulator. The diagram below illustrates the connections. Blue Sea Systems battery switches 9002 and 9004 have an AFD.
I'm still running the old Motorola 50A alternator (with integral regulator) so I put in a Sterling alternator protection device.
1911tex
Sustaining Member
Ken..thanks. Note, my original Motorola 50A alternator did not have an internal VR. It would charge at full capacity as long as the engine ran, even with batts at full charge...making constant topping off with distilled water. My new Prestolite 105A alternator does have an internal VR. Thanks for your answer and I am also installing in a Sterling APD..with alarm buzzer.
NOTE: My original Main Battery Switch apparently (which I should have taken seriously..sometimes had to wiggle the switch slightly to get green light contact!) had poor worn connections between off/batt 1/both/batt 2. That created the short from "batt 2" to "off".....and the ensuing calamity which drove me almost to a mental nutcase. The 9002e batt switch is going in this week.
What a grand relief!!!
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Yes
It definitely could have.
RCsailfast
E35-3 Illinois
I installed the Blue Seas Add a battery setup with the ACR. Added a #4 cable from the 50A alternator to the house battery and removed the jumper to the starter. Used Blue Sea Marine fuses, and #4 cable between the batteries and the ACR. Fused the House and Starter 4/0 with 350A marine fuses as well. Have been strongly reconsidering fusing the Starter after watching a video from Jeff Cote at Pacific Yacht Systems.
Boat hasn’t splashed as the winter to do list is still but moving the starter cable back to the battery post is an easy task
Sounds like replacing your switch should resolve the problem.
Boat hasn’t splashed as the winter to do list is still but moving the starter cable back to the battery post is an easy task
Sounds like replacing your switch should resolve the problem.
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Any special reason for such large on the cables and fuses? Just curious.
I fused both my starter and house batteries with MRBFs. I was told the starter draws 1000W (that's 80A); the glow plugs draw 20A. Those are the two highest draw items on my boat, at 100A combined, so upped it 50% and put in 150A fuses. Haven't blown one yet. The battery cables are 1/0.
I know in-rush currents can be a lot higher for motors, but the fuses are made to handle momentary spikes. And the starter is usually only engaged for a few seconds at a time. I carry 200A spare fuses in case there is ever a problem. But that is worth thinking about first--if a 150A fuse has worked well for two years and then all of a sudden becomes a problem, maybe some troubleshooting is advisable before just sticking in a bigger fuse.
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