#1
IP: 64.32.196.134
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Battery Switch: Field Disconnect Protection
After getting under way under sail yesterday, I switched from "BOTH" to "1". The VHF radio beeped and the GPS powered off. So either the switch on our 32-year-old boat is not a make-before-break switch or it's just plain gotten old. Either way: Time for a new switch.
Assuming our A4 has the original Motorola 35A alternator on it: Can I use the field disconnect protection "OFF/1/BOTH/2" switches that are so-equipped offer? I believe the original had an external regulator, and, if I understand correctly, that's what's needed to use this feature. Secondly: Would a switch rated at 250 amps continuous, 360 amps momentary be sufficient for an A-4? Heck while I'm at it: Wrenched on engines a lot in the past, but never had cause to do more than occasionally just out and replace alternators whole-sale. So how do I tell the difference between the original 35A Motorola and an upgrade? Between an alternator with an external regulator (as I understand the original would be?) and one with an internal regulator? Thanks, Jim |
#2
IP: 142.68.101.28
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I've been trying to figure this out too. Bought a new switch recently.
1. I understand the A4 has a maximum cranking current less than 200A. Don wrote "we believe that a 200 amp fuse would be a good choice to provide for starter operation" in http://www.moyermarine.com/forums/showthread.php?t=1044 and "The amp draw varies considerably depending on outside air temperature, compression values, etc., but we've never seen over 200 amps." in http://www.moyermarine.com/forums/ar...hp/t-1168.html. 2. Below is a photo of our alternator. I think the external regulator is the silver device attached to the front. I tried to figure out using Google which wire might be the field wire, but gave up -- too many variations between models over the years. It might even be inside the regulator/alternator connection, not outside. My plan is to take it to an alternator shop to check it out anyway, since it is only charging 13.1 volts. I'll ask them then. Update 10 August 2008: I took the alternator off and found a label on the external regulator. The Internet is a wonderful thing: http://195.125.241.148/cgi-win/product.exe?M5197A Transpo M5-197A REG MO 12V replacing OE MOTOROLA 105-197 5-197 8 RG 2010A Voltage Set Point: 15.0 V Regulation: B-Circuit Adjustable Voltage Short Key Hole Case Style Terminal Identification: PLUG-TYPE: K WIRING CODE 3 RED...................ISOLATION DIODE(+) BLACK .............GROUND GREEN..............FIELD YELLOW...........IGNITION There is no green wire visible, so as I suspected it must be inside the casing, so not easy to interrupt it to run to the battery switch field disconnect terminals. Last edited by rigspelt; 01-14-2010 at 05:21 AM. Reason: Added photo with regulator removed. |
#3
IP: 75.199.196.192
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Assuming you're referring to the field exciting lead that connects to the
positive terminal of the coil, that connection is not actually needed to keep the alternator online, once it activates. In other words, you can disconnect that lead and the alternator will continue to operate. Don |
#4
IP: 206.181.246.34
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Quote:
Quote:
This article contains the following information on this circuit: Quote:
Thanks for the info: Re: Main battery switch requirement. Sounds like a 250A continuous, 360A intermittent switch should be sufficient. As far as the alternator field wire: The description above sounds almost vaguely kind of familiar to me--the "F terminal" part, that is. It's been so long since I've wrenched on engines--especially an engine with an alternator with a detached regulator--that I cannot say for sure. I do vaguely recall having to replace a regulator... once. ISTM it was not mounted on the alternator, itself. Then again: I've poked-around in our P30's engine compartment pretty extensively, by now, and I don't recall seeing anything bolted-on anywhere reminiscent of an external regulator, either. Update: So I did a bit of quick research, and immediately found Alternator Good ol' Wikipedia . Contained in that article is this: Quote:
And more info: Atomic Four Specifications (Robert Hess) has this to say: Quote:
Jim Last edited by SEMIJim; 08-04-2008 at 10:07 AM. Reason: Additional info |
#5
IP: 142.68.101.28
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Quote:
Nigel Calder's Boatowner's Mechanical and Electrical Manual has a good alternator section. |
#6
IP: 206.181.246.34
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Quote:
Quote:
To be honest: The field disconnect thing isn't awfully high on my priority list. I'd like to have it, as a backup/safety feature, but I don't ever expect we or anybody else to change that switch while we're motoring. ("Expect" is the key word, there, I know .) My immediate concern is stuff powering-down while switching. So: I may get a switch with the field disconnect or I may not. (Probably will. It doesn't appear to add much cost to the switch.) If I do: I may someday get around to hooking it up--if it's possible, or I may not. It's certainly not important enough to me to pay a marine mechanic to come out and look at it. Quote:
It'll be interesting to see what your mechanic comes up with. Take pictures . I am kind of surprised the answer isn't here. Jim |
#7
IP: 70.108.234.35
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Jim,
I was thinking about adding a capacitor to the alternator to arrest spike voltages encountered when the batteries are not in the circuit. A capacitor would allow the engine and alternator run safely in the OFF position. Old cars used to do this. I haven't had time to spec this out yet, though. Short of that solution, I am thinking about adding a relay and buzzer to the battery switch field coil connections. The circuit would sound a buzzer when the battery switch is off and the alternator is running. Steve |
#8
IP: 206.125.176.3
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it's been here all along!
Hi all,
Kinda of an old thread, but relevant to my current tasking so no reason to start a new one. My local alternator shop made a comment about voltage adjustable bolt-on regulators for the original 35 amp Motorola when I took one of them in for service. What I discovered when I bought the boat was the OEM regulator didn't work. The P.O. disconnected the green wire (which I guess is the field wire, and as rigspelt surmised is in between the reg & alt housing, inside the USCG approved ignition protection felty stuff) and ran it to an external regulation source. Since I am cheap (and own two alternators, one with a new diode plate, and one with no regulator, but otherwise seem to be functioning normally) I was considering sourcing these regulators on the Internet. I have a diode based charge isolator on board, and this takes my original 13.8 volts at the alternator post (still a little low by today's charging standards), and reduces it to about 13.06-13.17v (depending on engine speed) at the battery during charging. Modern charge practices seem to indicate a (wet cell in this case) battery receiving 13.17v will die a slow death due to undercharging, and that number should be more like 14.2v As usual , rigspelt has already done the research...after I dug thru some non-english websites to find cross reference part numbers for the old regulator, a subsequent Google search with some of those numbers pops up this very thread, because of the information rigspelt posted above with all the cross referencing done. Now, the question is can anyone find these things on the Internet?? The link above pointing to ASE supply seems to be one of the only places that actually sell them ($23), but I cannot seem to get accurate stock information. The most readily available seems to be the Transpo (M5-197A), or possibly the Amsco (MA-201) regulators. Thanks!
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) Last edited by sastanley; 04-29-2009 at 07:59 AM. |
#9
IP: 64.231.83.142
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Quote:
"Regardless of setup, an important consideration is that the alternator-to-battery+ connection must never be broken while the alternator is generating current. Otherwise the energy stored in the alternators inductive coils would produce a large voltage spike, possibly destroying both the alternator rectifyer diodes and any connected electronics." (Boatowners Illustrated Electrical Handbook", Charlie Wing 2006 (P.61). Wing offers the following solutions to the problem: 1. A voltage snubber from alternator output to ground; 2. a warning sign on the switch; 3. in the case of a four-pole switch, a built-in "field disconnect" (which requires a seperate voltage regulator as opposed to one that is built-in the alternator). He also suggests a fourth: 4. permantly wiring the alternator output to the "house battery", so there is no danger of damage from interrupting the alternator output. A starting battery can be charged if hooked up with a switch that allows both batteries to be connected in parallel. and fifth option: 5. both batteries hooked up with a pair of isolation diodes (because the diodes look like closed circuits in the forward direction , they also solve the open-alternator problem). But they also drop charging voltage by .6 - 1.0 volts resulting in chronic undercharging of the batteries! Guess, you can't get something for nothing!!! (But if your voltage regulator is adjustable you can compensate by adjusting the output to compensate for the diodes.) |
#10
IP: 206.125.176.3
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Hmmm, #4?
I have problem #5.
I also have a solar trickle charger which I've been testing in the garage over the winter..It seems to bring the battery up just fine after a week or so of strong sunshine, even in winter. Summer should be even better (longer days, more sun.) I put a $25 controller on it (to avoid overcharging), and it seems to pump about 0.7 amps in bright sunshine into the battery. Not a stunning amount, but it is free! While I contemplate a permanent solution, I am currently considering simply removing the charge isolator from the circuit and keeping the solar charger on the start battery, and the alternator (all whopping 13.8v) connected directly to the house battery. The solar charger should be able to easily bring up the minimal voltage drop from starting the engine if I can't actually start using the house battery, which would be my normal procedure anyway. If necessary I could always move the alternator output back to the isolator if I needed temporary charging of both batteries. All of these items are in close proximity to each other & I have relatively good access on my Catalina 30.
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) Last edited by sastanley; 04-29-2009 at 03:41 PM. Reason: rambling on & on & on |
#11
IP: 70.108.180.192
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Quote:
I am not quite following your explanation. Do you have an external regulator or not? If you have an external regulator it is a simple mod to overcome the diode voltage drops associated with your isolator - with a $2 diode. Steve |
#12
IP: 206.125.176.3
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sorry, I tend to ramble..i am often not clear :)
Steve,
No I do not have an external regulator. The boat had one at one time (simple one wire automotive type) , but it didn't work either...the charging system on this boat was 'highly modified' by the P.O. What I am attempting to do is at least get it back to original configuration and then move forward from there. So far, I have sourced another 35amp alternator from a former A-4 owner with the stock regulator, which from what I can tell from my research was designed to put out 13.8v. This has at least gotten me back to a base configuration to work from. Now, I am considering replacing the OEM regulator with a bolt-on replacement regulator that has adjustable voltage. The alternator shop said the alt. itself is pumping out about 15 volts. These aftermarket regulators have a max rating of 15.1v so it sounds like the alt. is OK. My problem is sourcing this adjustable regulator. In the meantime, I am trying to find a way to get the voltage up in my charging system as far as I can. I already have one dead battery which I assume has been from charging it thru the 'modified' system I inherited along with a diode based isolator. (I did not test the output voltage of the modified system...basically the P.O. built his own regulator with a couple of diodes & a 3-way switch.) The isolator would also be great, if/when I can get 15 volts out of the alternator...I measured each side of the isolator and lose about 0.73 volts or so going thru it. Again, with the stock 35A Motorola only putting out 13.8v, my goal right now is to eliminate as much wire and junctions as possible, and get as much juice to the battery as possible, while I research alternatives. So, I am assuming using your suggestion, it tricks the regulator into pumping out more voltage? How does it do that if it is fixed at 13.8v? I thought the job of the regulator was to adjust the amperage put out by the alternator based on its sensing the battery's voltage (state of charge?), I do not understand how you can use a diode to modify the voltage output itself on a fixed unit? - I am a complete amateur at this electrical stuff, so you'll have to bear with me. In the interest of full disclosure & to try to be less confusing, the boat's previous owner was my father, & he is an electrical engineer and a tinkerer. He has all kinds of weird stuff going on this boat I am trying to figure out. You and him could probably talk shop all day. When I was a kid, he'd draw little diagrams like the one in your post trying to explain what he was doing. I've found a few random hand drawn diagrams in some of the manuals & books I've found in the boat.
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) Last edited by sastanley; 04-30-2009 at 08:58 AM. Reason: more rambling ;) |
#13
IP: 192.60.230.178
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Hi Shawn,
Going from the bottom up. . . Quote:
Quote:
Code:
So, I am assuming using your suggestion, it tricks the regulator into pumping out more voltage? Quote:
My boat came with the 55 amp unit Don sells and this was the main reason I opted for the ACR. The 55 amp unit has internal regulation. I saw no practical way to use an isolator except with a non-regulating alternator and a separate, external, regulator. Probably not what you wanted to hear. Sorry. Steve Last edited by High Hopes; 04-30-2009 at 02:05 PM. |
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