Batt switch and Alternators
 

"Now what I don't understand is how could running them in ALL effect the Alternator 12vdc is 12vdc no matter where the source I would think that one may shutdown (thinking the batt was charged) and let the other do the work but I can't see how it could hurt it. I would think that you would have to have a high current overcharge situation to smoke the alternator."

This is a question I had asked in the PQ forum we were talking about the Perko batt switches. I am having a Alternator rebuilt and don't want to keep frying it. But I just don't understand the logic if a Alternator has a diode to prevent back feeds why would running the switches in ALL position hurt anything? Or is this just a Wives Tale. :rolleyes:
I also have read that it could cause problems on a EFI system:confused: :confused:

Anyone have any facts??

Must be some of that voodoo stuff that Packinair was talking about:crazy: :D

Running the Batt switch in "ALL" position won't hurt the alternator. What will hurt it is if you, by mistake, switch it to off while the engine is running. That'll bow diodes. The batt switch should be the "make before break" type. What that means is that when switching from one battery to the other both batteries will be briefly connected before disconnecting the first battery. This way there's no loss of voltage while switching.

I dont even have switches in mine Scott, all 3 are hooked together through an isolator. I dont see how running with the switch in the all position would hurt an alternator either. Used to run them that way in the formula.

If twins, running in the all position for both engines can cause problems for the alternator regulators. Basically what you have done is hotwire the two together. One regulator will fight the other. I run three batteries. "1" on each side is the respective battery. "2" is the center. I run one side on "1" and the other on "both" to assure I don't hot wire these. You also can buy a battery isolator.

If I am correct the diodes in the alternator will isolate them from each other. A battery isolator does just that it Isolates the batterys from each other. Sorry I need more info backing this up before I worry about not running them in ALL not that it much matters if I don't.

I found out today that my alternator was o.k. I have another problem possible breaker or fuse on the output ??? possible bad guage or wireing to it?? I will find out this weekend with a volt meter, a load/charge tester and some test clips. This and a oil pressure guage have been a problem for over a year now I must find it soon:crazy: :crazy: :rolleyes:
BTW I have been running mine in ALL for three years.

I also think (not too sure) that the diodes we are talking about are used as rectifiers changing A.C. to D.C. so do they still isolate the input or is there another one for that.

I can't believe out of all the motor, electrical,engine, engineers,doctors,attorneys whatever no one on here used to own a alternator shop:D :D

Scott, 4 years of Electrical Engineering and with 3 years of shipboard systems experience count? I thought the same way as you until I fried 2 alternators. They guy at the alternator shop laughed me when I said I ran on "both" all the time. Maybe he was just giving me a hard time but I've never hard wired 2 alternators together again.:D :D :D

By the way if your at Kellys Island at the Casino, I be glad to talk in person (I'll buy you a beer).

I never go to the Casino:rolleyes: :p
I respect what you have accomplished but even you admit I may be on the right track. It could of been other problems that knocked out your alternators. I need a schematic shoved in my face that proves this:eureka:
All of this aside I will be happy to have a cold one with you and by all means thanks for the replies I am not trying to say you are wrong I just need to (want to) totally understand why he said that they said that we said that that must be right:crazy:

WARNING, If anyone buys wire terminals from Napa/Belden. Look at them very closely, They are marketing a line of terminals that are not supposed to be crimped, just stick the wire in and heat shrink. Well, I used one on an alternator output wire earlier this winter and when I fired the engine I fought no charge all day Sunday until I finally isolated it to that terminal. Looked great, read 12.8 volts and zero ohms until I started the engine and it started to pass current and then that loose wire in the "no clamp" clamp broke the circuit. What a pile of trash those things are. I took them all back to Napa at least expecting my money back and the guy just says 'Oh well". Dont know if this could have anything to do with your issue Scott but I had to vent. BTW. I also have an EE degree and 12 years as a Merchant Marine Chief Engineer.

Well if you try to use a connector thats not soldiered or at least crimped to pass a continuous 40 plus amps of current, you pretty much just went hunting and shot your dog. Second, diodes in alts do not keep electricity from backfeeding to another alt... it's part of what and how ac volts are converted to dc volts, by eliminating half of the sine wave ac voltage produces (60hz will run your blender). And Im not to sure I would admit using a jive ass connector in a wire that 99.9% of your voltage is created from to begin with. Alternators make AMPERAGE, NOT VOLTAGE, and if you have no other choice than to create a break ANYWHERE in the main charging wire to your batteries, and don't make a properly soldiered, weatherproof connection... then don't badmouth something that was never intended to be installed incorrectly or used for the highest current passing wire any vehicle, boat or whatever has... it's probably the closest to a fuseable link you could find, and WORTHLESS.

Scott, How did you know your alternator was bad? what were the symptoms? I have one engine that reads close to 14V on the gauge and the other is just over 12V. (when running) could the 12V one be bad?

My old Liberator {twinns} I ran the Batt switch in "ALL" for 10 plus
years...no problems.......My Cig says right on the panel..Do NOT
run in all unless you have to for short periods......
Got Me ???.....I have an Isolater...I thought that would be OK..
I just run 1&2 now..

Ray,
The Gauges on that side are all a little low compared to the other. I have been chasing a crazy oil pressure gauge problem for two years and have been told from Gaffrig "You must have at least 12vdc to the gauge for it to work like it should" I also show around 10 vdc on that side and the gauge does not budge when you rev it up. I finally decided to pull the Alternator when I did I fired it back up and there was no change at all on any of the gauges, I assumed the Alt was bad after seeing this! It is not bad and I am back to square one. I will find the problem and let you know. The first thing I will do after I re- install the alt is to check the charging system with my batt and charge system load tester if I have nothing I will start looking for a fuse or breaker on the output and it seems to me that I saw one when I was looking at the diagram.

Diodes and mixed charging!
I spent some time last night looking at alt schematics and hookups none were exactly what I have. I did notice on all the schematics the cathode side of the diodes were toward the battery that should stop the back feed. But I also realize ratings and current come in to the setup at this point.
One more thought why don't the battery chargers fry the alt if you think about it they are doing the same thing as having the switch in All you are sending a different 12vdc source to the alt.

Just a thought;)

I know I have beat this to death and everyone will and should do what they are comfortable with. I did learn one thing you should never change switch settings while the engines are running. This will or could fry the Alt (surge related) they like to see a load.

Hey FindMe, excuse me for trying to point out to other boaters that Napa was marketing a connector that sucks, and its right on the board with all the good ones with no clear difference. Geez. Have a beer.

Oh, by the way, soldering connectors on a boat is the worst thing you can do.

I use ultrasoft low temp solder on all my boat stuff. Love it. It's not brittle, and doesn't corrode (I put liquid tape on them anyhow).

Solid state voltage regulators won't fight each other - mechanical ones will.

My Formula has all the trimpumps (drives and planes) hardwired to the respective battery (port to port - stbd to stbd). If I don't run in ALL, then one battery goes tits up from the pump loads.

I only use "1" or "2" setting when rafted to avoid killing both batts. Back to ALL when ready to run again.

No isolator on this boat. In fact, it had no battery switch from the factory - it had to be added to be legal for dry rack storage.

12 years. No issues.

As far as what it might be that "kills" alternators on the "ALL" position, you got me. I don't see what the problem is. I have a hard time believing that "fighting regulators" would cause the trouble. All a regulator does is change the field voltage in order to vary alternator output current. It does this by reading line voltage. Voltage drops, it asks for more current output from the alternator. Voltage gets high, it tells the alt to stop throwing out current.

Diodes shouldn't argue about anything unless they have nowhere to pass the current being thrown into them. If the alt is throwing out a lot of current, and the batt switch gets flipped to OFF, there is a possibility that the ignition system will not be able to use as much current as is being thrown out. In that case, the diode or triac can possibly saturate and pop before the regulator gets the alternator shut down (it's a magnetic field, which does not respond "instantly" cause it has to "collapse" as opposed to just being turned "off").

I don't want anybody to have electrical troubles at all. I just don't see why running on ALL is an issue. Please continue to post explanations and I'm sure we can zero in on it.

M

You can run your switch in the "both" position all day long. This will not hurt your alternator. It is the same as running a double size battery. The only time not to is at anchor. If you leave something on, both batteries will be dead.

You should not use solder on most connections. Just be sure you are using a quality crimp tool and connector such as 3m brand. Having said that I still do solder some connections, such as the alternator output wire.

Two alternators running together will work fine, even if they are set at slightly different voltage. One will just stop charging before the other. This is used on many off road and heavy duty marine apps. Even some of the stereo guys are doing this.

It is not a good idea to flip your battery switch with the engine running. However most regulators these days are lightning fast and will probably live.

I agree, most connectors from most auto parts stores are useless.

oh yeah, I do own an alternator shop. Worked there since I was 12yrs old.

Steve H