battery selector switch wiring

[GLS062866]

Hello,

I am interested in getting a suggestion on a battery selector switch. I have a 1993 135 Yamaha that I have on a single starting battery. I also have 2 batteries hooked up for a 24 volt *****ing motor. Also hooked up is a 3 bank on board charger. I have a battery switch (just on/off) on the starting battery. I am interested in changing switches to one that I can wire to be able to use one of my *****ing motor batteries as a back up for my starting battery by moving the switch to either battery 2 or both. Does anyone have a preference on brand? Is the switch with the AFD necessary? Also would you look to see if the wiring diagram is correct.

[DennisG01]

Perko, Blue Seas, Guest. All of them will have wiring diagrams, too. You can check them out/download online.

An AFD isn't "necessary", but it kinda is. If someone would happen to switch the switch while the engine is running, without AFD, you can damage the engine's charging system. With AFD, it is a "make before break" and it won't cause any damage. Note... that you still don't want to to switch past "off" or the same damage applies.

[fairdeal]

An AFD isn't "necessary", but it kinda is. If someone would happen to switch the switch while the engine is running, without AFD, you can damage the engine's charging system. With AFD, it is a "make before break" and it won't cause any damage.

Hmmm. I suspect most inboard engines - "marinized auto engines" - have excited field alternators.

maybe some Merc outboards.

But since this is a Yamaha forum....

my F225txrd does not have an excited field alternator.

Does yours, Dennis?

[DennisG01]

Hmmm. I suspect most inboard engines - "marinized auto engines" - have excited field alternators.

maybe some Merc outboards.

But since this is a Yamaha forum....

my F225txrd does not have an excited field alternator.

Does yours, Dennis?

No, my engine does not have an alternator. But you knew that.

Maybe I've always misunderstood this, though. Or maybe I was "assuming" that the charging system on an outboard needs to "go somewhere" like it does with a stern drive, so it doesn't backfeed on itself? Does it not matter in the case of an outboard? Meaning, it won't cause any problems if the "charging juice" doesn't go anywhere?

[boscoe99]

No, my engine does not have an alternator. But you knew that.

Maybe I've always misunderstood this, though. Or maybe I was "assuming" that the charging system on an outboard needs to "go somewhere" like it does with a stern drive, so it doesn't backfeed on itself? Does it not matter in the case of an outboard? Meaning, it won't cause any problems if the "charging juice" doesn't go anywhere?

With an automotive type of alternator electrical power is generated based on demand. Little demand, little electrical power is generated. Lots of demand, lots of electrical power is generated.

With the Yamaha antiquated system, referred to as a PMG for Permanent Magnet Generator, all (the maximum amount) of the electrical power is being created all of the time. Whether it is needed or not. What is not needed is sent to ground (to control voltage) and then wasted in the form of heat. Some regulators use fins to dissipate heat and some use water.

Both types use electronics (diodes and such) to control the voltage and thus the current output. If and when a live system making lots of electrical power is turned off then voltage spikes can occur. Very high voltages are generated. The high voltage can, not will, damage some electronics.

Now if "demand" is not the best use of a word then let me have it!

[fairdeal]

Now if "demand" is not the best use of a word then let me have it!

demand is absolutely the right word, AFAIK.

I'm just rubbed the wrong way by just those "smart charger" enthusiasts and their "charging profiles"

[boscoe99]

demand is absolutely the right word, AFAIK.

I'm just rubbed the wrong way by just those "smart charger" enthusiasts and their "charging profiles"

Did you read the one from the Yahoo that said the F225 regulator must be "smart" because it can charge different types of lead acid batteries? Big ones, little ones, flooded ones, sealed flooded ones, unflooded ones, etc., etc.

[GLS062866]

I have looked on line and downloaded some manuals but have not been able to find the set-up in any of them that I was looking for. I emailed two of them and they basically would not answer my question and referred me back to the mechanic that works on boats. I assume without seeing everything it is a liability reason for not answering wiring diagram question.
Does the wiring diagram that i made look correct?
GLS

[DennisG01]

http://www.perko.com/images/catalog/...(8500INS1).pdf

Look at the first diagram, that is what you want to do. Forget about having two batteries tied together - it's that same as having one battery. Think of it as "banks" instead of "batteries".

[GLS062866]

Dennis,
thanks. i did see this diagram but I should have been a little more specific on my question. I was more concerned that my diagram showed the correct way to get 12v from the one *****ing motor battery. I wanted to make sure that I was not going to send 24v to outboard. Also if I ever had to put switch on both this would put batteries in parallel so it would remain 12V but more amps correct? *****ing motor batteries in series for 24Vwith same amps correct?
Any disadvantage to this setup as long I always remember to turn switch to off after using?
GLS

[fairdeal]

here's the diagram from your post



looks right to me:

- all battery negatives connected to ground
- *****ing motor sees 24 volts
- on Switch position #2, Yamaha gets 12V

and if you use a 1,2, 1&2 switch, then on 1&2 the Yamaha gets 12V with whatever amps it can get from both batteries.

As to the switch selection, as I intimated in my earlier post

(snarkily, I'm afraid - for which, Dennis, I apologize)

you don't "need" an AFD contact because there is no Alternator Field Winding on your Yamaha.

[DennisG01]

No worries, Fairdeal. I took it only as some good-natured sarcasm.

Yes, you are correct in that: Wiring batteries in series (as you have listed in your diagram) doubles the voltage (but amps stay the same). Wiring in parallel doubles the amperage, but voltage stays the same.

Now, as far as answering your question (sorry, I didn't realize this was what you're after), I've never tapped a 24V system for 12V so I wouldn't be able to answer you from experience. I'd have to Google it, first, and that would be cheating.

Another way to go for some extra insurance for your main engine is to carry a jump pack (check out the newer LiIon packs... they're about the size of a pack of cards).