Unregulated charge, 73 135hp v4 Johnson

[SCO]

I tested out the boat Sunday, after adding instruments and a new rectifier to the engine. I was alarmed to see the voltage peg to max at some 16vdc. When I would stop, shutdown, and restart I would find it at 14 for a while, then soon it peged back to max voltage. Questions are:<br />1) what is the normal voltage output by these unregulated alternators?<br />2) Is this a good way to produce hydrogen in the battery and blow up the boat?<br />3) Is there a certain type of battery that should be used with this type of system?<br />Thanks. There has to be a reason that they went to regulated charging. Can you retrofit?

 

[DJ]

Re: Unregulated charge, 73 135hp v4 Johnson

SCO,<br /><br />That's about right. You really need to load (turn something on) the system once in a while.<br /><br />I don't know if your engine has trim and tilt? If it does, that usually keeps the voltage in check.<br /><br />Otherwise, leave the lights or someting on. Any load will help.

 

[SCO]

Re: Unregulated charge, 73 135hp v4 Johnson

I ran it for about 2 hours at 3700rpm nervously, and did turn on the running lights but it remained peged. I'll have to think of other ways to take energy out but would taking more out just work the alternator more? This is when you need Schematic. Does the battery stop accepting charge? Does the current go to Zero or very small and if the current goes to zero does the work of the alternator and its draw from the power of the outboard go to zero? If this is all true, then in a sense it is self regulating. This motor doesn't have tilt and trim.

 

[DJ]

Re: Unregulated charge, 73 135hp v4 Johnson

SCO,<br /><br />There are essentially no moving parts in the alternator. They only put out about 6 amps. It's going to take alot of that to ruin a battery.

 

[Dhadley]

Re: Unregulated charge, 73 135hp v4 Johnson

How many batteries has it burned up since 1973 (or before you put the gauge in)? I'm betting none. Djohns is right - its a normal function of an unregulated system. <br /><br />Good luck!

 

[pkhiggins]

Re: Unregulated charge, 73 135hp v4 Johnson

These unregulated systems rely on the battery for whatever regulation there is. Without the battery being connected, the voltage can go much higher than 16 volts. That’s why the diodes and any equipment connected to the alternator can fail if the battery is disconnected. I suggest you use a battery intended for constant current charging. I saw one at Sam’s just a few days ago. Such batteries keep the voltage a little lower.

 

[rons boat]

Re: Unregulated charge, 73 135hp v4 Johnson

OK The stator has a max out which I believe is 10Amp for your stator. Somebody correct me if his is not 10A. The battery floats at about 14.5V and resists higher by acting as a load. The guys are right that the load should be increased if you go much above 15V. If you run two 55 Watt lamps you will be abosorbing all that your stator will put out, so there is no way of permenant damage. I suspect the following: Your voltmeter is incorrect, the battery has too high internal resistance( that means it's bad, or something else we have forgoten. I remember an episode on Science Fiction theater where someone found a suitcase and they could plug a whole citys electrical demands into it. No such luck. The stator is a saturated field design which limits your output to the design current. Most of the motors that are not regulated are limited to 10A. I am going to design a regulator which will be heatsinked to the transom and be cooled by water for some of the guys with those big stators. The mfg put those things under the hood so they can burn up and be replaced at high cost.

 

[rons boat]

Re: Unregulated charge, 73 135hp v4 Johnson

For those guys who worry about too much current and thus too much voltage cooking their battery. At the control panel of your boat put the primary of a small 12VDC relay thru a Zeiner Diode 6V at 2W and a 100 0hm 2W variable resistance and connect that to your swithed bus comming from the battery, adjust relay to fall in at 14.8V. Then connect your headlights up to the secondary. In parallel with your light switch. Auto regulation. A little on the dinky side. I am building a series regulator for a friend who doesn't like to look at his voltmeter and of course it will be wired in series with the output of his rectifier under the hood and return to the same point as the feed that went formally to that bridge. It will be mounted on a large piece of aluminum (fresh water) Brass for Saltwater. the regulator will set in the dry even though it is vertually waterproof on the inside of the transom and the heatsink will extend on over the transom into the water. Anybody else can do this if they want as it is too obvious to patent.

 

[SCO]

Re: Unregulated charge, 73 135hp v4 Johnson

There was a thread not long ago Ron about charging from the car while driving. Great relay idea for that and I could do the same thing here. I think Djohns is right about the 6amps(10 or 12 for subsequent regulated models) and if any old battery can handle that with no ill effect then ok. To be safe I'll look for a constant charge type per pk. Ill check voltages against a handheld. I'm trying to figure out where all this 6 a current is going. Does this alternator put out 6a regardless of the voltage it must overcome? In that case a good battery will charge to full then pass 6a across 14 or so volts for a power consumption of 14X6 watts as heat to the battery(or is it (14-12)X6 watts). I'm not sandbagging here. I know just enough elecrical to be dangerous. I dont understand how an alternator works other than moving a wire coil through a magnetic field creates a current( the 6 a). I conclude the 6 a current is proportional to the motor rpm. Is the current also proportional to the voltage or load it must overcome? If you disconnect the alternator, you don't get any current. Is that how you burn one up? How could you burn it up with no current therefore it shouldnt hurt an alternator to unhook the leads...si or no? Thanks to all so far.

 

[rons boat]

Re: Unregulated charge, 73 135hp v4 Johnson

You almost have it right. The stator windings are wound on an iron laminated core that will only support a magnetic field so strong. When it saturates that is all it will put out. Six, Ten, whatever. That usually happens at much less than full rpm. Battery chemistry is complicated, but sometimes it is best not to use a deep cycle battery as they tend to not have the starting power. They are better at coming back from deep discharges from which they get the name. They still slowly decay if left uncharged for any length. Cars don't use them because a car needs starting power and the battery is never supposed to get so low it starts decay. What matters is the way a battery is treated in a given situation. Put a deep cycle in a car and most would keep taking a charge when the regualar car battery would float, that is stop taking a charge. So a deep cycle in a boat takes it on the chin at higher voltages by absorbing energy and converting it too heat.

 

[rons boat]

Re: Unregulated charge, 73 135hp v4 Johnson

I forgot to say in that not so straight forward answer to your question: An altenator in a boat is almost a constant current device. Unlike an auto altenator it has no device to control the field strength, no brushes and no wire wound magnets controlled by a small voltage regulator.<br />You got it right, it is just a group of coils being passing by a fixed set of magnets. It's the magnetic field that produces a fixed limit on current, the voltage is controlled by load. That's why you have to have the battery in the circuit and that is your only overvoltage protection. Not to mention the mfgs could put capacators on components to limit voltage peaks and damage at very low costs. Instead they cover their ______ by saying "keep your connections tight and never let a battery go open when it fails. Make sure when it fails it shorts. HA Ha

 

[SCO]

Re: Unregulated charge, 73 135hp v4 Johnson

This is helping. So you are saying that regardless of what the battery is doing or the current load, when the battery is not accepting charge(meaning no current going to change the battery chemistry but full current passing through the battery from + to -??) or charging like crazy in the deep cycle case, that unregulated alternator puts out 6a current in all these cases that I should be able to measure with an ammeter. Please straighten me out on any point, and thanks for staying with this. I dont understand what you mean when you say the voltage is controlled by load. Do you mean the current is fixed at 6 a, and the voltage builds to whatever it takes to get the fixed amount of current, the 6 amps, through the resistance of the load?

 

[rons boat]

Re: Unregulated charge, 73 135hp v4 Johnson

Almost but not quite. This is one of those delicate balance situations and it sounds as if your system for whatever reason is causing your battery to keep taking a charge at a higher than normal voltage. It is about the same as an unregulated battery charger that you use in your garage. As the battery(good battery) becomes fully charged its impedance increases so that it being in series with the stator decreases the flow of current to much less than the maximum capable of the stator and a level that wouldn't produce high battery voltages. That tapering off occurs to an acceptable level for most batteries and for a normal operation of the boat without damaging the battery or accessories on the boat. An ammeter is a good idea along with your voltmeter, but you might have to go to the motor between the output of rectifier and the former connection that it supplied. Not sure in your case. Solution: Running lights don't use much current, so plan on using 55 watt fog lamps or something like that and you will need to make no further changes. The voltmeter and your use of the lamps will control the situation. <br /> Again I am providing to a friend a device, a series regualator, to go in the same place as an ammeter installation as described above to automatically increase the impedance of the charging circuit as the battery reaches its optimum voltage so he won't have to look at his voltmeter ever once in a while.

 

[SCO]

Re: Unregulated charge, 73 135hp v4 Johnson

So you're saying that the battery provides the impedence which cuts down the current from 6a to say 1 or 2 across the battery normally at say 14 to 16 v, and that in my battery the internal resistance may be too high in the battery causing the 16 to 18 volts(assuming the voltmeter is correct) to get the 1 or 2 amps across?

 

[wilde1j]

Re: Unregulated charge, 73 135hp v4 Johnson

I had a '73 Evinrude 135 (same motor as yours) and I'm certain the shop manual and the owner's manual recommended against using any sealed batteries (i.e Delco Voyager, etc.) with the motor, probably related to the unregulated dc charging output. Never had any problem with it, but only had an ammeter at the time. I wouldn't be worried about the voltage, unless you know you're using a device(s) which may be damaged by it.

 

[rons boat]

Re: Unregulated charge, 73 135hp v4 Johnson

Yes, you got it now.