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Discussion Starter #1
Hi everyone.

Thought of sharing the schematics of a voltage regulator/charge controller I have fitted to my trimaran.

The point is to regulate the voltage output from my Tohatsu OB going to the battery as well as to dissipate any excess current and/or voltage spikes that might try to overcharge the battery after it is fully charged.

The dissipation is done by means of a 12V/55W lamp that is fed throught a transistor which "opens" when the voltage reaches about 14V DC.

It has been working very well for me for quite a while now and so I thought of sharing it. Hope it is of any use to someone.

Here is the schematic




Before use there´s a calibration procedure THAT MUST BE ACOMPLISHED and which goes as follows:

1- Remove all the loads (dissipation lamps and/or lead acid battery)
2- Apply 14Vdc at the input
3- Measure voltage between TP1 and ground
4- Adjust R3 untill there´s a sudden voltage rise

And that´s it. You can now connect the dissipation loads and connect the circuit.

Notes:
-It is supposed that the output of your generator is allready rectified to DC. Most outboard manufacturers provide simple plug-and-play rectifier kits;
-Q2 must be installed in a dissipator with adequate dimensions;
-The lamp wil light and, consequently,WILL HEAT UP. Please make sure it is well away from anything sensitive to heat and in a suitably ventilated place. In my installation the lamp is on the outside of the assembly box;
-This circuit is designed for a generator with a maximum of 55W output (small outboard motors, solar panels etc). For higher power operation simply add as many Q2/L1 pairs as necessary until the desired capacity is achieved.
 

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Telstar 28
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Just curious, what trimaran do you have??? :)
 

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Telstar 28
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Telstar 28
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A guy with a slow boat... :)
In every forum, community, etc... there a black sheep

Who the hell is this "WouldaShoulda" bloke?
 

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Oh jeez...

Trimaran love.

Get a room!!
I am certain that Wouldashoulda is only joking with you guys. We must assume it is his attempt at being funny. I am sure that is all it is because he knows my tolerance level for intentionally trying to start arguments (ESPECIALLY OUT OF OFF TOPIC) is zero... especially right now.

We do joke around with SD and other membres. I do it. But I make sure they are people I know first. And they all take it in stride. I do not want to turn the forum outside of Off TOpic into something dry. However, we must all be conscientious of what we say on the internet because you cannot inflect tone. I have already mentioned that I am over worked right now as it is and we are short handed. I cannot imagine anyone not trying to make the extra effort here while we are going through this period (which may be a long period).

Enough said.

- CD
 

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Telstar 28
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While I don't mind wouldashoulda taking a poke at me... Pedcab is brand new to the forum and should be given a bit more space to get settled in... :)
 

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AEOLUS II
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I am certain that Wouldashoulda is only joking with you guys. We must assume it is his attempt at being funny.
Attempt??

Why, you... ;)

Message recieved, sorry pedcab, I didn't realize you were new when I went and busted your chops.

Yours is not a vessel one sees every day around here!!
 

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Telstar 28
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The December 2008 join date might have been a good clue. ;)

Attempt??

Why, you... ;)

Message recieved, sorry pedcab, I didn't realize you were new when I went and busted your chops.


Yours is not a vessel one sees every day around here!!
 

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Discussion Starter #15
Here where me and my boat come from we use to say that "Excuses are to be avoided, not given arround like candy..."

But that´s OK. I didn´t fell ofended in any way, I just found it a bit odd to take a look arround the site and observing that all of the posts by Woulda Shoulda I´ve read are variations on the theme of making fun out of stuff others write....

But, as I´ve said, I´m not ofended, just amazed :)
 

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Pedcab, interesting and good idea. I have the same problem you solved, Id bet a lot of others also do but maybe dont know it.

My about 1990 or so Honda BF8 (8 hp) has an alternator 5 amp charging system but NO regulator (I found this out when I had to fix the burned out rectifier from the previous owner). Id bet this is common in the smaller outboards with the 50-60 watt charging systems. Ive played a little with the charging system on my old Honda BF8 and it will continue to dump charge into the battery long after the battery voltage says it is "full".

There is one trip I take every year where I start the trip with fully charged batteries and end up running the outboard a lot and if I didnt know the outboard had no regulator, Id probably damage the batteries. I have flooded wet cell, Id really worry about this if I had AGM batteries.

One minor thing Id point out is that you may want to disconnect the circuit from the battery when the outboard is not in use since it would for example keep a three stage solar charge regulator from topping off the batteries as the charging voltage likely could not exceed 14 volts unless you had a big panel (the circuit shunts up to 50 watts or so to ground when 14 volts is exceeded).
 

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Discussion Starter #18
One minor thing Id point out is that you may want to disconnect the circuit from the battery when the outboard is not in use since it would for example keep a three stage solar charge regulator from topping off the batteries as the charging voltage likely could not exceed 14 volts unless you had a big panel (the circuit shunts up to 50 watts or so to ground when 14 volts is exceeded).
You´re right.

That´s why I have my electrical instalation arranged in such a way that, whenever I´m no t on board, neither the regulator nor none of the electrical appliances on board are connected to the battery leaving only my small solar panel directly connected, in order to keep the cells topped up.

In addition to this, my electrical switch arrangement only lets me charge the batteries whenever the electricl panel is switched off the grid (by means of an SPDT switch), to prevent any current spikes from the alternator to damage my auto-pilot, bidata, etc...

Like this



regards
 

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My previous owner had installed a switch between the outboard charging system and the battery. I’m guessing that opening this switch while the motor was running is why the rectifier was blown. (you likely already know this but the coil in the alternator makes a big voltage spike when the current is interrupted and it reverse breakdowns the diodes - with damage).

It looks like your circuit may also be fast and possibly low impedance enough to clamp this big spike if you disconnected the charger/regulator from the battery and protect the rectifier diodes. But I’m not sure... just wondering if you had tested this?

When I messed with my outboard, I added about a 100 uf, 100 volt cap on the output of the rectifier. This also clamps the inductive kick spike to safe levels and I can disconnect the alternator/rectifier/cap from the battery safely while the outboard is running (looked at with scope and tested about 100 times with no damage).
 

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Discussion Starter #20
Once again I agree with you and I must mention that I avoid to disconect the switch between the engine and the regulator while the engine is running. I´ve only fitted that to be able to select, prior to starting the engine, whether I want to charge my batteries or not and this way have the hability to keep the regulator from having to be dissipating when there´s no need for it.

Nevertheless, the selector switch which routes the circuit and selects between RUN and CHARGE modes can be switched on and of at will, provided that the ALTERNATOR/REGULATOR connection is not interrupted.

I have not tested it with a scope (for not having one available outside work) but I did test the circuit in use hundreds of times and, like you, I have no reason not to believe that this regulator/dissipator arrangement isn´t able to protect the rectifier from any transient phenomena.

Regards
 
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