Alternator - Improving Output

[Rauby]

I have a yanmar 3GM diesel fitted with the standard alternator.

At most the alternator charges at 14V and takes a long time to charge the batteries (as checked by open circuit voltage against battery manufacturer's chart). On previous boats I have had a separate regulator for the alternator that senses the battery condition and appears to charge the batteries more rapidly.

Is there any way that I can use the internal regulator supplied with this engine to improve its output or can I fit a better regulator to the standard alternator.

The alternator charges separate engine and domestic batteries through a splitter.

Thanks

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[steve_cronin]

Take a look at....

http://www.sterling-power.com/

click on products and look at the Pro Advanced. This will sort out your power demands. Others like the Adverc don't boost they just battery sense. We need usually around 45minutes running each morning to fully replenish our 2x180 Ah domestics which have powered the fridge overnight until the solar panels take over at dawn as well as our lighting demands and the windlass to pull up the hook. The Sterling remote control panel keeps you advised of what's going on during the boost cycle and is well worth the extra cost.

Steve Cronin



<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[maxi]

If, and it is sometimes a big if, you can find someone who knows his stuff, it is possible to make a very simple modification to most alternators to make them 'battery sensed'. Involves no kit, just a change of connection. This can make a difference of circa 0.75v which is a significant advance on what you are currently getting.

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[smb]

Welcome.

There are various methods available to you. I fitted an Adverc regulator (adverc.co.uk) 3 years ago and have been very pleased with it. It sits (electrically speaking) in parallel with your standard regulator and by cycling the output voltage ensures the maximum possible charge is accepted by the batteries. Its suitability for you may depend on what type of batteries you have.

Others on here swear by the Sterling which claims to work like a mains powered 3 stage charger.

I believe there are DIY soulutions as well that depend on the operator monitoring and adjusting the settings fairly regularly, but I do not have any details.

Try a search on these forums for some of the many discussions on battery regulation. Key words such as Adverc or Sterling should bring plentiful results, as battery charging must be the second favourite topic after anchoring.

The Adverc took an afternoon/evening to fit with no particular expertise required. Whilst I was at it I also fitted one of their circuit monitors. What that revealed was that there is little point in running the engine on tickover to charge the batteries as the alternator (in my case) is just not turning fast enough to give a good output. Now I increase revs until the current stops rising and nudge it down as the charge sinks in. (Cue topic No 3, bore glazing)

All the best

Steve



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[halcyon]

Check the voltage either side of the splitter, if you are getting 14 volt at the battery, and have a diode splitter, you should be getting 14.8 volt alternator side.
If this is the case you have all the output you need, simplist way then is to change to a good relay splitter, this means the alternator sees true battery voltage, and batteries see 14.8 volt charge. More costly and techinical is to try converting your alternator to battery sensed, depends on alternator, may be big or little job. Or fit a smart regulator, means rebuilding alternator, is expensive and only gets you back to 14.8 volt basically.
It's the old case of pays your money and takes your choice.

Brian

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[Oldhand]

Agree with Halcyon, your diode splitter may well be what is lowering the charging voltage seen by the batteries, you need to check the input voltage to the splitter. If this is OK, as I suspect it will be the easiest and cheapest fix is to replace the diode splitter with a voltage sensing relay splitter. I use the latter and it works just fine, it basically disconnects the engine starter battery when the voltage drops below about 12.7.

Installing the more cosly option of a new external regualtor, whatever type, is only an advantage if you run the engine for long periods as they overcome the reducing current of the standard constant voltage type regulator. If you normally only run the engine for say 20 minutes to get out of harbour, the standard regulator has little disadvantage over an additional external unit.

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[halcyon]

I would like to make an observation, that is the drop out level, we have always used 13.0 volt to drop out the relay. Why,? a flat battery on charge is at 13.0 volt ( nominal for lead acid ), thus below this it is not taking a charge, so there is no reason for a connection. The other main point is that it limits the power that can be drawn from the engine battery, 12.7 volt drop allows a fair power drain from a new fully charged battery before the relay drops out. Thus partly the reason for problems people have suffered, from running high current loads from a flat service battery with relay engaged, and subsequent damage to the charge system wiring


Brian

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[Oldhand]

Yes I would prefer a higher dropout voltage but mine is not adjustable. However, I installed 60A charging wiring with the relay to the engine battery and haven't had any problems.

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[johnneale]

An old trick is to put a diode in the line from the charge light to the field. - there will be a 0.5v drop across this diode and con the alternator that the batt voltage is lower than it realy is & so raises the charge voltage to 15v.
There is however a danger that you could overcharge your batts, so put a shorting switch in parallel with the diode and dont run it too for too long.

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[Geordie]

I fitted a Sterling regulator to the alternator on my Yanmar 3GM. It does what it says. It rapidly replaces used charge, but there are drawbacks.

Firstly, the Hitachi alternator has to be removed, disassembled and modified. Not as easy a job as Charles Sterling would have you believe, unless you have worked with alternators.

Secondly, it makes your alternator work much harder. My brushes wore out after 500 hours. Hitachi alternators are not designed for DIY replacement of brushes.

Thirdly, your fan belt must be as tight as your bearings and water pump can take. (My engine compartment became covered in a film of black dust).

Unless you are planning long passages, or otherwise need to be self sufficient in electricity generation, I would not advise fitting one. Now that I am back in the UK on pontoon moorings, I have removed mine.



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[William_H]

Hello Rauby A battery charged at 13.75 volts measured at the battery terminals will charge well at first and then the current tapers of so that the last portion of charge is seldom reached. This voltage is however chosen because the battery will not be damaged if the charge is left on for a very long period. As in your car on a long trip. The only way to get the battery to accept more current for a quicker charge is to increase the voltage however this could damage the battery if it continues after it is fully charged. I feel the smart chargers are only for people with large current usage who wish to run the engine to charge the batteries for the nminimum time with maximum charge. For normal battery maintenance that should not be necessary. As stated your splitter may be reducing the voltage from the generator to the battery check the battery voltage on charge compared to the alternator output voltage. A cheap solution would be to bypass the splitter however you would lose the separation of your batteries. A relay should have no volt drop or as stated you need to icrease the regulated voltage of the generator to over come the loss in the diode splitter. regards will

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