How to shutdown the alternator ?

[Maine Sail]

Originally Posted by rom

Thank you for the taking the time to answer. I do not think my solar will get me to 100%, I know.

Why ? Because I have spent the last 400 days disconnecting my alternors from my house batterie and I have reached 100% SOC almost every day, except those rare occasions where solar was not enough, really not. Yes I know how to know when 100% is reached.

How did I do that ? I have still not finished my electical system modification and thanks to the old system I can simply disconnect the alts from the house while they are still connected to the starter batteries.

Why am I asking this now ? Because I will soon finish the system and get rid of the starter batteries in favor of a safety batterie. Everything will be directly connected to the house bank. (partly based on your excellent suggestion of 1/2/both/Off system BTW).

Side note: I have 1000Ah@12V gel, 1320W solar.



Good ! as I said I don't need anything smart, what would be cheapest reg that does the job ?

Who's gel batteries are they? How are you determining 100% SOC? What is your average amp hour consumption over 24 hours?

The Hitachi alt is a bit of a PITA to interrupt field on but it can certainly be done.

The easiest solution would be to feed both alts to your emergency bank then use a Blue Sea ML-ACR (with additional isolate switch), ML-Remote Battery switch or a high current solenoid between the banks. Now all you need to do is to flip a switch to charge the house from alternator when or if you desired to.

Unfortunately with GEL you really should not set the solar at a 0.1V higher level than the alternator because that alternator is already capable of 14.4V +/- and for the longest cycle life with GEL batteries you really want 14.1V to 14.2V max. I have multiple GEL banks on cruising boats exceeding 10 years old with one bank now into it's 17th season. None of them charge at more than 14.2V.

[rom]

Originally Posted by Maine Sail

Who's gel batteries are they? How are you determining 100% SOC? What is your average amp hour consumption over 24 hours?

Ultracell batteries, 4x 250Ah. I know they are 100% SOC when they will not accept more than 10A @ float, that is 1% of capacity. That is somewhat confirmed by my BMV-700 showing close to 100% SOC. Of course the solar panels are willing to give (much) more at that time. To make sure this is really 100% I can also then start the boiler for a minute, the MPPTs go back to bulk, absorption, and then again to 10A in a few minutes.

Originally Posted by Maine Sail

The Hitachi alt is a bit of a PITA to interrupt field on but it can certainly be done.

OK ! It might be a good idea to buy at least one true 100A alt anyway.

Originally Posted by Maine Sail

The easiest solution would be to feed both alts to your emergency bank then use a Blue Sea ML-ACR (with additional isolate switch), ML-Remote Battery switch or a high current solenoid between the banks. Now all you need to do is to flip a switch to charge the house from alternator when or if you desired to.

Yes indeed ... That one I had in mind but I would rather keep the *safety* battery totally out of the network, well I mean just connected to the 1/2/both/off swith and that's it.
Plus it would require either: 1. the safety batt starts the engines, or 2. separate cables for the alt & starter. Not so simple.

Originally Posted by Maine Sail

Unfortunately with GEL you really should not set the solar at a 0.1V higher level than the alternator because that alternator is already capable of 14.4V +/- and for the longest cycle life with GEL batteries you really want 14.1V to 14.2V max. I have multiple GEL banks on cruising boats exceeding 10 years old with one bank now into it's 17th season. None of them charge at more than 14.2V.

That is interesting ! I have set absorption voltage to 14.8V (victron mppt) which is somewhat in the middle of Ultracell recommandation (14.5 to 15V). Of course it would take much more time to recharge a battery 14.1V ... Not sure what to think here ...

You said I could switch off the iginition cable from the external reg, but then will I still get the RPM ?
And then you got me thinking, couldn't I just switch off the iginition from the Yanmar panel without any other changes / additional equipment ?

[Locquatious]

Consider changing out the internal regulator with a lower voltage regulator, say a 13.7V near battery float regulator. This is better for times when you have long motoring trips. Hours or days of 14.4V charge is not good for the batteries.

Doing this was especially important for us when we had batteries in the engine room.

You can do it yourself as long as you take care to put toothpicks to hold back the brushes during reassembly. Or you can have any alternator/starter shop do it for you.

[rom]

Originally Posted by Locquatious

Consider changing out the internal regulator with a lower voltage regulator, say a 13.7V near battery float regulator. This is better for times when you have long motoring trips. Hours or days of 14.4V charge is not good for the batteries.

Doing this was especially important for us when we had batteries in the engine room.

You can do it yourself as long as you take care to put toothpicks to hold back the brushes during reassembly. Or you can have any alternator/starter shop do it for you.

Thank you Locquatious I like the idea ! But on the occasions I need the alternators I am not necessarily motoring ... I mean I will sometime start the engine(s) on purpose to recharge the batteries, so I will need full power upto at least 14.4v.

[stormalong]

Since you have a diesel engine it is very likely that the tachometer input comes from the alternator. Do you want to run without it?

If you don't want the alternator to charge the house bank just isolate the engine start battery from the house bank.

If it ain't broke don't fix it.

[Nauticatarcher]

Have a look at https://www.smartregulator.co.nz/ has an adjustable rheostat on out put voltage

[waterman46]

No need as many have explained, but if you must, just add a switch in the blue wire (field) of alternator.

[rom]

Originally Posted by Nauticatarcher

Have a look at https://www.smartregulator.co.nz/ has an adjustable rheostat on out put voltage

That is an interesting feature that could do the job however they don't say by how much I can lower the output of the alt. I think Balmar reg can cut the output by half with their "small engine mode", but that is not enough. From my understanding Sterling is not able to cut the output at all.

[rom]

Originally Posted by stormalong

Since you have a diesel engine it is very likely that the tachometer input comes from the alternator. Do you want to run without it?

You are right, I need that tachometer output from the alternator. Could it be working anyway if there is no field ?

Originally Posted by stormalong

If you don't want the alternator to charge the house bank just isolate the engine start battery from the house bank.

This is how it works right now and this is what allowed me to save somewhere between 200 to 400 EUR in diesel over the last year. Plus all the wear and tear on engines and alternators.

Originally Posted by stormalong

If it ain't broke don't fix it.

Poor alternators charging starter batteries is a broken design to me. I would like to fix it.

[NakedCity]

I have been running a 125 amp Powermax off my 12hp Yanmar for the last 20 years and have by own reasons for wanting to determine when I want to charge or not charge. A switch in the field wire has worked just fine for the entire period. I did have to replace the switch once because I used a cheap one that only lasted 8 years.I believe my field wire was yellow.

[rom]

Originally Posted by NakedCity

I have been running a 125 amp Powermax off my 12hp Yanmar for the last 20 years and have by own reasons for wanting to determine when I want to charge or not charge. A switch in the field wire has worked just fine for the entire period. I did have to replace the switch once because I used a cheap one that only lasted 8 years.I believe my field wire was yellow.

All good ! does your tachometer (provided it comes from the alternator) still work when the field is switched off ?

[Sailmonkey]

Originally Posted by rom

All good ! does your tachometer (provided it comes from the alternator) still work when the field is switched off ?

If the field is disabled, the alternator driven tach will not function, period.

However several yan mar engines have a flywheel magnetic pickup tach.

[Pizzazz]

Originally Posted by waterman46

No need as many have explained, but if you must, just add a switch in the blue wire (field) of alternator.

Best advice so far. If a Hitachi alternator, you need to open it up to get to the field wire and do some soldering. A half hour job. But whatever you do you need to be able to ground the field if you want your alternator to sleep while the engine is running.

A better solution is to open the alternator up, disable the internal regulation then feed the field to an external regulator.

[rom]

Originally Posted by Pizzazz

Best advice so far. If a Hitachi alternator, you need to open it up to get to the field wire and do some soldering. A half hour job. But whatever you do you need to be able to ground the field if you want your alternator to sleep while the engine is running.

A better solution is to open the alternator up, disable the internal regulation then feed the field to an external regulator.

So either I modify the hitachi, and preferably I use an external reg in addition. Or I buy another alternator with a field cable that is easily accessible. And then in both cases I loose the tach when I shut them down.

I wonder if it wouldn't be easier to switch off the ouput of the alt (B+). Of course I would need to stop the engine before. I guess I could live with it ...

[rbk]

Originally Posted by Maine Sail

In order to safely turn off an alternator the field needs to be interrupted (open circuit the brush). If you already have an external regulator simply put a switch in the ignition feed to the regulator and this will shut down the alt....

X2 look into this regarding Perkins 4108’s as the bank is charged the regulator starts cycling in and off and due to the tachometer running off the alternator this can cause undue wear on your tach. A lot of 4108’s have the exact above mentioned setup including mine. You lose the tech readout when it’s off but if I’m motoring that long it’s a set, forget and listen situation.