Help/Advice Please Battery Charging Question

[thompsontwins]

Hello,

Still rewiring the boat, and had lots of problems I won't bore you with, but getting there slowly. The alternator wasn't charging the batteries, so it occurred to me to wire the alternator direct to the batteries, which I did, and the result was a nice 14.5 volts of charging. I have read somewhere the 'exciter wire' should have a switch to switch manually off the supply when the alternator is not required, ie when the engine is stopped.

I have only run the set up for minutes to see if it works, which it did. I intend to manually switch the starting battery off when the engine is switched off.  Can anyone with more knowledge guide me please, as to whether I am doing the right thing? I believe that the alternator will not cook the batteries unless it is faulty, and exceeds 15 volts, I can monitor this with a voltmeter. 

Paul 

[chrismunson]

Paul, this is sounding like you are working on an already compromised charging system, and adding very risky short cuts. Charging should be managed by a Smart regulator, such as a Balmar. A direct hot wire will overcharge and fry your batteries, and does not provide the staged charging needed to properly charge and maintain the batteries. They could also overheat and possibly explode. The starter battery should be charged by a echo charger that detects starter battery state and automatically provides the correct charge. You're probably looking at a $500 cost for equipment excluding an alternator, and you'll greatly extend battery life. Fuses and breakers are absolutely necessary for protection. With your setup an electrical fire is a real risk. Insurance coverage could be an issue. I had my LM32 charging system reworked by a pro 18 years ago, and it has been flawless ever since. Batteries last 7 years, and that alone has paid back the cost. I recommend you seek expert local advice on this. Please!

[Sula]

Paul, I am afraid I have to disagree with Chris. A smart regulator is not the solution to your problem (though it could be a nice thing to have later). I agree with him you probably need expert advice, and that you should be very wary of making additional connections to the battery/alternator circuit, especially if you do not fully understand it..  



I know a fair bit about some aspects of electrics, but little about alternators, I'm afraid. That said I will try to narrow it down a bit for you.



If the alternator was not charging the batteries, then there is something much more fundamental amiss than whether your alternator regulator is smart or otherwise. 



It is not clear to me from your original post whether you mean that you have made new connections to the batteries from the alternator output (that charges the batteries), or the alternator input (that regulates the alternator output voltage/current ), or both sets of connections. That makes diagnosis difficult.  I suspect that you have at least connected the alternator input to the battery, otherwise why would you be talking about putting a manual switch in it?



I would advise against putting such a manual switch in the alternator 'exciter' connection, both for the safety reason Chris mentions, and because it will make fault finding more difficult. You need to get back to the position where the original automatic switching via the instrument panel, start/stop switch(es) etc. does the job. You will complicate fault-finding (now and in future) if you’ve got alternative or added wiring.  If you have previously temporarily connected the alternator input to the batteries to get them charged, then I suggest disconnect again.



Most likely an inadequate alternator output is a result of a failed or poor connection.  Most often it is a broken, dislodged or corroded connector or switch or fuse; less likely a wire broken internally. The failed ‘connection’ could also be a result of a wire shorting out to ground.   

Such a failed connection could be in either (or both!) the path of the (charging) output from the alternator, or the (regulating) input path to it (though I suspect the latter).  I do not think your problem is the alternator itself, or the regulator (which is probably on the back of the alternator) itself.

I guess your problem is most probably along the thin green wire which (according to the DV10 Owners Manual) goes from the alternator terminal labelled ‘61+’, through a red multi-connector, to the instrument panel block pin 8, or the further connections onward from this (which then gets more complicated than I can address here).


First check check the fuses in the back of the instrument panel!  Then check connections and continuity along that green wire from alternator to the instrument panel.  Check also the relevant terminals for that wire on both the alternator and at the instrument panel have not themselves come adrift.   

Beyond that you will probably need someone who does know what they doing, actually on the boat, and armed with a multi-meter and the Bukh wiring diagram.

(Note also that the simple circuit board in the Bukh instrument panel which controls the warning lights and buzzer (and is linked to the connection I mentioned above) is rather notorious for failing and introducing mysterious faults.)

Good luck, and do let us know how you get on.



SMART REGULATORS
As I mentioned above, the problem you are having is nothing to do with not having a smart regulator.

You do not need a smart regulator – they are a ‘nice to have’. Despite the sometimes alarmist advertising by smart regulators, your charging and batteries will be fine without one.

The vast majority of the hundreds of thousands, probably millions, of boats in the world do not have them and manage fine. My own boat, for example, has managed without for 40 years without a problem. My previous boat had no smart regulator and its batteries lasted, like Chris’s, for 7 years or more, and that even included AGM batteries which ideally should have had a lower regulated voltage than the standard for normal batteries.

Yes, a standard, non-smart regulator is a bit crude, but quite good enough to have been used in millions upon millions of boats, cars and many other machines for decades. Smart regulators are not perfect either, just quite a lot less crude.

Smart regulators are nice to have. They will give you a faster charge when your batteries are low, and generally treat the batteries more gently when they are well charged. (They will still ‘overcharge’ the engine battery in a twin engine/domestic battery set up, though.)

In my view, if you have the money to spare, and have run out of more pressing jobs, fitting one would a good thing. (Note that, depending on type, you may need to partially dismantle the alternator to make the relevant connections for it, and that in choosing a regulator you may wish to allow for potential future upgrade in alternator output, or number of batteries, etc.)

I would, though, strongly recommend you do not fit one until after you have solved your current problem.

[johnc]

I was going to post that I was not in agreement with Chris as I am not a fan of "Smart" things but did not wish to cause any problems. I prefer simple change over switches and an ammeter in the charge circuit. My other motorsailer (don't ask) has two betteries, one is 15 years old, the other is 10 years old and are charged via a conventional 1/both/2 change over switch. I just look at the volts and charge rate and switch between 1 & 2. My LM has a smart change over charge system which I really dont trust and if there is time before I launch, it will get ripped out and 1/both/2 switch installed.

I agree that there is something wrong with either the exiter wiring or a fault in the alternator in Paul's engine so as a first step, I would take the alternator to a repair shop and ask them to run a full test. I did have a proplem when I wired up the Ford Diesel in my other motorsailer as I forgot to run the exiter lead through a 12 volt bulb as it did not charge. One problem I did have on another boat was that I had to blip the engine to get the alternator to kick in.

[Sula]

JohnC's mention of bulbs reminds me - check the bulb in the charge warning light on your instrument panel. It's a long shot, but a failed bulb can upset the balance of voltages that the little diode/resistor circuit board in the instrument panel uses in its triggering of the shared alarm. I am unclear about whether or not that could affect the alternator's regulating input, but it's such an easy check to eliminate that as a cause or complication.

I think it unlikely that either the alternator itself, or the regulator (probably mounted on the back of the alternator) itself are at fault. Paul said he was getting charge, and at the correct voltage, when he did his extra/alternative connections to the battery.

[chrismunson]

I've had 3 charging failures at or near the alternator, all were due to a hidden failure in a connection, either a broken or pulled wire inside a crimp connection, or a corroded eye ring connector. The corrosion is a slight dark crust between the ring terminal and the post. Its removed by light rubbing/scraping and dielectric grease. So every 2 years I take each bugger apart, clean and grease every connection. Especially every ground connection on the engine block. My LM 32 has a hidden barrier strip connection for all house circuits, its located below the switch panel, and is inaccessible except with a chainsaw. After 35 years of marine exposure, that's my next project, dig it out and replace. Hope this is helpful and not critical.

[thompsontwins]

Phew!
Thanks to everybody for your input. I have a lot to think about here!
Paul

[Brian & Glenda]

I am not a guru of boats or batteries and charging systems, but I'll offer the following link and some personal thoughts:

Here is a link to a great little booklet called "Electicity on Board". Written by Victron Energy it offers advice about determining the power needs of boats, their batteries and charging systems:

www.victronenergy.com/upload/documents/Book-Energy-Unlimited-EN.pdf

Second my thoughts:

I think that the decision to choose to have (or not have) a 'smart' voltage regulator, should be related to how you use your boat, and how active you want to be in managing it's systems.

The size of your battery bank should depend on the electrical needs of your boat, and your anticipated availability of shore power or other alternate charging systems. The output of your alternator should then be matched to your the size of your battery bank.

I strongly agree with those who suggested you get a pro to look at the boat's wiring and electrical systems and give you advice based on your intended use.

An ABYC certified marine electrical technician recommended the following to me, for my boat and style of operation; but different strokes are required for different folks.

Different types of batteries require different charge profiles if you want to maximize battery life. Having a 'smart' or multi stage voltage regulator associated with your alternator, is like having a multi-stage shore power battery charger. A 'smart' regulator will match the alternator output, to the needs of the batteries.

Personally ... I like to maximize my batteries life, and when out on the water I typically want my batteries to be recharged as quickly as possible. Thus, an alternator that is regulated to deliver a fast bulk charge initially, then drops the output during the absorption stage, and then lowers it again later for the float stage of the charge cycle is highly advantageous.

The original(?) Paris Rhone 50 amp (?) alternator on my LM32 died three or so years ago, and as I like to anchor out for extended periods and sail rather than motor whenever possible; I replaced it with a larger 90 amp alternator so that the batteries would be charged more quickly when the motor is running. However: as I didn't want the increased rate of charge to boil my batteries if they did not need a high rate of charge, an external 'smart' regulator (Balmar ARS5) was installed to regulate the output of the alternator to match the amount of charge required by the batteries.

I now also have an Automatic Charging Relay (ACR - Blue Seas 7610) that switches the alternator output between the engine start and house batteries when appropriate. My solar panel output (with it's own charge controller) is also directed by this ACR to the appropriate battery bank thus ensuring optimal charging of both battery banks.

Last, and perhaps most useful ... I added a Link-Lite Battery Monitor to my electrical system, to keep me informed as to the state of charge of my batteries.

All that said: If you have a low output alternator, then perhaps a 'smart' regulator is not as important. as the probability of boiling your batteries is less with lower alternator outputs.

I am somewhat inclined to agree with those who follow the KISS principle and avoid the automatic stuff as much as possible ... adding complicated stuff means there is more that could go wrong, and does make troubleshooting more time consuming as you have more variables to check out, but I am quite happy with my revised electrical system.

My most recent charging problem arose when a plate dropped in my engine start battery ... thus it would not charge and needed replacement. Checking the electrolyte level was key to finding the problem in this case. The faulty cell remained filled while the good cells boiled nearly dry as (I believe) the shore battery charger was delivering a constant full output in its attempt to make this faulty battery achieve full charge.

Just one guy's opinion.

Cheers,
Brian

[chrismunson]

I bought my LM 32 with a Volvo MD17D in 2002. The failure of the 50 amp Paris Rhone alternator was what triggered the complete redo of the charging system, as I wanted reliability for cruising away from port. We opted for a complete Balmar system, with no regrets. This included a Link monitor, with an added switch to the starter battery to read its condition. These monitors "...selectively display voltage, charge and discharge current, consumed amphours, remaining battery capacity and the time remaining of your battery bank." Very nice to have all that info at hand. BTW, we had to fit a larger pulley on the new alternator, to reduce its speed, due to large diameter of the flywheel on the Volvo. The regulator of this system puts out a code reporting its condition, and if there a fault, the code will tell what part of the system has an issue, such as a loose connection. I know I sound like I'm selling this stuff - I'm not, but the overall simplicity and lack of trouble has been well worth it. And certainly I respect other approaches to charging systems. The redo of the electrical system uncovered a number of bad connections and broken fuse holders in the factory installation that would have been hard to find otherwise. All this was 1000 engine hours ago.