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When I first fitted out our boat I used a second hand insulated return 24 volt alternator from a commercial breakers yard, It was a good sized beast physically and would happily self excite at about 600 rpm engine speed, so I just connected it with two wires -ve & +B When it went to meet its maker in the scrap yard I replaced it with a larger electrically but smaller physically speaking one. This would not self excite so I fitted an "Ignition" light to it, A sealed push in thing that I had in the bits box. Thinking about it it may have been a 12 volt warning lamp, I cant find any markings on it and its popped. So now I need to replace it which set me thinking. As its a 24 volt alternator would it need to be a higher wattage than a 12 volt one, I am thinking of the current flow in the windings to get excitation. If so what sort of wattage would be needed? If the one I had was 12 volts then I dont know what sort of impedance the field would be so I dont know how much it was over run by and what its equivalent wattage of the bulb would be.

The use of an earth return for onboard electrical equipment is discouraged as it is a potential source of hull corrosion ? YET most of us use high power alternators with exactly that, so what's the difference ? If a few mA from a radio will cause damage, think what 100A will do !

I have a Leece Neville alternator that provides power to engine and domestic batteries. Is it worth carrying a spare just in case? I've heard that an alternator can lose magnetism if left in store for a while so will not work when needed. Advice appreciated

Hi Everyone, I have a BV1305 Beta marine engine fitted with an A127 type alternator rated at 75A. The Engine has a pulley size of approx. 10cm (4") with an alternator pulley of approx. 6.4cm (2.5") giving a ratio of 1.56:1. The engine rated RPM is 3600. When I run engine statically, for power and hot water, at around 1000rpm (a little above idle) the maximum I get out of the alternator ( I have a sterling power alternator to battery charger unit which turns it into a 4 stage battery charger)) is about 35Amps, nowhere near the maximum rated output for obvious reasons. It takes a while to charge my 500Ah of batteries I have 320Watts of Solar panels with a MPPT charge controller to help things along, but there are times when I need to run engine, especially when using high powered things like my washing machine. I looked into getting a second big alternator, but have not been able to find anyone that can supply this, with the necessary pulleys and brackets to fit my engine. Beta marine themselves tell me that, even though engines of this size are now fitted with twin alternators for inland waterway applications, my particular engine was originally fitted out for Sea use (it still has cooling heat exchanger, even though it is currently not in circuit) and its not possible to upgrade. As I see it, my only other option is to try and get the best out of the alternator that I have. That means trying to source a suitable replacement set of pulleys to increase Alternator RPM. Increasing the crankshaft pulley size would be the best option, but this would also increase the Water pump RPM and I'm not sure what the maximum safe rpm of this is? Does anyone have any suggestions as to where to source the pulleys ( I guess I could go for serpentine type pulleys if the whole set was available) or, better, where I can get a second alternator kit or expertise to make me something? Any ideas would be great. Regards Andy

Hey guys, When I was re-fitting out the engine room and sorting the engine out I accidentally/stupidly connected the wrong wire to one of the terminals on the alternator. The cable went up in flames and now I guess the alternator is dead.. The engine runs fine without it but the LED light is always on indicating that the batteries aren't charging. The alternator fitted to my engine has the following markings: Which has led me to the following websites after a quick google of the barcode number and model number: http://www.recambioverde.es/detalle-pieza-1572965.html http://www.hcparts.com/Default.aspx?ID=773&GroupID=RemanufacturedStartersAlternators/Alternators&ProductID=CA305IR#Austin To me this looks like a standard car alternator. Am I right in this assumption? What do you believe is my best course of action in either repairing it or replacing it? If replacing it should I find an identical model or would any alternator do? Its not essential that I replace this immediately as I have the batteries hooked up to a charger but I'd like to get this sorted before I take the boat out in Spring Many thanks for any help or advice you can give..

Here we go again, one problem fixed now another!!! Can anyone help with this alternator query. I had a new Beta 38 fitted in March 2013 which has 2 alternators, one for the starter and the other or the domestic batteries. Until yesterday I've had no problems with it (although when it was fitted I was told my wiring is a bit odd). I went to start the engine and the warning buzzer continued to beep even after the engine was running. Also the domestic battery charge lamp was out. Then I noticed the smell of burning plastic and on opening the boards was greeted with a cloud of acrid smoke. After turning the engine and batteries off and letting the smoke clear I found the green/yellow (earth?) wire from the alternator had melted off most of the insulation and the wire was exposed and snapped in places. I tried to replace the earth cable and turned the batteries on only to hear more cracking and smoke issuing from the repaired wire. I've now disconnected the Domestic Charge Sub Loom (95 Amp) and fortunately because of my odd wiring the smaller alternator is charging both my starter and domestic batteries although it seems at a slower rate and not as deep. I fear the worse that the alternator has died but as a minimum the Domestic Charge Sub Loom (95 Amp) will need replacing - am I missing anything obvious do you think? I'm very much an electrical novice, so please use idiot proof terms for me

My Niehoff A1-104 alternator has failed; I think it needs a re-wind as the B+ to B- resistance is over 3kOhms. Does anyone know where I can get it rewound? Somewhere near Crick would be great. Its output is 14V, 80A - can anyone suggest a robust alternative? Thanks!

Hi All, First off apologies if this is already covered but every search I do keeps freaking the forum out, producing no results and instigating flood control. Apart from that its going very well. I've just bought 4 x 230AH 12v Monolith Semi traction Batteries. I intend to eventually hook up Solar power and I intend to get a smart alternator regulator, probably the alternator regulator first. Something like this: http://www.shop.sterling-power.com/acatalog/ProSplitR.pdf Solar panel wise I hope to get 2 x290W panels with a 60A MPPT controller. Am I better off having 2 banks of 2 x 230AH 12v Batteries or 1 bank of 4 batteries. Everything on the boat is run off 12V. i have an inverter but don't would only have to use it once in a blue moon. I had originally thought of having 2 banks. the first for essentials and the second for luxuries. Essentials: Bilge Pump Water Pump Shower Pump 2 x 12V lights Headlight Horn Luxuries: 12V Fridge (in summer) 12V TV laptop via 12v car charger USB Phone Charging Car Stereo, Amp and Sub Additional Lighting Having 2 banks I feel like I can run down my luxury bank without worrying about whether I can have a shower in the morning, but another mate suggested that with a big enough bank I'd be less likely to run out in the first place. Another suggestion was that having a fall back system is always good on a boat, maybe i should just put both banks on one of those big switches that lets you use 1,2 or both. I've a sneaking suspicion I've just answered my own question, but I've typed it now so never mind Any thoughts would be much appreciated, particularly a link to a wiring diagram for 3 banks (Starter battery is a 110AH sealed battery), a 12v switch, a 3 output alternator regulator and an mppt controller. Cheers, Ben Heron