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Altenators


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Can be ok. What belts?

 

120amps is too much load for a 3/8 or 1/2 inch belt. The flat type belts can go higher.

 

However, in your situation, if the batteries are good, you would need an awful lot of lighting - appraoching 1000w from each alt to load it fully, so it's likely the alts were not fully loaded. Also, some tractor and truck alts are hot rated for this reason - although that won't fix undersize belts!

 

So, yes you can get away with smaller belts in some apps. The real marine app, with large deep cycle batteries, that are down to 50% charge, and need refilling, is about as demanding an app as an alt can get....

 

The belt sizing is not guesswork. Belts are only so strong, and can reisit only a certain load before slippling or breaking, and it takes X load to create a set number of amps. To many amps,= too much load = slipping or (or then) broken belts.

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The belt sizing is not guesswork. Belts are only so strong, and can reisit only a certain load before slippling or breaking, and it takes X load to create a set number of amps. To many amps,= too much load = slipping or (or then) broken belts.

Spot on.

Most small marine diesels, (and some larger ones) come with basic non marine alternators that are not isolated neg.

While that is true, Yanmar did tend to use the Marine Alts. I am pretty sure they came with Hitachi units.

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Tractor alts are almost always hot rated, and often rated to significant currents - often electrical loads other than lighting and running gear can exceed 50 amps on modern gear - many different electronic gadgets all sipping power, linear actuators, electric motors etc. I know that the alternators on my tractors are all 150a, or larger, and I have seen consistent current draw of 130a on one tractor ( it does have 18 halogen and xenon lights on it - all 55w or brighter. )

 

They are also often harsh environ rated - and, judging by the ones I have, have separate outputs for both positive voltage and 0v reference.

 

So probably if the bosch ones are the same ( I think mine are bosch actually ) then they will be just fine in a marine setting.

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Hi To Tall, yep, those ones are the same as the marine ones... Same sort of harsh environment as well...

 

The other thing I forgot to say before, was that good marine ones also will start their high output at much lower revs than automotive ones. My one, for example, is a 75amp. It puts out 60 amp at 1000 rpm.... Yes pully size has some to do with it, but it's startup curve is much better than a automotive one.

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I swapped out a basic Velco(I think) alternator on a 90's 40hp Volvo a few years ago for a Balmar. Jeez did it get hot in the engine room though! Used to run with the hatch open initially. Great for cruising as we were sailing around the Med..

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We have a Balmar 80a and a Motorolla 8MR2070t - the Motorolla was fitted by a not overly competent engineering firm as a replacement for another Balmar 80. Unfortunately I was not present when this was fitted and Dad did not know any better. It does the job, and is an alternator which is suited to marine use, but I do wonder about its quality when comparing it to the balmar... They both run very hot when running heavy electrical loads such as the 80 odd amps to run the fridge compressor.

 

External regulation makes a huge difference, and also can make a huge difference to how long they last. Both of ours are controlled by a Balmar MC614, on which I have opted to allow for a 3 minute "warmup" period after engine start before it will apply heavy loads, and also I have limited the alternators to 90% of max output. This reduced the body temps of the alternators from very hot to quite warm, something I personally feel will extend their lives far more than the amount of output they were reduced by. I may be proven wrong on this of course.

 

The MC614 also monitors the temps of the battery banks and the alternators, and will reduce, or shut down totally should preset thresholds be exceeded.

 

Yes, its expensive to fit all this, and many simply would not need such an elaborate system as we have, but if your a cruiser and are looking at having to spend money on your charging system, its worth getting the correct advice. And don't believe, without confirming for yourself via the net and forums, what your engineer is telling you - the one who fitted the Motorolla to our boat really did not know what he was talking about at all.

 

But don't go getting a standard "car" type alternator - it simply will not last long. Its only designed to have high output for a short period to recharge the battery from the start drain, not to recharge several batteries from a more deeply discharged state.

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I can't overstate the importance of the external 3 step regulator as well. It is every bit as important as the alternator itself. To give you an idea the cranking battery in Atom Ant was 18 months old when I bought the boat. I owned the Ant for 10 1/2 years and that same battery is still in the boat. 12 years of service from a cranking battery is outstanding! The house battery is also old although I bought it second hand around 5 years ago so I don't know how old it is. (And yes the new owner was made aware of the ages of the batteries before he bought it and my advice that they need replacing)

 

But my point is that a good regulation system will greatly extend the life of batteries and lead to greater reliability of said batteries.

 

Best money I spent on the boat. A hot rated marine alternator and a next step regulation system along with a BEP monitor. simple, effective and it has more than paid for itself.

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OK so I'm bamboozled. We run a fridge, stereo, lights, Nav and all that crap off a 72W 'lighting coil', as they call it, plus a 40W solar panel goes on a cruz for longer than 3 days.

 

Just WTF are you lot running that needs so much power generation capacity?

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This threadcould go on forever!... KM, that lighting coil gives you about 6amps charging current. That's only when the outboard is running. The Solar panel about 3.5 amps. When it's sunny, and in excellent order.

The whole process is calc the loads - some boats have a lot of stuff!

 

Fridge

Stereo

Lighting

PC's or TV's for movies and stuff

SSB

VHF

Instruments

Autopilot

and more

 

Also, 3 days is not long. I can run IT for 3 days with No charging if I want to. In your case, the batt goes out 100% charged, prob comes in 60% (or something) charged, and then spends the week recharging from the solar panel or shore power so you can do it again next week. Different if you live aboard, where daily input must =daily output, + about 25% as battery charging is not 100% efficent.

 

An example would be - 3 day trip with a 100amp/hr batt. Fridge is on for 10 hours @ 3 amps =30 amp hours, lighting stereo etc total 10 amp hours. Come back in with 60% charge, need to replace 40 amp hours - with the loss of efficence say 50 amp hours to get back to 100%. That would be 10 hours motoring, or say 15 hours of good sunshine to replace. Or a combination, which you'll have. And this is an oversimplification, butI'm sure you get the idea!

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OK so I'm bamboozled. We run a fridge, stereo, lights, Nav and all that crap off a 72W 'lighting coil', as they call it, plus a 40W solar panel goes on a cruz for longer than 3 days.

 

Just WTF are you lot running that needs so much power generation capacity?

 

Fridge, computer, electronics, lighting, winches but most importantly, a very large house bank. Not allowing the bank to fall below 80% charge increases the lifespan of the batteries dramatically.

 

Also, having a large amount of generation capacity means that when the solar is not performing as well as we would like, say, quite overcast days, etc, engine run time is kept to a minimum. With the charging ability we have, and the refrigeration/freezing system we have, we have to run the engine about 30 minutes a day with no solar boost. This will keep the freezer below -10 degrees, and will keep the batteries well charged. When the boat is on the marina, its always on a 60 amp charger anyway, so the batteries are always fully loaded when we leave, and generally the boat is away from the marina for a minimum of 4 nights at a time. Batteries last very well like this - the extra investment in the 3 stage charger is covered simply in the first set of batteries, let alone the other benefits. Having 2 alternators running means that should one fail, there is not an immediate requirement to replace it, and if your in a difficult situation, this could be very handy.

 

Lots of benefits, few negatives other than the cost.

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The big stereo will draw an average of around 18-20amps peaking in the late 20s depending on the baseline!

So that's about most peoples daily usage in 1 hr.....

 

 

Use sensible amplification - class D - and efficient speakers, and you would be seriously damaging your hearing with much more than a 10 amp drain on a 12v system.

 

A house stereo, at normal listening volumes, is often only running not much more than 1 watt per speaker. At even quite high volumes, that might be 10 watts per speaker. Throw into that mix highly efficient speakers, and your 10 watts per speaker will be in excess of 100dB. Throw in a high pass filter at 40hz ( you wont miss the bass ) and you will probably be using 5 watts for that same 100dB+ SPL level. Personally, I will not subject myself to 100dB for very long at all when sober!.

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My gear is not flash and yes I think it could damage hearing.

That's running 2 x amped 12' subs (with low pass filter), 2 x amped 6x9s (with high pass filter), and a 4 x 6.5' speakers.

Its just old car stuff, not flash at all and probably power hungry but I really only run it for a party.

 

It goes just fine.

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That's running 2 x amped 12' subs (with low pass filter), 2 x amped 6x9s (with high pass filter), and a 4 x 6.5' speakers.

This is how BOOBOO goes fishing... he turns up the sub and the fish around the boat float to the surface stunned! :lol:

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OK so I'm bamboozled. We run a fridge, stereo, lights, Nav and all that crap off a 72W 'lighting coil', as they call it, plus a 40W solar panel goes on a cruz for longer than 3 days.

 

Just WTF are you lot running that needs so much power generation capacity?

 

Autopilot, fridge, laptop, stereo, TV are the big suckers on my boat.

 

Ms Tuffys hair dryer and hair straightening irons tends to get left in the boot of the car, accidentially.

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That's running 2 x amped 12' subs (with low pass filter), 2 x amped 6x9s (with high pass filter), and a 4 x 6.5' speakers.

This is how BOOBOO goes fishing... he turns up the sub and the fish around the boat float to the surface stunned! :lol:

 

:lol: :lol: :lol: :lol: I want to go fishing with booboo now especially after the party he put on after the crew rum race last year :D :D

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Also, 3 days is not long. I can run IT for 3 days with No charging if I want to.
In 'essentials only less stereo'* mode I can last 6-7 days on one battery load without any input, actually a couple of days longer but I work on the shorter to give me a margin. The 3 days comment was if we go for a cruise for more than 3 days I tend to chuck the solar panel aboard to help other wise it's what we get off the motor only, which as you point out is bugger all. The boat has been tuned to be a very low power use machine.

 

I was stripping my mast last night and found the bulb in the masthead tri-colour is massive, about the same size as a house one, which probably explains the radiation burns after a night sail. That is one thing I have still to tweak power wise but we're onto that, aren't we IT.

 

I know Boo's stereo, Wheels washing machine, IT's a offshore cruiser and things like that but some of the others seem to need a massive amount of charging power but for what? It's knot like we don't have everything everyone else has got, or at least the usual suspects including auto pilots.

 

* - the stereo is usually regarded as essential but if push really came to shove it would be turned off to extend the life of Nav lights and things that will stop me being run down by a big ship.

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So to finish the original story about my alternator, I just picked it up from ‘Auto Electrical Spares’ in Henderson. Final bill was $150 and the thing looks like brand new. Fully grit blasted, all new components and seriously it looks like a brand new unit. when they gave it to me I gave it straight back and told then that was not mine, they promised me that it actually was.

I was very impressed, they knew exactly what all the options were and recommended the best thing to do, rang me when they said they would and had in ready in just a day for less than what they quoted.

Highly recommend their services to anyone.

http://www.aespares.co.nz/

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