Alternators

[Fish 0]

Snapping a stud from B+ to battery in full flight will fry any number of the 9 diodes in your rectifier.

Might want to check strain relief on main cable to bats. Bit of slack etc.

 

Disclaimer:   My thoughts are worth exactly what they cost.

Ah, that would explain how the rectifier would get damaged. I assumed it was a stud holding the alt to the engine, not a power lead stud...

 

Detail! BP, attention to detail!

 

How do you break a power lead stud?

[Island Time 1,230]

Heavy cable, unsupported, years of vibration....

[Fish 0]

Heavy cable, unsupported, years of vibration....

Sounds like nothing a new engine wouldn't fix ay BP?....

[Island Time 1,230]

Yep, Graham, (Smartreg manufacturer/owner) is a good guy. Lots of good stuff on his website for the DIY type.

 

I've installed a few of his regs, and now normally keep one in stock. They are a good mid level external reg, suitable for most applications.

 

If you have large batt banks, want to live aboard or cruise long term, AND have large, hot rated alts though, you may be better with a top end reg (Balmar for example) with belt management, and temp sensors for the batts and the alt/s.

 

As a rule of thumb, V belts max out at around 80-100 amp, then should be matched pairs, or change to a serpentine belt. I know people get away with larger, but in my experience, if you really need the 80amp output for 10 hours or more, a single belt will give issues.

[Crazyhorse 47]

Yep, Graham, (Smartreg manufacturer/owner) is a good guy. Lots of good stuff on his website for the DIY type.

 

I've installed a few of his regs, and now normally keep one in stock. They are a good mid level external reg, suitable for most applications.

 

If you have large batt banks, want to live aboard or cruise long term, AND have large, hot rated alts though, you may be better with a top end reg (Balmar for example) with belt management, and temp sensors for the batts and the alt/s.

 

As a rule of thumb, V belts max out at around 80-100 amp, then should be matched pairs, or change to a serpentine belt. I know people get away with larger, but in my experience, if you really need the 80amp output for 10 hours or more, a single belt will give issues.

Grahams "bosch" alternators are actually cheap OEX Chinese made for Holden etc. He told me you cant get Bosch alternators anymore, his are "bosch type", doesn't say that on his website. Rang a supplier in Whangarei and asked him if you can get Bosch alternators "how many do you want?. His regulator uses a timer to switch between bulk and float so doesn't sense battery capacity, only voltage and you need to tell him how big the battery bank is so he can set the timer so when suddenly under full load, 50% charged batteries and running a 1000w windlass, it jumps the alternator into full output which actually cooked ours. You will need to wind his regulator right back to zero field current, start the engine then slowly bring the voltage up to compensate for the power something like a 1000w windlass would use. Suggest you get a proper belmar system, don't go down the road we did. I now have temperature sensing directly off our BOSCH replacement alternator plus a 90 deg thermal switch on the field wire. So far works very well with the ZM4 but still have to slow start the charging on engine startup and slowly over about 10 mins bring the voltage up to 14.4. No major drama.

[Island Time 1,230]

The Bosch alts are not hot rated. If you try to run them at capacity for hours and hours they will melt. Any decent hot rated alt cannot be "over fielded" and will be fine at full load. Most of the Balmars, some of the leece nevilles etc.

IMO the worst of the current common alts are the Hitachi's.

I use a (now obsolete Next Step reg) with a balmar alt, never had an issue even with heavy charging cycles. (Well, I did, on the new motor its currently the standard crap setup,on my list to upgrade)

[Island Time 1,230]

yep, but batt only, not alternator...

[Crazyhorse 47]

yep, but batt only, not alternator...

Depends on battery. The lead crystal and led carbon ("superconductor") types can take all you can throw at them and no melt down.

My experience to date is that your average car alternator can NOT be converted to external regulation without some safe guards and compromise, all depends on power requirements. Heat dissipation is paramount on standard automotive size alternators that are externally regulated where the regulator has no idea how hot the alternator is getting, like Mr.Polley's ZM4 which simply keeps loading it up until you smell burning windings. Car type alternators and those that come with a lot of marine diesels are internally regulated and also reduce field current when things begin to heat up. The trouble we have experienced is the extractor fan on the alternator isn't drawing enough air through it to keep the windings cool so low RPMs will soon heat it up. Adding a blower might help. The engine at idle or low RPMs will cook the alternator unless it has sufficient air flow depending of course on battery bank size and state of charge plus load or the external regulator can reduce field current from sensing the heat. One way is to install a thermal switch on the field wire from the regulator. The GENUINE Bosch alternators are rated to 120deg but couldn't find out for how long it would run at that, my thinking is not long! I decided on 90 deg as being pretty bloody hot so have heat glued a thermal switch to the alternator housing that once triggered will shut off the field current then it resets at 70 deg turning the alternator back on again. Being a genuine bosch alternator, to date it hasn't triggered.

[Island Time 1,230]

My comment about the batt only heat sensor was only for the next step regs.

 

The temp sensor mod CH has made is beyond most DIYers.

 

A proper, hot rated alt cannot be overheated at any given RPM, its cooling is designed to be sufficient at the max output it can produce at those revs.

 

I know some alternators will cut back output very quickly from max - within a few minutes. The hitachi ones are particularly bad at this. Not sure how long the bosch ones would last, but I've seen 2 failed due to heat.

 

The whole point of all this is NOT to cut back the output, but to put as much charge into your batts as they will accept at a given voltage, without overheating the batts = charging them as quickly as their design allows.

 

With alts, like most things, you get what you pay for... 

[Ladyhawk 37]

This is a great thread, lots of awesome info, thanks guys

[Crazyhorse 47]

All well and good saying put a large frame alternator on as they are heat rated, seen the size of them!? For us on a 2GM20, simply not a viable solution so had to adapt a different mount high current alternator to the Hitachi mount, now works great and using our "oven" remote temp monitor, can see at a glance how hot it gets under load, 47 deg C. Yet to fit it but have a bilge blower I was going to adapt to force air through but not needed now. IT is right, those Hitachi alts are the pits, don't even get to 14v before winding back the output. Great for a starter battery, useless for anything else. Also against popular belief, we run a single belt but it is a notched USA made "green" belt and after 2 years no sign of wear or belt "dust". If you have the room, certainly go for a big frame job but the bosch units will also do the job if you have protection against over heating and monitor them for a while after start up. Incidentally, bosch also has theirs assembled in China, better quality control than others perhaps but some earlier units had plastic holders for the diodes! Check to make sure you have one with alloy diode mounts.

[Island Time 1,230]

The Bosch ones I've seen melted were both single fan models.

You can get small frame hot rated alts - the balmar 7 series is one range. Dual fan...

I've used a balmar 6 series 70 amp small frame dual fan, for the space reasons mentioned above. It was a direct, drop in replacement for the crap ingram alt the old engine had, and charged a 400a/h bank for 8 years before the internal reg failed (wasn't being used, it was externally regulated, but the failure stopped the alt).

Balmars are not cheap though.

[Black Panther 1,581]

If I could borrow my thread back for a moment.

With IT's brilliance at the end of the phone we found a blown fuse between the reg and the batteries (i never knew they were there, being under the battery boxes and 2 mm from the hull - I wonder about some boat builders).

Immediately the reg woke up and said all is well.

But the light at the ignition is now flickering on and off, the tacho still only comes on after half throttle and I'm only getting about 12.8v at the back of the alternator.

I'm thinking to try moving around the smaller wires that supply field, light tach in case I got them wrong. Can I damage anything if I do that?

[Fogg 427]

BP - time to get some onboard help. Co-incidentally I’ve been going through identical charging issues and realised 12v can be more dangerous than mains power (which is simpler and stable). Whereas 12v involves huge currents and potential for dangerous overloads & overheating. It sounds like you’ve given it a good try but in my view 12v charging issues are not for DIY troubleshooting - I’d concede defeat and get pro help on this one mate. Seriously.

[Crazyhorse 47]

BP - time to get some onboard help. Co-incidentally I’ve been going through identical charging issues and realised 12v can be more dangerous than mains power (which is simpler and stable). Whereas 12v involves huge currents and potential for dangerous overloads & overheating. It sounds like you’ve given it a good try but in my view 12v charging issues are not for DIY troubleshooting - I’d concede defeat and get pro help on this one mate. Seriously.

240v less dangerous!? Wattage is still going to be the same if you are drawing 50 amps at 13.8v or 2.87 amps at 240v (rms). Dialetric break down is higher at 240v so arcing and the human body allowing current to flow is also much higher not to mention the ocilating current creating fibrillation of the heart. I hear what you are saying in that current equals heat (wattage) but please don't say AC is safer to work with than DC when the DC on most boats is below DC 60v.

[Fogg 427]

240v less dangerous!? Wattage is still going to be the same if you are drawing 50 amps at 13.8v or 2.87 amps at 240v (rms). Dialetric break down is higher at 240v so arcing and the human body allowing current to flow is also much higher not to mention the ocilating current creating fibrillation of the heart. I hear what you are saying in that current equals heat (wattage) but please don't say AC is safer to work with than DC when the DC on most boats is below DC 60v.

 

What I mean is that mains / shore power should be 'set & forget' and any problems you just call in the certified pros i.e. it's not for DIY. And the onboard systems are generally simpler for a small cruiser like us.

 

Whereas 12V seems to attract a lot more DIY activity and whilst bits can be totally safe (like fixing a faulty nav light) other bits of 12v systems are potentially hazardous with multiple place things can go wrong and overheat especially when you're dealing with charging / alternators / batteries which might be venting etc.

[Crazyhorse 47]

 "the human body allowing current to flow is also much higher not to mention the ocilating current creating fibrillation of the heart."

 

Yep, where one hand is on live AC and the other on neutral or earth and your'e wearing 10,000V gumboots.

Straight across your heart.

If the AC is above about 60v depending on the resistance of the "body" concerned, the skin moisture level, salt etc. Holding the wires from your wind turbine (3 phase) will do nothing. At 240v rms you are looking at just a few milliamps of current to meet your maker. True, a circuit (return path) needs to be created. One reason why sparkies will touch mains unprotected gear with one hand, the other behind their back and usually the back of the hand but footware does not necessarily make you safe. At 240v and higher, even a high resistance between the body and earth will allow sufficient current to flow to kill. Moisture on the rubber, the floor. Mains power kills.

[Fogg 427]

I think we’ve been talking cross purpose (or is that cross wires)?

 

Anyway, if you’re handling the bloomin cables then yes of course mains / AC is fR more dangerous than 12V D.C. to the human body. But that’s not what I was referring to or worried shoot with BP. I’m not worried about him frying his brains - he’s done that already - I’m worried about the consequences on the electrical equipment in the system and even the risk to the boat. There are way more parts and complications to 12V than an amateur DIYer will appreciate and hence some hidden dangers. Heat and fire bring the big one. Not electrocuting yourself.

[Black Panther 1,581]

Update.

Matt gave me instructions for a test that essentially by passed everything and forced the alternator to alternate. But it didn't. So I called the shop that fixed it(gtautoelectrix on the shore , good guys). He asked a few questions and figured out a change he had made ( above ground?) Meant I was now missing a connection from the back of the alt to engine block. Did that and hey presto.

Light is still on but think I just burnt out the switch.

[Crazyhorse 47]

Update.

Matt gave me instructions for a test that essentially by passed everything and forced the alternator to alternate. But it didn't. So I called the shop that fixed it(gtautoelectrix on the shore , good guys). He asked a few questions and figured out a change he had made ( above ground?) Meant I was now missing a connection from the back of the alt to engine block. Did that and hey presto.

Light is still on but think I just burnt out the switch.

Yep, separate earth (isolated) alternator. In other words, the engine chassis is isolated from the batteries so the starter motor must have its own earth cable too as will heat and oil senders, all to do with electrolysis in metal boats. Your battery supply will have a heavy duty common (negitive) wire running to the engine body somewhere if its not earth isolated, then it will run to the starter motor direct. This is where you should run the earth wire from your alternator, NOT direct to the engine!! Most engines use the engine body as a common, same as automobiles but some isolate the electrics totally so the alternator does not earth through the chassis but has a separate earth wire. One issue with this is the alternator stator not directly connected to the frame is liable to over heat as ours did as it can't use the frame to dissipate heat.