DC to DC charger - not needed for boats with proper alternators.

[newhaul]

Originally Posted by CaptainRivet

Why does then ISO and ABYC require parallel cables to be the exact same length and exact same diameter?
Iso then specs you can spec the 2 cable with half current carry capabilities each while ABYC requires same current capabilities then 1 cable and paralleling is for reducing voltage drop only.

Because they regulate new construction and many service mechanics will use the recommendations to brow beat a job out of it .

[CaptainRivet]

Originally Posted by newhaul

Because they regulate new construction and many service mechanics will use the recommendations to brow beat a job out of it .

They also regulate refits. LFP install from factory are still very rare, so even new ships are retrofitted.

[newhaul]

Originally Posted by CaptainRivet

They also regulate refits. LFP install from factory are still very rare, so even new ships are retrofitted.

Not in my country they dont they try and fail

[Fuss]

Originally Posted by Fuss

I still don't understand what you mean...
what saved hundreds of alternators from burning when owners added drop in lifepo4?

Originally Posted by CaptainRivet

An underdimenioned and/or corroded and or strands broken wire between alternator via starter or directly to batteries. This crap cable with high resistance limits the current drawn from the alternator and saved it this way.

Lifepo4 or eg a huge agm bank is basically a short and a proper sized new wire presents a low restistance too so the alternator would have delivered full throttle wide open full power with running flag till it dies.

Originally Posted by Fuss

So what you are saying is, that if I have a corroded wire or a thin wire, then the alternator can’t put out its full current and so is saved from overheating…

Originally Posted by CaptainRivet

Exactly.
Just a new cable parallel gave him 3A more that created already 4 degrees at alternator.
The 36Si delco Simi is using here is a beefy large case school bus alternator optimsed for low rpm means relying mostly on self cooling. This one can actually output its 100A @24V in a good ventilated engine room all day long.
And Simi derated it to 70% and still then just 3A more cause already a raise of 4 degrees at the alt in his installtion. His crusing rpm is basically idle speed for the alternator.
You cannot get much better alternator without paying a liver for it but you need the space for to install it.
So and now take that to a small case alternator optimized for higher rpm like most engines have stock which has a very small self cooling capacity. 3A is easliy 10 degrees or more for them. A large case won't fit on many engines or engine rooms.

Originally Posted by Simi 60

Strange how my apparently, old, crap and possibly undersized alt cabling never saved the two previous big frame atls from cooking while charging AGM

Originally Posted by CaptainRivet

Was the regulator internal or externally ?
The crappy high resistance cable fouls the internal regulator to output less. If the regulator was externally it cannot be fouled, so they delivery full output but less reaches the battery while basically running at idle=not much self coooling capacity.

Which big case exactly? High rpm alternator big case, which are majority out there have significant self cooling capacity only above 25-30% of max rpm. At idle they have a bit more then small case in the end when they heated up but they need significant longer time till they heat up then small case. Good Small case like 115A Mitsubishi typically needs 20min, big case high rpm 50-60min under same conditions till they reach critical temps if running full throttle while a low rpm should need approx 2h...

Well, finally, there we have it. Proof that a DC to DC charger is not needed at all, you just need an undersized cable or a bad connection creating high resistance that fouls the alternators internal regulator to output less.
But, I guess even better, why then would you pay 6-7 hundred dollars for a Wakespeed external regulator when you can just install high resistance either by cable size or bad connection and use a cheapo internal regulator.
Your alternator is then completely protected against overheating.


For some reason, my alternator works differently, when the cable has high resistance, then there is voltage drop which causes the alternator to full field and never come out of bulk charging as it never reaches absorption voltage.
Anyone have any ideas what is wrong with it?

[newhaul]

Originally Posted by Fuss

Well, finally, there we have it. Proof that a DC to DC charger is not needed at all, you just need an undersized cable or a bad connection creating high resistance that fouls the alternators internal regulator to output less.
But, I guess even better, why then would you pay 6-7 hundred dollars for a Wakespeed external regulator when you can just install high resistance either by cable size or bad connection and use a cheapo internal regulator.
Your alternator is then completely protected against overheating.


For some reason, my alternator works differently, when the cable has high resistance, then there is voltage drop which causes the alternator to full field and never come out of bulk charging as it never reaches absorption voltage.
Anyone have any ideas what is wrong with it?

Over think8ng it all would be my answer . Just install a DC2DC and all is well.

[donradcliffe]

Originally Posted by Fuss

Well, finally, there we have it. Proof that a DC to DC charger is not needed at all, you just need an undersized cable or a bad connection creating high resistance that fouls the alternators internal regulator to output less.
But, I guess even better, why then would you pay 6-7 hundred dollars for a Wakespeed external regulator when you can just install high resistance either by cable size or bad connection and use a cheapo internal regulator.
Your alternator is then completely protected against overheating.


For some reason, my alternator works differently, when the cable has high resistance, then there is voltage drop which causes the alternator to full field and never come out of bulk charging as it never reaches absorption voltage.
Anyone have any ideas what is wrong with it?

Fuss, somewhere in the last 20 pages you may have told us what kind of regulator you have, but I'm not going to go looking for it.

With an internally regulated alternator, the higher cable resistance will save the alternator. In fact if the cable resistance is too high, the alternator will loaf along and never get the batteries charged. I had an Express 34 that I prepped for Pac Cup, and I had to put a parallel wire to the starter wire to get the 65 amp internally regulated alternator to put out 40 amps into a depleted LiFe battery. I called it good enough, and it worked fine for the race and return, because the boat also had a lot of solar.

With an externally regulated alternator the regulator field current is controlled by the battery sense voltage. Resistance in the output wire should still drive the alternator to full field and higher output voltage. The prolonged full field operation may overheat the alternator, and all externally regulated alternator should have an alternator temperature sensor to prevent this.

That's the theory, but I just delivered a Santa Cruz 70 which had new (AGM) batteries and had the big Balmar alternator tested before the race. The race crew had to charge 4-6 hours per day because the battery voltage never got above 13v. A mechanic in Honolulu found a corroded and burned alternator output wire and replaced it with a new and one. The system worked perfectly on the delivery. When I saw the battery voltage rise above 14 and then drop back to float at 13.4, I did no further testing. Don't mess with success.

[Putt-Putt]

donradcliffe

I don't see how a high resistance circuit could save the alternator regardless of the type of regulator, barring alternator temp. sensing or an overall derate.

My understanding is that most internal regulators control the voltage at the alternator and have no ability to know what happens in the distribution circuit or the battery. They simply run flat out until a voltage set point (14.2V+/-) is achieved for some preset duration of time and then continue to cycle on and off with varying periods of on and off, to maintain that voltage. This would be your Bulk (CC) to Absorption (CV) transition. They have no float, which is a problem for deep cycle (antimony) batteries, but not for starting (calcium) batteries.

External regulators do the exact same thing, run flat out (CC) and then once this voltage set point is reached, cycle on and off to maintain some predetermined (CV) voltage. The differences are basically the set points are user defined, as is the duration of CV, they have a float cycle, you can derate their output, plus alternator and battery temp. sensors that will modify their output. The other thing is that they monitor voltage at the battery which allows the regulator to increase voltage to offset the voltage drop in the circuit. But to be fair, a lot of new internally regulated alternators also offer this feature.

So,

If you have an internally regulated alternator, it knows nothing about what happens downstream. If your distribution circuit has high resistance and turns half of your alternators output to heat, the alternator being clueless will just continue at full trot for twice as long as it really should need to, until the voltage set point is reached and then will run at almost full trot to maintain this voltage. Voltage sensing at the battery does not help you. You will likely at some point cook the alternator as it has run too hard for too long. Remember your alternator is likely designed to replenish the start battery and then provide power to your lights, wipers, heater and radio in your car, thats it.

If you have an externally regulated alternator, the same thing happens. The alternator's output is twice that of the input to the battery. The alternator has to work just as hard and just as long to raise the voltage to the set point as one with an internal regulator with voltage sensing. When you are fully fielding the alternator, the regulators location is almost meaningless.
Your alternator might be saved by it's temp. sensor or the fact that you downgraded its output when you programmed the regulator. Otherwise you will likely cook it, just as quickly.

The problem here is the wiring, or the capabilities of the alternator, not what kind of regulator you are using.

Then again I could be all wrong, if so let me know as to where, as I'm always eager to learn.

[Simi 60]

Originally Posted by CaptainRivet

Which big case exactly? High rpm alternator big case, which are majority out there have significant self cooling capacity only above 25-30% of max rpm. ..

Genuine Delco 20si 45 amp was original on engine
Clone 22si 70 amps was the next and that was money back under warranty

Both dead after several hours pushing amps into 840ah of 24v agm

[newhaul]

Originally Posted by Simi 60

Genuine Delco 20si 45 amp was original on engine
Clone 22si 70 amps was the next and that was money back under warranty

Both dead after several hours pushing amps into 840ah of 24v agm

With that big of a bank why didnt you upgrade to the 150 amp one if not the 250 amp ?
Just curious

[Simi 60]

Originally Posted by newhaul

With that big of a bank why didnt you upgrade to the 150 amp one if not the 250 amp ?
Just curious

Alts only work when we are doing miles
Often we sit for a week, go 10 miles, sit for a week
We recently spent over a month in a lagoon 100 nm out, didn't use the motor once.

A Delco Remy alt the size you talk of in Oz would be a $5000 install if buying new
That buys a lot of Genset hours

Even the 100 amp ones we have now are $1500+ new here
I was lucky to find them unused for $300.

We have 2500 watts of solar as our main charging source
And a 7kva Genset pushing out 120amps @ 24v when needed

[newhaul]

Originally Posted by Simi 60

Alts only work when we are doing miles
Often we sit for a week, go 10 miles, sit for a week
We recently spent over a month in a lagoon 100 nm out, didn't use the motor once.

A Delco Remy alt the size you talk of in Oz would be a $5000 install if buying new
That buys a lot of Genset hours

Even the 100 amp ones we have now are $1500+ new here
I was lucky to find them unused for $300.

We have 2500 watts of solar as our main charging source
And a 7kva Genset pushing out 120amps @ 24v when needed

That price I see why you don't go bigger.
Here that 250 amp one here is under 500 new and used certified I can get it for about half from one of the truck repair yards here likely less from one of our salvage yards .
( great living on the largest protected deep water port on the west coast of the USA.

[Putt-Putt]

As far as I know the only Delco alternator that is rated at 250 Amps at 24 Volts is the 55SI. Although a J180 mount is available (its rated at 275 Amps), most that are on the market are a Pad mount as that is what OTR trucks generally use.

The current US of A pricing for a new unit runs about $3000. Even the Chinese clones from Rare Electrical run about $3k. Yeah, I see a near new 275A 24 Volt unit on ebay for $550, but again pad mount.

Thats just the start of your problems, as where are you going to get a 12 groove flat belt pulley to fit on your torsional damper?

Where did you find a 250 Amp 24 Volt alternator for under $500?

[CaptainRivet]

Originally Posted by newhaul

Over think8ng it all would be my answer . Just install a DC2DC and all is well.

If you stay at around 40-60A at 12V or half at 24V a DC2DC may make sense if you want to keep lead.
But if we talk about charge of 70-100A @24V or 100-200A @12V a DC2DC makes no sense at all. Then charge directly LFP and if you wanna keep lead use a small DC2DC to trickle cahrge lead.

[newhaul]

Originally Posted by Putt-Putt

As far as I know the only Delco alternator that is rated at 250 Amps at 24 Volts is the 55SI. Although a J180 mount is available (its rated at 275 Amps), most that are on the market are a Pad mount as that is what OTR trucks generally use.

The current US of A pricing for a new unit runs about $3000. Even the Chinese clones from Rare Electrical run about $3k. Yeah, I see a near new 275A 24 Volt unit on ebay for $550, but again pad mount.

Thats just the start of your problems, as where are you going to get a 12 groove flat belt pulley to fit on your torsional damper?

Where did you find a 250 Amp 24 Volt alternator for under $500?

The diesel shop that used to do my fleet maintenance before I sold everything and retires from otr.

[Simi 60]

Originally Posted by Putt-Putt

As far as I know the only Delco alternator that is rated at 250 Amps at 24 Volts is the 55SI. Although a J180 mount is available (its rated at 275 Amps), most that are on the market are a Pad mount as that is what OTR trucks generally use.

The current US of A pricing for a new unit runs about $3000. Even the Chinese clones from Rare Electrical run about $3k. Yeah, I see a near new 275A 24 Volt unit on ebay for $550, but again pad mount.

Thats just the start of your problems,

And there was that

I did have a try for some Leece Neville alts that were j180 around the 200 amp and acceptable coin but information on the output at low rpm is almost impossible to find
And
What information I could find on not the same but similar models indicated output would be pretty average
Better than Balmar but not as good as the Delco's