Shredded belts after lifepo4 upgrade

[PineyWoodsPete]

Originally Posted by CaptainRivet

I knew that exactly this would come.... There is a big difference in genny and inboard propulsion diesel with an off the shelf alternator to fullfil the minimum spec of the boat manufacturer.
Again i don't know how you run 5kw with only 0.4l gas,you seem to have magic engines.
Honda eu22i needs 1l per hour running 1800W. You can find this in reviews and its a very efficent one.
That is a genny running in the optimum range of an optimized engine exactly for that purpose.

Heh, that was the engine approx. displacement in liters, not fuel consumption, which was about 4L/hr at max. output.

I'm still wondering how you estimated the huge 10-12HP demand of your 1200W/1.6 HP alternator at full output. Fuel consumption would be the most accurate - how it changed from no alt. load underway at, say 2000 RPM, to consumption at the throttle setting needed to maintain the 2000 w/ full alt. output, but this requires a flow meter, which would only be accurate in a common-rail diesel - and something drawing over 1200W running.

Without a flow meter, you could estimate the HP difference from the RPM drop on the prop demand curve for your engine, which closely mirrors fuel consumption.

[CaptainRivet]

Its 1000W heat at 30Ax 13.3V so 1400W in total.
Your 100A heavy duty alternator will create minimum 2000W heat, likely more+ 100x13.3V =3300w

These ballpark numbers with 8-12hp are from different persons incl. 2 very experienced surveyors I know. Also don't forget the 30hp of your inboard are at the crank, add a saildrive losses and you see what is really available at the propeller.
You can be sure that Lagoon controller who calculate with 3 ahd 4th digit after the comma puts the bare minimum in you need...

[PineyWoodsPete]

Originally Posted by CaptainRivet

Its 1000W heat at 30Ax 13.3V so 1400W in total.
Your 100A heavy duty alternator will create minimum 2000W heat, likely more+ 100x13.3V =3300w

These ballpark numbers with 8-12hp are from different persons incl. 2 very experienced surveyors I know. Also don't forget the 30hp of your inboard are at the crank, add a saildrive losses and you see what is really available at the propeller.
You can be sure that Lagoon controller who calculate with 3 ahd 4th digit after the comma puts the bare minimum in you need...

Well, I'll tell you what. Of all surveyors, Nigel Calder is the one I would pick, and I quote from: https://oceannavigator.com/deficit-reduction/

"Assuming we could run the alternator at its full rated output (in practice, we’ll never achieve this), at 200 amps and 14 volts the charge rate would be 2.8 kW = 3.6 hp, which, given 50 percent alternator inefficiencies, translates into a load on the engine of 7.2 hp (perhaps a bit higher with belt and other losses)."

Or for your setup, 3.6HP. Okay, make it 4HP...

[Statistical]

Yeah 80% alternator efficiency is too high but 20% is just silly.

Sadly most OEMs don't provide the critical piece of data which is the "power take off".

Balmar does for some of their alternators.
https://balmar.net/balmar-technology...es-technology/

170A 12V alternator has PTO of 5.2 HP (3920W). The rated output hot at 6k rpm is 166A @ 13.5V = 2240W or 57% efficiency.

100A alternator is going to be around 3 HP power take off not 12 HP. Alternators have pretty poor efficiency but it is going to be in the 50% to 60% (hot) range now 20%.

[CaptainRivet]

Originally Posted by Statistical

Yeah 80% alternator efficiency is too high but 20% is just silly.

Sadly most OEMs don't provide the critical piece of data which is the "power take off".

Balmar does for some of their alternators.
https://balmar.net/balmar-technology...es-technology/

170A 12V alternator has PTO of 5.2 HP (3920W). The rated output hot at 6k rpm is 166A @ 13.5V = 2240W or 57% efficiency.

100A alternator is going to be around 3 HP power take off not 12 HP. Alternators have pretty poor efficiency but it is going to be in the 50% to 60% (hot) range now 20%.

Balmars are heavy duty and underrated spec means they really deliver the rating:and yes its 5.2hp at the alternator, take the belt losses into account and we are at 6hp. With optimum ventilation at 6000rpm which is 2000rpm engine... How does that look with 1400rpm...put this in all incapsulated cave like on many monos and we are talking about 8hp or 6hp but 140A output. Would love to see these balmar numbers checked in a real setup on a boat.
And now take standard like the 115A Mitsubishi that delivers 60A constant so real 60A will use 3hp,well ventilated and 4.5hp if not.
How much force and hp that really is you can see on the belts.
Important is how much of the 30hp engine you have left on the propeller and saildrive loss is % of total hp available...
I agree 12hp are really on the high side but better count with worst case and have some room...

Same discussion that Tesla can do 400km,well if i drive it in real life below 200km in summer...

[Statistical]

Originally Posted by CaptainRivet

Balmars are heavy duty and underrated spec means they really deliver the rating:and yes its 5.2hp at the alternator, take the belt losses into account and we are at 6hp. With optimum ventilation at 6000rpm which is 2000rpm engine... How does that look with 1400rpm...put this in all incapsulated cave like on many monos and we are talking about 8hp or 6hp but 140A output. Would love to see these balmar numbers checked in a real setup on a boat.
And now take standard like the 115A Mitsubishi that delivers 60A constant so real 60A will use 3hp,well ventilated and 4.5hp if not.
How much force and hp that really is you can see on the belts.
Important is how much of the 30hp engine you have left on the propeller and saildrive loss is % of total hp available...
I agree 12hp are really on the high side but better count with worst case and have some room...

Lack of ventilation or higher ambient temps don't increase the power take off. It just decreases the output.

So Ballmar unit is never going to be more than 5.2 HP. That is the point of power take off. As efficiency falls you get useful OUTPUT for the same input. Keep in mind that is for a 170A unit. A 100A unit would be more like 3 mayb 4 HP power take off.

I agree being conservative is good but no 100A rated alternator has 12 HP power takeoff.

12 HP would be something like the massive full fame alternators used on coast guard vessels (200A @ 24V).

[CaptainRivet]

Originally Posted by Statistical

Lack of ventilation or higher ambient temps don't increase the power take off. It just decreases the output.

So Ballmar unit is never going to be more than 5.2 HP. That is the point of power take off. As efficiency falls you get useful OUTPUT for the same input. Keep in mind that is for a 170A unit. A 100A unit would be more like 3 mayb 4 HP power take off.

I agree being conservative is good but no 100A rated alternator has 12 HP power takeoff.

12 HP would be something like the massive full fame alternators used on coast guard vessels (200A @ 24V).

Question is on my mono, encapsulated engine room want real 100A charge on 1400rpm cruising speed, how much hp is the take off and how much is the loss at the propeller. and i am sure we will talk about 6-8hp minimum which at the end is somewhere between 25 and 30% overall efficiency. Thats real life setup and the right question with an expensive high duty alternator and external regulator.... Now same question with standard with integrated regulator....

[Statistical]

Originally Posted by CaptainRivet

Question is on my mono, encapsulated engine room want real 100A charge on 1400rpm cruising speed, how much hp is the take off and how much is the loss at the propeller. and i am sure we will talk about 6-8hp minimum which at the end is somewhere between 25 and 30% overall efficiency. Thats real life setup and the right question with an expensive high duty alternator and external regulator.... Now standard with integrated regulator....

At least we are down to 6 to 8 from the original 12. No it wouldn't be 6 to 8 HP. Alternators have bad efficiency they don't have that bad efficiency.

[mitiempo]

What I have heard over the years from Balmar, and Ample Power in their day, is that 25 amps from an alt is 1 hp. Yes it has less output when things heat up but the load is still the same.

So 100 amp alt uses about 4 hp.

[witzgall]

Chris from Balmar here.

Belts fail prematurely due to a few factors:


1. Misalignment
2. Improper tension

The actual culprit is usually heat, due to one or both of these issues.

Check for both carefully. I doubt that the HP requirements are to blame.

Chris

[CaptainRivet]

Originally Posted by Statistical

At least we are down to 6 to 8 from the original 12. No it wouldn't be 6 to 8 HP. Alternators have bad efficiency they don't have that bad efficiency.

Well for th real life above you need min the 140A balmar, if not the 170A to deliver the real 100A and then you are at 6-8hp loss at best.
Total power needed is amps really delivered+ heat creation in watts. So if heat goes up the efficiency goes down.
Efficiency is really bad in real world...
had a 250A alt on a Volvo md30A in a quite well ventilated engine room on my previous pilothouse ketch and the real world deliery was between 160A and 200A...invest and hassle till this was slip free was massive, diesel went up by 1-2l/h. Had no other choice as no space for much solar or a beefy generator.

[Statistical]

Originally Posted by CaptainRivet

Well for th real life above you need min the 140A balmar, if not the 170A to deliver the real 100A and then you are at 6-8hp loss at best.
Total power needed is amps really delivered+ heat creation in watts. So if heat goes up the efficiency goes down.

Well no. It is 5.2 HP at full RPM which delivers ~160A HOT. At lower RPM the power take off is lower (and so is the electrical output).

Efficiency is really bad in real world...
had a 250A alt on a Volvo md30A in a quite well ventilated engine room on my previous pilothouse ketch and the real world deliery was between 160A and 200A...invest and hassle till this was slip free was massive, diesel went up by 1-2l/h. Had no other choice as no space for much solar or a beefy generator.

Efficiency is 40% to 60% not 15% to 20% in the real world. Your own fuel consumption numbers taken at face value are much higher than 20% alternator efficiency.

Using the middle of your numbers 1.5l/h diesel and 180A delivered. Diesel has 10,000 Wh of energy per liter. So 1.5 l/hr = 15,000 Wh/hr or 15,000 W. However the diesel powerplant is only about 35% efficient so it converts that into 5,250 W of mechanical energy. 5,250 W = 7 HP. So your 180A true output alternator has a power takeoff of 7 HP. Which matches roughly with the rule of thumb of 25A per HP.

As for efficiency you are getting 14v * 180A = 2520W using 5,250W input power = 48% efficiency.

So even using your numbers are reference alternator efficiency is not 15% to 20%. It is 40% to 60% depending on speed, temp, and OEM. 40% to 60% is already pretty low efficiency compared to other more expensive designs. The liquid cooled "alternator" in a marine generator is 80% to 90%+ efficiency.

[witzgall]

Max PTO for the XT-170 is about 5.5hp at 7500 Alternator RPM...

Chris

Originally Posted by CaptainRivet

Well for th real life above you need min the 140A balmar, if not the 170A to deliver the real 100A and then you are at 6-8hp loss at best.
Total power needed is amps really delivered+ heat creation in watts. So if heat goes up the efficiency goes down.
Efficiency is really bad in real world...
had a 250A alt on a Volvo md30A in a quite well ventilated engine room on my previous pilothouse ketch and the real world deliery was between 160A and 200A...invest and hassle till this was slip free was massive, diesel went up by 1-2l/h. Had no other choice as no space for much solar or a beefy generator.