2.7 Alternator Upgrade

[Banshee]

70A alternator requires ~2.0 HP at full output
125A requires ~3.5 HP
Thats around another 1.5 HP through the belt, about 75% more!

What are you're suggestions re this Ray?

 

[Lazy-Ferret]

70A alternator requires ~2.0 HP at full output
125A requires ~3.5 HP
Thats around another 1.5 HP through the belt, about 75% more!

I guess that explains why all the higher power ones I have looked at have the wide flat ribbed belt pulleys, so they can get more friction and drive.

How do you work that figure out? I have been looking at a 175amp alternator!

 

[rayf3262]

What are you're suggestions re this Ray?

Just building on Rick's comment re the pulley size, expect to chew through belts more quickly at this kind of loading and possible slip.

 

[rayf3262]

I guess that explains why all the higher power ones I have looked at have the wide flat ribbed belt pulleys, so they can get more friction and drive.

How do you work that figure out? I have been looking at a 175amp alternator!

Very true on the flat belt, much more contact area.

125A at 14V = 1750 Watts
1 HP = 746 watts
given the efficiency of the alternator and losses in the belt etc. then figure on around 500W out per HP in.
Not very accurate, but certainly close enough.

 

[Lazy-Ferret]

Very true on the flat belt, much more contact area.

125A at 14V = 1750 Watts
1 HP = 746 watts
given the efficiency of the alternator and losses in the belt etc. then figure on around 500W out per HP in.
Not very accurate, but certainly close enough.

Thanks for that, I always wondered how to get to HP. so a 175amp is 5HP.... wow, I need a second engine...LOL

 

[solarman216]

yep power needs power, on my boat I had stock toothed pulleys bored to suite the respective shafts large on the engine small on the alternator so no slip whatsoever, but as a previous post went through alternators, then I discovered Sterling power products multi alternator controller, problem was solved it favoured the start battery first then when up to scratch fed both alternators to the cabin bank at enhanced rates which worked really well, Rick

 

[Lazy-Ferret]

I have not looked into this on the engine, so it may be impractical in the space given, but I have seen alternators with double pulleys, so I wonder if you could get one of those, and then run a longer AC compressor belt round the alternator as well. you wouldn't need the idler pulley then either.

 

[rayf3262]

I have not looked into this on the engine, so it may be impractical in the space given, but I have seen alternators with double pulleys, so I wonder if you could get one of those, and then run a longer AC compressor belt round the alternator as well. you wouldn't need the idler pulley then either.

As I see it to significantly increase your generation capacity you have two choices:
1) Deal with the mechanical issues associated with driving a large alternator.
or
2) Deal with the electrical issues associated with combining the output of two alternators.

 

[Banshee]

As I see it to significantly increase your generation capacity you have two choices:
1) Deal with the mechanical issues associated with driving a large alternator.
or
2) Deal with the electrical issues associated with combining the output of two alternators.

I think I'd go with 1 and just carry enough belts with me to deal with any roadside breakdowns I may encounter

 

[solarman216]

combining two alternators to one battery is not a problem you just link the outputs, and supply a bulb to excite the second one, running a second belt from the AC pulley is feasible but would need an idler pulley to adjust it, Rick

 

[solarman216]

I think I'd go with 1 and just carry enough belts with me to deal with any roadside breakdowns I may encounter

that will largely depend on how often and how long the one alternator is loaded to a high rate, bearing in mind that although it will have a much higher capability it will probably not be used in other words the bigger alt will only supply what you use now so = no difference but if you suddenly use lots more power then the bigger alt will supply it given the belt does not slip etc, Rick

 

[Banshee]

that will largely depend on how often and how long the one alternator is loaded to a high rate, bearing in mind that although it will have a much higher capability it will probably not be used in other words the bigger alt will only supply what you use now so = no difference but if you suddenly use lots more power then the bigger alt will supply it given the belt does not slip etc, Rick

Still a mod worth doing if you ask me though

 

[solarman216]

Still a mod worth doing if you ask me though

absolutely, if it is seen as an occasional extra load compensator then it will be fine, that is why I fitted a 2nd big alternator just for the winch, it cannot possibly supply enough for the winch all the time but like most things it is done in fits and starts so giving the battery a bit of time to recover, ( 2 x 95 amp hour ones ) one in the front and one in the rear for the rear winch links between the two are 50 mm sq cable this allows the rear winch to draw current from the front battery as well as ensuring the rear battery is charged to as high a rate as pos, Rick

 

[kitchenman]

Rick, have you got your second alt in the aircon pump place? if so could you send me some pictures please
I have a mount I got from CNC but not sure how to go about it.
Do you work from below or is it a radiator out job to gain access ?

 

[solarman216]

yes it is on the AC bracket, as it is on my off road motor it does not have a rad so mounting was not bad, as for pics I will have to jet wash it first as is covered in thick mud, Rick

 

[Banshee]

yes it is on the AC bracket, as it is on my off road motor it does not have a rad so mounting was not bad, as for pics I will have to jet wash it first as is covered in thick mud, Rick

What a bloke!!!!

 

[solarman216]

best I can do for now you can see the top mount and just make out the bottom adjusting bar which has been welded to make it long enough to reach a bolt on the timing case

 

[solarman216]

side view and water pipes going to rear rad, Rick

 

[kitchenman]

Thanks Rick those pictures will help

Which crank pully does the 2nd alt go to? looks like the belt is behind the main alt belt

Did you do the work from underneath or take the main rad out? to gain access

I have a second battery on wing behind the headlamp so I can't see much until I take it out

When I do mine I will do a write up with pictures

 

[solarman216]

Thanks Rick those pictures will help

Which crank pully does the 2nd alt go to? looks like the belt is behind the main alt belt

When I do mine I will do a write up with pictures

yes it goes on the AC pulley, re the write up, you reminded me when I put mine on together with the winch and rear rad I posted it all on here with pics, but do not ask me to find it, I am hopeless at searching, but must have been close on2 years ago, Rick