alternator not man enough!!

[dreadnought]

hi, i`ve just fitted a lithium battery in a hybrid configuration,150ah,and on starting up the alternator temperature, steadied off at about 70c after about an hour,the alternator is a simple lucas type 127 70amp,i have two lead acid.The lithium battery was at 37 percent so was taking as much as the alternator could give but the alternator belt was screeching at cruising revs,the belt is tight,so is there anthing i can do to stop this screeching or should i upgrade the alternator to what?any help much appreciated,many thanks 

[David Schweizer]

If the alternator still has it's original pulley, it may be worth having the crankshaft pulley groove widened to 13.5mm, and  fitting a 13.5mm alternator pulley and belt. I had to do that when I upgraded my alternator to a A127 70amp, and was experiencing belt slip with accompanying screeching. The widened pulley grooves and belt cured the problem.

 

 

[Mike Adams]

I doubt the current alternator will last very long with your set up. You need a larger alternator but that is only part of the problem. Depends on the engine, possible location of the alternator and the drive belt. You will probably need a multi ribbed pulley and if you require it to charge at tickover a different ratio. Trying to take too much current at low alternator speed will probably overload and overheat the alternator. One option is to fit a watercooled alternator or a second alternator but this depends on the engine. I ended up fitting two to ensure you get enough charge if, for example you are locking through a long flight all day.

[Tony Brooks]

34 minutes ago, dreadnought said:

hi, i`ve just fitted a lithium battery in a hybrid configuration,150ah,and on starting up the alternator temperature, steadied off at about 70c after about an hour,the alternator is a simple lucas type 127 70amp,i have two lead acid.The lithium battery was at 37 percent so was taking as much as the alternator could give but the alternator belt was screeching at cruising revs,the belt is tight,so is there anthing i can do to stop this screeching or should i upgrade the alternator to what?any help much appreciated,many thanks 

 

I think that this is why some stick an A to B, or a B to B, or a long length of wire between the lithiums and the LA battery. To limit the current taken from the alternator. Otherwise, it will take maximum output util your lithium charge control or the BMS isolates the lithium bank.

[BEngo]

Two issues here:  Alternator temperature and drive belt capacity.

 

The first is endemic to Lithium battery/alternator as charge source. Alternator fans are not the greatest.  For an A127 you can try fitting a tractor regulator ( with the extra flying lead)  and using that to  tweak the voltage down, so reducing the charge rate or you can use the long wire bodge, or you can fit a BtoB .  Changing the alternator is unlikely to have much effect as the Li battery will still soak up the max  output and cause it to run hot. If you change the alternator and go for  an all singing and dancing controller like the Wakespeed or Balmar or the Nicknorman DIY one then you can control on output or temperature as you wish.  Big money for the Wakespeed or Balmar though.

 

 

Drive capacity is about bigger belts- going from  Z section to A section is reasonably easy.  Fitting a multi-rib belt in PJ or PK section, usually 6 ribs wide,   is better but may be more difficult, depending on the engine. You can't easily do it on a BMC because of the torsional damper in the engine pulley, for example.  In  either case there needs to be good wrap round on both the engine and the  alternator ideally 180 degrees plus and you may need an idler pulley to achieve that. You also really need a positive tensioner for a multi-rib, but that is easier to arrange.

 

N

[ditchcrawler]

12 minutes ago, BEngo said:

 

Drive capacity is about bigger belts- going from  Z section to A section is reasonably easy.  Fitting a multi-rib belt in PJ or PK section, usually 6 ribs wide,   is better but may be more difficult, depending on the engine. You can't easily do it on a BMC because of the torsional damper in the engine pulley, for example.  In  either case there needs to be good wrap round on both the engine and the  alternator ideally 180 degrees plus and you may need an idler pulley to achieve that. You also really need a positive tensioner for a multi-rib, but that is easier to arrange.

 

N

Or maybe just a new belt would stop it squeaking, a single belt should handle 70 Amps

[Tony Brooks]

6 minutes ago, ditchcrawler said:

Or maybe just a new belt would stop it squeaking, a single belt should handle 70 Amps

 

Especially if it is notched. Then there is the question about are all the pulleys and the belt matched profile wise.

[BEngo]

20 minutes ago, ditchcrawler said:

Or maybe just a new belt would stop it squeaking, a single belt should handle 70 Amps

The belt is working close to its limits if you are going to sustain 70 A (over 1kW transmitted power)   on a Z section belt, so much depends on the speed up ratio, the engine speed (higher speed lowers torque and belt tension) and the pulley layout, particularly the wrap and  alignment.

Cogged  belts only really help if there is a small pulley to be negotiated.

 

N

[Tony Brooks]

10 hours ago, BEngo said:

Cogged  belts only really help if there is a small pulley to be negotiated.

 

And in inland marine use there very often is, on the alternator. But without the engine make and model, one can not be sure but if the OP decides to change the belt they might as well get a cogged one.