Uprated replacement alternator 3jh4

[Foxy]

So, ongoing plan is to be spent rewiring Foxglove. Im aiming to do this as several projects, the first being the battery storage/charging/high current distribution.

im currently running on my spare aftermarket replacement for my yanmar/hitachi 80a alternator and looking to replace this with a decent one for long term use (relegating thhis one back to the spare store. theres a good offer on electromaax until the end of today (500usd) Another option are balmar (super pricey) but imho neither of these are manafactured in-house,so does anyone have a view as to a suitable replacement that isnt a 'marine' special.

Alternator is 'regulated' using sterling alternator to battery regulator, so int/ext regulation is probably not a problem.

i am also converting to serpentine (also on offer) as am gping through belts faster than diesel.

Any thouhts appreciated

Pat

 

[lpdsn]

What can your Sterling A2B regulator actually push into your batteries? The most I've seen my A2B charger doing is 49A (from a 55A alternator) but generally it starts at circa 20 to 30A and quite quickly drops from there. I've measured it at up to 14.8V so I don't think it can do any better. That's 2 X 180Ah batteries. On that basis I've concluded that a bigger alternator wouldn't be much gain for me.

 

[pvb]

Prestolite alternators are good (they make Balmar's), and they're also sold under the Leece-Neville brand. Available easily in the UK. But remember you need a big battery bank to absorb big charging current.

 

[Foxy]

What can your Sterling A2B regulator actually push into your batteries? The most I've seen my A2B charger doing is 49A (from a 55A alternator) but generally it starts at circa 20 to 30A and quite quickly drops from there. I've measured it at up to 14.8V so I don't think it can do any better. That's 2 X 180Ah batteries. On that basis I've concluded that a bigger alternator wouldn't be much gain for me.

Interesting. I have only seen similar but from an 80A alternator usually at approx 14.5v, That said, my high current wiring is all over the place and im sure theres a fair loss of efficency.
Perhaps better going for an ext regulated alternator instead. Plan is for approx 440ah or poss 600 if I can fit it in.

 

[Foxy]

Prestolite alternators are good (they make Balmar's), and they're also sold under the Leece-Neville brand. Available easily in the UK. But remember you need a big battery bank to absorb big charging current.

Had a look on their site. lots to choose from, any idea which would be the best replacement, ie high current at low speed etc

 

[pvb]

Had a look on their site. lots to choose from, any idea which would be the best replacement, ie high current at low speed etc

Most of their alternators have a good output curve, with high output at lowish revs. Remember that, regardless of the alternator's output rating, it can't push more current into the batteries than they'll accept, so the larger the battery bank, the more amps you'll be able to charge with. I fitted a 12v 90A alternator on my last boat, charging a 660Ah battery bank, and it worked fine. If you go much above 90A, you need to change to a twin V-belt, or a flat multi-V belt, otherwise you'll get lots of belt slip and black dust everywhere. Also, if you go much above 90A, you tend to get into large case alternator territory, and there can be lots of mounting problems. As a starting point, ask Adverc for a recommendation and price for a suitable Prestolite alternator - they're very helpful and reasonably priced.

 

[lpdsn]

Interesting. I have only seen similar but from an 80A alternator usually at approx 14.5v, That said, my high current wiring is all over the place and im sure theres a fair loss of efficency.
Perhaps better going for an ext regulated alternator instead. Plan is for approx 440ah or poss 600 if I can fit it in.

Was that 14.5V at the battery? Or at the alternator? If you're losing 0.3V it sounds like that supports your argument for tidying up the wiring. And there is the potential to push more into the battery with the extra 0.3V

Even Sterling himself doesn't seem to advocate increasing the voltage at the battery beyond 14.8V for bog-standard lead acid batteries (which is the voltage I seem to be getting) so in my case I couldn't use more Amps. A 600Ah bank will be able to use more. But more than an 80A alternator could output is another question.

 

[Foxy]

was considering going down the merlin route with one of their complete solutions (which use agm batteries) however not made up my mind as to whether to recreate using other parts.

 

[RobbieW]

...
i am also converting to serpentine (also on offer) as am gping through belts faster than diesel...

Bit late on this so you may already have made a decision. I'd do the serpentine conversion first and deal with the belt wear, then look at what was going on afterwards because the geometry will undoubtedly change with the belt kit. Mine span the alternator about 30% (iirc) faster which also changes the rev counter reading btw.

Its also my understanding that the relationship between the inputs and outputs of an A2B charger isnt necessarily as direct as you might assume. I understand the A2B drives the alternator quite hard then does all the conversions of voltage required for its outputs internally. Depending on your long term use for the boat, ie frequent hard charging, it may be worth changing the alternator to one that is designed for high loads which might then have better longevity. From the sound of your battery plans, 80A may slow down the initial charging from a low state which means the output will need to stay higher for longer.

For comparison I have a nominal 720Ah AGM bank (now 5 years old so probably somewhat less in reality now) charged by a Balmar alternator with a Balmar external regulator. With a 150-200A batttery deficit I see charge rates of about 110A for a while which tapers off to 50 ish then 20 ish over about an hour. That I've not 'plugged in' for a couple of months now means the batteries seem to be getting harder to charge as theyve not had a proper 100% charge in that time (need to do a 12 hour motor somewhere )

 

[Foxy]

Bit late on this so you may already have made a decision. I'd do the serpentine conversion first and deal with the belt wear, then look at what was going on afterwards because the geometry will undoubtedly change with the belt kit. Mine span the alternator about 30% (iirc) faster which also changes the rev counter reading btw.

Its also my understanding that the relationship between the inputs and outputs of an A2B charger isnt necessarily as direct as you might assume. I understand the A2B drives the alternator quite hard then does all the conversions of voltage required for its outputs internally. Depending on your long term use for the boat, ie frequent hard charging, it may be worth changing the alternator to one that is designed for high loads which might then have better longevity. From the sound of your battery plans, 80A may slow down the initial charging from a low state which means the output will need to stay higher for longer.

For comparison I have a nominal 720Ah AGM bank (now 5 years old so probably somewhat less in reality now) charged by a Balmar alternator with a Balmar external regulator. With a 150-200A batttery deficit I see charge rates of about 110A for a while which tapers off to 50 ish then 20 ish over about an hour. That I've not 'plugged in' for a couple of months now means the batteries seem to be getting harder to charge as theyve not had a proper 100% charge in that time (need to do a 12 hour motor somewhere )

Really useful thank you and ive done just that. The serpentine kit was on offer in the US, it arrived in a day and a half. The idea is to fit it and see what happens but what you say on the a2b and a higher powered alternator etc makes sense. As we arent currently cruising, I can postpone that until ive a better idea of the overall lay of the land with respect to the complete system.

Thanks again.

Any views as to whether Merlin or Advec etc and alternator preferences gratefuly received too. I might start a seperate post on this including merits of an easily bypassed three wire system (sort of basic can-bus but just for high current distribution)

 

[pvb]

Any views as to whether Merlin or Advec etc and alternator preferences gratefuly received too.

Which model A-to-B charger do you have? Will it cope with a bigger output alternator if you decide to get one? If not, it might be worth replacing it with a good external regulator.