Two alternators on FL 120?

[Fotoman]

I currently have a Leece-Neville 55 amps on my FL 120 and I always found that it was a bit short on power to recharge my batteries when I am travelling for a few days. I just had the opportunity to buy a Balmar 912-75 along with a ARS-4 regulator for a really good price. I was originally thinking of replacing my Leece with it but could I install the Balmar on the other side of the engine to run both? One could charge bank 1 and the other could charge bank 2.
Any drawbacks on the engine? Loss of power?

 

[DavidM]

A good setup with two alternators is to have the low output one charge the starting battery and the high output charge the house bank.


The only problem will be figuring out bracketing and belts for the new Balmar alternator.


Having said that you probably won't get much benefit out of the current alternator with a high output Balmar also installed. But it does give you redundancy. Is it worth the effort though to set up a separate mount for the Balmar?


David

 

[Fotoman]

Thanks David. I think the PO had two alternators at some point because I remember taking apart some bracketing system on the left side of the engine. I still have the parts somewhere so maybe that won't be so difficult.

My starting battery is charged by an echo charger and that works really well. I would use the second alternator to charge my second house bank (that is currently not charged while running, only at the dock). I use that bank to run the fridge and a couple of non-essential devices.

 

[Sabre602]

My Lehman 120 has a small alternator (single belt) for the starting batteries and a big, dumb one (double belt) for the house bank. The bracketry is straightforward.

I'll be upgrading to a "smart" alternator system when I can afford it and will leave the smaller one there.

 

[Irish Rambler]

Just my 2 penn'orth.
Why don't you talk to sales@adverc.co.uk I had charging problems and fitted two identical Bosch 90 amp alternators (we can't get spares for Balmar or Leece-Neville easily in Europe).
Fitted correctly by any competent diy'er the smart charge system is fully automatic, not prohibitively expensive and above all reliable.
I highly recommend it.

 

[Fotoman]

Irish Rambler and Sabre602, would you have pictures of your setup? I'm having a hard time figuring out how to install the second one on the other side of the engine.
I found the instructions online and it says I could wire the alternator to a switch (instead of the ignition) to turn it on or off. That would be a great system since I don't need two alternators when I cruise over the weekend. I could only use the second one when I travel.

 

[Irish Rambler]

Would you be kind enough to speak(email) Mark Godwin at Adverc sales@adverc.co.uk let him know you were in touch with me, (Geoff Woolley) and ask for a spec sheet 510 which will explain to you in precise detail all you need to know regarding the wiring installation.
No picture of my installation would be good enough for you to make any sense of it. What I do advise is stick strictly to the colour coded wiring and laminate a copy for your boat records file for ease of future identification.
I use Bosch alternators simply because of the after market spares situation here in Europe.
Mark will walk you through step by step with any technical info, obviously you need to mount the second alternator yourself.
To help him help you, you need to describe your (projected) 12 volt requirements in full in order that he can advise you best.

I'm not shifting the issue, just giving you a contact for a person better able to advise on your issue and become a satisfied customer like me.
I'm a spanners man meself, electrics are a black art.

 

[Tator]

Not sure what country you are in, but American Diesel sells a mount for installing another alternator on the left side of the Lehman. I'm assuming that you have another pulley on your crankshaft that will be used for the larger alternator.

Tator

 

[Irish Rambler]

At the moment were cruising the canal du Midi, see our post.
Our boat came with 2 alternators, 1 for Domestic and 1 for starter batteries and of course a dual groove crankshaft pulley.
When we bought the boat our electrical requirements were far more than the PO's as we added aircon, fridge, freezer, dishwasher, washing machine, inverter etc so the alternators simply weren't capable off providing sufficient charging capability.

If you can buy the second mounting bracket from American Diesel then go ahead and fit it as its the easiest option, when you install it put 'Loctite' on the engine block mounting bolts so they don't vibrate loose over time.
Usually the generally agreed maximum size alternator for a single belt pulley is 100/110 amp, after that you are liable to belt slip, premature bearing failure etc.
If you follow the Adverc route you will, via split charge relays be capable of a charging 900 amp battery installation as they generally think in terms of the alternator producing 25% of the battery capacity.
Fit your brackets and then decide which route you will choose.

 

[Pack Mule]

I have a Perkins 6.354 . There was plenty of room in front of the engine so the PO made a bracket and mounted the second alternator facing the engine . You have to look close but you can see it in the bottom left corner of the pic.

 

[Fotoman]

Well, if American Diesel offers a bracket to mount a second alternator, that makes it a whole lot easier! And yes I do have a pulley with dual grooves so I guess it was planned from the beginning.