Running Two Alternators

[rja]

Originally Posted by S&S

Balmar said they can't handle Niehoff's field current- in any event there'll be two different chemistries(LiFePO4 and AGM) so I think two seperate systems is the easiest way to go.

Hello,

You might want to check with Balmar again. They recently came out with the "Centerfielder 2" which is suppose to handle more field current (and up to 4 alternators).

-rja

[S&S]

Well the engine is being installed, next up getting the wiring and panels etc renewed to take the alternator and battery rig.
that's a 100A alt on the engine. The big pulley you see is the PTO for the 400A Niehoff primary.

On the crane:

Where it's going: (note the crossed fingers :laugher )

Squeeek!

close one:


Phew, it's inside

Making the turn -they had to take the bolts off the bottom of the PTO bracket to make it past the sole stringer (cleared by 1/2"!!!)

almost there.....

In place- now they just have to slide it forward:

[hellosailor]

Reminds me of the joke line where the Madame says "You ain't gonna put that in there!"

I hope you brought the crane crew a round of drinks, that looks like a damn fine operation all around!

[SV Demeter]

I am currently running two alternators. One is a 100amp balmar for charging my house bank. Externally regulated with Balmar 614. The other alternator is a 70amp Motorola that is internally regulated and being used to charge my start battery. The motorola came with the boat and was not being used when I bought the boat. Engine start was being charged via an isolation diode. I did not like that set up and put the motorola back in service and eliminated the isolation diode. I was going to use a digital duo but thought why not save some money and use the motorola that is jsut sitting there spinning with the water pump? I had it tested and cleaned up and reinstalled with new wire.

Problem is that the motorola is putting out close to 15volts and my start battery is a 4D Gel. I put the isolation diode back in between the alt output and the starter to step down the voltage but Im still seeing 14.35-14.40 volts at the start battery. Gels dont like more than 14.2 IIRC. Any suggestions on what to do here? I was hoping to not have to buy another external regulator and pay to have the internal regulator disabled. I also was hoping to not have to replace the start battery with one that can handle the output as its a good battery with life left. I dont want to prematurely kill the gel though and worried about it seeing 14.35 volts.

[hellosailor]

"Problem is that the motorola is putting out close to 15volts"
"Any suggestions on what to do here? "

Yes. First, disconnect that alternator to avoid damaging those batteries. Then find out what voltage they need, from the mfr. And take that alternator out to have the internal regulator replaced, if the gels can take a standard 14.3-14.4 volts. If they need something special, you can easily modify the alternator (or have it modified) to use an external regulator which will charge them properly.

If the budget gods are generous, I would suggest modifying the Motorola to use an external alternator, and then buying a second Balmar 614, or something that is pin-compatible with it. That way IF your primary regulator goes south, you can steal the one from the starter and use it as a hot spare.

It is possible that someone had the Motorola internally modified in the past, to accomodate the voltage loss from the isolation diode, and you may just need to "unmodify" whatever was done. (i.e. there may be an extra diode inside it, to be removed.)

Better to fix it right than to kludge around. And to label & document the system afterwards, because years later, we tend to forget about this stuff.

[SV Demeter]

Pretty much what I was figuring. I need to double check but I believe the Gel battery I have wants 14.2 volts. I had not thought about the possibility of motorola being modified, but it had not been hooked up prior to now so not sure. The start battery had been getting charged by an isolation diode on the 100 amp balmar.

Would it be possible to have the internal regulator configured to properly charge the gel or is the only way to properly charge a gel via a multistep external regulator?

If I am going to the effort to buy another external regulator (614=$300) and have the internal regulator disabled $$ and the additional wiring $ I might just as well buy a digital duo charge off the balmar and leave the motorola disconnected. Part of my reasoning for putting the motorola into service was to create some redundancy in charging. Such that if the balmar alternator or its regulator failed I could parrallel the banks and use the smaller motorola to temporarily charge until I fixed the main alt. I suppose a wet cell would handle the internal regulator better too but I dont feel like replacing a perfectly good battery.

Thanks,

[hellosailor]

"Would it be possible to have the internal regulator configured to properly charge the gel" I'm not sure. It is possible that Motorola or someone else offers different internal regulators, typically that's a $25 part wholesale that gets marked up to $100 over a retail parts counter. You can always trick an alternator into putting out MORE voltage, by adding a diode. Or adding a resistance (could be 20' of battery cable) in the output lead, to drop the output voltage, but there may be a more elegant way.
I haven't messed around with gel batteries so haven't looked into the options for dropping alternator voltage for one. Probably, someone who sells the gel batteries would have those answers at their fingertips. Or a parts supplier might be able to tell you if there are any optional lower-volt regulators to fit in that Motorola, if you have the exact part number for the alternator. Motorola might also be able to tell you that directly, sometimes they accidentally let their techs on the phones.<G>

[SV Demeter]

Starting to look like I might just end up pulling the motorola alt and having the internal regulator disabled. Then adding an external regulator but nothing fancy like the 614. Just a basic one that I can set the voltage limits on.

[hellosailor]

That's probably the most cost effective solution. You can find specific instructions for doing that on the web and in a couple of the basic 12-volt books, usually all you have to do is remove the regulator chip or remove one wire from it, and take that lead out to an external regulator, not a hard job at all!

At the same time, you get a chance to inspect the bearings & rings & brushes inthe alternator, to see if it is worth any bother at all. If you haven't ever opened an alternator, the most important tool to have on hand is a toothpick. Honest!

Usually there's a hole where you can insert a toothpick, to prevent the brushes from springing out of position. If you take them out--they should go back in the exact same place, same orientation "this side up" because they've worn in to fit exactly that way.

The rest is about as complicated as taking the batteries and bulb out of a flashlight.

[SV Demeter]

Yeah I suppose I should give it a shot myself. Always wanted to anyway. Its jsut a shame because I pulled the thing a few weeks ago and took it to a local shop for bench testing. They said it was fine and I paid to have it taken apart and cleaned up. Would have made sense to have the regulator disabled then. Can you point me to these directions or are they in Calders boatowners book?

[hellosailor]

Probably Calder, probably the 12-volt doctor, and now there's a "12 volt doctor's alternator book" out as well. I remember one of them having pages and pages of alternator descriptions in it, since there are so many designs on the market. You may be able to find it by looking up the model # on the internet, and seeing if there are instructions for yours in particular.