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Voltage Regulators

C

captrob

Robert Cohen
<div>Have any of you that have the 3QM30 (33HP Yanmar) engine
converted the alternator to a 3 stage external voltage regulator?
If yes are you happy with the conversion? I have had some
"experts" claim that once you convert the alternator to external
regulation that the efficiency drops to only about 24 amps once
it heats up and therefore conversion is not really worth the
effort and experse. Experience? Opinions?Thanks,Vic
</div>
 
Victor,
The 'experts' might be right. A small, stock alternator is designed and built for long, slow, taper charging and definitely not for bulk charging via a 3-stage voltage regulator. A stock alternator can't get rid of heat fast enough and will burn up if run at or near full output for any appreciable length of time. It would be a good idea to contact the alternator manufacturer and ask them what the "hot rating" of your alternator is, and then set your 3-stage regulator to bulk charge at or below that number.
Good luck...
 
Victor: The standard alternater on the 3QM30 is a Hitachi 35 Amp unit which is small. However I used an Automac regulator on it as has a friend and they have been working for years. Limit output to 80%and all has remained OK. Any questions call. Happy Sailing
 
I have the 3QM30 but have a 105ah alternator with originally a 3step Cruising Equipemnt reg. That reg was put in a secondary mode because I installed a L2000R. Due to my planned cruise, it was highly suggested I have a back-up. don't know if this helps or answers anything, just throwing in my 2 cents.
 
<div>Just a follow on the VR question. I just finished installing a Link 1000 monitor and decided to check and see what the stock 3QM30's alternator was actually putting out. Would you believe about 11 amps just after startup tapeing off very quickly (within 5 min.) to 8 amp. and decreaseing with time. Now I know why I could not keep my batteries up.Do any of you know if this is typical for this alternator or is it just plane wore out? I guess the real question is it worth rebuilding?Thanks,Vic C.
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Why even keep it on the boat? Purchase a 105-130 amp alt.
and charge your batteries faster and more efficiently.
 
The amount of power an alternator puts out is somewhat dependant on the demand of the battery and the ability of your wiring to tranmit the power. If your engine starts up quickly, your battery may not have expended much power and not need much in the way of a charge. If you do change to a more powerful alternator, make sure the wiring leading from the alternator to the primary battery cable can carry the load. When transmitting 100 amps, you need awg wire #s 10 or 8 for any distance over a couple of feet. West Marine has tables available for determining wire size in their store and catalogs.
 
We put a 3-step external regulator on our 70 amp alternator. The Link 10 gives us good data on the batteries. A 2x6v (golf cart) bank with 210 ah capacity will accept chart from the alternator at almost 80 amps if the batteries are down below about 75%. The max ougput from the alternator lasts until the voltage comes up then it begins to taper off. I'm definetly sold on the 3-step.
Nick
 
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