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Old 12-31-2013, 07:26 AM   #1
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Auto V regulators BRAIN

Many folks have a stock auto or truck style alt on their propulsion engine.

They are cheap so and work very well for a car , but are a problem in a cruiser IF used for house battery charging.

The auto brain expects to have to replace 1% or 2% of the start batts charge , used in starting and to simply keep the voltage up during operation for lights , wipers and HVAC blowers.

AS a charger it will attempt to provide 1/2 of what the batt needs to reach full charge every hour..

So your 120A house batt is 60A low , the V regulator will provide 30A of charge plus about 4-8A more to push it in.

The second hour you are 30A shy , so 15A plus a few more will be provided, the third hour 15A shy and so on.

With a large bank of 4 or 8 batts you can see the car profile will work OK till the tapering starts , IF it doesnt burn out charging the big bank from overheating.
This seldom happens as the HOT rating of most auto alts is not at all high , why folks see 50A from an 80A alt .

If more rapid house batt charging is needed a switch to a smarter V reg is in order.

IF FAST charging is wanted a larger alt with a robust HOT rating will need to be installed , along with usually dual belts.

Unless folks have big buck fast absorbing batts instead of std Lead Acid , the charge can only be so fast , and for most a 135A truck alt with 3 stage regulator is the modest buck solution .

Folks that anchor out a great deal may be better served with the BIG alt belted on the noisemaker , as that would be the most likely engine operating.
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Old 01-20-2014, 10:35 PM   #2
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charging

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Originally Posted by FF View Post
Many folks have a stock auto or truck style alt on their propulsion engine.

They are cheap so and work very well for a car , but are a problem in a cruiser IF used for house battery charging.

The auto brain expects to have to replace 1% or 2% of the start batts charge , used in starting and to simply keep the voltage up during operation for lights , wipers and HVAC blowers.

AS a charger it will attempt to provide 1/2 of what the batt needs to reach full charge every hour..

So your 120A house batt is 60A low , the V regulator will provide 30A of charge plus about 4-8A more to push it in.

The second hour you are 30A shy , so 15A plus a few more will be provided, the third hour 15A shy and so on.

With a large bank of 4 or 8 batts you can see the car profile will work OK till the tapering starts , IF it doesnt burn out charging the big bank from overheating.
This seldom happens as the HOT rating of most auto alts is not at all high , why folks see 50A from an 80A alt .

If more rapid house batt charging is needed a switch to a smarter V reg is in order.

IF FAST charging is wanted a larger alt with a robust HOT rating will need to be installed , along with usually dual belts.

Unless folks have big buck fast absorbing batts instead of std Lead Acid , the charge can only be so fast , and for most a 135A truck alt with 3 stage regulator is the modest buck solution .

Folks that anchor out a great deal may be better served with the BIG alt belted on the noisemaker , as that would be the most likely engine operating.
Could a non marine regulator cause the alt to charge as high as 16.5
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Old 01-21-2014, 06:03 AM   #3
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Few gensets found on recreational trawlers will tolerate the mounting of a 135A+ alternator on them. They are supplied with more like a 20A alt suited to topping off the genset Start battery: a genset's 20-35hp won't support much more than that. In twin engine configurations, two good-sized alts both feeding the House bank is the way to go (with the Start battery echo-charged) to achieve fast re-charge. On a single screw, two alts can be mounted again with both charging the House bank
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Old 01-21-2014, 09:33 AM   #4
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>Could a non marine regulator cause the alt to charge as high as 16.5<

Most will stop in the mid 14V area.

>Few gensets found on recreational trawlers will tolerate the mounting of a 135A+ alternator on them.<

The problem is not the power available from the noisemaker , its usually a case of only a single belt , a poor alt mount , or the difficulty fitting into the hush box.

This hassle is easily solved when specifying a replacement noisemaker , just ask.

Some converted yard equipment engines do not have a large enough front bearing to take the load of twin belts and a good sized alt.

Simply ask the mfg for 2 alt mounts on either side , and use 1 smaller alts .
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Old 01-23-2014, 10:53 PM   #5
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recently replaced my starboard engine and am happy to be up and running but after the initial turn of the key on the new engine all the ground wires to all lower helm gauges heated up so much it melted the casing on the wires.I replaced the solid state regulator with an automotive style plus tested the alternator and reinstalled all. No more shorts but both the starting battery's that are charged via the starboard engine and the house bank battery's charged via the port engine show around 13.5 idle but up as high as 16 on the dash gauge. My multi meter shows about 14.9 at the battery's. The battery's have been on charge via a/c chargers so the question is should I be concerned or head out. My starting battery's are deep cycle Trojan 6 years old and the house battery bank is 8 6volts no idea how old but the all tested ok I get spooked when I see the dash gauge bouncing of 16v. Im thinking maybe the batterys are old so demand constant charge Any help would be great
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