Alternator load question
10-03-2023 | 07:07 AM
#12
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From: Cortlandt Manor NY
I'm no electrician but have always been told that an alternator only puts out what is called on...meaning if the batteries are calling for everything it can give then it's putting out in your case 170 amps/full load which makes it harder to turn to produce that power....when the batteries are charged and the only load is boat accessories be it lights, stereo, etc. it may only have to produce 30-40 amps to keep up with the load which is much easier to turn so it makes sense that a belt system designed to spin a 65 amp alternator is having trouble keeping up with the 170 amp load.....at least in my simple mind it makes sense hahahaha. If your batteries don't go dead you will probably never have another issue but I would keep an extra belt and jumper cables on the boat just in case...I have seen guys keep jumper cables on the boat to essentially "tie" the 2 batteries together in a straight shot to get rid of any voltage drop going through a switch or isolator or whatever until the dead battery gets some life back in it...might help distribute the load a little potentially instead of calling for all 170 amps like now cramming it into a dead battery? Again I'm no electrician hahahaha
The boat fired right up off the 2nd battery but like a knucklehead after it was running I switched to batt 1 tryin\g to put some juice back into it and that's when things went wrong. The battery is now fully charged so I'm going to put it back in the boat tonight with a brand new belt and go for a rip, if it doesn't smoke the belt then this theory is proved that the load on the alt indeed is what caused it to smoke the belts from trying to put out maximum output.
When I drive my boat 99% of the time it is day time so the only draw on the alt is the boat running which is ignition and some gauges, I don't even drive with the stereo on "big block with open pipes is my music"!!!!! At night if I'm out with lights on in not above idle as I refuse to drive on plane in the dark so this issue never showed up.
True test will be tonight, I had to do as I alway do and overkill things, the stock 65amp is more than enough but NO I HAD TO BUT A 170AMP in it and its costing me power LOL
10-04-2023 | 05:38 PM
#13
artselectricinc.com
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From: Longview, WA, USA
I have been rebuilding and selling batteries, starters, and alternators since I was a teenager. (I'm 60 now) One thing I have learned over the years is that installing super high output alternators
on anything, especially boats and motorhomes is a mistake. As said above it takes serious horsepower to turn one when your battery is low. When you are demanding full output, a single V-Belt is
not up to the task. If you need more amps than stock, I strongly suggest using Prestolite 110-602 90A alternator (OEM ONLY). It has plenty of overall power, made in the USA and makes over 60 amps at most idle speeds.
They're not cheap, but nothing in this business is.
on anything, especially boats and motorhomes is a mistake. As said above it takes serious horsepower to turn one when your battery is low. When you are demanding full output, a single V-Belt is
not up to the task. If you need more amps than stock, I strongly suggest using Prestolite 110-602 90A alternator (OEM ONLY). It has plenty of overall power, made in the USA and makes over 60 amps at most idle speeds.
They're not cheap, but nothing in this business is.
10-05-2023 | 07:21 AM
#14
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From: Cortlandt Manor NY
Well Tuesday I put a freshly charged battery and i brand new belt on the boat she ran perfectly! I had no idea an alternator can create that kind of load a full demand I thought it would generate more heat but not actual drive load to that extent. Learn something new each day.
10-06-2023 | 03:50 PM
#15
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From: East Tennesseee
Well Tuesday I put a freshly charged battery and i brand new belt on the boat she ran perfectly! I had no idea an alternator can create that kind of load a full demand I thought it would generate more heat but not actual drive load to that extent. Learn something new each day.
10-06-2023 | 04:28 PM
#16
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Another item you may or may not have considered is the wire that connects the alternator output to the battery (or most likely connects at starter to pos batt cable). That wire should be replaced with a lower gauge wire (larger diameter) since it can flow considerably more current with the larger alternator.
Also car/boat batteries don't like being charged at really high currents for sustained periods (i.e. charging a dead batt). It causes a lot of heat inside the batt which can shorten their life. Most shop-type fast-chargers I've seen max out at ~40A (not including the "Crank" option).
Glad to hear you're back on the water. As long as you don't seriously deplete a batt, you'll probably be OK as-is.
Also car/boat batteries don't like being charged at really high currents for sustained periods (i.e. charging a dead batt). It causes a lot of heat inside the batt which can shorten their life. Most shop-type fast-chargers I've seen max out at ~40A (not including the "Crank" option).
Glad to hear you're back on the water. As long as you don't seriously deplete a batt, you'll probably be OK as-is.
10-06-2023 | 07:02 PM
#17
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So here in New York this past week we got a mother load of rain and i kept checking on my boat and it seems to be fine. First sunny day was yesterday so I pulled her in off the whips to go out and I found one of the bilge pumps stayed on and killed battery #1. I fired it off on battery #2 then switched over to batt #1 so it could put some charge in it. Went to go for a ride and the second I came up on plane I saw the volt gauge drop and it smoked the V-belt.
I of course could not find the correct belt but I was able to get a new shorter on one it, I went for a ride again and did the exact same switch to batt #1 and it again smoked the belt. I have a brand new 140amp alt in the boat does it but put a huge load on the belt since it was trying to charge a dead battery? Boat was out all season with NO issue and now it burns up 2 belts?
I took the batt home and put it on a slow charge and im going back with a new correct belt but I wonder what changed to cause this? All I can think of is the alt becomes that hard to turn under load from the dead batt?
I of course could not find the correct belt but I was able to get a new shorter on one it, I went for a ride again and did the exact same switch to batt #1 and it again smoked the belt. I have a brand new 140amp alt in the boat does it but put a huge load on the belt since it was trying to charge a dead battery? Boat was out all season with NO issue and now it burns up 2 belts?
I took the batt home and put it on a slow charge and im going back with a new correct belt but I wonder what changed to cause this? All I can think of is the alt becomes that hard to turn under load from the dead batt?
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