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Old 25-07-2019, 09:13   #1
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Alternator questions

I looked at my alternator today and the wires that output the charge are too small. I can tell by the melted plug in the photo. I am pretty sure this is a Iskra alternator and puts out 65 amps (that is the standard on a Beta Marine 30hp). I would like to connect to the stud marked B+. I ran an Ohm meter between the 6mm stud and the two spade connectors. There was continuity. Am I correct? I am thinking of connecting the alternator output to the house battery with a 12mm wire for a
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Old 25-07-2019, 09:23   #2
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Alternator questions

I m not familiar with that alternator at all, but the stud marked b+ is I believe the normal place to connect to the battery for other alternators
When I went from an 80 amp alternator to a 165 my wiring was undersized too, so I connected to the big wire from the battery bank that connects to the starter.
Iím not sure why thatís not done from the factory, must be a reason, but I donít know what it is.

Your problem may have been dirty or loose contacts too, you would think the factory would have sized correctly?
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Old 25-07-2019, 09:30   #3
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Re: Alternator questions

[QUOTE=a64pilot;2938729]
When I went from an 80 amp alternator to a 165 my wiring was undersized too, so I connected to the big wire from the battery bank that connects to the starter.
Iím not sure why thatís not done from the factory, must be a reason, but I donít know what it is.

/QUOTE]

They do this cause its cheaper, the proper way would be to have a large cable from start battery to starter, a separate large wire from alternator to house bank and an ACR to connect the house and the start batteries.
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Old 25-07-2019, 13:45   #4
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Re: Alternator questions

Quote:
Originally Posted by a64pilot View Post
I m not familiar with that alternator at all, but the stud marked b+ is I believe the normal place to connect to the battery for other alternators
When I went from an 80 amp alternator to a 165 my wiring was undersized too, so I connected to the big wire from the battery bank that connects to the starter.
Iím not sure why thatís not done from the factory, must be a reason, but I donít know what it is.

Your problem may have been dirty or loose contacts too, you would think the factory would have sized correctly?
Wire was definitely undersized. Two number 10 wires. I am going to upgrade to a 12mm wire tomorrow.
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Old 25-07-2019, 14:24   #5
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Re: Alternator questions

Are you guys saying the main power lead is in that plastic spade connector block? That is totally goofy. It should go to a stud on the back somewhere. Spade connectors don't handle loads like that. Shoot that connection with a heat gun sometime, you'll see.
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Old 25-07-2019, 15:26   #6
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Alternator questions

[QUOTE=Thank you dad;2938735]
Quote:
Originally Posted by a64pilot View Post
When I went from an 80 amp alternator to a 165 my wiring was undersized too, so I connected to the big wire from the battery bank that connects to the starter.
Iím not sure why thatís not done from the factory, must be a reason, but I donít know what it is.

/QUOTE]

They do this cause its cheaper, the proper way would be to have a large cable from start battery to starter, a separate large wire from alternator to house bank and an ACR to connect the house and the start batteries.

Iím saying that I donít understand why not a heavy gauge wire from the alternator to the starter, thatís a short run, seems to be the cheap way out too. The wire that runs the starter is real heavy gauge.

I can only theorize that the original wire was run to the battery 1,2,all switch to charge all banks? The way I did it only charges the bank the starter is connected to, but I leave my switch to all, so they both get charged.
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Old 25-07-2019, 16:18   #7
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Re: Alternator questions

Quote:
Originally Posted by Charlie View Post
I looked at my alternator today and the wires that output the charge are too small. I can tell by the melted plug in the photo. I am pretty sure this is a Iskra alternator and puts out 65 amps (that is the standard on a Beta Marine 30hp). I would like to connect to the stud marked B+. I ran an Ohm meter between the 6mm stud and the two spade connectors. There was continuity. Am I correct? I am thinking of connecting the alternator output to the house battery with a 12mm wire for a
I believe you are correct and I would do the same.

I would also do the same for B- wire - mainly because a ring terminal is more secure than a spade terminal.
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Old 25-07-2019, 16:26   #8
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Re: Alternator questions

[QUOTE=a64pilot;2939028]
Quote:
Originally Posted by Thank you dad View Post


Iím saying that I donít understand why not a heavy gauge wire from the alternator to the starter, thatís a short run, seems to be the cheap way out too. The wire that runs the starter is real heavy gauge.

I can only theorize that the original wire was run to the battery 1,2,all switch to charge all banks? The way I did it only charges the bank the starter is connected to, but I leave my switch to all, so they both get charged.
Actually that is the way most of them are hooked up at the factory. Cheaper and easier to install. But it forces you to manipulate the 1-2-Both switch to charge the starter and house banks. If not done correctly that can lead to a flat start battery or damaged alternator if you pass through Off on the way to 1 or 2 or Both. The "better" way is with a large cable from alt output direct to the house bank without going through the switch, and an ACR or battery combiner to charge the start battery. With that setup you never touch the 1-2-Both switch unless the start battery somehow fails. It's a long run so you need really big cable.
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Old 25-07-2019, 17:55   #9
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Re: Alternator questions

I even have a blue seas ACR in Spareís, just as I never put the switch to anything but both and donít have a separate start battery, Iíve never bothered.
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Old 25-07-2019, 18:16   #10
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Re: Alternator questions

To the question of why was it done this way, here is my opinion (and not supported by documentary evidence )

The Iskra alternator is simply a massed produced unit sold to dozens and dozens of OEMs. They provide two different styles of terminals (spade and stud) for B+ and B- for the output wiring and they leave to the OEM to choose what method to use.

The spade terminals are fine for light duty and intermittent heavy duty use, say the recharging of the start battery and smaller house banks.

Beta supply engines for a variety of marine uses and have chosen the cheapest / quickest method. Again it is suitable for recharging start batteries and smaller house banks.

Perhaps Beta think if the boat OEM (or end user) is planning to draw heavy continuous loads, they are smart enough to rewire to the stud terminals, change wiring sizes and have smart regulators and so on and so forth.

The concept of wiring the alternator output with 10 AWG direct to the large battery wire on the starter motor is common place on smaller diesels although using spade terminals is not so much (AFAIK).

I do think the OP is on the right track by rewiring to the stud terminal(s) with larger wire for the B+ (assuming the negative is via the engine chassis).
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Old 25-07-2019, 18:37   #11
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Re: Alternator questions

The b- had me wondering if it had an isolated ground.
That would be unusual Iíd think but would make fitting an alternator shunt if you desired one easier.
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Old 25-07-2019, 18:42   #12
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Re: Alternator questions

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The b- had me wondering if it had an isolated ground.
That would be unusual I’d think but would make fitting an alternator shunt if you desired one easier.
Quite possible, the B- stud sort of looks insulated from the alternator frame but is hard to tell from the photo; perhaps the OP can confirm?

If so, then wiring size to the B- becomes a consideration for the OP to think about.
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Old 25-07-2019, 20:58   #13
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Re: Alternator questions

I have never seen an alt with a spade battery wire. no idea what is going on there. normally the spades are voltage sense, ignition, lamp, tach, feild etc. the B+ is always a post.

I would never put more then 20a through a spade.
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Old 25-07-2019, 21:42   #14
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Re: Alternator questions

Quote:
Originally Posted by Wotname View Post
To the question of why was it done this way, here is my opinion (and not supported by documentary evidence )

The Iskra alternator is simply a massed produced unit sold to dozens and dozens of OEMs. They provide two different styles of terminals (spade and stud) for B+ and B- for the output wiring and they leave to the OEM to choose what method to use.

The spade terminals are fine for light duty and intermittent heavy duty use, say the recharging of the start battery and smaller house banks.

Beta supply engines for a variety of marine uses and have chosen the cheapest / quickest method. Again it is suitable for recharging start batteries and smaller house banks.

Perhaps Beta think if the boat OEM (or end user) is planning to draw heavy continuous loads, they are smart enough to rewire to the stud terminals, change wiring sizes and have smart regulators and so on and so forth.

The concept of wiring the alternator output with 10 AWG direct to the large battery wire on the starter motor is common place on smaller diesels although using spade terminals is not so much (AFAIK).

I do think the OP is on the right track by rewiring to the stud terminal(s) with larger wire for the B+ (assuming the negative is via the engine chassis).
The Iskra is what comes to Beta on the Kubota engines. It is not intended to charge a house bank. It is intended to put the power back into the battery that started the engine and maybe power a few lights. Remember that the Kubota started as a small tractor engine before it was marinized.

Beta has a second alternator bracket available. I had one fitted when I bought my 50HP BV2203. That is the most practical way to charge a house battery. Don't think of the Iskra is anything more than a very light duty alternator. Any attempt to drive it at 65 amp output for more than a few minutes will burn it up.
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Old 25-07-2019, 23:26   #15
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Re: Alternator questions

Thanks stormalong, pretty much supports my opinion - AKA WAG.
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