OT: Charging system 24V.

[NovaNewfie]

Hello all.
I was hoping someone on here might have an idea for me. I've got a commercial fishing boat. Its got a 24volt 150 amp internal reg. Leece Neville Altenater on it. For years it would charge fine at 29volts from an idle to WOT. A couple of weeks ago it started acting up. At 1000rpm it would charge but as soon as you dropped back below that it would drop the voltage to 24v or below, which isn't enough to maintain the batteries. I thought the v.reg. was probly going bad so I tried a spare rebuilt alt. I had and it acted the same way. Bought a new reman alt and replaced both banks of batteries 4-8D 12v. All of the connections are brite clean and tight but I have still go the same problem. It won't charge off an idle and won't maintain the batteries in normal usage.
Any ideas or suggestions would be appreciated.

 

[Tramway Guy]

Check the ground path..?

 

[souNdguy]

That system should charge from 26.4 to 29.4v

is it an isolated ground setup?

is it internally regulated.. or externally regulated?

Does it use an external sense wire from the battery to judge SOC at the battery bank?

if internally regulated, is it expecting an excite wire on a switched line with somewhere between 15 and 45 ohms of resistance in the line?

we have some 24v systems on heavy equipment and i've had to work on a few of them.

post back.

soundguy

 

[NovaNewfie]

Its a Leece Neville 8SC3068V alt. Internally regulated. It has a pos. and a neg. post. It does have one wire that runs to the reg. on mine. A buddy has the same alt on his boat and doesn't have this wire. I tried mine both ways and neither made a difference. The alt. is grounded to the engine block and the batteries are grounded to the engine block in a different place.
I've only known these alt. to work or not to work. I've never had one that would charge over a certain rpm and not charge under it. I've noticed when the engine is running at an idle 650 rpm the volt guage shows 24 volts and if I kill the engine then turn the key back on it will show somewhat higher like 27-28.
The alt is supposed to charge at a shaft rpm of 1200. There is a 7 inch pulley on the engine and a 3 inch pulley on the alt so I'm sure with the engine turning 650 rpm the alt is turning over 1200.
I bought a new guage for it as well but wasn't sure weather to change it or not. As I changed the batteries and the alt. if I change to much I'll not know what the problem was. I put a multimeter on the alt and on the batteries and they are showing the same charge as the voltmeter in the dash.

 

[Dunk]

(quoted from post at 23:02:40 12/17/09) Its a Leece Neville 8SC3068V alt. Internally regulated. It has a pos. and a neg. post. It does have one wire that runs to the reg. on mine. A buddy has the same alt on his boat and doesn't have this wire. I tried mine both ways and neither made a difference. The alt. is grounded to the engine block and the batteries are grounded to the engine block in a different place.
I've only known these alt. to work or not to work. I've never had one that would charge over a certain rpm and not charge under it. I've noticed when the engine is running at an idle 650 rpm the volt guage shows 24 volts and if I kill the engine then turn the key back on it will show somewhat higher like 27-28.
The alt is supposed to charge at a shaft rpm of 1200. There is a 7 inch pulley on the engine and a 3 inch pulley on the alt so I'm sure with the engine turning 650 rpm the alt is turning over 1200.
I bought a new guage for it as well but wasn't sure weather to change it or not. As I changed the batteries and the alt. if I change to much I'll not know what the problem was. I put a multimeter on the alt and on the batteries and they are showing the same charge as the voltmeter in the dash.

I think I have a 12v one that does the same thing.

On my '88 Blazer.

It has about 500,000 miles on it.

At a red light, the radio will sit and reboot.

Start back off, and it is fine.

 

[souNdguy]

usually when an alt starts being unable to charge at low rpm, it's getting ready to die. Not specifically regulator.. but perhaps a slipring issue. you see gennies with worn brushes do the same thing.

soundguy

 

[NovaNewfie]

The problem is I've had three of them act the same way. I don't believe they are all ready to die.

 

[NovaNewfie]

The problem is I've had three of them act the same way. I don't believe they are all ready to die.

 

[TimPa]

(quoted from post at 05:27:58 12/18/09) The problem is I've had three of them act the same way. I don't believe they are all ready to die.

with the engine turning at a selected rpm, put the voltmeter directly on the output connectors of the alternator and read the voltage, and then on the battery and read the voltage. change engine rpm, repeat voltage readings. 1)if the voltage readings from alt to batt are different, then you have a problem between alternator output and battery - possibly cables/connections or other components(?) in the circuit. 2) if the voltages from alternator output at certain rpm's do not match what you expected, then alt is bad.

 

[souNdguy]

anyone else3 use this unit that may be doing something to the elec system?

soundguy

 

[JMOR]

(quoted from post at 08:27:54 12/17/09) Hello all.
I was hoping someone on here might have an idea for me. I've got a commercial fishing boat. Its got a 24volt 150 amp internal reg. Leece Neville Altenater on it. For years it would charge fine at 29volts from an idle to WOT. A couple of weeks ago it started acting up. At 1000rpm it would charge but as soon as you dropped back below that it would drop the voltage to 24v or below, which isn't enough to maintain the batteries. I thought the v.reg. was probly going bad so I tried a spare rebuilt alt. I had and it acted the same way. Bought a new reman alt and replaced both banks of batteries 4-8D 12v. All of the connections are brite clean and tight but I have still go the same problem. It won't charge off an idle and won't maintain the batteries in normal usage.
Any ideas or suggestions would be appreciated.

This sounds like a possible 'excite' problem to me and your statements regarding when it will & will not charge fit with that as well, Plus, your words, ". It does have one wire that runs to the reg. on mine. A buddy has the same alt on his boat and doesn't have this wire. I tried mine both ways and neither made a difference. ", lead me to believe that the disconnected wire is very likely the excite wire. Regardless of your buddy's experience in not needing this excite connection, I recommend that you verify that this excite wire receives voltage when "ign" is turned on & that it is properly connected. Do you have access to the other three connections between the regulator & the alternator (Grn, Blk, Orn) or are those not accessible? As a test, you might also want to temporarily jumper the B+ terminal to the D+ (R) terminal to see if that solves your problem. Don't leave the jumper connected with engine shut down or it may drain battery.