Import Manager
05-01-2004, 06:40 AM
#0, Low Voltage at Starter Motor on Excalibur
Posted by Capt Art on Dec-09-03 at 10:13 AM
I am measuring only 9 volts on my 23 ft 1982 albacore special with its aqad40 40 diesel. I am planning on cleaning/replacing the cable ends, but I am wondering if the main switch for the engine power has too much reisitance. The cables themselves look like they are foa from the battery box in the cabin and cannot be replaced. Any of you 23 owners had any experince with replacing/servicing cables?
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#1, RE: Low Voltage at Starter Motor on Excalibur
Posted by NoSlack on Dec-09-03 at 05:58 PM
In response to message #0
Art, I did some test today on my cables and the voltage drop when starting the engine, and here is what I found.
Battery cable resistance test: Disconnect the battery cables(+ and -) from the batteries and then from the starter. Bolt the cables together at one end and check the resistance between the two wires at the other end. I used a simple volt/ohm meter to take my readings and checked them against readings I took with a fancy test meter from work. I game up with 0 ohms both times. In theory there would be no voltage drop from the batteries to the starter with 0 ohms of resistance in the cables.
The problem with this test is, the meters are only using very low voltage for the test and won't tell you if your wires are large enough to carry the current needed to start the engine.
Now for the voltage drop test.
My batteries are 4-5 years old with a current hydrometer readings between 1.240 and 1.260. Not great batteries, but they still start the engine. Cables and started are original 1981 vintage. I've always suspected the starter of being week and drawing to much current to get the job done. Some days it turns over slow and the next time you hit the key it turn over like I think it should.
With that being said here is what I found. I used 2 volt meters for test 1. One on the batteries and one on the started. Before turning the key I had 12.4 volts at the batteries. With the engine cranking the batteries dropped to 10.2 volts(old batteries?) and the voltage at the starter was down to 7.8 volts. I was shocked at how low the voltage was at the starter.
For test # 2 I measured the voltage drop on each cable. I made up some long test leads so my meter leads would reach from the battery box to the starter. I hooked one meter on the + at the battery and the + on the starter, the other meter I put on the - at the battery and the - on the starter. Crank the engine and the meters will show you the voltage drop on each cable. My negative cable is short (12') and showed a .8 volt drop while cranking. The + cable could be twice as long, runs through the disconnect switch and showed a 1.7 volt drop while cranking. One thing I should have checked was the voltage drop across the switch but I didn't think of it until after dark.
Looking at my numbers, there are a few things I should look into to improve my voltage to the starter. New batteries, larger battery cables and a new starter. At $500 a shot for starters, I'll probably live with the one I have for a while longer.
Mike
If I lost you along the way, let me know and I'll add some pictures if that would help.
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#2, RE: Low Voltage at Starter Motor on Excalibur
Posted by moo fish on Dec-10-03 at 06:02 AM
In response to message #1
Have you checked the ground on the engine block?? I hve been tracing cables, connections, etc. and found the ground on the engine block suspect. Cleaned it up as part of the maintenance routine.....rt on the Moo Fish
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#3, RE: Low Voltage at Starter Motor on Excalibur
Posted by NoSlack on Dec-10-03 at 07:12 PM
In response to message #0
LAST EDITED ON Dec-10-03 AT 07:32 PM (PST)
Art
Did another test tonight. I brought home a heavy duty battery charger (60 amp) from work and cranked the engine over with it connected to the batteries. Even with the extra boost from the charge, I was only measuring 8 volts at the starter. The engine did turn over a lot faster today with the extra boost.
When I get a chance I'll take a voltage reading on my Ford diesel's starter to see if 8-10 volts at the starter in nornal for a diesel engine.
Edit: 1985 F250 6.9 diesel had 12.5 volts on the batteries. Hit the key and the voltage dropped to 9 volts at the starter and she fired up in 2 seconds with no pre-warming from the glow plugs. I think 8-10 volts at the starter during cranking is not out of the normal.
Mike
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#4, RE: Low Voltage at Starter Motor on Excalibur
Posted by Capt Art on Dec-10-03 at 08:38 PM
In response to message #3
Mike,
Thanks for the information, I really appreaciate your help. I assume you have a 23 with the same diesel as mine. I am using 2 new group 24 Interstate deep cycle batteries which are ment to be used as starting batteries also. I need to measure the voltage on my batteries during cranking, I noticed you measured a 2.4 volt drop at the batteries due to the internal resistance of the batteries. I figure the starter should draw 200 to 250 amps and I am wondering if the Interstate starting batteries might have been a better choice. My batteries are on the port side and the cables disappear through a foam filled hole in the cabin bulkhead. I am not sure I could replace the cables since they are foamed in. Does the ground cable go straight back to the engine compartment? The positive cable goes to the breaker panel with the egine main switch and then I guess it goes down the starboard pvc tube to the engine box. Is this the way your boat is set up? The battery cables are 2/0 guage which are adequate for the 30 to 40 ft total run. Again, thanks for help.
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#5, RE: Low Voltage at Starter Motor on Excalibur
Posted by NoSlack on Dec-10-03 at 09:36 PM
In response to message #4
Sound like are boat are set up the same way on with battery cables. My rig is a 1981 23' Flybridge. It dosen't look easy to replace the negative cable or the positive that runs up to the switch. next time I do boat maintanence I'll give them a good tug to see how well foamed in they are. If I get lucky they will only be foamed in at the bulkhead aft of the battery box.
As far as battery choice I would get away from the dual purpose batteries for the engine and pick up a pair of starting batteries. I have seen group 24 batteries with ratings as high as 1000 CCA(cold cranking amps)per battery. For the house battery I would stick with a deep cycle battery.
Mike
Posted by Capt Art on Dec-09-03 at 10:13 AM
I am measuring only 9 volts on my 23 ft 1982 albacore special with its aqad40 40 diesel. I am planning on cleaning/replacing the cable ends, but I am wondering if the main switch for the engine power has too much reisitance. The cables themselves look like they are foa from the battery box in the cabin and cannot be replaced. Any of you 23 owners had any experince with replacing/servicing cables?
--------------------------------------------------------------------------------
#1, RE: Low Voltage at Starter Motor on Excalibur
Posted by NoSlack on Dec-09-03 at 05:58 PM
In response to message #0
Art, I did some test today on my cables and the voltage drop when starting the engine, and here is what I found.
Battery cable resistance test: Disconnect the battery cables(+ and -) from the batteries and then from the starter. Bolt the cables together at one end and check the resistance between the two wires at the other end. I used a simple volt/ohm meter to take my readings and checked them against readings I took with a fancy test meter from work. I game up with 0 ohms both times. In theory there would be no voltage drop from the batteries to the starter with 0 ohms of resistance in the cables.
The problem with this test is, the meters are only using very low voltage for the test and won't tell you if your wires are large enough to carry the current needed to start the engine.
Now for the voltage drop test.
My batteries are 4-5 years old with a current hydrometer readings between 1.240 and 1.260. Not great batteries, but they still start the engine. Cables and started are original 1981 vintage. I've always suspected the starter of being week and drawing to much current to get the job done. Some days it turns over slow and the next time you hit the key it turn over like I think it should.
With that being said here is what I found. I used 2 volt meters for test 1. One on the batteries and one on the started. Before turning the key I had 12.4 volts at the batteries. With the engine cranking the batteries dropped to 10.2 volts(old batteries?) and the voltage at the starter was down to 7.8 volts. I was shocked at how low the voltage was at the starter.
For test # 2 I measured the voltage drop on each cable. I made up some long test leads so my meter leads would reach from the battery box to the starter. I hooked one meter on the + at the battery and the + on the starter, the other meter I put on the - at the battery and the - on the starter. Crank the engine and the meters will show you the voltage drop on each cable. My negative cable is short (12') and showed a .8 volt drop while cranking. The + cable could be twice as long, runs through the disconnect switch and showed a 1.7 volt drop while cranking. One thing I should have checked was the voltage drop across the switch but I didn't think of it until after dark.
Looking at my numbers, there are a few things I should look into to improve my voltage to the starter. New batteries, larger battery cables and a new starter. At $500 a shot for starters, I'll probably live with the one I have for a while longer.
Mike
If I lost you along the way, let me know and I'll add some pictures if that would help.
--------------------------------------------------------------------------------
#2, RE: Low Voltage at Starter Motor on Excalibur
Posted by moo fish on Dec-10-03 at 06:02 AM
In response to message #1
Have you checked the ground on the engine block?? I hve been tracing cables, connections, etc. and found the ground on the engine block suspect. Cleaned it up as part of the maintenance routine.....rt on the Moo Fish
--------------------------------------------------------------------------------
#3, RE: Low Voltage at Starter Motor on Excalibur
Posted by NoSlack on Dec-10-03 at 07:12 PM
In response to message #0
LAST EDITED ON Dec-10-03 AT 07:32 PM (PST)
Art
Did another test tonight. I brought home a heavy duty battery charger (60 amp) from work and cranked the engine over with it connected to the batteries. Even with the extra boost from the charge, I was only measuring 8 volts at the starter. The engine did turn over a lot faster today with the extra boost.
When I get a chance I'll take a voltage reading on my Ford diesel's starter to see if 8-10 volts at the starter in nornal for a diesel engine.
Edit: 1985 F250 6.9 diesel had 12.5 volts on the batteries. Hit the key and the voltage dropped to 9 volts at the starter and she fired up in 2 seconds with no pre-warming from the glow plugs. I think 8-10 volts at the starter during cranking is not out of the normal.
Mike
--------------------------------------------------------------------------------
#4, RE: Low Voltage at Starter Motor on Excalibur
Posted by Capt Art on Dec-10-03 at 08:38 PM
In response to message #3
Mike,
Thanks for the information, I really appreaciate your help. I assume you have a 23 with the same diesel as mine. I am using 2 new group 24 Interstate deep cycle batteries which are ment to be used as starting batteries also. I need to measure the voltage on my batteries during cranking, I noticed you measured a 2.4 volt drop at the batteries due to the internal resistance of the batteries. I figure the starter should draw 200 to 250 amps and I am wondering if the Interstate starting batteries might have been a better choice. My batteries are on the port side and the cables disappear through a foam filled hole in the cabin bulkhead. I am not sure I could replace the cables since they are foamed in. Does the ground cable go straight back to the engine compartment? The positive cable goes to the breaker panel with the egine main switch and then I guess it goes down the starboard pvc tube to the engine box. Is this the way your boat is set up? The battery cables are 2/0 guage which are adequate for the 30 to 40 ft total run. Again, thanks for help.
--------------------------------------------------------------------------------
#5, RE: Low Voltage at Starter Motor on Excalibur
Posted by NoSlack on Dec-10-03 at 09:36 PM
In response to message #4
Sound like are boat are set up the same way on with battery cables. My rig is a 1981 23' Flybridge. It dosen't look easy to replace the negative cable or the positive that runs up to the switch. next time I do boat maintanence I'll give them a good tug to see how well foamed in they are. If I get lucky they will only be foamed in at the bulkhead aft of the battery box.
As far as battery choice I would get away from the dual purpose batteries for the engine and pick up a pair of starting batteries. I have seen group 24 batteries with ratings as high as 1000 CCA(cold cranking amps)per battery. For the house battery I would stick with a deep cycle battery.
Mike