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  #1  
Old 08-06-2014
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Voltage Drop Problem: battery, wiring or both

Setup: House bank of two 6 volt golf cart batteries wired in series. Few years old, good shape. Boat has very low amp needs. Starter battery: 7 year old Napa Grp24 dual purpose, used to start a 22 hp Vetus Diesel. Batteries separated by a Blue Sea Charging Relay and Switch. Wiring is 4 years old 1/0. Appears clean and tight.

Symptoms: Starter slow, or intermittently does not engage. This has been going on for the last two seasons. Bit worse this year.

Tests: Start battery at 12.6 or 12.8 volts between posts. When cranking, voltage drops to low 10's, possibly high 9s. Combining house and starter batteries using the Blue Sea switch does not help. Having fully charged batteries does not help.

Where is the problem?

1. Battery? Starter battery at 7 years old certainly is on its last breath. However, I've had it load tested and they tell me it is still fine. And, combing batteries does not help. I believe house batteries to be fine, though I've not checked them recently. Symptoms persists with all batteries fresh off the charger in the spring.

2. Wiring setup? I've got a 150A Blue Sea BusBar for the various ground wires. The ground from the starter connects to this Busbar, with a separate wire to the negative stud on the battery. Could I be loosing voltage though the busbar? Better to connect starter ground directly to battery?

3. Poor Connections? I did this wiring myself, using good quality 1/0 wiring, and an Anchor Lug Crimper and a vice, with heat shrink over the joint. Do I simply have a loose/bad connection?

I'm aware that there are more indicative tests to help find wiring issues specific to which circuit, but in my situation they require longer leads on the multi-meter, and three people, which I don't have at the moment.

I'm thinking there's a connection issue, but I'd love to hear from the experts on this.

Preserved.
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Old 08-06-2014
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Re: Voltage Drop Problem: battery, wiring or both

Where were the test points for battery voltage?

I will guess that you checked at the battery. It would be most revealing to test again at the starter solenoid (+ lug, and engine ground).
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Old 08-06-2014
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Re: Voltage Drop Problem: battery, wiring or both

Quote:
Originally Posted by preservedkillick View Post

Tests: Start battery at 12.6 or 12.8 volts between posts. When cranking, voltage drops to low 10's, possibly high 9s. Combining house and starter batteries using the Blue Sea switch does not help. Having fully charged batteries does not help.

[B]
Where did you measure that low 10s/9s at? If it was at the battery terminal you have a bad battery. If it was at the starter you have a wiring problem most likely a terminal. If it was at the starter solenoid you have a bad start switch, wiring problem, or a connection corroded.

If your start circuit takes power from the battery to the start switch and then to the solenoid any little corrosion in that circuit will cause a start problem.
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Re: Voltage Drop Problem: battery, wiring or both

The 10s/9s were measured at the battery posts while cranking. I get 12.6+ under no load, then low 10s while starter in cranking. The thing is, when I take the battery to Napa they load test it and tell me the battery is fine. And, wouldn't combining the batteries (house and start) help if it were the start battery?
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Old 08-06-2014
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Re: Voltage Drop Problem: battery, wiring or both

Common problem with wiring in older boats. Simplest solution is to install a relay. I finally bit the bullet and did that with my 26 year old boat. And I had new batteries! Get a relay from NAPA. Half hour job and the engine will start every time you push the button.
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Re: Voltage Drop Problem: battery, wiring or both

Quote:
Originally Posted by Vasco View Post
Common problem with wiring in older boats. Simplest solution is to install a relay. I finally bit the bullet and did that with my 26 year old boat. And I had new batteries! Get a relay from NAPA. Half hour job and the engine will start every time you push the button.
Rick,

I'm not sure I understand? Is this to address an engine control panel switch issue? In my boat, the engine control panel is about 12 to 15 years old, but all other wring is new?
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Re: Voltage Drop Problem: battery, wiring or both

I've had the same thing happen to me on my starboard diesel, where the ground and hot wire run about 12 feet to that engine. Find Your black wire engine ground. Remove it from the engine, and clean it with sandpaper or put on a new lug and then screw it back onto the engine. In my case I installed new wire lugs on both 12v and ground. The problem was solved and it didn't cost anything.
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Re: Voltage Drop Problem: battery, wiring or both

Quote:
Originally Posted by TropicCat View Post
Find Your black wire engine ground. Remove it from the engine, and clean it with sandpaper or put on a new lug and then screw it back onto the engine.
Thanks Tropicat. All wiring is shiny new clean. I don't think corrosion is an issue.
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Old 08-07-2014
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Re: Voltage Drop Problem: battery, wiring or both

Quote:
Originally Posted by preservedkillick View Post
Rick,

I'm not sure I understand? Is this to address an engine control panel switch issue? In my boat, the engine control panel is about 12 to 15 years old, but all other wring is new?
It's for the engine control panel wiring. Installing a relay between the panel wiring and the solenoid will boost the voltage and it'll start every time you push the button. Here's the instructions that I borrowed from another site. Cleaning all the contacts from the control panel might help but installing a relay really works well.

The relay part# I use:
Tyco
12V
V23234-A0001-X032

There are 5 pins on the relay:

87 - Jumper to starter male spade terminal
86 - Wire from Yanmar panel (used to go directly to starter)
30 - Positive jumper from large positive cable attached to starter.
85 - To Ground
87a - Not used


So, without this relay, you have 1 large nut on your starter, with a rather thick positive cable on it (this should come from your start battery). And, you should have 1 smaller cable, with a spade female disconnect on it that is connected to a spade post on the starter (this will come from the Yanmar engine panel at your helm station).

You need to remove this wire from the spade on the starter, connect it to position 86 on the relay. Then you make two short runs of cable, one going back to that spade male terminal on the starter from position 87, and another one from the big nut/positive cable on the starter to position 30 on the relay. Then a short ground wire to your engine ground from position 85 on the relay.
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Last edited by Vasco; 08-07-2014 at 11:49 AM.
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Re: Voltage Drop Problem: battery, wiring or both

If the starter motor brushes and commutator are not healthy that's what you can get. A little bilge oil and water ?? If starter wherrzz but doesn't engage look to the Bendix spring and or shaft it slids on (ford type)
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