New Port Battery still requires crossover switch to start.

thenaz007

New Member
Jun 2, 2011
16
Ohio River - Louisville, KY
Boat Info
2001 340 Dancer
Engines
454 Mercruisers
My '01 340 requires the crossover switch to start the Port side even though it has a brand new battery on that side (?). I recently tested all the batteries resting voltage / parasitic draw, alternators, charger, connections, etc. and everything seemed to be fine. I do have a sticky solenoid on the left house bank - but it is not tripping, but sometimes needs to be actuated a few times before it works. Could this solenoid be working for a minimal house load but failing to provide starting current / voltage or the continuity from the ignition switch in the left house bank? Could my charger be faulty or failing on just one of the two banks? I am in a slip on shore power with weeks between visits. I really wasnt certain the old battery was that bad and put the new one in to be certain, I guess I should double check the new battery...
 
I recently tested all the batteries resting voltage / parasitic draw, alternators, charger, connections, etc. and everything seemed to be fine.
What was the voltage, especially the suspect battery?

Is there a dedicated on/off switch for that bank? If so, whats the voltage on the output/engine side with the switch on and cross-over switch off? What is the voltage as the input side of the switch? Should be the same as directly at the battery, at both spots.
 
Solenoids do fail in a way where they can audibly click, yet inside they are not making enough of a connection to pass enough "juice" (amps) for a high demand circuit. You can jump the solenoid to check this.
 
My '01 340 requires the crossover switch to start the Port side even though it has a brand new battery on that side (?). I recently tested all the batteries resting voltage / parasitic draw, alternators, charger, connections, etc. and everything seemed to be fine. I do have a sticky solenoid on the left house bank - but it is not tripping, but sometimes needs to be actuated a few times before it works. Could this solenoid be working for a minimal house load but failing to provide starting current / voltage or the continuity from the ignition switch in the left house bank? Could my charger be faulty or failing on just one of the two banks? I am in a slip on shore power with weeks between visits. I really wasnt certain the old battery was that bad and put the new one in to be certain, I guess I should double check the new battery...
You might want to check all the cells with a Hydrometer
 
You described testing everything in the charging system and finding it to be good. You also mention a sticky solenoid.
I’d replace the solenoid next. They’re pretty cheap.
 
You described testing everything in the charging system and finding it to be good. You also mention a sticky solenoid.
I’d replace the solenoid next. They’re pretty cheap.

What solenoid is “bypassed” when the emergency (parallel) switch is used? I think....none.

The starters and starter-mounted solenoids are fed directly from the battery switches aren’t they ?

My guess is a loose or corroded battery cable end at the suspect batteries or on their switch.
 
You need a voltmeter so you can measure voltage along that circuit while you attempt to start it up. That will show you where the poor connection is.

It looks like he may have already done that before he posted here.
 
It looks like he may have already done that before he posted here.

He needs to test starter supply voltages along the circuit while he’s attempting to crank the engine. A poor connection will show sufficient voltage when it’s not “loaded” but the voltage will dive when you attempt to push high current through it.
 
Voltage drop each thing in the circuit from the battery to the starter with a multimeter, while its cranking over. When the voltage spikes that the bad connection/part.
 
Solenoids do fail in a way where they can audibly click, yet inside they are not making enough of a connection to pass enough "juice" (amps) for a high demand circuit. You can jump the solenoid to check this.
You should try this ^^^^
Use a heavy screwdriver and bridge the two main large poles on the solenoid (yes it will spark so make appropriate precautions with no gas fumes etc). If the engine turns over strongly while bridged, you know your wiring and battery is fine, and it is the solenoid that has failed.
 
When the emergency bridging switch is activated, it supplies the voltage to the output side of the solenoid. Change the solenoid. If you would like to rule out the solenoid, switch the port and strbd and see if the problem moves to the other motor. And yes, you can get 12-14 volts to show at the output side of the solenoid - but it is the amperage that falling short due to poor conduction through the solenoid.
 
When the emergency bridging switch is activated, it supplies the voltage to the output side of the solenoid. Change the solenoid. If you would like to rule out the solenoid, switch the port and strbd and see if the problem moves to the other motor. And yes, you can get 12-14 volts to show at the output side of the solenoid - but it is the amperage that falling short due to poor conduction through the solenoid.

Are you sure the emergency bridge circuit supplies the output side of the starter solenoid? That would bypass the solenoid and the starter would turn immediately wouldn’t it?

Ohhh. I have now clued in that you are talking about the output side of the emergency bridge solenoid itself. I was talking about the starter solenoid.
 
Last edited:
You should try this ^^^^
Use a heavy screwdriver and bridge the two main large poles on the solenoid (yes it will spark so make appropriate precautions with no gas fumes etc). If the engine turns over strongly while bridged, you know your wiring and battery is fine, and it is the solenoid that has failed.

There you go!
Try the simple stuff first.
 
Are you sure the emergency bridge circuit supplies the output side of the starter solenoid? That would bypass the solenoid and the starter would turn immediately wouldn’t it?
The parallel switch simply combines both banks. Voltage remains the same, amperage is doubled.

What this means is, in a 12V setup, two parallel 12V batteries still stay as 12V, but their amperage is combined. Voltage does not increase.

Now obviously, if one battery is low on voltage and the other is fully charged, their voltage will equalize given enough time in parallel.
 
I discovered that the internal connections in my start switch were bad. If I used the parallel switch, I was just starting the port engine off the starboard battery bank. I swapped the starter switch connections, and the starting problem went to the starboard engine. New switch, problem solved.
 
Thanks everyone! I am on my 7th time ONLY cranking the Port with the Emergency crossover switch, this time the engine will immediately start and run. Once was a bad battery (now load test all batteries first thing). Once was slightly out of neutral, once was key or switch turned off in cabin, once was corroded battery terminals, once was bad engine ground and misc. wiring connections that looked great from the outside (replaced Slave solonoid cuz I was in there), and once was the relay solenoid for the Port bank and Engine (in the e-cabinet between the engines on the bulkhead where I cannot reach or fit). This time is either the dash ignition toggle switch (I will try to switch switches) or the solenoid relay switch needs to be replaced even though it seems to be working. When it failed previously the scrawny mechanic was able to duck down between the engines and actuate it 100 times until it seemed to work fine again. Note - I do not seem to be getting hardly any volts just barely getting power to my Port bank in my salon. The Port starter does not click when depressed, but starts normally with the Emergency switch. I have to think if my ignition switch was bad the engine would not continue to run. My question is does the e switch bypass the weak solenoid or overpower it? Also, is it possible I am not getting enough power into the Port bank (without the E switch) to tell the Slave Solenoid by the starter the ignitions are on? Really Appreciate the Help!! BTW replaced the charger.
 

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