Engine starting with dead house battery on R25 Classic

[captstu]

Hi, Both my house batteries failed - they were several years old so it was time.

Prior to removing and swapping for new batteries, I tried to start the main engine - nothing but a very hard to hear click. Throwing the switch to "emergency start" had no effect since the remaining battery didn't bring the house battery up to a level sufficient to engage the solenoid.

It appears both the HOUSE and START batteries must have power to start the engine.

It seems the start switch draws power from the HOUSE bank to engage the solenoid. This is clearly an error. My start battery was charged above 12 Volts and easily had sufficient power to start the engine once the HOUSE recovered enough to power the start switch.

Has anyone fixed this? /Stu

 

[joempo]

Stu,
Unless someone changed the wiring on your R-25, the engine start battery is separate from the house batteries unless you engage the lower "crossover" switch at the entrance to the cave. Normally, when one turns on the engine battery there is no connection to the house batteries, which have their own switch. The house batteries should have no bearing on starting the engine. The engine battery has only one function - starting the engine. Similarly, the thruster battery has only two functions - thruster and windless operation.
If you heard a "faint click" when engaging the starter with only the engine battery turned on, go back and check your battery connections. If you have not done so, swap out the braided ground strap for a more substantial (2/0) ground cable.
Just a couple of comments based upon what you posted and my own experiences. I hope this helps.
Joe

 

[Favunclerich]

I had the same problem with my 2008 R-25. It was mis-wired and the engine was starting using the house battery. After a night on the hook, using the half-drained house batteries to start the engine pulled the voltage down to unacceptably low levels. This resulted in shortened life for the house batteries. A pair of AGM's only lasted 1.5 years. It took a while and required removing insulation to chase the wires and figure this out. Once I understood the root cause, it was easy to connect the engine to the engine battery by way of the appropriate switch. Things have been fine ever since.

 

[captstu]

Joe and Favon, I think we are having trouble communication. Engine starting takes 3 separate circuits - and all must be connected to the START battery via a dedicated switch to function.

The three circuits are:
1. The high current circuit dedicated to the cranking motor and glow plugs. On my R25, this is correctly connected via a solenoid and switch to the dedicated START battery.
2. A low current dedicated to the Yanmar instruments, the engine controls that operate such things as the glow plugs, and draws its power from the switch output of the key.
3. The low current supply to the key. It is this circuit that should be on the engine start circuit (1) rather than the house circuit.

The thick, heavy cables are wired correctly. The relatively small wire that feeds power to the key must be moved from the house to the engine START battery to operate as the boat was, I presume, designed.

I'm hoping to get an owners manual for the R25 soon. In the meantime, with two new House batteries, I don't expect any problem.

BTW, I doubt that engine cranking materially shortened the life of the AGM batterees. Two group 27 AGMs should have a cold cranking power in the range of 1200 to 1500 Amps and our tiny little 150 engines don't draw nearly that amount. If they died in only 1.5 years, they ran out of water - even though AGMs are sealed, they use water just like regular flooded batteries - they are just packed with extra. Each time you cycle them, they drink more water - if you cycle them a lot or over charge them a little, water them every 6 months or so.

/Stu

 

[walldog]

I'm hoping to get an owners manual for the R25 soon. In the meantime, with two new House batteries, I don't expect any problem.

BTW, I doubt that engine cranking materially shortened the life of the AGM batterees. Two group 27 AGMs should have a cold cranking power in the range of 1200 to 1500 Amps and our tiny little 150 engines don't draw nearly that amount. If they died in only 1.5 years, they ran out of water - even though AGMs are sealed, they use water just like regular flooded batteries - they are just packed with extra. Each time you cycle them, they drink more water - if you cycle them a lot or over charge them a little, water them every 6 months or so.

/Stu

quote="Bruce Moore"]R-25 Owners Manual - Posted Dec 2008[/quote]

I do not believe that I will be adding water to my AGM batteries.
http://www.tirebusiness.com/article/201 ... -batteries

Third, never try to add water to any AGM battery. Not only will this maneuver not rejuvenate an AGM battery, it will ruin the unit by exposing its innards to unwanted outside oxygen.

Chemically, outside air poisons the contents of an AGM battery. If you discover that someone else has forced open an AGM battery, replace that battery. Period.

 

[Andrew Custis]

Hello Stu,

One thing to note is on some of the diesel engines, the starter and alternator are connected by a jumper installed from the engine manufacturer. We started disconnecting the jumper wire leading from the starter to the alternator and running the starter to the engine start battery and the alternator leading to the house battery but this all depends on which engine you have installed because they are all setup just a little different. I know you purchased the vessel used from a third party so you may want to check with the original owner to see if anything was changed. There are many times that I get on a boat and it is not setup the way the factory originally set it up.

Take care,

Andrew Custis

 

[captstu]

Andrew,

Thank you for your note. I understand the need to disconnect the start/alternator connection to provide for the isolation of the three banks and ensure the starter bank doesn't discharge through the isolation device in an attempt to keep the house bank charged.

I don't think, however, this is related to my boat's problem.

The previous owner provided a wiring diagram for the R25 that has the look of a factory diagram (thank you). It clearly shows the switch being fed from the engine harness, as it should.

Somewhere in the boat's history, the switch must have been moved to the house bank, either in error or with some purpose I can't imagine in mind.

No big deal, it should be easy to find the changed wire and move it to the engine bank as shown in the wiring diagram -- and common sense.

Clearly, the desire is to have the engine crank normally even when the house bank is low - that is how it is diagramed and I'm sure is how it was originally wired.

Thanks again - a lovely boat gets better with excellent factory support - even for an owner down the road. 🙂

/Stu