Battery Problem

[Gypsy]

I just spent last night on hook. This morning, the starting battery was dead. I was able to use the crossover switch to provide power to start the engine. I don't know why the battery went dead. Here is some background info. Soon after we left the dock we encountered a bad thunder storm that went on for a few hours. When we got to our destination, we had difficulty holding bottom so had to use the windless a lot. Then, to monitor our holding, I kept the chart plotter on until well after the storm subsided. In the morning, I used the inverter to make coffee, then started the generator to cook breakfast. When we got ready to leave, the starting battery was dead. I didn't notice the voltage reading on the engine display, but just checked it and it reads 13.8 volts. On the electrical panel there is a small toggle switch that shows the condition of three batteries, I have four, but from what I can tell, none of them are for starting the engine. My boat is a C28 with 148 hours on it. The AGM batteries should all be good. Something I did ran the battery down - I Just don't know what, and I don't want to do it again.
Any ideas will be appreciated.

 

[BradOwens]

I can't help you with why the start battery died, but I may be able to help with the battery meter. The top toggle position should be for your two house batteries, center for the start battery, and bottom for the thruster battery.
I usually turn my start and thruster battery switches off while on the hook and have never had one die.
Also, I never use windlass with the engine off. I'm not sure which battery yours draws from.

 

[Gypsy]

Brad,
Thanks for the info on the switches.

 

[Shibumi]

I had similar problem. Had to do with the way the engine battery was installed—it just always bled current at a low rate. If house was fine I’d look at that. And (it’s a thing with me) if you overdischarge a battery you gotta replace it. At least for lead acid. Not sure how f AGM MIGHT withstand that.

 

[BB marine]

Reason for engine start battery would be a mystery to me if the batteries are in a factory install configuration.
Open this link and look at Page 39
download/file.php?id=260

You will see that all the equipment that you used while on the hook was powered by the house bank. The engine battery would not be used for power to any functions that you used. With one exception the Generator start circuit. If the generator started without issue it would have used the same battery as the engine start. The generator would also charge the engine battery while the generator was running. Did you have the battery charger circuit on while running the generator? If you are on the hook and operating the generator this is a good time to help maintain the batteries. Turn the charger on when you are cooking.

The toggle switch for the analog battery meter on the electrical panel has 3 battery circuits connected to it. Engine (1) battery,Thruster (1) battery and house (2) batteries (factory install) If you open the manual link above and go to page 32 you will see the wiring schematic for the battery volt meter and page 15 shows which toggle position is for each battery bank.


None of this answered your question. Why did the engine battery not start the engine? My first thought is a weak or failing battery or marginally sized battery for the application, (it did start the generator so it had enough reserve to do that it wasn't dead) next poor battery connection loose or corroded.Or you may have a poor connection at the starter itself that is increasing resistance and demanding more amperage to crank the engine over. The last thought is the starter motor may have an issue requiring more battery. You said it would start with the cross over switch on this is combining both engine and house bank together. I'm surprised the house bank had enough battery capacity to had assistance after all the AH used during the anchor time.

My first check would be the condition of the engine battery and its CCA capacity. Clean the connections and load test the battery. If the battery checks out to be in good condition work down the line until you get to the starter. My guess is a weak engine battery.

 

[Gypsy]

Brian,
You are a good info source - Thanks again.

 

[Cutwater28GG]

i have a similar problem occasionally on my cutwater (2012) with the universal AGM's I've deduced that basically the engine battery when its cold in the morning after a night at anchor juset doesnt have the cranking amps. it works fine when the air is warm and when the engine is not cold, and the battery has not been left sitting not being charging recently. I will be replacing the engine start with an optima high CCA battery (cheaper than a northstar AGM)

Previously I also thought that when at anchor with the original installed PWM morningstar solar controller, that it was also confusing the acr's with variating voltages from the solar panel while the boat swings in the sun causing all batteries to get drawn down. (only during trickle loads and not high loads like the inverter)
ive since removed that issue as I have upgraded to a victron MPPT only charging the house batteries.

 

[Gypsy]

Well, I solved the dead starting battery problem. First, the batteries all checked out fine. From there, we traced the positive and negative cables from the battery to the engine. The positive cable was fine, but the negative cable was loose. The cable ground was fastened tightly to the cable lug, but the cable lug was not tight to the engine. So far, the engine starts each time.

 

[Cutwater28GG]

Nice!

 

[Gypsy]

Well, I'm back with another battery problem. Last night I drove the boat to a restaurant. After dinner there wasn't enough power to start the engine. What is also a mystery, is that there wasn't enough power to run the thrusters. I switched on the crossover and everything worked. As soon as the engine started, I switched off the crossover. When we got back to our dock, the thrusters worked fine. The volt meter showed that the batteries were charged. We had recently done a load test on the batteries and they were all good. I'm thinking that there must be a bad connection somewhere, but why would there be the same problem at the same time with two separate batteries? Sure could use some ideas.

 

[knotflying]

There are many connections that are involved. The fact that you had two different systems loosing power (thruster and engine) leads me to think you should check all your connections on the negative buss bar. I find it hard to believe that you would have a parasitic draw on two different systems as a coincidence, hence the common element being the buss connections.

 

[Gypsy]

Does the starting battery use the negative buss bar? When we checked the previous starting battery problem, we traced the negative wire directly to the engine where we found a loose connection. Tightened up the connection and thought we solved the problem.