House Batteries

[My Poggy]

Hi Everyone,
My boat (SR 36DB) was in a harbor with no shore power a while and some of my batteries got depleted to less than 12v. Starting the engines was not a problem. So I thought that when I drive the boat going home, I expected the batteries to get recharged by the alternators. Unfortunately, after 3 hours or driving the boat at 2000rpm, it seems that some of my batteries completely died so that my fridge, freezer, bilge pumps, and stern thrusters are without power (but bow thruster worked). Someone told me that house and thruster batteries are charged only by either shore power or generator, and not by the alternators. Is this true?
Thank you.

 

[bobeast]

Not true on my boat. My alternators charge both banks. However that may be because my house bank also serves as the starboard starting battery. I guess it just depends on how your boat is wired.

With the correct combination of Isolators you can charge 3 (or more?) banks off two alternators. I'd get some advice from Blue Sea Systems to figure out what you'd need.

All that said, running batteries down below 50% or so of their capacity will often damage them to the extent where they will no longer take a charge. Extended use without a charge source is an expensive recipe. If this is a recurring condition, you may need to shift your mooring strategy by adding a solar charger, and/or making sure you switch off the loads before you leave the boat. This is especially true of your fridge.

 

[My Poggy]

Thanks for the reply. I am aware of the danger of depleting batteries. Good thing it only lasted for a few hours and I was able to hook-up to the shore power right away. I hope no permanent damage to the battery happened. Will check how exactly my wiring was done. Thanks again.

 

[Henry Boyd]

Hi Everyone,
My boat (SR 36DB) was in a harbor with no shore power a while and some of my batteries got depleted to less than 12v. Starting the engines was not a problem. So I thought that when I drive the boat going home, I expected the batteries to get recharged by the alternators. Unfortunately, after 3 hours or driving the boat at 2000rpm, it seems that some of my batteries completely died so that my fridge, freezer, bilge pumps, and stern thrusters are without power (but bow thruster worked). Someone told me that house and thruster batteries are charged only by either shore power or generator, and not by the alternators. Is this true?
Thank you.

Its possible. I know the smaller boats up through I think 340 ish don’t actually have a dedicated house bank, there may be extra batteries like on our 280, but everything is wired into the batteries. In a sense on these the engines are wired into what on a larger boat (like yours) would the house system.

Our Sabre is built with two chargers (one being combination inverter charger) and the engines charge their own batteries. The house batteries are charged by the inverter charger either from shore power, or off the gen. The engines are charged by the alternators or the pro mariner charger via shore power or gen. We tend to run the gen underway, otherwise we would have run the inverter as the ice maker and one of the fridges are AC only.

 

[My Poggy]

Its possible. I know the smaller boats up through I think 340 ish don’t actually have a dedicated house bank, there may be extra batteries like on our 280, but everything is wired into the batteries. In a sense on these the engines are wired into what on a larger boat (like yours) would the house system.

Our Sabre is built with two chargers (one being combination inverter charger) and the engines charge their own batteries. The house batteries are charged by the inverter charger either from shore power, or off the gen. The engines are charged by the alternators or the pro mariner charger via shore power or gen. We tend to run the gen underway, otherwise we would have run the inverter as the ice maker and one of the fridges are AC only.

Thanks for the reply. So for now, I will have to run the generator while out of shore power to make sure it doesn't happen again.

 

[Sgrochow]

Before assuming it’s a charging issue, I would start with the basics, check electrolyte levels in all batteries (if applicable). For the connections to the batteries, inspect, clean and tighten/replace if needed. Trace all battery connections to their source and inspect, clean replace etc.

 

[My Poggy]

Before assuming it’s a charging issue, I would start with the basics, check electrolyte levels in all batteries (if applicable). For the connections to the batteries, inspect, clean and tighten/replace if needed. Trace all battery connections to their source and inspect, clean replace etc.

Yes. Will also do that along with the inspection of the wiring scheme. Thank you.

 

[dvx216]

Alternators don't do a very good job recharging deeply discharged batteries. Alternators by design are made to replace and maintain the batteries that are charged. Get the batteries on charger then you can look at each cell with a hydrometer to tell you the cell health.

 

[My Poggy]

Alternators don't do a very good job recharging deeply discharged batteries. Alternators by design are made to replace and maintain the batteries that are charged. Get the batteries on charger then you can look at each call with a hydrometer to tell you the cell health.

Thank you. That's good to know. I have AGMs so it's probably a battery tester that I need, or is there another method?

 

[dvx216]

Since you can't use a hydrometer a load test is your next best thing once they are fully charged voltage.

 

[My Poggy]

Since you can't use a hydrometer a load test is your next best thing once they are fully charged voltage.

OK, will do that. Thank you.

 

[spikedaddy99]

Get a load tester ay any auto store and disconnect each battery and test them. Relatively cheap (under 40$) way to test each battery.

 

[My Poggy]

Get a load tester ay any auto store and disconnect each battery and test them. Relatively cheap (under 40$) way to test each battery.

Yes, I got one now. Thank you.