Newbee... How does the charge system work in a boat?

[NoGin]

Hey guys. I have a 1987 Thompson with twin 470 IOs. Currently I have the original stator set up but am considering the alternator conversion kit.

I launched my boat on July 4th and have her at a mooring with no 110 power supply to charge. She has dropped to just over 10 volts and will not start. I ran her 2 times for about 3 hours each time this past Sat and Mon. That did not seem to help charge the batteries (I have 4 batteries).

1) When a boat is running, does it charge the batteries like a car?

2) Can something like a boats stereo that has a very low constant draw drain the batteries a few volts over the course of 2 or so weeks?

 

[IVAZ]

Re: Newbee... How does the charge system work in a boat?

Hey guys. I have a 1987 Thompson with twin 470 IOs. Currently I have the original stator set up but am considering the alternator conversion kit.

I launched my boat on July 4th and have her at a mooring with no 110 power supply to charge. She has dropped to just over 10 volts and will not start. I ran her 2 times for about 3 hours each time this past Sat and Mon. That did not seem to help charge the batteries (I have 4 batteries).

1) When a boat is running, does it charge the batteries like a car? Yes

2) Can something like a boats stereo that has a very low constant draw drain the batteries a few volts over the course of 2 or so weeks?

Im going to say no only because you have 4 batteries.

On my boat I only have one battery. My radio is also hooked up to draw a little current to use the radios memory feature. I also use the radio during the week (while parked in the driveway) and not charge the battery afterwards. It still keeps enough charge to start the boat at the end of the week. Some of your batteries are bad or you have a charging issue.

 

[NoGin]

Re: Newbee... How does the charge system work in a boat?

The PO said the batteries were all just 1 year old so I am leaning towards the charging system problem. I stayed on the boat last night and hooked a small generator up to 2 car chargers charging both banks. They both read 11 when I left at 6:30 this morning. I filled the generator with fresh gas and left it running. I am going back to see if she is up closer to 12.

I do have a feeling I will be doing the alternator conversion soon!

 

[Bifflefan]

Re: Newbee... How does the charge system work in a boat?

If you left them charging all night and they arent up to 12 volts, then you have a 1 or more bad batts.
Ponder this:
Used to different charging systems on the same set of batts and got the same result. 1 OR MORE BAD BATTS. 1 bad one will suck the life right out of the others.

 

[NoGin]

Re: Newbee... How does the charge system work in a boat?

I checked the batteries the other day and they were all short on H20 so I topped them all off. I guess it's time to buy one of those 5 ball battery tester jigamawatzees and test the batteries! I splashed the water in my eyes on one of them (not on purpose) and it burned like hell. Don't want to repeat that test if I can avoid it!

 

[rbh]

Re: Newbee... How does the charge system work in a boat?

remove all the batteries, take them and due a proper charge and load test,
replace all the bad batteries.
but make sure you clean all the terminal connections as dc voltage has a hard time working through corrosion as well as loose connections.
rob

 

[HT32BSX115]

Re: Newbee... How does the charge system work in a boat?

Howdy,

If you have 4 batteries, you probably have some sort of switch that selects one or more batteries at a time.

You may have problems with the batteries themselves or the charging system. Since you have engines that have a rather unique (read usually defective) charging system you should start by checking the battery voltage when the engines are running.

Use a simple DVM on each battery like the one below.

Just check the batteries one at a time when the engine is off, (around 12 V)

Then check them with the engines running 13.5V or more.

If you have 12v or no increase when both engines are running, then your battery switch is NOT switched to the battery you're checking OR your charging system is defective (no surprise here....you have 3.7L Mercs)

If the voltage is above 13.5v or so.......at the batteries then they're charging. If the batteries won't hold the charge, then they're defective and should be replaced.

You might check and see if there's water in them etc....

You also might have a switch problem. People who install multiple batteries usually also install a switch to select those batteries etc...


Cheers,


Rick

 

[NoGin]

Re: Newbee... How does the charge system work in a boat?

Thanks for the advice guys. I ran the generator all day and she only went to just under 12 volts both banks. I just left the boat and filled the generator with some fresh gas so she should continue to charge for another 4-5 hours.

I did switch to charging through the 110 charger I have installed on the boat. I wanted to see if she was working and doing her job. The charge is increasing but at a very slow rate.

Guess it's time to buy some equipment tomorrow to test the circuits and outputs.

 

[NoGin]

Re: Newbee... How does the charge system work in a boat?

Think I need to take a step back and better explain my situation for some much needed help.

~ Purchased the boat in April and stored her in my yard with constant 110 hooked up.

~ Ran the refrigerator almost constantly figuring the 110 would maintain the batteries.

~ I am now not 100% sure but I do believe I had the 110 battery charger on 24-7 while she was on land April - July 4th.


..... I did use a lot of the larger 12 volt accessories such as water pump and refrigerator during the time she was on land. I think I may have slowly drained all the batteries over that period of 4 months.


..... ~ Now I am on my mooring with 4 batteries now reading just over 11 volts with about 20 hours of charging. I have water batteries and had to fill all 4 batteries with water as they were all low.

How long should it take to charge all the batteries to 13 volts?

Since I am using an inflatable with no motor and rowing about 1/2 mile each way, I can't take the batteries off the boat to test/charge.

Any suggestions?

Thanks for the help guys!

 

[NoGin]

Re: Newbee... How does the charge system work in a boat?

Bought a digital auto range volt meter. Checked my batteries and here are the results:


Engines Off:
12.4 Volts

Engines Running at 1800 RPM:
Drop to 11.96 Volts

All 4 batteries showed the same readings within .5 volts.

Any tricks to testing the charging system/stators?

 

[rbh]

Re: Newbee... How does the charge system work in a boat?

ok then by the sounds of it your charging system is hooped. you should be getting between 13.5-14.5 vdc.
if you are trying to charge 4 large group 27 batteries from dead, you will burn out your system, you said you "do not have an alternater", then do you have a generator/starter?
the generator is not as efficient as an alternator.
"yes I got a little carried away but" use ohms law, and you will have to convert from watts to amps to watts and back?

do you know how many watts you need for your boat. for example (add up appliances 6-40watt bulbs, radio-x watts fridge-x watts, horn, bilage pump etc) if these things were on all the time, you need a alternator that will charge x amount of amps and you need x amount of ? amp batteries to run the stuff and you will have to start your engine and charge the batteries every x minute
hope that wasnt to confusing
rob

 

[NoGin]

Re: Newbee... How does the charge system work in a boat?

Thanks Rob. Minus the windlass, I would say I am around 35-40 amps for fridge, Radio, GPS, Radar, Bilge Pump, Blower, Dock lights, Water Pump and Nav lights. My boat has a 40 AMP charge system on board. I do have a separate portable generator I bring on board for my shore power since I am on a mooring.

How do I determine if my charging system is "hooped?"

 

[rbh]

Re: Newbee... How does the charge system work in a boat?

if you dont have 13.5 to 14.5 volts dc across your batteries while engines running it aint charging.
if you suspect you have a dead battery or two or four disconect all and test them one at a time.
do you have two batteries or four batteries for each engine?
rob

 

[NoGin]

Re: Newbee... How does the charge system work in a boat?

I tested each individually but while connected. Disconnecting will better show each batteries condition?

 

[rbh]

Re: Newbee... How does the charge system work in a boat?

did you catch the edit

 

[NoGin]

Re: Newbee... How does the charge system work in a boat?

yup, 2 batteries per engine. All 4 showed the same results with initial test and none increased in volts during run test.

 

[rbh]

Re: Newbee... How does the charge system work in a boat?

engine# one charges 2 batteries/ engine#2 charges 2 batteries?
and on both sets of batteries, they dont show a charge rate of over 12volts dc, and you dont have a alternator on either?
Better get alternators on both engines

 

[NoGin]

Re: Newbee... How does the charge system work in a boat?

You got it right. I did a bunch of electrical work on the helm with new gauges, rocker switches and radar and gps. All my wiring was done in the electrical compartment accessed through the bathroom. Is it possible that I disconnected something? Just a little coinsadental that I am not charging from both engines when there wasn't a problem a few months ago.

 

[rbh]

Re: Newbee... How does the charge system work in a boat?

well let me think about this one.
uh uh drink some rum uh uh
ok first find the wiring diagram for your motor in the sticky section
"adults only"
and do a trace of the wires as well it has a great fault finding sections with all the voltages you are supposed to get.
rob

 

[NoGin]

Re: Newbee... How does the charge system work in a boat?

Will do, thanks for all the help Rob. Will be back on board in the am continuing. Will post results.