Dead battery, wont jump?!?

[Twenty7]

1996 Mercruiser 7.4ltr 454.
Have 2 batteries with switch, both only 1.5 yrs old and appear in good coodition. I?ve had the boat for 3 weeks and this is my first problem. I?ve always started with battery one like previous owner suggested. The engine will turn over slowly once then do nothing. I tried both batteries and got the same result.

Got my truck (GMC 1500 4.8 v8) over and attempted to jump it with similar results. A friend of mine suggested that my truck battery doesn?t have enough cranking amps to start the larger boat engine. I set up a charger over night and attempted to start once the charger said ?charged?. Same results.
What now? Get bigger charger, replace battery, jump with bigger truck?
Thanks for any advice.

 

[Don S]

Re: Dead battery, wont jump?!?

Pull the spark plugs and see if you have water in the cylinders. Do you boat in salt water?

 

[bruceb58]

Re: Dead battery, wont jump?!?

If after you determine you have no water in the cylinders and you can rotate the engine by hand you should check to see if you have loose or corroded connections between your batteries, switch and starter. You should make sure all are tight and corrosion free. Also make sure your grounds are also tight and corrosion free. Sometimes it takes takinging them off and cleaning them and putting them back on.

 

[Twenty7]

Re: Dead battery, wont jump?!?

Only boat in fresh water.

 

[crackerjack]

Re: Dead battery, wont jump?!?

Could be a short in the battery. I had a truck that wouldn't start one time. Even with a jump from the tow-truck driver, the starter wouldn't turn. Turned out the lead plates in the battery had shaken loose and were shorting things out.

Maybe remove the batteries and have them tested at an auto parts store...

 

[Twenty7]

Re: Dead battery, wont jump?!?

That sounds a lot cheaper than water in the engine.

 

[Don S]

Re: Dead battery, wont jump?!?

Pull the spark plugs and check ASAP. You don't need water in there causing rust on the cylinder walls and rings. If there is water, the longer you wait to find it, the worse it gets to fix.

 

[boat1010]

Re: Dead battery, wont jump?!?

Once you have checked for water and if you don't find any then have the batteries and the starter checked at a auto dealer. Have you tried to turn it over without the spark plugs?

 

[Twenty7]

Re: Dead battery, wont jump?!?

No water in cylinders =). Pulled out both batteries. This is what I discovered.
1. battery #1 (MAY 07)is completely dead and has low water levels.
2. battery #2 (JUN 09)was wired to battery #1 bypassing the battery switch.
The positive for battery #2 was connected directly to battery #1 and the ground for both batteries were connected to the switch. So now my question is how are they supposed to be wired? With a set up like this I?ve been using battery #2 the whole time even when it wasn?t selected. I will take both batteries to have them checked but expect #2 to be good and #1 will need attention. How would you suggest I reconnect batteries once properly fixed?
Again, thanks for the help.

 

[PuddleJumper]

Re: Dead battery, wont jump?!?

http://forums.iboats.com/showthread.php?t=356026&highlight=battery+switch+diagram

Check this thread. I think it answers your question nicely.

 

[Twenty7]

Re: Dead battery, wont jump?!?

Thanks Puddlejumper, that thread sounds pretty solid. But I can?t get the Diagram to load. Can you try to upload it to this thread?

 

[Fun Times]

Re: Dead battery, wont jump?!?

Thanks Puddlejumper, that thread sounds pretty solid. But I can?t get the Diagram to load. Can you try to upload it to this thread?

Scroll down to the bottom of post number 3 in that link, You should be able to see that diagram of the dual battery switch from silvertip.

http://forums.iboats.com/showthread.php?t=356026&highlight=battery+switch+diagram

 

[Apollo75]

Re: Dead battery, wont jump?!?

No water in cylinders =). Pulled out both batteries. This is what I discovered.
1. battery #1 (MAY 07)is completely dead and has low water levels.
2. battery #2 (JUN 09)was wired to battery #1 bypassing the battery switch.
The positive for battery #2 was connected directly to battery #1 and the ground for both batteries were connected to the switch. So now my question is how are they supposed to be wired? With a set up like this I?ve been using battery #2 the whole time even when it wasn?t selected. I will take both batteries to have them checked but expect #2 to be good and #1 will need attention. How would you suggest I reconnect batteries once properly fixed?
Again, thanks for the help.

So, it sounds like like battery-1 positive was connected to battery-2 positive and the grounds were connected / isolated through the battery switch from your description. It can be done this way ---> however, any switch should be installed in the positive / non grounded lead.

You were trying to jump two dead batteries and start the boat at the same time ---> this would account for low cranking speed. When trying to charge a bad battery the charger may show the battery fully charged if it sensing voltage only. The only real test for a battery is a load test.

Disconnect the battery switch and connect it too the main positive cable lead instead of the main negative lead.

Connect the battery grounds together and to the main boat / engine ground lead. Isolate the batteries through the switch by connecting battery-1's positive lead to the battery-1 connection and the other batteries positive lead to the battery-2 connection on the switch.

I hope this was all there was to your starting problem.

OFM

 

[bruceb58]

Re: Dead battery, wont jump?!?

When trying to charge a bad battery the charger may show the battery fully charged if it sensing voltage only.

That's how a charger senses if a battery is charged...by voltage! How else would it do it?

A battery can indicate fully charged granted that none of the cells are shorted out. It does not mean that the battery can deliver enough current to start an engine though. As batteries age, get discharged or are not kept fully charged their capacity drops. This may be the case here. If the batteries are not deep discharge batteries(starting batteries) letting them discharge completely as few as 3 times can cause them to fail.

 

[Apollo75]

Re: Dead battery, wont jump?!?

If the battery is sulfated it will not take a charge and the voltage will rise --- a partially sulfated battery will only accept a partial charge and the voltage will again rise, yet the battery is bad and will not pass a load test.

Sometimes a long slow charge will help a battery but if the crystals on the plates have been there for awhile they will harden and the battery will never charge.

OFM

 

[bruceb58]

Re: Dead battery, wont jump?!?

If the battery is sulfated it will not take a charge and the voltage will rise --- a partially sulfated battery will only accept a partial charge and the voltage will again rise, yet the battery is bad and will not pass a load test.

Sometimes a long slow charge will help a battery but if the crystals on the plates have been there for awhile they will harden and the battery will never charge.

OFM

i agree with you here but that is not what you said before. You said that the charger can't tell that the battery is charged by voltage alone. Even if a battery is sulfated, it can be fully charged. It just can't deliver its full current because the plates are coated and there is not enough surface area of the plates to create the chemical reaction necessary to deliver the current demand.

 

[Apollo75]

Re: Dead battery, wont jump?!?

i agree with you here but that is not what you said before. You said that the charger can't tell that the battery is charged by voltage alone. Even if a battery is sulfated, it can be fully charged. It just can't deliver its full current because the plates are coated and there is not enough surface area of the plates to create the chemical reaction necessary to deliver the current demand.

I said : "When trying to charge a bad battery the charger may show the battery fully charged if it sensing voltage only."

If this is the case ----> not a dial to select time that is operator controller --- It is a dumb charger, it senses voltage only --- It will indicate a full charge when the battery may be too sulfated to accept a charge.

I use a computer power supply to charge my batteries, they are voltage and current limited, I select the voltage --- I charge them for two days every 30-days through the winter ---> A smart charger.

OFM

 

[bruceb58]

Re: Dead battery, wont jump?!?

It is a dumb charger, it senses voltage only --- It will indicate a full charge when the battery may be too sulfated to accept a charge.

You have that backwards.

Smart chargers do sense voltage and change the current based on the voltage.

Dumb chargers are the ones that have the dial where you set time.

 

[Apollo75]

Re: Dead battery, wont jump?!?

You have that backwards.

Smart chargers do sense voltage and change the current based on the voltage.

Dumb chargers are the ones that have the dial where you set time.

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I relate dumb with the fact that the charger cannot make a decision as to how long to charge the battery, what voltage, and what current when a battery is sulphated.

Even a three stage charger that is computer controlled is dumb when faced with a battery that will not accept a current flow because of sulphation. In the bulk stage the voltage rises too fast so it switches to the charging / topping off mode and if the battery cannot accept even a small current it will switch to the float mode. It may or may not at this stage go into error mode and alert the operator ---> even if the charger was programmed with a minimum charging time algorithm, a test load at startup, etc., it cannot determine the battery is sulphated and switch to long charge sulphation mode.

Yet, the operator who knows the battery is sulphated may allow the battery to undergo a long charge cycle to remove sulphation. This is smart charging a sulphated battery.

Any simple voltage regulated charger, including an alternator will charge the battery to the maximum current it can to bring the voltage up to regulation voltage with a good battery.

OFM

 

[bruceb58]

Re: Dead battery, wont jump?!?

OMG...this is hopeless!