alternator or battery

[78 Sprint]

Left the key on in my boat the other night and drained the battery. so i charged it for about an hour before i went to the lake, got there boat started right up took it out to warm it up and noticed the amp gauge was peged out went back to get the wife and kids and the thing would not start dead as dead, would a bad battery do this or is the alternator screwed and are they explosion alternator or not. motor is open not covered. would appreciate any help thanks. 79 eliminator sprint??????

[77charger]

Check your connections at the battery terminals. quick way to test alternator is disconnect the batt while running you shouild not stall.Best way is a voltage gauge or ammeter.

[78 Sprint]

will it still run with the battery unhooked even if the alternator is high ammping, do you think the alternator high ammped and smoked the battery?????????/

[77charger]

i am not a battery expert or electrical for that matter :rolleyes: .just things that i have had probs with that i was able to fix.i am sure it is possible to overcharge a batt.im sure people have done it before.
Can a voltage regulator be going crazy?just another thought

[DUCKY]

It sound like you cooked one or more cells in the battery, and it's feeding back a low volt reading to the alt, which will make it full field. Buy a cheap volt meter at walmart and check it. A fully charged battery should be between 12.2 and 13.2 volts at rest (no load). With the engine running, it should be between 13.2 and 15.5 volts, and the voltage should never drop below 9 volts under full load (cranking). Hope this helps. The trick about disconnecting the battery while running works (make sure you pull the ground, should you choose to try it) but, If you have any electronic devices, such as ignition boxes, HEI dist, etc.... don't do it.
[ June 18, 2003, 10:21 PM: Message edited by: DUCKY ]

[78 Sprint]

thanks for the help. ijust don,t see how a bad battery would make the amp gauge high amp unless it had to to keep the motor running, not quiet sure how that works i guess i'll pull it out and see if ican have it checked it seems like every time you have someone do that for you it is always bad know matter what, at least where i live. do you have to have explosion proof alternator or what seems like it would be vented fine with an open engine. Any thanks alot for all your help.

[78 Sprint]

sorry didn"t read your reply before i posted so a bad battery can make your amp gauge high amp. thanks for the info on the electronic devicess i have an hei haven't heard that one before what would it actaully do to the hei

[Taylor LP]

My experience in a Ford truck........
If you remove a battery terminal with the engine running the alternator output can go up to 80-100 volts instantly. It took about 2 seconds to cook an ignition module and a $300 CD reciever.
I wouldn't try it. JMO

[Jet Junk]

Taylor LP:
My experience in a Ford truck........
If you remove a battery terminal with the engine running the alternator output can go up to 80-100 volts instantly. It took about 2 seconds to cook an ignition module and a $300 CD reciever.
I wouldn't try it. JMO Exactly correct. The battery supresses voltage spikes. Without it, you run the risk of blowing any electronic circuit on the boat, including the regulator inside the alternator, so even if your alt. is good, this test may damage it. Besides, it only takes a couple of amps to run an ignition system. Would you consider an alternator that only makes 5 amps good?

[Taylor LP]

My guess is that your battery is sulfated and wont take a charge. The alternator is trying to put a charge into the battery and tries to put max output to the battery like ducky said.
Sounds like the alt is good, battery bad. Lots of places that will check a battery for free, so I'd try that before pulling the alt.
And if you do need an alt. you can get away with a regular alternator in an open engine compartment. Just make sure it doesn't get soaked.

[mickeyfinn]

Have to agree...Bad Battery. You got high amps on the alternator because it is charging like hell to try and charge a dead battery. On some older type alternators you could take something made of a ferrous metal (something a magnet will stick to) and hold it to the backside of the alternator while running. If the alternator is functioning properly you will feel the alternator working like an electromagnet. When you pull the piece of metal away it will feel like you are pulling it off of a magnet.