Battery term's red hot?!?!

[_brad_]

Alright, well I'm posting this for a friend that does not know what a computer is but anyways.. My buddy has a 1978 or so 85 HP Evinrude on a Forester 15' tri-hull. So, he's not the smartest one around and, he did not have his boat strapped very good while towing... And he comes around this corner a little to fast like a moron and you guessed it... Boat came off trailer and slammed on the ground.

Luckily, somehow, very minimal damage happened to the boat and virtually no physical damage to the motor. So, he gets the boat back on the trailer by himself somehow and proceeds home after strapping it good this time.

He goes out and launches the boat the next day. While having some problems with it starting (cranks fine with a strong yyynnnynnnnnynnnnynn) it would not start. He proceeds to check the battery connections since when the boat flung off the trailer it pulled all the connections off the battery.. While doing this he notices the battery terminals are RED HOT! So he thinks, ok, I had it hooked up wrong.. He proceeds to swap pos and neg. Same results. No start and RED HOT terminals.

What the heck could this possibly be? I'm thinking something to do with the starter... But he says it turns over fine...

Any thoughts?

 

[TerryMSU]

Re: Battery term's red hot?!?!

Most likely, a bad connection at the terminal. Two possible causes.

1. Most likely the connection at the terminal is dirty. Remove the wing-nuts and clean the surfaces with a wire brush. Tighten the wing nuts with a pair of pliers to ensure a good connection.

2. The crimp on the battery terminal is bad. Re-crimp it. If you don't have a good crimper, then use a pair of vise grips or channel-locks to squash down the connection. I have had this problem on more than one occasion.

It is quite likely that the heat is an old (and different) problem. The fact that it cranks strong indicates that the wireing to the battery is probably still good. Also, strong cranking says that the starter is good. However, the bad connection could result in a lowering of the battery voltage while cranking.

One other thought... Check the battery. They don't like being dropped and could be damaged. Still I think the issue is not the battery or the starter or the connections between the battery and starter. Perhaps something else is either getting a bad connection or is broken. The issue may not even be electrical at all.

TerryMSU.

 

[tashasdaddy]

Re: Battery term's red hot?!?!

dirty, loose connection, bad cables, create resistance on the electrons, causing them to generate heat. connection have to be tight. finger tight is not tight. a lot of people just put the wing nuts on finger tight. also, crossing the cable, may have blown the rectifier 99%, and maybe more.

 

[mikesea]

Re: Battery term's red hot?!?!

i would think the initial problems may have been something small,like carbs didnt get fuel,or choke not working,perhaps flooded,the hot terminals could have been simply from excessive cranking,the minute he went and reversed the battery terminals,the problem undoubtly made the situation larger,reversing the polarity is a big mistake,
he should now start with an even head,make sure he knows the negative from positive,connect correctly,at that point ,invest in a spark tester and check each cyl for spark by removing all spark plugs and cranking for 10 seconds looking for strong blue spark,if he has spark,proceed to insuring fuel is getting to the carbs,no spark,its then time to invest in some more test equipt,get a book with step by step test procedure,or see a reliable mechanic,

 

[luckyinkentucky]

Re: Battery term's red hot?!?!

If the batteries worked fine before. Why did he switch the terminals????

Not the sharpest tool in the shed.

 

[F_R]

Re: Battery term's red hot?!?!

The bottom line to all this is that the terminals are getting hot because of electrical resistance as everybody has already said. Electrical resistance is what makes a light bulb glow white hot. Same thing anywhere else.

Also, you can go to the bank on the statement that the rectifier is shot after hooking it up backwards. That will blow it faster than instantly.

 

[jtexas]

Re: Battery term's red hot?!?!

Terminals got hot but cables and starter motor didn't? Unlikely to be starter issue. Possible this battery sustained internal damage. Take the battery to a car parts store and get it tested. Be sure to tell 'em it might be damaged.

Inspect all the wiring in and around the battery compartment.

Most boats, I'm going to say, wouldn't slide off the trailer - he must've bounced it over a curb - tell 'im to inspect his trailer, all the bolts, bunks, lights, welds, the bow eye on the boat...........

 

[Monkaroo]

Re: Battery term's red hot?!?!

If the batteries worked fine before. Why did he switch the terminals????

Not the sharpest tool in the shed.

Bless his heart lol . It was bad enough that he didn't secure the boat to the trailer . But then to cross the battery cables ? WOW ! How old is this guy ?

 

[rudedude]

Re: Battery term's red hot?!?!

The shock to the battery is more than likley the culprit, also in switching the battery cables he may not get it to start even with a new battery, he may have cooked the motors little brain.

 

[TerryMSU]

Re: Battery term's red hot?!?!

He may have gotten away with the switch. The motor never ran, so the rectifiers may be OK. The remainder of the electronics is likely protected for reverse voltage. I work designing automotive electronics, and we always put in a reverse battery (and double battery and load dump) protection circuit. I would expect that boat electronics would have the same standards. (Load dump is what happens when you run the alternator with no battery attached.) What he did is not much worse than connecting jumper cables backwards. Not good but often surprisingly survivable. (He should still hire a real boat mechanic if he is going to make those kinds of mistakes.)

The real problem is likely whatever stopped it from running in the first place.

TerryMSU

 

[_brad_]

Re: Battery term's red hot?!?!

Wow lots of good replies! Thanks you all!

OK, so he made another mistake in reversing the polarity. What exactly does the "rectifier" do anyways in regards to an outboard? I know that it converts AC to DC but where in an outboards electrical system is this "rectifier"?

I will have him try another battery, and have him test for spark on all cylinders.

So if no spark then something is wrong with electrical system, right? And the most likely culprit would be a rectifier or ignition switch, correct?

Yeah, dude is not the brightest bulb.. Bad decision making skills.

 

[F_R]

Re: Battery term's red hot?!?!

The rectifier is a cylindrical unit with a triangular mounting flange, with two yellow wires and one red one going to it. For TerryMSU, it is nothing but a bridge rectifier with four diodes. No reverse polarity or dump features whatsoever. Connect the battery backwards and it is impossible to disconnect it fast enough. It is history.

 

[Texasmark]

Re: Battery term's red hot?!?!

Sorry but you can kiss the rect goodbye.

The reverse rectifier(s) of the bridge is(are) connected right across 12v (doesn't have to be 14.5 v like when the engine is running and the alternator is charging the battery).

When you reverse the leads, even for an instant, you can put several hundred amps thru the rect that normally sees a portion of 20 amps or less, in a heartbeat. BTDT Believe me.

Hot terminals indicate that he was on the starter for a long time and may have melted the insulation in it also causing a short which would make for high current from the battery aggravating the existing situation and dirty terminals at the batterty (the ones getting hot) which could include the lug crimp on the cable.

If both terminals are hot it's cable to terminal crud, not wire to lug crud. Sounds like the guy just keeps digging the hole deeper.

Mark

 

[_brad_]

Re: Battery term's red hot?!?!

Yeah, he's gunna be pissed when I tell him the news. Ohh well.

OK so if you have a blow rectifier, does that cause NO spark at the plugs? Is the entire electric system reliant on this rectifier in order to function?

 

[ezeke]

Re: Battery term's red hot?!?!

edit

 

[TerryMSU]

Re: Battery term's red hot?!?!

Quoted from FR post, "The rectifier is a cylindrical unit with a triangular mounting flange, with two yellow wires and one red one going to it. For TerryMSU, it is nothing but a bridge rectifier with four diodes. No reverse polarity or dump features whatsoever. Connect the battery backwards and it is impossible to disconnect it fast enough. It is history." Given the simple bridge, you are correct. It is toast. Anybody know anything about the current rating of the bridge? $30 US sounds a little pricey (from my perspective) but who knows what the markup is.

Terry

 

[jtexas]

Re: Battery term's red hot?!?!

It may be highly probable that reversing the battery cables fried the rectifier, but my experience says you can get away with it...early one morning I accidently tried it - I was warned off by a nice big arc, so the circuit was only closed for as long as it took me to react and no harm was done. 1979 model 3-cyl. I suspected a crowbar circuit like what Terry described saved my a##, but never studied the schematic to verify.

$30 might be pricey....marine parts are (theoretically) constructed to withstand a harsh environment - and these rectifiers are pretty robust.

The motor will run without a rectifier, it just won't charge the battery. Actually it'll run without a battery, but that would smoke the rectifier.

Rectifier and keyswitch might not be the most likely suspects in a no-spark condition but they are the easiest to rule out. A rectifier can fail in a way that will supress the spark - some configuration of diodes failing open/short - not sure how common that is - spark test with rectifier disconnected rules that out. Spark test with wiring harness disconnected rules out the keyswitch and emergency kill switch.

 

[ezeke]

Re: Battery term's red hot?!?!

edit

 

[Texasmark]

Re: Battery term's red hot?!?!

You were lucky j. Few are so fortunate.....including yours truly.

Mark

 

[TerryMSU]

Re: Battery term's red hot?!?!

Last night, I acidentally hooked up my battery backwards. Drew some small sparks and the choke solenoid smoked a little. Scared me that I might have screwed something up, but apparently no damage to the motor.

TerryMSU