Engine Starting Power Surge

MCI9Guy · December 06, 2016, 08:11:02 PM

I have a 1983 MCI 9. It's been about a month since I started it last. The temperature has been dropping so I thought I would fire it up. I tried starting it a couple of times. I could her it starting to warm up. On the fourth attempt, just when the engine started to fire, there was a power surge that blew the positive battery terminal off the battery closest to the main battery shut-off. I'm wondering if it could also have been a short. But what would cause a short when the engine fired up? Has anyone else run across this problem?

The electrical seemed to be working fine. The starter was cranking over just fine. It was only when the engine started to fire that I the surge or short happened.

Before I switch out the battery and try again I want to understand and try to prevent this from happening again. Any suggestions? Has anyone put a breaker on the positive battery cable? Your thoughts and comments are appreciated.

gumpy · December 06, 2016, 08:16:44 PM

Blew it off? Was it burned? Melted?

I suspect it wasn't tight on the post and the heating caused by the high current draw of 4 attempts cranking a cold engine caused it to slip off the post.

What are the voltages on the two batteries?

luvrbus · December 06, 2016, 08:20:57 PM

As Craig stated loose cables and the 600 to 900 amp draw from a starter will do it every time

MCI9Guy · December 06, 2016, 08:36:14 PM

I can clarify a bit more. The battery has both automotive and stud terminals. I had it connected to the stud terminal. The metal stud popped right out of the metal holding it in place. It turns out that the stud is just a regular bolt. The metal looked more fractured than melted. However, the positive cable was really hot. A little bit of smoke coming off of the insulation.

Would you recommend that I install a fuse or breaker. And how would I go about determining an appropriate amperage.

brmax · December 06, 2016, 08:44:45 PM

I deleted what I thought and like mentioned

The metal is lead even with dual post connectors, maybe not pickin up what your saying.

possibly make a new wire end to fit the existing connection ?post

better luck tomorrow
Floyd

gumpy · December 06, 2016, 08:54:19 PM

Quote from: MCI9Guy on December 06, 2016, 08:36:14 PM
I can clarify a bit more. The battery has both automotive and stud terminals. I had it connected to the stud terminal. The metal stud popped right out of the metal holding it in place. It turns out that the stud is just a regular bolt. The metal looked more fractured than melted. However, the positive cable was really hot. A little bit of smoke coming off of the insulation.

Would you recommend that I install a fuse or breaker. And how would I go about determining an appropriate amperage.

No. Don't try to put a fuse in it. The starter needs as much current as that long cable can supply.

The bolt was probably cross threaded, or the heat melted the lead it was screwed into. Suggest you get a terminal end which connects to the regular battery terminal, but has a threaded stud and wing nut. Then you can just attach the cable to the stud on the new terminal.

gumpy · December 06, 2016, 08:54:48 PM

Oh, and plug in your block heater for several hours before trying to start it in the cold.

luvrbus · December 06, 2016, 09:04:24 PM

Use a military style terminal they cost a few bucks more but worth it IMO

MCI9Guy · December 06, 2016, 09:12:46 PM

I can't believe that I totally spaced on not plugging in the block heater. It was the first cold start of the winter and I knew I was missing something. DUH.

I'll give it another go tomorrow.

Boomer · December 07, 2016, 06:45:32 AM

I had a new post poured on an 8D a couple years ago, but had to look around at several battery distributors to find someone who had the mold and would do it. Everyone said too much liability and they don't do it anymore after someone blew a battery in his face. A lost art like a lotta stuff now days. Oh and they did it no charge.

unclewilly · December 07, 2016, 07:33:40 PM

What happened when you applied the load to the starter to start the engine
it also puts a load on the cable and the battery.
As a load is applied to a battery it produces hydrogen which is highly explosive.
Battery's some times develop a leak around the post and with the combination
of a dirty or loose battery terminal could have created a slight spark that set the gasses off that escaped from around the battery post causing an small explosion
which will blow the terminal and post off.
Make Sure the terminal is tight and clean. Good luck

Jeff Willard · December 08, 2016, 07:51:26 AM

UncleWilly... Is that you Mr. Holt? Are we going ot see you and your Scenic at Quartzsite this year? Hope so.

eagle19952 · December 08, 2016, 12:12:28 PM

I too have poured terminals....I simply put a short sheet metal screw about 1/4 inch into the remainder and made a mold from a beer can and a pair of vice grips... melted old tire weights...sinkers work too...finish with a rasp...

MCI9Guy · December 08, 2016, 12:57:58 PM

I got the bus started today. Yay. I think Grumpy (the 1st responder) was right, too much draw from multiple starts on a cold engine and probably a poor connection on that terminal.

I live in northern Idaho between Coeur d'Alene and Sandpoint. The highs during the day have been around 20* and at night dropping below 10*.

I checked the wires on the starter and starter switch relay solenoid and luckily nothing else had melted.

This time I charged the battery's fully. Cleaned and tightened all the battery terminal connections. Ran the block heater for about 2 hours. I also put an oil heater in the engine compartment for those 2 hours. It started on the second attempt.

Live and learn. You have to follow proper cold weather procedures.

luvrbus, I ordered those military style terminals.

Thanks everyone...