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May 29, 2020, 05:14:54 PM

Generator melt down

This is a discussion for the topic Generator melt down on the board Beach Buggy Electrical Help.

Author Topic: Generator melt down  (Read 330 times)

this user is offline wilksy

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on: August 27, 2019, 01:43:17 PM
I'm trying to understand what I did to my generator this weekend which basically destroyed it, although it still goes round it doesn't charge.

So I was going to fix a Ctek battery conditioner to the battery which entailed connecting a positive and negative terminal to each battery clamp (8mm eyelets).

So before a started I ran up the engine (as it hadn't been ran for a week) and then turned it off and left the key in the ignition barrel.  I then loosened the positive connection on the battery and started to attach the eyelet, there were a couple of sparks as I was doing this, when I noticed a burning smell and a wisp of smoke coming out of the generator, I immediately pulled off both positive and negative terminals from the battery however the damage was done and the generator was very very hot and I could hear what I guess was resin burning from within, the voltage regulator was also very hot.

Yesterday I went back to the car and this time removed the ignition key and connected up the negative first and then the positive, and finally started the car, which fired up first time however the charge light does not go out.

Obviously I have fried the generator but would like to understand how I did it so I don't do it again.

   


this user is offline Dave DND

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Reply #1 on: August 27, 2019, 03:36:24 PM
Cannot comment on yours as wasn't there,

However, I can comment on scenarios we see every day in the modern sector which may be relevant.

Leaving a key in the ignition can be bad news, as when systems are powered up correctly, you have a great big thick supply and return cable going to the battery, but when these are disrupted the heavy current that was used to traveling down these cables will now go through anything that is powered up and switched on, meaning many circuits are completely overloaded.

We have seen circuit boards burnt out, air bags deployed, ecu's fried, etc etc and as a repair centre, we see just how much damage can be done from leaving a key in the ignition during a battery change. I think the most expensive to date that I am aware of was a Volvo that deployed 11 airbags as the battery terminals sparked upon refitting with the key still turned - it wrote the car off.  Toyota's usually fry the engine ecu, anything VAG will corrupt the stereo bios and anything french will illuminate the dash like a christmas tree. We see this every single day.

So, key turned and your generator smoked . . .
Assuming nothing was shorted out and you knew what you were doing, then I have a suspicion what may have happened  :-\

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this user is offline PhillipM

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Reply #2 on: August 27, 2019, 04:36:56 PM
Should have turned the ignition off - with the power on you would have had all the coils, etc, energised and then when you pulled off the battery terminal it'd got no buffer to control the voltage, any charge remaining in any of the circuits, etc, would have seen a voltage spike as the magnetic field collapsed with no battery to absorb it - you probably sent 30-40 volts through everything for a split second.
One of them mucky ones. Sorry.


this user is offline wilksy

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Reply #3 on: August 27, 2019, 04:51:31 PM
That was sort of my take on it as well, although I can't be sure how far the key was turned, when I reconnected I took the key out just in case, so new generator to buy after holidays


this user is offline Dave DND

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Reply #4 on: August 27, 2019, 05:05:15 PM
It happens . . .

You are not the first and sadly won`t be the last to do it   :'(

We also see a lot of garages sending us broken electronics when these so called "Code savers" are used to prevent the radio from losing its code, these also cause problems.

What does worry me though is the number of so called "Spark Arrestors" being connected across the battery when welding - very bad idea -
just disconnect it
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this user is offline snoopy

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Reply #5 on: August 27, 2019, 06:22:52 PM
Reads like you cooked the regulator and turned the dynamo into a motor that could not turn the engine so overheated.


this user is offline Paul1953

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Reply #6 on: August 28, 2019, 07:46:08 AM
It happens . . .

You are not the first and sadly won`t be the last to do it   :'(

We also see a lot of garages sending us broken electronics when these so called "Code savers" are used to prevent the radio from losing its code, these also cause problems.

What does worry me though is the number of so called "Spark Arrestors" being connected across the battery when welding - very bad idea -
just disconnect it


Dave... What is occuring with the "code savers"? I thought this was just a means of providing 12v via a "cigarette lighter" style socket. I have used a slave battery connected via jump leads when changing out a duff battery.

"Spark Arrestor.... Not come across this before.  It was always an "old school must" to disconnect the battery before any electric welding equipment was used and this was long before the advent of "electronics" to vehicles.


this user is offline Dave DND

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Reply #7 on: August 28, 2019, 08:33:10 AM
This sort of thing

https://www.ebay.co.uk/itm/Car-Battery-Surge-Protector-Auto-Voltage-12-24v-Welding-Surge-Protection/163689403690?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D40733%26meid%3Df42ae314c3764f719b859037a0306e01%26pid%3D100005%26rk%3D2%26rkt%3D3%26sd%3D163689400847%26itm%3D163689403690%26pmt%3D1%26noa%3D0%26pg%3D2047675&_trksid=p2047675.c100005.m1851


The problem with the code savers is to do with keeping systems partially powered, but not all, and then when the battery is reconnected the rest of the systems will draw power to reboot in an incorrect sequence. When reconnecting a battery, the radio memory and dash are usually the last to power up and if disconnected in an incorrect sequence can often view the random power outages as something more serious, like a crash, and this is where SRS (airbag) problems can occur.

Trouble is, cars are so sophisticated these days that so much needs reprogramming when battery disconnected that we are trying to eliminate this. I recall a Merc in our workshop many years ago that we disconnected the battery on and it wouldn`t start afterwards until a Main Dealer technician had come to visit with his laptop to reprogram the car as the ecu memory had been lost.

I can fully understand why people try to use such devices, but the trouble is, I see the other side of it as my business has been built on what happens afterwards.

« Last Edit: August 28, 2019, 08:37:02 AM by Dave DND »
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this user is offline Paul1953

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Reply #8 on: August 28, 2019, 02:39:48 PM
Understand this Dave... I had immense trouble the first time I worked on a car without realising that what I had always thought of as a "fuse box" in the dash compartment was no longer just a "simple" fuse box and that it remained powered up after ignition key was removed for immobilisation etc.

I do understand why someone would use a "back up" device as they would believe this resolves the issue of removing the battery and retaining codes etc. I havn`t looked at one of these but they should be made to have some sort of awareness notification. I have two obd11 scanners and both give a warning at the point of code reset asking if you are sure you want to proceed as corruption may occur.

Everything so complex now which is why I love the 60`s and early 70`s cars. Just needed a bit of faith in yourself and a simple tool set and away you went. (No iva as well ha ha).