Checking for voltage surges

[Mr Spigot]

I have had a problem with my indicators, with the green lamp on the stalk not working, even though the indicators flash satisfactorily. I have tracked it down to a faulty flasher relay which is being replaced. However, I have been told to "check for potential voltage surges prior to fitting it". How should I do this?

The system is negative earth with an alternator and has LED bulbs fitted. I have never had any problems before and this may have just been a faulty relay, but how can I check for and in future, prevent, voltage surges?

[geoberni]

I have had a problem with my indicators, with the green lamp on the stalk not working, even though the indicators flash satisfactorily. I have tracked it down to a faulty flasher relay which is being replaced. However, I have been told to "check for potential voltage surges prior to fitting it". How should I do this?

The system is negative earth with an alternator and has LED bulbs fitted. I have never had any problems before and this may have just been a faulty relay, but how can I check for and in future, prevent, voltage surges?

Who told you that??
It's a car alternator, not the national grid.
If you've not experienced any other signs of problems, such as headlights going brighter and then dimmer, then just go with it.
A car generating system, Alternator or Dynamo, is designed to provide 13-15 volts in order to charge the battery for starting it.
Components therefore need to tolerate a wide operating voltage of 10-15 volts.

The layman is not equipped to go looking for 'surges', to do that you'd need an oscilloscope or such.

You can check the drive belt is the right tension and that the connections/connectors are a good fit and not corroded, apart from that, just stick with .....
Faulty Flasher Unit diagnosed.
Replace Flasher Unit.

[Mr Spigot]

"Who told you that??"...the company I bought the relay off - Classic Car LEDs. I must admit, while electrics are not my strong point, I had never come across voltage surges on a Moggy!
I suspected it was a faulty relay and they are sending me a free replacement as I only bought it less than 2 years ago. I have always found them very good, supplying quality parts and a speedy, helpful service and would happily use them again.

[geoberni]

"Who told you that??"...the company I bought the relay off - Classic Car LEDs. I must admit, while electrics are not my strong point, I had never come across voltage surges on a Moggy!
I suspected it was a faulty relay and they are sending me a free replacement as I only bought it less than 2 years ago. I have always found them very good, supplying quality parts and a speedy, helpful service and would happily use them again.

By their very nature, 'surges' are often random and infrequent. When a generator is fitted to a random speed power source, it can't be laboratory standard stable.
My reaction would have been 'Really, and how would you suggest I do that?'


If you really want to try something, then put a multimeter/voltmeter across the battery, i.e. from Pos to the Chassis and with the engine running play with the throttle and see if the voltage jumps wildly above 15 ish volts.

[Mr Spigot]

Thanks for all your advice. I will try that but it does not look as if I will be losing much sleep over it!

[mike1864]

I've fitted a Ring RMS3 cigarette lighter 1>3 distribution box. It's main function is to enable simultaneous use of satnav, dashcam and phone charger.
But it has an inbuilt voltage detector which indicates low, 12V, mid and hi volts, via coloured LEDs (like traffic lights, but with FOUR colours!).
Although I'm fine with meters, this device is really handy for quickly reassuring me (at startup or even when driving) that the alternator, battery, fan belt etc are all OK.
But I too don't understand SURGE in this context, nor how to monitor it!