Alternator voltage spike

Ask for and share advice on using the PicoScope kit to fix vehicles here.

Alternator voltage spike

Postby millermilla » Tue Mar 20, 2018 12:07 am

Hi,

Apologies for a question with my first post but hoping someone may be able to shed some light.

I've been helping build a classic mini race car with a friend and we have experienced a problem with a control unit for the electrics that was tested and reported as having suffered from a voltage spike. The car is built from all new components and a custom loom, fuse box ect. The starter motor and alternator are lightweight racing items from Brise and the battery is a Lithium Ion race battery.

I tested for voltage spikes using a Pico Scope with the result below! The spike is from the alternator as when disconnected there are no problems. When a more conventional lead acid battery is used the voltage spikes are absorbed by the battery. I've spoken to the alternator manufacturer and they say the alternator is compatible with Lithium Ion batteries. Obviously the lead acid battery is a higher capacity and better capable of absorbing spikes but should the alternator be spiking that high in the first place? Has anyone had any experience of this?

Image


Many thanks,
millermilla
Newbie
 
Posts: 2
Joined: Mon Mar 19, 2018 11:43 pm

Re: Alternator voltage spike

Postby kona » Thu Mar 22, 2018 5:14 pm

Hi,

It seems your description of the problem is not very informative ...
I dare to assume that because of incompatibility of your components or errors in their connection.

Perhaps you see pulses of the injectors (which can have such a voltage), but there may be ignition pulses.

It would be nice to see two more channels:
- working of injectors;
- Ignition work.
And all this simultaneously on one screen. Record to a file and upload it here.

Good luck. :D
kona
OneWave
OneWave
 
Posts: 32
Joined: Thu Feb 22, 2018 10:14 pm

Re: Alternator voltage spike

Postby millermilla » Thu Mar 22, 2018 8:06 pm

Thanks for the reply and apologies for the lack of info. It had crossed my mind that it could be ignition but when testing back to back with the alternator connected / disconnected it is clear that the spikes disappear with the alternator out of the circuit.

The car is running a Webber carburetor so no worries about injectors.

I contacted the alternator manufacturer and sent it back. They tested and said there was no problem with the regulator however they did say they had replaced it, fitted Zenner diodes and a suppressor as a precaution!

I will test when it comes back and report.

Thanks :)
millermilla
Newbie
 
Posts: 2
Joined: Mon Mar 19, 2018 11:43 pm

Re: Alternator voltage spike

Postby kona » Fri Mar 23, 2018 9:08 am

millermilla wrote:....... The starter motor and alternator are lightweight racing items from Brise and the battery is a Lithium Ion race battery. ...........


Hi,
well,then further:
- from which car you use PCM (brand, year, part number from the catalog) ?

- although you do not use injectors does the PCM have injectors drivers inside ?

- the alternator with PCM control (intelligent alternator control) or without ?

- describe the connection diagram.

Good luck. :D
kona
OneWave
OneWave
 
Posts: 32
Joined: Thu Feb 22, 2018 10:14 pm

Re: Alternator voltage spike

Postby victor2k » Tue Mar 27, 2018 9:10 am

Hello,
How is protected from overcharghing or overheating your Li-ion battery?
Every cell must be monitored for voltage and temperature and the battery not work like a lead acid battery.Please post some more info about the used battery(voltage, charging strategy(constant current,constant current+pulsed,pulsed)).Also try to make a new capture with voltage and current or a spectrum for your signal ,I think your captured spikes is from duty-cycle of your battery charging module :D
Regards
victor2k
TwoWaves
TwoWaves
 
Posts: 237
Joined: Thu Jan 28, 2016 9:17 am


Return to Diagnostic discussion

Who is online

Users browsing this forum: No registered users and 0 guests