Anti-spike protection, is it needed ?

[Drew]

Hi,

I've spent a bit of time with my mate google :frown: and started to read up about relays and the need for some form of anti-spike protection.

Well the question I have is that Patrols have relays anyway, stick driving lights in and there's another etc.

The question I have is that is it a good idea to install something or do the Patrols have something already.

[patch697]

Mate power spikes only really become an issue if the Rig in question runs an onboard computer management system or something to that effect ie, phones. satnavs, laptops & the likes. I have none of head units that have been spiked through jump starting but again not overly common & simple precautions can be taken to prevent this from being an issue.

The onboard relays & your smaller 40 to 50 amp after market relays that you would use to install things like driving lights for example are whats called "soft start" relays which are generally safe from causing power spikes.

The larger solenoid switchable 100 to 300 amp type units, the likes of which would be commonly used as a duel battery link up for a duel start system or even an in line on/off option for say an Anderson plug are known for causing power spikes due to the fact they can jump a spark between the to connecting points before a full connection is made because of there high conductivity. When this type of option is needed an in line capacitor can be installed to prevent any power spikes from reaching any other systems.

We have a member here who is an auto elec who would most definitely be able to shed a lot more light on the subject then I, so hopefully he will see this thread & post up a reply for you.

[threedogs]

You can buy jumper leads with spike protection on them,

[oncedisturbed]

Projecta have an anti-surge protector for $25-35 depending where you buy from. A + and - lead on the battery terminals and all done. Has a push button gauge on it as well to check the charge in your battery.

Have a couple at home that i am yet to put on.


Tap, Tap Taparoo

[the evil twin]

All good points but almost every post is talking about different things. I think the OP means the relays with a diode across the coil.

The "spikes" caused by relays as opposed to the gear they are switching is from the collapsing magnetic field inducing a voltage in the relay coil when the signalling power is removed. It isn't anything to do with the load on the cct but that also causes issues as Patch says.

I've never had any hass from relay spikes on a vehicle and given almost all of the factory relays already fitted do not have spike prevention I don't see much point in bothering with aftermarket spike protection UNLESS you are using an electronic output to switch the relay EG a Torque Converter Lock Up cct.

Bottom line is pretty much this...
The electronics in the vehicle (ECU, TCU etc) are already protected from spikes in the 12 Volt supply and you have the worlds biggest filter capacitor you can fit anyway, the Battery.
What isn't protected from aftermarket mods 'spiking' electronics is a back EMF from a relay into the onboard equipment thru a sensor or whatever.
Soooo... if you are switching 12 Volts to the relay coil (EG spotties) then don't bother BUT if you are using an output from an electronic device then, Yes, not a bad idea at all.

[Drew]

Thanks for that.

So I've run power to the back for the van and I only want it live when the engine is running (not starting) so I thought I could put a relay in and find somewhere to tap into hence my "wandering"

[my third 256]

have you put in a duel battery system and battery managment (redark ) then van will run off the second battery and not the crank battery
then no problems with a surge

[Drew]

have you put in a duel battery system and battery managment (redark ) then van will run off the second battery and not the crank battery
then no problems with a surge
That's the preferred battery but I don't want the aux battery drained either. So the way I see it, regardless of where it comes from, I put another isolator in (room is getting squezzy) or put a relay in.