surge protection

naughtyboy · Posted: Thu Oct 13, 2011 6:38 am Post subject: surge protection

can i fit a surge protector to my jump leads, am thinking of taking clips of it and fitting straight to jump lead clips?
keep getting asked to jump start people at work and am bit worried about doing damage to the newer cars.
one of them i didnt don had like a card and a button instead of keys.

cheers

Winnet · Posted: Thu Oct 13, 2011 7:02 am Post subject:

I think for newer cars they need to read the owners manual to see what the manufacturer says about jump starting. It used to be that you were meant to turn the lights and heater on full to try and disperse the surge around the car.

G

mrcheese · Mud Obsessed Joined: 14 Oct 2003 Odometer: 6339

You can disconnect the dead battery and charge it from your vehicle for a few minutes before reconnecting it. The owner will need to know their radio codes and it may upset the alarm system.

More expensive jump leads are protected with MoVs (Metal oxide Varistors). These protect against voltage spikes. They are connected across the positive a negative terminals. It would be simple to buy some and make up some leads that clip across the terminals of the dead battery. If you want to go belt and braces you can permanently wire some across your battery terminals.

Go for one with a rated voltage of 18V. I just need to figure out the size.
There is not much energy in the transient so it will not have to be too large. But for a permanent fitting I would rate them to the automotive load dump standard.

I'll look out some suitable part numbers later. Zener diodes can also be used as they do the same job.

nivapilot · Guest

Correct procedure is :-

Both cars switched off, connect leads battery to battery, (f you cant get to the battery there WILL be connection points under the bonnet.

Leave connected for a couple of minutes to stabalise voltages.

Start the donor car and, wait a minute and start dead vehicle, leave running for 5mins, switch off both vehicles and disconnect leads.

Start dead vehicle, if it starts, leave running, if not, reconnect leads and run for another 5mins, until the dead car starts on it's own battery.

If dead vehicle will not start on it's own battery, replace it.

The thing that kills most ECU's and other electronics, is starting the dead vehicle, and then disconnecting the donor car, whilst the dead one is still running, (and no amount of surge protection will protect against that)

Never disconnect battery leads with engines running, it spikes 'em.
Never leave keys in ignition when connecting leads (alarm/immobiliser can shut down and lock car...or keys will lose their program)
Don't try and slave start a Mercedes unless you know what you are doing. SAMS unit is very susseptable and damages very, very easily, and is damned expensive to replace.
If someone has already tried to slave start then be extra wary, make sure the owner knows that damage may already have occurred.

Good luck out there, it's a minefield.

nivapilot · Guest

As Winnet says, most newer cars have a set procedure for boost starting....follow the instructions to the letter, don't cut corners.

Hooli · Posted: Thu Oct 13, 2011 12:57 pm Post subject:

mrcheese · Mud Obsessed Joined: 14 Oct 2003 Odometer: 6339

Some good advice from Nivapilot and Hooli. Especially about warning the owner. So I will keep it in mind for the future.

Assuming it is not an automatic, are there also risks when bump or tow starting a newer vehicle?

By the way, does anyone know where I put the new jump leads I bought this summer? Embarassed

TheClunk · Posted: Thu Oct 13, 2011 6:27 pm Post subject:

Always connect the earth lead to the engine of the dead car, not the battery. This will take the surge straight to the engine, avoiding most electrical systems.

Darrell · Posted: Thu Oct 13, 2011 7:02 pm Post subject:

Wonder how useful this would be. Must admit at work we did have a draper unit with a black box and crocodile clips which got broken. I had a look inside and there was next to nothing in it, which made me wonder why not just make it a little unit like this one.
http://shop.conrad-uk.com/car/maintenance-servi...ation/857474.html

nivapilot · Guest

mrcheese · Mud Obsessed Joined: 14 Oct 2003 Odometer: 6339

Thanks. All noted.

jeepmadmike · Posted: Sat Oct 15, 2011 9:13 am Post subject:

I would say surge protection when using jump leads is unnecessary

The real problems are
reversed polarity (can easily cause damage to electronics- but if the cars designed correctly it should just blow fuses) in danger is batteries exploding!

Or jump starting a 12v car from 24v

All the damage I have ever looked at has been caused by people either clipping jump lead earths to the wrong thing or shorting the positive against electronics in metallic boxes