Will an MX-5 battery start a 4x4?

[durbster]

Quick question I think

Got back from holiday recently and the battery on our Fourtrak is dead. I was going to jump start it but hesitated when I remembered what a tiny little battery the MX-5 has, especially compared to the enormous lump sitting in the Fourtrak.

Have I got any chance of starting the Fourtrak with a jump from an MX-5 at idle, or am I likely to blow something up?

[bigdods]

Simple . Both engines off. Connect jump leads. Turn on MX5. Leave running for 10 mins, this will use the charge from the mx5 alternator to push some juice into the other battery. Now start the fourtrak, should be fine as the battery has some juice and the mx5 is now only assisting.

Or just stick a battery charger on for 20 mins, if its a half decent charger that will give you enough juice to start it. Does on the TVR anyway

[wombat172a]

Sure, just remember to connect the jump leads and let the 4track battery charge for about 10-15mins before cranking.

[durbster]

Great, thanks all.

[durbster]

Just thought I'd add this for future reference - I actually failed to jump the Fourtrak from the MX-5.

I ran it for about ten minutes giving it a few revs every now and again, but even after that there wasn't enough juice to do anything but make the solenoid click when the key was turned.

I borrowed a charger instead and it's been starting fine for the last couple of days so I think the battery is OK.

[thinfourth2]

Odd

I have managed to jump start my landrover off a caterham and my lawnmower, that said the lawnmower has a bigger battery then the caterham

[durbster]

Hmm... then I wonder if it's the jump leads. I've jumped the MX-5 with them a few times but never anything bigger.

[McSam]

It sounds stupid, but did you remove and reconnect all the jump lead connectors to make sure you were getting a good contact? I've seen it happen a few times, a battery that should easily be able to jump a car fails because the crocodile clips needed to be put somewhere slightly different. With the MX5's alternator helping, I'd be very surprised if it can't start the Fourtrack, especially if it's petrol.

[Davi]

durbster said:

Hmm... then I wonder if it's the jump leads. I've jumped the MX-5 with them a few times but never anything bigger.

Jump leads are rather critical when jumping something that requires any oompf to get going. TBH as a one off you can usually start pretty much any vehicle with any battery (within reason!) but if you have a pair of cheap and nasty jump leads, you'll be severely limited. I melted a friends jump leads, they were so poor quality that just cranking the engine for a few seconds was enough to overload them, and that was only jumping a 2ltr 4 pot!!!