Driving a car with a completely dead battery.

[Offgrid]

Obviously this thread is not suitable for drivers of those inconvenient electric cars. Yesterday I had to move Cinders ( 1988 744 ), and it has been on a sorn for a few months pending a major overhaul. Stupidly I hadn't diconnected the battery, as I have been in the habit of firing it up at intervals. I attempted to start the car, and the battery was completely dead. A few months ago I bought one of those brick sized booster boxes, so I thgought that there wouldn't be a problem. I could just jump start it. Wrong! The battery was beyond dead, and just caused the booster to complain about being associated with something that was beyond resurrection. I tried another battery that was destined for the scrap yard, and had the same result.

So what to do? I needed to move the car to gain access to the boot. Suddenly, I was hit by a blinding flash of the obvious. Why did I need a battery, when I had the booster box? So I removed the battery, and placed the booster box in the space. Then I clipped the box terminals to the battery leads for the car. The car started immediately, and I was able to drive it for a short distance.

Obviously this is not a permanent solution, as the box was unsecured, and I hadn't placed any extra insulation around the connecting clips. I've started this thread to alert people to the possibility of using these boxes as a get you home solution, and to encourage people to carry one in the car. They are small and cheap, and can get you out of a number of problems. You can also use them to charge mobile phones and laptops if they support USB charging.

[yoda960]

Are you sure that is safe? The instructions on my booster pack state that it should be disconnected asap after the engine starts. I don't think they are designed to be charged through the clips via an alternator

[john.wigley]

Originally Posted by yoda960

Are you sure that is safe? The instructions on my booster pack state that it should be disconnected asap after the engine starts. I don't think they are designed to be charged through the clips via an alternator

Good point, 'yoda960'. I think that it may depend upon the type of 'booster' that you have. Mine is old technology incorporating a sealed 17 A/H lead acid battery and is chargeable both from the mains and via the car's cigar lighter / 12 V socket.

The instructions warn against extensive charging from the 12 V outlet, and later models did not come with a 12 V charging lead. Both my original one and it's replacement were Aldi £30 specials; the first came with both, the second with the mains charger only.

On that basis - and I have not tested the theory - I think this type would probably be OK, although it might be prudent to remove the alternator drive belt before starting. I do like 'Offgrid's style, though!

Regards, John.

[Tannaton]

Id be careful on this one - the alternator in a car, especially an older one, relies on being connected to a battery for voltage regulation and also to excite it. Even a late 80's car will some some electronics.

That said - saw a video on facebook this morning with someone starting a van with a low battery using 2 x 18v drill batteries to boost it. Melted the cables but it started....

[Offgrid]

Thanks for the comments, and the further thought provoking ideas. I only drove the vehicle for about 50 yards, so I doubt if it did any damage. Please remember that I am not an auto-electrician, so any comments or suggestions by me should be considered with caution and independent research.

The comments here have given me some further thoughts. The most significant one is - why do you need a battery? Obviously you need it to start the vehicle, but once it is started, then the car should run from the electricity generated by the alternator. What would you need to place between the positive and negative battery terminals to allow the vehicle to run without a battery. The booster could be used to start the vehicle, and removed once it is running ( perhaps ).

[Simmy]

why not go and buy a battery from a car dismantlers yard there are loads of nearly new battery's off almost new cars which have been written off by insurance company's

[john.wigley]

Originally Posted by Offgrid

Thanks for the comments, and the further thought provoking ideas. I only drove the vehicle for about 50 yards, so I doubt if it did any damage. Please remember that I am not an auto-electrician, so any comments or suggestions by me should be considered with caution and independent research.

The comments here have given me some further thoughts. The most significant one is - why do you need a battery? Obviously you need it to start the vehicle, but once it is started, then the car should run from the electricity generated by the alternator. What would you need to place between the positive and negative battery terminals to allow the vehicle to run without a battery. The booster could be used to start the vehicle, and removed once it is running ( perhaps ).

It's worth noting that all mopeds, autocycles and many lightweight two-stroke motorcycles, not to mention lawnmowers and suchlike, made do without any battery. Lighting was direct and a parking light, when required, was powered by a dry cell battery in the headlamp casing.

It is difficult to see how a modern vehicle with it's plethora of electric and electronic equipment could manage without a battery, but I see no insurmountable reason why the basics could be covered in the way that you envisage, 'Offgrid'. In fact, that was the norm in early cars. The engine was started by hand, lighting provided by acetylene gas. Even if a battery was provided, it was unlikely to have an independent charging system on the vehicle.

Might be a little more difficult with an E.V., though!

Regards, John.

[Offgrid]

If I could do that, then I'd buy a new one. This thread is really about emergency situations. For example, you've been parked in a picnic area, and you've got a dead battery, and it is 2100 hours. You haven't got a chance of getting a spare battery, unless you have taken it with you.

Now that raises another interesting possibility. Just suppose you have a small leisure battery and a split charger. Would that be enough to satisfy the alternator if you remove the starter battery?

[john.wigley]

Originally Posted by Offgrid

If I could do that, then I'd buy a new one. This thread is really about emergency situations. For example, you've been parked in a picnic area, and you've got a dead battery, and it is 2100 hours. You haven't got a chance of getting a spare battery, unless you have taken it with you.

Now that raises another interesting possibility. Just suppose you have a small leisure battery and a split charger. Would that be enough to satisfy the alternator if you remove the starter battery?

In the situation that you describe, you wouldn't need a replacement battery, 'Offgrid', just a jump start. I've actually been in a very similar situation myself, the only difference being the time of day. I was near Scarborough and needed to get to Loughborough. The AA chap said he could give me a jump start, but warned me not to stop the engine until I got home, or he could fit a new battery. As it was no more expensive than Halfords and a lot more convenient, I opted for the new battery.

Regards, John.

PS. I always carry jump leads, as much to help others as myself. J.

[GMcL]

Not sure why EVs are thought to be exempt. They still have a 12v battery to kick things off. I had to jump start my wife's EV in a car wash when the 12v battery decided it had enough. Same as using jump leads on any other car.