Battery jump starters

[DealorNoDeal]

So if the alternator will fully recharge the battery very quickly, then why do journeys of less than 30 mins not charge it? And since when was a 30 minute journey "very short"?
Also, given your knowledge, sitting in slow moving traffic in winter with heated seats on, heated steering wheel on, heated windows on, A/C pumping away - is the alternator still putting out enough to keep those going AND recharge the battery fully?

If the battery is flat, and you have to jump start the car, then only a longer journey will fully recharge it.

If the battery is close to fully charged before you set off, then it doesn't take long to replenish the charge consumed by the starter motor, even with all of the above.

Everyone thinks it's the starter motor which drains a battery. But with most modern vehicles, it's the parasitic drain when it's not being used which is the real problem.

[WTFH]

If the battery is close to fully charged before you set off, then it doesn't take long to replenish

Sure, if you only do very short journeys every day, it can be problematic..

If you use the car every day, for reasonable length journeys, then the alternator will do this.

So, what is a "reasonable length journey" that is required for the alternator to keep battery topped up?

And what is your suggested solution to the OP's request of what is a good jump starter to carry in the car in case of emergency?

[DealorNoDeal]

So, what is a "reasonable length journey" that is required for the alternator to keep battery topped up?

5 miles between cranks of the starter motor should do it. Remember, if the starter motor was really a massive drain on a battery, then start-stop would be a non-starter.

And what is your suggested solution to the OP's request of what is a good jump starter to carry in the car in case of emergency?

I wouldn't bother. If you keep the battery charged up then it should be so rare that in the event you could just call the breakdown service. That may be the safest thing to do anyway, especially if you can't think of any reason why the battery may have gone flat.

[d000hg]

If you keep the battery charged up then it should be so rare that in the event you could just call the breakdown service.

Sure if you don't mind a 4 hour wait in the middle of some remote place. And if you don't mind being totally at the mercy of someone else. You should know how to jump-start your car, how to change a wheel in my view.

In our case, the battery was too flat to start the car but running even on idle for 15 minutes was enough to keep it going - we've managed on that basis with no tiny journeys the last week until we can get it fixed.

I'm not sure on all this parasitic drain stuff either, we've left our car for a month before and it started fine.

[ladymuck]

I guess that's why you see people with dashboard solar panels? Just to combat drain if they don't use it too often?

Yep. I have one. There's a cheapo AA one you can get which is ok or you can splash out for something beefier from these guys (https://www.optimate.co.uk/). I have both but haven't used the Optimate one yet. I should probably try it out as the one I got from them has 40W power compared to the 4.8W from AA

I also have a jump starter which I will check the charge on ahead of any trips just in case (https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1). It doubles up as a compressor for pumping your tyres up, which is very handy, and it works well on tyres and airbed mattresses.

[DealorNoDeal]

Sure if you don't mind a 4 hour wait in the middle of some remote place. And if you don't mind being totally at the mercy of someone else. You should know how to jump-start your car, how to change a wheel in my view.

Fair enough but personally I couldn't be bothered investing in a jump starter, or even jump leads for that matter. And, as I said, if you can't think of any plausible explanation as to why the battery should have gone flat, you could be taking a risk driving the car.

Example:
If the battery has gone flat because the alternator has failed, jump starting will get you going and put enough juice in the battery to keep you going for a while but it will only be a matter of time before the engine dies. Imagine that happening on a fast road.

I'm not sure on all this parasitic drain stuff either, we've left our car for a month before and it started fine.

It varies from car to car. I know with mine, if I left it for a fortnight, it would be touch and go whether it started.

[WTFH]

Fair enough but personally I couldn't be bothered investing in a jump starter, or even jump leads for that matter.

Funnily enough, I carry jump leads, tow rope, etc in my car in case I can help someone else. It's not always about me me me.

[DealorNoDeal]

Times when it's probably safe to jump start a car ie. where there's a harmless reason why the battery has gone flat:

• you left the side lights on overnight
• it's been stood for a month or so
• you've only been doing very short journeys eg. ½ mile school run

If you even suspect it could be the alternator, do NOT jump start it. Driving a car with a failed alternator is really dangerous.

[DealorNoDeal]

Funnily enough, I carry jump leads, tow rope, etc in my car in case I can help someone else. It's not always about me me me.

Good for you. However, since I'm hardly ever on the road, there wouldn't be much point.

[DealorNoDeal]

As a cheapskate, if I had to leave the car for any length of time (eg. at the airport), I'd put a fully charged spare car battery in the boot. (I happen to have an old one which is still in fairly good condition.) It's straightforward to hook up jump leads on my car because the battery is in the boot and easily accessible.

I don't know how expensive the jump starters are but a cheap new car battery might do the job equally well. Car batteries can be left on the shelf for quite a long time without losing charge, so you'd only need to charge it up once in a while. If the car's battery is in the boot, like mine, you could even charge the spare one on the road by hooking it up to the car's battery with the jump leads.