Portable jump starters

[FiF]

Thesprucegoose said:

Brother D said:

Tried the last one, and it couldn't crank the 3L. How are people able to start 7L diesels with similar packs??

i bought one, never worked when i needed it.

Two dog walkers parked up at the common car park, one of them with a Mitsubishi Shogun with the 3.5L engine. Battery struggling to do much more than engage the starter. Overheard them discussing the logistics of whether it was quicker to go back to one of their homes to get some jump leads or just head a couple of miles down the road to a car spares place and buy some leads.

I offered use of my jump pack link no longer available apparently, sorry, and there certainly were some doubts expressed as to outcome. Connected up, waited a few seconds, first attempt Shogun fired up as if on a new fully charged battery. Both of them reckoned they were off to buy one each. Certainly seems to benefit from waiting a short while between connecting and operating the starter, perhaps revitalizing the engine battery even if only a little.

In practice found it much more useful as a portable power source, e.g. driving the 12v tyre pump, USB charging phones, torch batteries what have you when mains not handy, then charging up the thing itself next day whilst driving.

[AW10]

FiF said:

Certainly seems to benefit from waiting a short while between connecting and operating the starter, perhaps revitalizing the engine battery even if only a little.

I can well believe that. But I do wonder what happens if you leave it connected too long before trying to start the car - can't help but think it will spend too much of its energy trying to charge the dead battery and one would end up with 2 part charged batteries; neither of which is enough to charge the car?

[DuraAce]

I have a couple of these

https://www.hardwarexpress.co.uk/jump-starter-boos...

Started a mates 535d a few weeks ago no problem. Doesn't crank quite as quickly as the fully charged car battery but more than enough to get it going.
Wouldn't leave home without one these days.

Edited by DuraAce on Sunday 4th November 13:24

[FiF]

AW10 said:

FiF said:

Certainly seems to benefit from waiting a short while between connecting and operating the starter, perhaps revitalizing the engine battery even if only a little.

I can well believe that. But I do wonder what happens if you leave it connected too long before trying to start the car - can't help but think it will spend too much of its energy trying to charge the dead battery and one would end up with 2 part charged batteries; neither of which is enough to charge the car?

My technique is connect, extra check to see it's correct way round, count to ten, ignition on, start. First time everytime so far.

[robbocop33]

Just joined in here to add what some have hinted at here, if you're going to buy one buy expensive, buy once!
I think at the last count i must have three knackered cheapish versions of these kicking around my sheds, the ones with lights, toasters, radios etc built in.

[Sheepshanks]

FiF said:

AW10 said:

FiF said:

Certainly seems to benefit from waiting a short while between connecting and operating the starter, perhaps revitalizing the engine battery even if only a little.

I can well believe that. But I do wonder what happens if you leave it connected too long before trying to start the car - can't help but think it will spend too much of its energy trying to charge the dead battery and one would end up with 2 part charged batteries; neither of which is enough to charge the car?

My technique is connect, extra check to see it's correct way round, count to ten, ignition on, start. First time everytime so far.

AA man used this type of device on my Merc 270CDi the other day. He left it a few mins before asking me to start the car. Was completely dead before (hadn't been run for a few weeks) but it turned over fast and started pretty well instantly.

[Brother D]

227bhp said:

GreenV8S said:

Brother D said:

How are people able to start 7L diesels with similar packs??

No idea, but it seems to me the booster would be connected in parallel with a flat battery which would be sucking a lot of current out of it.before you even start cranking. If you get stuck, it might be worth disconnecting the flat battery and starting the engine with just the booster, then connect some jump leads to the flat battery once it is running. I'm skeptical about those little boosters though and surprised by the reports that they work well.

If you're in the habit of flattening batteries, an automatic battery isolator might be a better investment.

Or a brain transplant.
Or read my post above and be a bit more specific about what exactly is happening.

Ah my battery was completely flat. There wasn't anything saying they couldn't be used on a flat battery thou? I ended up having to remove the battery - massive pita (who puts a battery under the electrically driven drivers seat?!??) and then had to sit on a trickle charger for 48 hours...

[227bhp]

Brother D said:

227bhp said:

GreenV8S said:

Brother D said:

How are people able to start 7L diesels with similar packs??

No idea, but it seems to me the booster would be connected in parallel with a flat battery which would be sucking a lot of current out of it.before you even start cranking. If you get stuck, it might be worth disconnecting the flat battery and starting the engine with just the booster, then connect some jump leads to the flat battery once it is running. I'm skeptical about those little boosters though and surprised by the reports that they work well.

If you're in the habit of flattening batteries, an automatic battery isolator might be a better investment.

Or a brain transplant.
Or read my post above and be a bit more specific about what exactly is happening.

Ah my battery was completely flat. There wasn't anything saying they couldn't be used on a flat battery thou? I ended up having to remove the battery - massive pita (who puts a battery under the electrically driven drivers seat?!??) and then had to sit on a trickle charger for 48 hours...

Well you can lead a hoss to water:

227bhp said:

I bought one of these and it works ok apart from one thing. It needs some current (from the car battery) to actually trigger it, so if you've got a battery which is 100% flat they don't work.

Edit to add:
If you read the spec it has a current checker for those who don't know the difference between red and black and + and -. It has to determine which of these you've connected up to before switching it on, so if there is zero current it won't switch on.

The other point is why not tackle the problem at source? It seems a bit ridiculous to spend money on this item when you can't work out how to turn the lights off on a car. On any vehicle i've driven in the last 20yrs or so it makes a noise when the lights are left on, ign off. Failing that (you may be deaf) what about the shiny shiny things at the front and the red glowing things to the rear? Do you not learn from your mistakes or are you walking around in a permanent daze?

Edited by 227bhp on Monday 10th December 09:44

[Hi]

mine works fine on totally dead batteries. I've also used it when the battery has been removed and I've just hooed up the jump cables straight to the battery terminals dangling in the battery tray. It works great!