Which jump starter to get

[EmilysDad]

..... When it comes to jump starting, buying a cheap one with "hot" leads (powered during connection) is not a good choice.

Merc jump started my car with an also ran booster pack ..... that had live leads when connecting.

 

[L John]

Yes they work fine, still not a good choice though as spikes caused when it sparks can cause damage.
It might not be a huge risk but it is a risk that doesn't need taking.

 

[EmilysDad]

Yes they work fine, still not a good choice though as spikes caused when it sparks can cause damage.
It might not be a huge risk but it is a risk that doesn't need taking.

Surely the car's battery will absorb any spike ..... it does in general running. Many years ago I scooter that started getting through more than it's fair share of headlamp bulbs, as it was kick star only, I din't notice a goosed battery. The battery in this case was the surge arrester for alternator.

 

[s5tuart]

As the OP is only in Cambs (I'm in Bedford) I have the battery I took out of my SL when I replaced it with a new one.
I'm fairly sure there's nothing wrong with it, it only let me down once after not having the car running for over 3 weeks, but I like things perfect so it got changed. I kept it so you are very welcome to come to collect it, no charge. Keep it on a trickle charger and it'll turn over anything!

 

[ajlsl600]

The ones I recommended both have internal switching (not powered during connect or disconnect, though the DBPower one can switch back on if left connected after starting) and reverse protection so are better for the electronics than a car to car jump start. The leads are dead during connection unless forced override is selected but that should only be selected after connection, some cheaper ones don't have the same level of safety and protection.

ajsls600 The safest way is to connect a smart charger and wait until it has enough in the car battery to do a unassisted start but that's usually not practical. When it comes to jump starting, buying a cheap one with "hot" leads (powered during connection) is not a good choice.

sound. i will remember, cheers. handy things those .

 

[L John]

Surely the car's battery will absorb any spike ..... it does in general running. Many years ago I scooter that started getting through more than it's fair share of headlamp bulbs, as it was kick star only, I din't notice a goosed battery. The battery in this case was the surge arrester for alternator.

It should yes, not quite that simple though.
Have a read of this...>CLICK<

As a side note, my father once told me it was impossible to get a shock from a 1.5V AA battery if it was just being connected or disconnected to any circuit.
So I said, what about if it was just connected and disconnected to a small coil of wire.
That would be completely impossible he said.
So, off I went to get a wire and wound it around my finger to make a small coil.
Made the wire ends slightly wider than the connections on the AA battery so he could hold the coil between his thumb and finger then squeeze to touch the AA battery.
When he released his grip he got a good shock, around 70 volts was my guess.
The battery was just 1.5V and the wire was just that, a piece of wire, so how could the wire be a different voltage at each end to give a shock?
Clue, back EMF.

 

[JohnArnoldBrown]

I agree that this does sound like black magic, but check out "The Joule Thief". The bit I'm curious about, is how they prevent the device discharging back into the dead battery when the supercaps are fully charged, but still allow the starting current to flow. I'm guessing they have some circuitry that senses the sudden voltage drop across the battery terminals when starting is attempted, and open up the current path, probably with big FETs, at that time. I can't imagine how else it would work.

Damn clever idea, in my opinion. Shame it's so expensive.

 

[umblecumbuz]

For jump starting only, the Sealey unit looks a good investment, especially if you leave you car at an airport for extended periods.

But horses for courses - no good for the other uses I put my Ring unit to when I'm camping off-grid.

The Toolstop price is a match for any of the Ebay listings, so good value.

 

[Frontstep]

I noticed that Costco had one of the large phone charger type battery packs. Not showing on line but they were £60odd .... no idea if they're good or bad

I have one of the Costco ones and it has started my big lump easily, pumped up its tyres, charged a phone and provided a light,
all covered by their amazing warranty, if your not happy take it back.
I took something back 7 years later and they just gave me my money back !!!!

 

[L John]

The bit I'm curious about, is how they prevent the device discharging back into the dead battery when the supercaps are fully charged, but still allow the starting current to flow. I'm guessing they have some circuitry that senses the sudden voltage drop across the battery terminals when starting is attempted, and open up the current path, probably with big FETs, at that time. I can't imagine how else it would work.

Some of the lithium packs do use FETs. Not 100% sure but I think this just has a relay to switch over.
When it gets to 14.4V it switches to give that voltage to the battery, if the car is not started within around a minute or so it switches back off.
If the car is started during that time and the alternator is good, it cuts the power and switches back to capacitor charge mode.
It does discharge back into the battery but not enough to cause any problem.
It can even power the glow plugs on a diesel before turning the key.
Surprisingly it doesn't need a lot of energy to start an engine if it starts within a few seconds but it does need to give that energy over a very short period of time.

 

[LostKiwi]

no good for the other uses I put my Ring unit to when I'm camping

Must resist smutty innuendo... must resist smutty innuendo...

 

[umblecumbuz]

Must resist smutty innuendo... must resist smutty innuendo...

I no unnerstand, no spik the english good.

What is mutty sinuendo?

 

[Wheeler3108]

As the OP is only in Cambs (I'm in Bedford) I have the battery I took out of my SL when I replaced it with a new one.
I'm fairly sure there's nothing wrong with it, it only let me down once after not having the car running for over 3 weeks, but I like things perfect so it got changed. I kept it so you are very welcome to come to collect it, no charge. Keep it on a trickle charger and it'll turn over anything! View attachment 42168 View attachment 42169

Many thanks for the offer Stuart but I want something I can carry round in the boot should I have a problem when out and a battery in the boot is a bit too much .



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[s5tuart]

Many thanks for the offer Stuart but I want something I can carry round in the boot should I have a problem when out and a battery in the boot is a bit too much .



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No problem! It is a heavy lump!!!!