Jump starting?

[Jugster]

Hi
Not sure if this is possible without causing damage?
can anyone answer this please?

Can I jump start my van from the leisure battery to the starter battery? Just wondered in case I wake up with a flat starter battery one day! Thanks.

 

[Spriddler]

I would think that provided that it's only now and again and the engine starts quickly without a lot of grinding over first it won't do any harm. Word on the street is that drawing a starter current from a LB (if it will deliver enough) will damage the battery's internal plates but in very many years I've never heard first hand about that happening.
(In an emergency I fitted a starter battery as a temporary fix to serve as the m/h's LB. It's still going strong after 6 years).

 

[Jamesh]

I think it's the other way round you need to watch deep cycling a starter battery isn't good for it.

 

[Yorick]

I did on mine a few times.

 

[Jev88]

Yes it's possible.
My RV has a solenoid switch on dashboard exactly for this but you MAY find a true leisure battery won't give you the cranking amps. Best carry a lithium battery starter like NOCO. Very small and light

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[chaser]

Yes it's possible.
My RV has a solenoid switch on dashboard exactly for this but you MAY find a true leisure battery won't give you the cranking amps. Best carry a lithium battery starter like NOCO. Very small and light

My ex ambulance as an emergency start button on the panel, only used it once just to try it and yes it joins the batteries together.

 

[Two on Tour]

Yup, have done that as a get out of jail free when the starter battery decides to go west one morning while we were away.

 

[autorouter]

One way to do it is to get a device that will charge the starter battery from the leisure battery over a period of several minutes, so it avoids the huge current surge of a direct connection. Something like this.
Amazon product ASIN B0035FAVI8

 

[eurajohn]

One way to do it is to get a device that will charge the starter battery from the leisure battery over a period of several minutes, so it avoids the huge current surge of a direct connection. Something like this.
Amazon product ASIN B0035FAVI8

Really don't think in the real world that would be up to the job, do you have an idea of the amount of amps a starter requires and how much that device is likely to manage to transfer in a short amount of time?
Best / most likely is that it would blow the fuse on the donor socket.

 

[autorouter]

Really don't think in the real world that would be up to the job, do you have an idea of the amount of amps a starter requires and how much that device is likely to manage to transfer in a short amount of time?
Best / most likely is that it would blow the fuse on the donor socket.

Let's say the starter uses 600A for 30 sec. 30 sec is 1/120 of an hour, so that uses 600/120 = 5 amp-hours.

If this device can run at 10A, it will take just half an hour to transfer that amount of charge. I can think of several situations where it's better to wait for an hour charging the battery than call out a breakdown service out in the sticks.

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[Spriddler]

One way to do it is to get a device that will charge the starter battery from the leisure battery over a period of several minutes, so it avoids the huge current surge of a direct connection. Something like this.
Amazon product ASIN B0035FAVI8

If you look at the reviews the only people who has given it 'Good' are those who say they haven't actually used it yet.
I'm not surprised that every one of those who has used it posted: 'Rubbish', or 'Doesn't work', or 'Waste of money', or 'Don't bother'.
As eurajohn has said, there's no way that a cig lighter socket could deliver a sufficient charging current or capacity in the claimed 'as little as five minutes'.
At home I keep my starter battery charged with a conventional 'Smart' charger connected to the starter battery via the cig lighter socket but the socket is fused at 10 amps so there's no way the the advertised item could charge a battery in as little as 5 mins - especially as the battery will be de facto well discharged otherwise it would have started the vehicle without any need for any charging in the first place.

 

[autorouter]

As @eurajohn has said, there's no way that a cig lighter socket could deliver a sufficient charging current or capacity in the claimed 'as little as five minutes'.

I would entirely agree with that. But the question was

Can I jump start my van from the leisure battery to the starter battery? Just wondered in case I wake up with a flat starter battery one day!

If you have 200Ah of leisure battery, fully charged with solar, this is a method to put some charge into the starter battery. The '5 minutes' thing is a joke, but an hour or two should be enough to charge the starter battery enough to get the engine going.

 

[Jamesh]

One way to do it is to get a device that will charge the starter battery from the leisure battery over a period of several minutes, so it avoids the huge current surge of a direct connection. Something like this.
Amazon product ASIN B0035FAVI8

Waste of money I had one - didn't work....

 

[eurajohn]

I would entirely agree with that. But the question was

If you have 200Ah of leisure battery, fully charged with solar, this is a method to put some charge into the starter battery. The '5 minutes' thing is a joke, but an hour or two should be enough to charge the starter battery enough to get the engine going.

Unlikely I think as to adequately charge a 12 volt battery you need a charge around 14 + or - a bit volts, your fully charged 200AH of leisure batteries are likely to be resting at around 12.7 volts.
I may be wrong but that's my thought, I have however a few times jump started the engine via heavy duty jump leads from my leisure to van batteries and would / will be the way I'll do it should I need to in the future.

 

[Jugster]

Thanks everyone, as per eurajohn, it’s only likely to be an emergency start, so will go with this. I do have solar so unlikely to need a jump, but you never know!

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[gerry mcg]

I thought jump starring off the leisure battery was a no no as it could fry stuff in the EBL / Split charge etc as there was current flowing the wrong way round the system...