Jump start car using caravan battery box terminals ?

aastek · Veteran Member

Jump start car using caravan battery box terminals ?

Whenarewethere · Guru

One thing is the terminals. What is their cross sectional area mm².

How long is the cable between each battery? Then double it, + & - to calculate wire resistance.

I have installed a 175amp Anderson plug on each battery group to jumpstart myself & the cables can be used with clamps or plugs. Using welding cable, can reach 6 metres. So 12 metres for calculating wire resistance.

If desperate I can use them on the solar panels to reach sun if desperate, with the 175 to 50amp adaptors.

-- Edited by Whenarewethere on Wednesday 25th of August 2021 07:25:48 PM

dabbler · Guru

Just buy a decent lithium jump starter and carry it in the tow vehicle. That way your covered without the van being behind you. By the time you modify the things needing modification then you will have spent more money by far. Redarc have wiring diagrams for jump starting from a dual Battery system if you really want you give it a go.

PeterD · Guru

As Doug (dabbler) said, it will be cheaper to get a jumpstarter than getting cable heavy enough to get a quick start from the van's battery.

bomurra · Veteran Member

Hi Kurt

As others have said, Lithium jump starters are a modern, safer and often cheaper alternative to jumper leads.

Look for one that has the largest storage battery (within reason), plus the other features that are handy like USB outlets, 12V charge ports, Torch, Digital Display, battery check function, carry case, etc.

Look carefully at the respective weights of the units on offer, relative to the claimed battery size, and then make your decision on all of the parameters important to you.

These are small portable units, transferable from vehicle to vehicle, always with you and work almost instantly.

With the van jump start option, you need the van to be present and may have to wait, depending on the cable size you use..

Hope this helps.

Regards,

Bob.

-- Edited by bomurra on Friday 27th of August 2021 02:33:24 PM

-- Edited by bomurra on Friday 27th of August 2021 02:34:04 PM

Craig1 · Guru

Dont forget to actually recharge the jump starter as per the instructions though. Put it in your version of diary and record the last charge date on the box.

Aus-Kiwi · Guru

Go back to battery connection
I put jumpers on there .

Derek Barnes · Senior Member

aastek wrote:
Is it possible or are the terminals to thin to carry that sort of amperage to start a car.

Also remember that some batteries are not able to supply to huge surge of current needed to start the car. The batteries in my caravan (lead calcium) specifically state that they are for both engine starting and deep cycle applications. Most people do not recommend that you use batteries designed specifically for deep cycle applications to start an engine.

Whenarewethere · Guru

Unless you have an utterly dead battery, it will supply about half the amps while jumpstarting. Connect the batteries for a minute or so before starting helps.

The starter motor for my 2.0L petrol engine is 238amps.

Peter_n_Margaret · Guru

We use a standard 125Ah AGM to start the OKA (4L diesel).
I replaced it recently before a trip. The old one was 9 years old and still going fine.
If you have a flat cranking battery you can hook the house batteries to it with any thickness of cables to transfer charge and wait. How long you need to wait will depend on the size of the cables. Small cables might take a few hours.
We have a big cable between the house batteries and the crank battery that are 6m apart. Big enough to allow starting from the house batteries at any time. In fact we had a crank battery fail on a trip about 12 years ago. We started from the house batteries for 3 months until we got home.
Cheers,
Peter

Whenarewethere · Guru

The actual cable for my jumper leads I got from a scrap metal merchant. The old welding cable looked a bit tired but other than that it works a treat. In today's money cost about $20 for 12 metres.

I bought quality Australian made Utilux 2mm thick solid copper clamps 200amps continuous rating.

If you prefer soldering over crimping a heat gun works really well with lead/tin solder.