[dhanushs]

About 6-8 months before, when my battery was on the verge of getting replaced, I have jump started my IKON atleast 10 times, and lots more push starting. I have never faced an issue.

I guess, as long as the jumper cables are secured properly, there is no problem.

In any case, keeping the headlights (electrical load) on is a safe practice.

EDIT: A similar thread exists. I guess its better to merge it. http://www.team-bhp.com/forum/techni...-your-car.html

[ghpk]

MY Car battery is also acting up a little, I might change it in coming months
but to be on safer side, I am again trying to make a D.I.Y. Jump Start cable.

Will be posting full details along with lots of Pics in next 7 to 10 days.

any suggestions are welcome as I would shop for this on coming Friday.

[Aroy]

Originally Posted by ghpk

MY Car battery is also acting up a little, I might change it in coming months
but to be on safer side, I am again trying to make a D.I.Y. Jump Start cable.

Will be posting full details along with lots of Pics in next 7 to 10 days.

any suggestions are welcome as I would shop for this on coming Friday.

. Use good thick copper clamps, desist from getting thin brass ones. You may have to do a bit of hunting at junk shops, as brand new heavy duty clamps may be hard to locate.
. Use thick cable. It should preferably be thicker than the cable to the starter motor, and ideally be at least one car length long. If possible use RED and a BLACK cable, else wind RED tape at both ends of one cable, so that polarity is maintained.
. Get the cable soldered by a Radiator Repair person. They use hard solder for repairs (giving a stronger mechanical bond), and this is better than the softer solder used for electronic work at home.
. Finally after testing, get/make a carry bag of stiff canvas/leather. This is often ignored and the cable gets damaged due to indifferent storage.

Some useful links
Jump-start cable - Conrad Electronic - Jump-start cable

From what I can make out a 25 mm.sq. cable is adequate for most of our vehicles. This translates to around 5.6mm dia conductor, or 6mm to round it off. In case you want a cable longer than 4m, use thicker conductor.

[Sutripta]

Originally Posted by Aroy

. Get the cable soldered by a Radiator Repair person. They use hard solder for repairs (giving a stronger mechanical bond), and this is better than the softer solder used for electronic work at home.

What flux do the radiator repairers use?

Regards
Sutripta

[Aroy]

Originally Posted by Sutripta

What flux do the radiator repairers use?

Regards
Sutripta

It has been over 20 years since I visited a radiator repair person, but I do notice that they have a roaring business still. The flux is a liquid concocted by them, I suspect it has acid as the moment they use it, the copper parts shine like new, and they are careful to use very little of it.

The solder is a hard type, and requires a kerosene blow torch (similar to the Primus stove. I had one till my wife disposed it off, due to non-use), to melt it. They heat the soldering iron with the blow torch, and then apply it to the part to be soldered. A picture of a similar one. Notice the two brackets at each end to hold the iron.

Redirect Notice

[Sutripta]

Originally Posted by Aroy

I suspect it has acid as the moment they use it, the copper parts shine like new, and they are careful to use very little of it.

Acid(ic) flux is OK for electrical soldered joints?

Regards
Sutripta

[mukeshgoel]

Originally Posted by ghpk

MY Car battery is also acting up a little, I might change it in coming months
but to be on safer side, I am again trying to make a D.I.Y. Jump Start cable.

Will be posting full details along with lots of Pics in next 7 to 10 days.

any suggestions are welcome as I would shop for this on coming Friday.

You can buy this for Rs.579/-.

Booster Cable (500AMP) Car battery Jumper | eBay

I (and few other BHPians on Civic thread) have bought it and it is of decent quality.

[Aroy]

Originally Posted by Sutripta

Acid(ic) flux is OK for electrical soldered joints?

Regards
Sutripta

I will do some research on it. As far as I know, all fluxes are acidic apart from having degreasing agents, so that they can clean the metal surface properly. It is only when the flux remains on the metal that it can corrode, but I guess that at high temperatures, all the flux evaporates. I do not see any special requirement in electrical joints, except that it is usually copper and not other metal.

As you know, the metal parts are "pickled" in acidic solution, prior to painting or plating to get rid of all surface contaminants, so acid is not bad.

[Aroy]

Originally Posted by mukeshgoel

You can buy this for Rs.579/-.

Booster Cable (500AMP) Car battery Jumper | eBay

I (and few other BHPians on Civic thread) have bought it and it is of decent quality.

This is a decent buy, but I prefer solid copper clamps to copper plated steel clamps, where the copper can get weathered out if thin, or peel off if thick. SS-Traveller got excellent jumper cable set with solid copper clamps from Bangkok at a comparable price.

[mukeshgoel]

Originally Posted by mukeshgoel

You can buy this for Rs.579/-.

Booster Cable (500AMP) Car battery Jumper | eBay

I (and few other BHPians on Civic thread) have bought it and it is of decent quality.

Please DO NOT buy these cable.

Day before yesterday, I recommended these cables and yesterday I needed them and they did not work.

More on this:

http://www.team-bhp.com/forum/long-t...ml#post2491616

[Aroy]

Originally Posted by mukeshgoel

Please DO NOT buy these cable.

Day before yesterday, I recommended these cables and yesterday I needed them and they did not work.

More on this:

http://www.team-bhp.com/forum/long-t...ml#post2491616

That is one of the reasons I recommend that you make the cable yourself. The procedure is simple
. Get a pair of sturdy clamps. Thick copper is ideal.
. Get starter cable (4-8mm diameter copper core), preferably same quality as in your vehicle, but a little thicker, as you will be having longer cable.
. Go to a radiator repair person and get them soldered.

[condor]

What current should the jump start cable be capable of carrying ? I see cables with different rating - from 100 to 600 Amps. Did try to search for information, but the closest I got was:

100 Amps for 4 cyl engines
200 Amps for 4 -6 Cyl engines
400 Amps for 6-8 cyl engines

Another site mentioned 400-600 Amps for diesel engine vehicles.

While 400 Amps seems a safe bet, it will help to have clarity on this aspect. At least to understand how much should the cable be capable of.

[Aroy]

Originally Posted by condor

What current should the jump start cable be capable of carrying ? I see cables with different rating - from 100 to 600 Amps. Did try to search for information, but the closest I got was:

100 Amps for 4 cyl engines
200 Amps for 4 -6 Cyl engines
400 Amps for 6-8 cyl engines

Another site mentioned 400-600 Amps for diesel engine vehicles.

While 400 Amps seems a safe bet, it will help to have clarity on this aspect. At least to understand how much should the cable be capable of.

More than the current rating; which may mean different ratings for the same cross section for different jobs; you should be concerned about the voltage drop when starting the engine. The normal cable in a car is barely 1.5m long. The one in jump start cable is at least 4 meters long. That it self would mean a heftier cable if the drop is to be same. The easiest method is to double or even better triple the cross section of the existing starter cable in your vehicle. So if you have a 4mm square cable in your vehicle go for a 8 or 12 mm. square cable.

The clamp should be able to carry the current with minimal drop, so get copper clamps (4 of them), preferably heavy duty stuff.

[condor]

@Aroy, thanks, but the points you have mentioned would be easier to understand if I had some figures to use for illustration.

Also, shorter cables are available quite easily (8, 10 or 12 ft), compared to the longer ones. The longer ones are used by professionals (20 - 25 ft).

The current rating is fairly important because it can help you select the right cable. You wouldnt want to end up with a 100 Amp cable when trying to start a large diesel. Like I said earlier, my question was also to understand the rating vs vehicle type.

[Aroy]

Originally Posted by condor

@Aroy, thanks, but the points you have mentioned would be easier to understand if I had some figures to use for illustration.

Also, shorter cables are available quite easily (8, 10 or 12 ft), compared to the longer ones. The longer ones are used by professionals (20 - 25 ft).

The current rating is fairly important because it can help you select the right cable. You wouldnt want to end up with a 100 Amp cable when trying to start a large diesel. Like I said earlier, my question was also to understand the rating vs vehicle type.

. The current rating is based on two parameters - heat and voltage drop. The more the cross section area the less resistance, hence less heating and lower voltage drop. Heating is of lesser importance as the jump start will be used for a few seconds. Voltage drop is more important as it will ultimately reduce the current going to the starter motor, and in extreme cases the starter would refuse to start. Normally a voltage drop upto 0.5 volts is tolerable, more is not recommended.

. Shorter cables are fine, but in emergency (and we are talking of emergency) you may not be able to have the two vehicles side by side. Hence you have to plan for contingency where the two vehicles will be end-to-end. This means that the cable has to be at least your car length and a little bit longer. My hatch is 4m, a large SUV may be 5-6m, so a practical cable will be 6-7m long, though in ideal condition a 2m cable may suffice.

. Given the current drawn by the vehicle you want to start, you can calculate the cross section area for nominal voltage drop over a 7m length.

http://www.seas.gwu.edu/~ecelabs/appnotes/PDF/techdat/CCCofCC.pdf
Current carrying capacity of copper in terms of cross sectional area
American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies

As the figures are for constant use, you can increase the rating by a factor of 5 for short term use. Thus 8 gauge which has a 73A rating can be pushed to 300A. Various options

10 gauge is 2.59mm dia conductor, translating to 5.26 mm.sq, 55A->250A
8 gauge is 3.26mm dia conductor, translating to 8.30 mm.sq, 73A->300A
6 gauge is 4.11mm dia conductor, translating to 13.3 mm.sq, 101A->500A

From what I could gather the current drawn varies from 100A for petrol hatches to 300A for large diesel SUV. The current requirement goes up during cold primarily due to higher viscosity of the engine oil. So a 300-500A rating should be good enough for most occasions.