Jump Starting--Any Special Precautions? - PeachParts Mercedes-Benz Forum

shertex · #1 10-28-2006, 09:07 PM

My battery's about to give up the ghost...will take it in early next week and get a new battery.

In the meantime, if I have to jump it, are there any precautions I need to take (e.g. not have the engine of the car with the good battery running when I try to start the dead one). I've done plenty of jump starting over the years, but never with a diesel...didn't know if glow plugs and what not make for special circmstances.

Thanks.

Brian Carlton · #2 10-28-2006, 09:20 PM

The diesel is no different. However, the current required to start is much higher, and, if the battery is totally dead, you'll probably not get enough current through the clamps.

If the battery is very weak, the best solution is to leave the cables connected with the donor vehicle running for about 15 minutes to "charge" the weak battery to a minimal degree. You've got a much better chance with this approach than to just connect 'em and turn the key.

However, the temptation to "just turn the key" is great. If you fail, you'll need to repeat the 15 minute charge time.

If the engine will start very quickly (1 second), then you probably don't need to go the full 15 minutes........or.........if the battery still has some juice in it, a standard jump will be OK.

carnut · #3 10-28-2006, 09:24 PM

Requires a battery rated close to yours in order to have the power to spin a diesel! Maybe a V/8 truck, diesel truck or full sized V/8 car. A diesel requires a certain RPM to fire. A slow cranking cold diesel does NOT like to start. Good thick jumber cables as well. Small gauge cables will get very hot in use on a diesel!

stcbenz83 · #4 10-28-2006, 09:30 PM

Quote:

Originally Posted by carnut

Requires a battery rated close to yours in order to have the power to spin a diesel! Maybe a V/8 truck, diesel truck or full sized V/8 car. A diesel requires a certain RPM to fire. A slow cranking cold diesel does NOT like to start. Good thick jumber cables as well. Small gauge cables will get very hot in use on a diesel!

Not true. I left my fog lights on for 5 hours once. battery totaly dead would only "tick". my friend brought over her Mazda tribute "the small SUV mazda makes" hooked them up, waited 5 mins and jumped perfectly.

as long as u got good compression & of course GP's the cold diesel should be a sinch to start

shertex · #5 10-28-2006, 09:30 PM

Should I leave the engine of the good car running when I start the diesel, or could that damage something (like the alternator) on the good car?

#6 10-28-2006, 09:30 PM

Use two sets of jumper cables for better amperage transfer.

#7 10-28-2006, 09:41 PM

Quote:

Originally Posted by shertex

Should I leave the engine of the good car running when I start the diesel, or could that damage something (like the alternator) on the good car?

I have jumped my diesels from another running car (mostly my POS Jeep) on several occasions without any problems, but I wouldn't want to tell you there is no risk to the running car's charging system. The safest way to do it would be to leave the cables connected long enough to get a decent charge in your battery, then start the diesel with the other car shut off. YMMV.

BTW, I agree that heavy cables with a good connection are important if you want to start the car without waiting for the battery to charge. I have started mine immediately with a completely dead battery by using good cables, I have also had to wait 10-15 minutes when using cheap cables.

vstech · #8 10-28-2006, 10:17 PM

it's best to charge your battery up, then disconnect the cables and try to start. the modern computerized/IC board alternators will fail very quickly with the load a diesel requires to start. if your battery will not take enough of a charge to start, you should disconnect the charging vehicle's neg cable and jump off just their battery with heavy gauge jumper cables.
if you anticipate the need for a jump in the near future, buy a jump kit box and carry it with you whereever you go. get the highest amperage kit you can find, usually around 500apms. it's better than replacing a friends alternator due to your heavy starter draw.
John

shertex · #9 10-28-2006, 10:23 PM

Quote:

Originally Posted by vstech

if you anticipate the need for a jump in the near future, buy a jump kit box and carry it with you whereever you go. get the highest amperage kit you can find, usually around 500apms. it's better than replacing a friends alternator due to your heavy starter draw.
John

What's a "jump kit box?"

vstech · #10 10-28-2006, 10:32 PM

it is a battery with jumpercables built in. they sell them in most autoparts places. wallmart has a few differant styles.
they are not perfect, but they really come in handy.
John