Jump Starting
02-10-2005, 12:14 PM
#1
Burning Brakes
Thread Starter
Jump Starting
In the interim, until I get my electrical/battery drain issues resolved, jump starting is a necessity. While the end result of my 928 running is obviously worth the task, I'm considering getting one of the "jump start" boxes to make it quicker and easier. Has anyone had any bad experiences with these and recommend NOT using one?
If no problems, I've seen two different versions with different cranking amps (+/-350 and +/-600). Is too many amps a bad thing for jump starting? I don't want to create any more electrical problems.
Any suggestions greatly appreciated!
If no problems, I've seen two different versions with different cranking amps (+/-350 and +/-600). Is too many amps a bad thing for jump starting? I don't want to create any more electrical problems.
Any suggestions greatly appreciated!
02-10-2005, 12:16 PM
#2
Nordschleife Master
More cranking amps is always better. You can never have too many.
If your going to go through all the trouble, why not just disconnect the battery when you don't use the care. Couple of rounds of the wing nut, and the battery is disconnected, and all should be well till you come back.
If your going to go through all the trouble, why not just disconnect the battery when you don't use the care. Couple of rounds of the wing nut, and the battery is disconnected, and all should be well till you come back.
02-10-2005, 12:22 PM
#3
928 OB-Wan
Rennlist Member
Rennlist Member
repeated jumping only increases the chance of doing other damage to the electrical system
I agree with Viribus on disconnecting it
have you checked to see if the ground strap isn't itself causing the problem, I've seen this on a couple obs..
I agree with Viribus on disconnecting it
have you checked to see if the ground strap isn't itself causing the problem, I've seen this on a couple obs..
02-10-2005, 12:24 PM
#4
Burning Brakes
Thread Starter
Not a bad idea, but my drain takes place within only a day or two. Also, some stereo mods by the PO make this a little more difficult than typical battery access. I still have some "research" to do and parts to replace, but will hopefully not have this problem in the near future and, weather permitting, will be driving more often.
02-10-2005, 12:24 PM
#5
928 Collector
Rennlist Member
Rennlist Member
Jumpstarting has worked for me from one to another Porsche. However, we KNOW that there is a possibility of frying the LH on later models. On your '81 I see no reason why you couldn't use a defibrilator if you wanted 
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02-10-2005, 12:32 PM
#8
Continual jump starting and using the alternator to recharge battery is not a good idea.Automotive alternators are not designed to recharge totaly dead batteries,they are designed to replace the charge used in starting vehicle and to supply voltage to vehicle when running.Unhook rear ground strap under the tool kit .
02-10-2005, 12:32 PM
#9
Pro
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Too many amps is only a bad thing if you cross the terminals and do some inadvertent arc welding. The ampacity of the booster relates to the amount of energy which is available from the booster's battery bank. Your starter may require 200 amps at 13.8 volts to crank the engine for 10 seconds; but the battery booster has the capacity to provide x number of 200/13.8 bursts of energy, with pauses between each burst to reduce heating of components. Here's some pointers: always make sure you have a clean and solid connection to the positive and negative contact points. Just clipping on an alligator clip only gives a few tiny contact points (at the teeth). The best way to jump start is to use a commercial battery connection terminal. That is a very heavy duty cable set bolted to the battery terminals (or jump starting terminals) which has a big plug on the end. The battery booster box can be modified to accept the other end of the battery cable, which is bolted to the native connectors of the booster and then terminates in a big plug. You plug them together and you have a very efficient connection. Next, make sure that you allow the booster system to flow into the low or dead battery for a few minutes before cranking. Allowing the booster to do a "recharge" will avoid the possibility of collapsing cells within the internal battery. You can easily do this by clipping on and cranking away. Allow some time between cranks. I usually give it about 15 seconds for the first few cranks, then lengthen that pause to 30 seconds. You should feel the cables and battery sides to see if anything is getting hot. If it is too hot to touch then you are cranking too much. (I told an old girl friend this once, but she hit me). Finally, if you need to do a very long time engine crank, say for testing or mechanicals or what ever, pull the spark plugs -- you can usually turn the engine by hand then, but the starter motor will turn it all day long. HTH, YMMV
Dave
Dave
02-11-2005, 12:19 AM
#14
Dave,
Well said, well put!
Spoken like a true 'Ground Pig'.
That Army experience is like the Energizer Bunny,
it keeps going and going ....... pass it on!
You wouldn't have a spare set of NATO male and female connectors would ya?
Well said, well put!
Spoken like a true 'Ground Pig'.
That Army experience is like the Energizer Bunny,
it keeps going and going ....... pass it on!
You wouldn't have a spare set of NATO male and female connectors would ya?
02-11-2005, 01:42 AM
#15
My 81' will drain the battery if it sits for more than a few days, especially in the winter. I got an inexpensive battery maintainer and wired it to my battery and keep it plugged in when I have the car parked. Keeps the battery at full charge, and have not had a problem since I hooked it up.