Truck idles better with Booster box

[Jeremy_C]

Had to jump off ole blue with the big jump box today. It idles better with that box running 200 amps in start mode.

I'm sure this is a idiot question, but thats never stopped me from asking before.

There was a considerable difference when taking off the hot lead. Sounded like it dropped quite a few RPM.

Think a new battery, battery cables and terminals are in order?

 

[Fordum]

It takes mechanical power to make electricity with an alternator. The more current an alt has to put out, the heavier the load on the engine.

It may just be that the extremely dead battery was drawing more current to charge it up.
The boost box was making up part of the load, and when you took it off, all the load fell on the engine.

However, if the alt is not up to the task, then the voltage may be dropping so low that it is affecting the electronics or the spark.

Only way to tell is to put a voltmeter across the battery, while the engine is running, and see what voltage is getting to the battery.

If its better than about 13.7 or so for a completely dead battery, and not over 14.6 under any condition, then the alt is probably OK.

If you can spare the time, I would charge the battery with a charger, after removing, cleaning, and rehooking all the connections, and then take the truck to a battery type place and get the battery load tested.

But, it needs to be charged before you do.

 

[1BEATK5]

a 63 amp alternator will be workin hard to recharge a dead battery

 

[Jeremy_C]

I put a new altenator on it after it tested bad. I haven't had to boost it off anymore since then. The battery looks to be 2-3 years or more old. I had planned on changing the battery and cables before this cold weather hit but never had the time.

I'll try it again and see what happens before long.

 

[dhcomp]

And remember, as much as we all jump trucks when they are dead, the alternator was never designed to charge a dead battery. Mainly to just maintain charge.