Dead Battery... what's the best solution?
#16
Chronic Tool Dropper
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...If not, the 13-14V from the other car is the same that your alternator would be producing so it shouldn't cause any damage. In fact the second battery and electrical system would be somewhat of a buffer against any starting surge.
This is one of the parts of the discussion that bothers me. If there was zero resistance between the two batteries you'd be OK. But the batteries are separated by jumper cables (typically by cheap 10ga jumper cables), poor clamp connections, the connection (small) between the jump-start post and the starter, and only then the battery cable to the battery. I'd be less bothered if you attached the cables to the battery directly.
...I have never successfully jumped a 928 from a non-running car. Even running cars with small engines can be a problem unless you step on the gas. Jump start packs and running cars work fine on either end of the electrical system.
The challenge in jump-starting comes when two charging systems, two batteries, and wildly varying loads, are connected together with tiny wires and expected to somehow come to a perfect electrical balance between the cranking current and the initiation of charging. All it takes is a little bit of load juggling between the two alternators, one sixth of one alternator revolution as it tries to adjust charging current demands based on sensed voltage, and decides for that instant as current draw changes that it needs full excitation. It corrects itself on the next cycle, but the damage to the brain is done. Probably would only happen once in a while. Worth the risk? Not to me. It's too darn easy to do it correctly and avoid that risk completely.
YMMV, of course. Proceed at your own risk.
#17
Team Owner
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Bob, I agree with your prognosis, I would add a few other thoughts, one keep the battery charged this is first defence to fend off other problems that will arise with low voltage batteries.
Dont try to jump start another car with your 928 unless your jumpers are connected to the 928 battery and the engine is off.
This prevents the old diode board on the your expensive alternator, from killing a diode, you will know in a few days when your battery all of a sudden wornt start the car and its charging at 13.1 or so. SB 13.6 or better.
Dont try to jump your 928 with the jumpers to the hot post, as Bob stated the other elex connections in the car can come into play and since most of the wire connections are 20 years old it wont be like a new car, IE old ground strap connections, CE panel connections, and hot post connections. Its best to connect your starting battery to the 928 battery with the other cars engine off, as this can also spike the brains, we have had to replace a few batteries and then to discover that the brains were also dead, only to find out that the car had been jumpstarted a few days previous, since the battery was dead to begin with.
So if your battery is low charge it with a trickle , and if your not going to be driving the car for over 2 or 3 weeks disconnect the battery and still charge it every few weeks, Keep em flying
Dont try to jump start another car with your 928 unless your jumpers are connected to the 928 battery and the engine is off.
This prevents the old diode board on the your expensive alternator, from killing a diode, you will know in a few days when your battery all of a sudden wornt start the car and its charging at 13.1 or so. SB 13.6 or better.
Dont try to jump your 928 with the jumpers to the hot post, as Bob stated the other elex connections in the car can come into play and since most of the wire connections are 20 years old it wont be like a new car, IE old ground strap connections, CE panel connections, and hot post connections. Its best to connect your starting battery to the 928 battery with the other cars engine off, as this can also spike the brains, we have had to replace a few batteries and then to discover that the brains were also dead, only to find out that the car had been jumpstarted a few days previous, since the battery was dead to begin with.
So if your battery is low charge it with a trickle , and if your not going to be driving the car for over 2 or 3 weeks disconnect the battery and still charge it every few weeks, Keep em flying