Can jump starting hurt. Not only yes but heck yes. When an alternator is charging hard and you have an inductive reactive discharge is introduced into the system from a second motor vehicles starter motor that alternator is vulnerable to transient voltage damage to the voltage regulator and also to the engine ECU unit. This is not theory or conjecture it is reality and here is how you should start a car by jump starting.
Use the car doing the jumping to recharge the battery in the other car. Disconnect the cables then start the disabled car. This stops the sending of a transient voltage spike from the disabled car after it starts into the electrical assembly of the car doing the jumping. To be specific the transient voltage spike entering the jumping cars circuit amplifies and the alternator and then resonates through the jumping cars electrical circuit. You can see this on an Ocilloscope if you are technically oriented or if you wish you could read it in your car's owner manual it's plenty clear and specific. This phenomenon is less pronounced with today's switching power supplies chargers.
Don't do this if you have a bad heart but if you hold your finger on the terminal of the starter solenoid that connects to the starter motor crank the engine then release the key you're going to get a 100 volt + shock.the starter motors solenoid interrupts the positive transient but it does nothing to interrupt the negative oriented transient. The proof of this is in the shock so if you are brave try it. Rectifiers and regularors don't like it much either. Neither do intregrated circuits. The effect acts much like an electronic term called a "tank circuit" and can "ring" the charging car's alternator like The Bells of Saint Mary's. The effect is ugly enough on an oscilloscope never mind your wallet or purse.
The automobile industry tried to counter the effects of transient voltage damage by installing special diodes actually rectifiers in alternators. Those rectifiers are referred to as avalanche rectifiers. And finally, yes, using the starter on an onboard generator eventually takes its toll on house electrical electronics such as refrigerator boards hot water heater boards and anything else that has integrated circuits or transistors in it. This is much of the reason why RV 12volt electrical equipment in the house seems to be so fragile. The very newest motor vehicles contain avalanche rectifiers in the ECU computers and sometimes in the charging circuit the alternator circuit.
Ah yes those little fluorescent stickers with the el cheapo rebuilders stuck on their alternators. the stickers bond both halves of the alternator Shell together to detect whether or not the customer had broken the seal and rotated the rear of the alternator to fit different applications. The stickers that said warranty void if battery not fully recharged before using is a mark of a garbage alternator. We in the rebuilding industry used to laugh and laugh about people that would use these particular stickers. To claim the production of 60 or 70 amps would damage the alternator then your alternator could not recharge a 40 amp maximum charge rate battery + vehicle load and survive is ludicrous. Motorhome alternators frequently start and max their charge rate for hours on end. Motorhome alternators frequently arrived with worn out brushes or blown voltage regulator. 100% were rebuilt with 150 amp rectifier bridges special voltage regulators and St Mary"s Carbon copper graphite brushes. I was forced to discard useless 12-SI Delco "turbine fans" with the old 13-blade fan on the earliest Delco 10-DN alternator. I ENCOURAGED my customers to install my alternators then load them 100% into discharged batter banks
My one-year warranty yielded .6% failure rate note the decimal with 10,000+ remans made with my own two hands. I spent a lot of time with "Big Al" the owner of Renard Rectifier and Frank Oropeza of Transpo Electronics.
Concludes the novel of the month. Any errors are the products of psychotic voice recognition and or clumsy fingers.
But in those long long response time should be taken to clarify that jump starting using a solid-state meaning light weight charger to jump started engine is an entirely different procedure then jump starting from another motor vehicle when its running. The battery charger is far less damaging.
