What else controls the alternator to charge? New DMW 120 Amp installed, won't charge

[dn010]

Buy a universal battery ground cable at the auto store, you'll obviously need one long enough and one that has loops on both ends and not a battery terminal on one end. Disconnect and bypass the cluster of brown wires with the ground cable, running it from the alternator large post directly to the bulkhead +bolt. Then see what your voltages are.

[David T]

"Back-in-the-day" before cars got so complicated, a quick and "dirty" test of an alternator or generator was, once the motor was running, disconnect the battery and if it kept running it meant the alternator or generator was making at least some electric. If you try that today you risk damaging the sensitive electronics because the battery dampens out the pulses from the alternator and "sinks" or stabilizes the voltage. No need to do that, most auto stores will test your battery and alternator for free.

[Josh]

I remember in highschool shop class we had no batteries. So to get a car going we would start it with a battery charger to the battery leads, then disconnect it after it was running so we could drive the cars around the shop/building.

[Bitsyncmaster]

I remember in highschool shop class we had no batteries. So to get a car going we would start it with a battery charger to the battery leads, then disconnect it after it was running so we could drive the cars around the shop/building.

It would work with no electronics. But the battery acts like a big capacitor and filters the rectified AC from the alternator. Most electronics should have capacitors that filter the car voltage and may work fine but your really testing unknown voltages at different RPM on the alternator.

[Ron]

I remember in highschool shop class we had no batteries. So to get a car going we would start it with a battery charger to the battery leads, then disconnect it after it was running so we could drive the cars around the shop/building.

LMAO! Man, does that bring back memories!...a red shop rag and one of those wide oversize red rubber bands for the hot terminal...
Next up, 6 foot of hose and a can of ether. Makes a car with a bad fuel pump jump like this guy -

And since we're in a playful mood- I hereby promise to never mention disconnecting the battery while the engine is running again, with or without mentioning it is extremely hard on the regulator, underlining it, and stating not to try it, never, ever. So help me God and keep me steadfast in the due and true performance of the same.

[Bitsyncmaster]

My battery disconnect relay disconnects the ground on the AUX relay that powers the ignition then waits one second before turning the battery off.