For both the case you mention and jump starting, which is done by having a second car alongside the car needing a jumpstart, heavy gage cables with large alligator clips (so called jumper cables) are hooked from the jumper to the jumpee positive to positive and negative to negative. With the jumper running you allow a bit of time to bring up the jumpee battery and then crank it to start.
Personal experiences I'm sure you've had, but don't confuse amplifiers which are designed to do low impedance with someone trying to provide an amplifier more voltage than it's designed for. That's an apples and oranges comparison. By the way, yes my Crown amplifiers for my home theater system can handle and sustain a 2 ohm load, even though that really doesn't have anything to do with feeding an amplifier more voltage than it's generally designed for.
Perhaps you're confusing me with MarcelvdG? 😉 Either way I use to work at both a Chrysler and GM dealerships for a total of 12 years of my life as a service adviser. But they do make booster packs to jump start vehicles, one of the booster packs our dealership had would produce 6 or 12 volts and another one could be adjusted from 12 to 16 volts. Some jumper packs can do even higher voltages than that, but they'er mostly made specifically for racing purposes where higher voltages are needed to crank over high compression engines.
I am not confusing anything, The risk comes down to
- over voltage within 5% tolerance, if they are using 16v parts (at maximum design voltage which is likely to be slightly lower and not sustained) or
- amp is poorly built because it has been rated for a higher voltage then the parts used
- but since car amps need to work at varying voltages, it likely has tolerance built in (16v or more parts etc...)
- nice one with the crown, a commercial product, the original was advertised as a scientific instrument, hardly consumer audio. My point was this particular design feature, general car audio design at a higher standard than home audio
- over voltage within 5% tolerance, if they are using 16v parts (at maximum design voltage which is likely to be slightly lower and not sustained) or
- amp is poorly built because it has been rated for a higher voltage then the parts used
- but since car amps need to work at varying voltages, it likely has tolerance built in (16v or more parts etc...)
- nice one with the crown, a commercial product, the original was advertised as a scientific instrument, hardly consumer audio. My point was this particular design feature, general car audio design at a higher standard than home audio
Ok I'll forget I ever saw multiple 16 volt capacitors being popped at 16 volts after less than a minute once. If you think they don't make cheap, over spec'd parts in the electronics world then more power to you I guess, you're more than welcome to do what you please. All I can say is 1 of the 2 car amps on my bench right now would defiantly show how poor several car amplifiers are built, and the reason why car audio equipment has an extremely high failure rate.
I would be cautious about running it over 16V.
Part of me says that no engineer would specify a max safe operating voltage as the maximum voltage rating of the parts inside.
Then again this is an amplifier designed for use in a car. Nominal 12V, on alternator around 14.5V max.
Now car electronics standards do specify parts that can survive reverse polarity connections, transients up to a couple of times the nominal operating voltage of the car and operation with the engine on and the battery disconnected.
It's basically a toss up. If the JBL engineers have done their jobs correctly it will survive, especially as the 18650s will sag under load.
I wouldn't expect higher output power from the higher running voltage though. I'm assuming an internal boost converter with a fixed output voltage for the power amplifiers. This should remain constant regardless of input voltage (within reason).
The simple answer is to use the diodes to lower the operating voltage.
JBL Stage Amplifier A9004 | Class D Car Audio Amplifier
However says that all stage amplifiers have overvoltage protection implying it will shut down if you give it too much juice. So who knows.
Part of me says that no engineer would specify a max safe operating voltage as the maximum voltage rating of the parts inside.
Then again this is an amplifier designed for use in a car. Nominal 12V, on alternator around 14.5V max.
Now car electronics standards do specify parts that can survive reverse polarity connections, transients up to a couple of times the nominal operating voltage of the car and operation with the engine on and the battery disconnected.
It's basically a toss up. If the JBL engineers have done their jobs correctly it will survive, especially as the 18650s will sag under load.
I wouldn't expect higher output power from the higher running voltage though. I'm assuming an internal boost converter with a fixed output voltage for the power amplifiers. This should remain constant regardless of input voltage (within reason).
The simple answer is to use the diodes to lower the operating voltage.
JBL Stage Amplifier A9004 | Class D Car Audio Amplifier
However says that all stage amplifiers have overvoltage protection implying it will shut down if you give it too much juice. So who knows.
Do 18650's have that flat of a discharge curve to be worried (more than to add a single diode drop)? It would be the only battery chemistry I've heard of -- if it could maintain the 'fully charged' voltage more than the first few seconds, or 10's of seconds, of C/2 or 1C discharge.
Cheers
Cheers