My radio in my car will not work

Check in fuse box under hood and dash look for blown fuses and bad starter relays. Also check ground cable from battery this needs to have a good connection. Could be a bad positive cable connection to starter solenoid. Well there's a list of things to check. Hope this helped

Never disconnect a battery with the engine running or when key is on. You can cause a spark (even on the negative) which can cause a battery explosion, and/or you can easily fry the fragile computerized electronics if a power surge were to occur.
That being said, what you did was prove that the new alternator is not putting out any current. Check all your fuses in the power distribution box. Also, a loose or poor connection on the battery or alternator may be the problem. Check that your battery cables still appear in good shape. Check the ground for the battery, and all the engine grounds you can see. Possibly one or more of the maxi-fuses in the distribution box may have blown.
Don't try jumpstarting the car. Take the battery off and have it fully charged up. Then you can resume checking for why the alternator is not working. Good luck.

it could be a fuse,, check in the fuse box under the hood for one that says Start or ignition, if you have zero power to the car, No lights, radio, nothin, check the battery posts , clean them and tighten them up, if they were to bad then the alternator couldn't recharge you battery , try jump starting it but let the powered vehicle run for a while with the cables attached to your car to assist in charging your battery ,, then try and start the vehicle

did you see the smoke before or after you jumpstarted the car? if it was before the cables were hooked up incorrectly and with the switched polarity it can not only kill your battery but also computer components. if the smoke was after the jump start, depending on the car jumped, their alternator could have sent too much amperage to your battery causing an overcharge and you will need to replace it. A battery can turn lights and the radio on with low voltage but it takes at least 12.6 to turn your starter and start the car.

First off check the fuses under the dash. And make sure battery terminal connections are tight and clean.Check for proper tension (roughly 1/2 inch of deflection) on Alternator belt and that belt is present.Sounds like there is a alternator issue.Did your battery light come on while driving? Have a friend jump start you (follow safe jumpstart procedures or you could damage your friends car or yours ie:Ignition key off,Postive cable goes on first when attaching cables,negative cable comes off first when discconnecting cables. Let charge for 15 min or so before trying to start your vehicle ) If it starts look for a battery light on the dash. If no battery light is on then alternator is probably ok and battery is bad (take it out and have it tested at your local autoparts store). If the light is on then you have an alternator problem.To confirm alternator problem check output voltage across battery terminals. Should be min 13.5-14.5 no more than 14.5 If you have to replace the Alternator make sure battery is good and has a full charge and negative batt. cable is disconnected,if not you could potentially ruin you r new alternator

If you have replaced the alternator and the battery has been checked and showed to be in good working condition then the only thing left is either a bad fusable link or cable (negative or psitive) going from battery to engine. You should inspect these cables and there connections. Corrosion on these connections can cause these problems. You also mention that the alternator will not keep car running. It should when you disconnect the negative battery cable while the engine is running.If all connections and cables are good and you haven't replaced alternator then you should do so.

Did he connect the cables wrong? I would have the alternator tested. I've seen bad alternators blow there fuses. If the cables were hooked up backwards, it may have damaged the alternator.

SOUND LIKE DEAD BATTERY.CHECK BATTERY CABLE FOR TIGHTNESS AND FREE FROM CORROSSION AT BATTERY POST AND BATTERY CABLES.MAKE SURE BATTERY VOLTAGE IS 12.5 VOLTS.IF NOT BATTERY NEED CHARGING AND TESTED.IF BATTERY GOOD.SOUND LIKE ALTERNATOR BAD.BEFORE REPLACING OR DISCONNECTING BATTERY CABLES OR BATTERY AND ALTERNATOR.TURN OFF RADIO SO YOU WONT LOSE PLAYING CODE.

There are a couple of factors here:

1. If you noticed the car getting harder to start when warm lately, it could be the starter is bad; a bad starter will work when cold but once it heats up, will require more and more power to turn over
2. Bad battery; a dead battery won't turn the car over even with a jump; it would need a slow charge to work again; even sealed batteries have caps that can be pried open to do a cell check (battery cell checkers inexspensive at the auto parts store) if you have 1 dead cell, the battery needs replacement
3. Corrosion; just because the posts and cables may be clean at the battery, doesn't mean there's no corrosion on the other ends of the cables

Hope this answers your question and gives you a good place to start. All the best.
Greg

Bad cable from alternator to battery?

Also, this sounds suspiciously like one of the cells of the battery are dead...