70 or 80 amp alternator?


My 1994 Camry needs a new alternator. The original seems to be rated at 70 amps, but an 80 amp alternator is also available. Would it hurt anything to go with the one that has a higher rating? Everything is manual on the car: transmission, windows, seats, and locks.


That will be a 13% higher load on the cables. It might be alright if the cables are overrated to start with, but they might not be. If this is for a different trim line Camry (electric everything) the plugs on the alternator might be different forcing you to do some splicing.


I’ll start by saying that you should replace the alternator with what the car was supposed to have. If it was a 70 amp then replace it with a 70 amp.

I will also say that you won’t hurt anything with installing a 80 amp alternator, the system will only draw what is needed from the alternator.


The 80 amp alternator will do just fine. There will not be a higher load on the cables because the load not the ammeter output, controls the current. If an 80a alternator is available for your car, that’s the one I would get.


Either one will work. Personally, if there is no difference in cost, I’d go with the 80 amp alternator.


When it comes to Toyota alternators I would always go with a direct replacement. If a 70 amp is what it came with and that worked fine for you until now then you should use a 70 amp.

BTW, the most common reason for alternator failure is a bad battery. Make sure your battery is not more than four years old and is checked properly for capacity. A new battery every four years is much cheaper than a new alternator. I learned my lesson on a 1983 Tercel where I “nursed” a 7 year old battery through two alternators. When I installed the third one I put in a new battery and never had a problem again.


If 70 amps is specified, no need to go higher. On American cars a higher amps alternator was always an option; I had a Chevy with a trailer towing package which had a heavy duty battery and an extra large alternator. The rest of the wiring was the same however. Agree that you should buy the best battery you can fit in your car; it makes the alternator’s job easier, and batteries cost a lot less than Japanese alternators. In a mild climate a premium quality battery should last up to 7 years; in the Northern states 4 winters and 5 summers will likely be the best time for change out.


You say that with a dead battery and all the accessories on, an 80 amp alternator is going to produce the same current as a 70 amp?


Another thought is that the alternators could have considerably more differences than the peak current. Some are designed to approach peak curent at a lower RPM than others.


Yes, no, maybe. If the battery is just dead and not internally shorted, then probably it will. Higher capacity alternators are a pretty standard option on a lot of vehicles. The only way it puts more current on the wiring is if some load is drawing more than normal. Your worst case situation above is unlikely to occur and then only for a few minutes as the battery starts to charge up the load will decrease.

I agree with others, if the price and quality are the same, I’d go with the higher rating, but the 70 amp is clearly enough so I would not spend any extra money to get more unless there was some specific reason to do so, like a big stereo with lots of amps and the like.