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saand · 12-29-2010, 06:18 AM

I suspect with almost any non stock change you are likely to need to make some brackets to make it fit right.

t Vago Sorry i should have explained the permanent magnets more. Standard alternators adjust the field to change the amount of energy that the alternator generates. A permanent magnet alternator would not be able to do this. To adjust the rate of battery charging it would instead electronically "chop" the output of the 3 phase coming from the alternator and generate a variable output power from the alternator.

pounsfos i like your ambition to make a better alternator maybe others will benefit from your work on it as well. I would expect this will be quite a hard modification so if your after just high mpg i hope this is at the end of your list of mods.
Also regarding your question on the amperage of the alternator, if you have a higher current alternator its likely to run at exactly the same rate as a higher amperage alternator (when your up at a rating or 45 amps). The alternator will produce a voltage of say 15v, the battery will be charged up to an extent. The battery will take whatever charge it wants at the voltage given. If the alternator is unable to supply that charge it will either get damaged or it will reduce the voltage output.

If your designing your new alternator you probably want to design it to suite the maximum working load of the car so whatever the car will take from the battery when the head lights are on, the radio, wind screen wipers, power windows ...
add that all up and the size your alternator to generate at least that amount.
anything else will just increase the rate at which you charge up your battery. So it make give you some ability to take away energy when breaking but i have found with my setup i don't really break all that much, i am typically only having the alternator charge when i am in neutral.
Also you can only force so much current into your battery until it starts cooking. if you put more than 15v on the battery to try to force more current in it will just start to get damaged. Note: electric cars are more able to regeneratively break due to the high voltages and large battery packs.

12-29-2010, 06:18 AM	#9 (permalink)
saand Wiki Writer Join Date: Jul 2010 Location: Melbourne, Australia Posts: 236 bugler - '91 Mazda 626 90 day: 35.89 mpg (US) Thanks: 15 Thanked 25 Times in 22 Posts	I suspect with almost any non stock change you are likely to need to make some brackets to make it fit right. t Vago Sorry i should have explained the permanent magnets more. Standard alternators adjust the field to change the amount of energy that the alternator generates. A permanent magnet alternator would not be able to do this. To adjust the rate of battery charging it would instead electronically "chop" the output of the 3 phase coming from the alternator and generate a variable output power from the alternator. pounsfos i like your ambition to make a better alternator maybe others will benefit from your work on it as well. I would expect this will be quite a hard modification so if your after just high mpg i hope this is at the end of your list of mods. Also regarding your question on the amperage of the alternator, if you have a higher current alternator its likely to run at exactly the same rate as a higher amperage alternator (when your up at a rating or 45 amps). The alternator will produce a voltage of say 15v, the battery will be charged up to an extent. The battery will take whatever charge it wants at the voltage given. If the alternator is unable to supply that charge it will either get damaged or it will reduce the voltage output. If your designing your new alternator you probably want to design it to suite the maximum working load of the car so whatever the car will take from the battery when the head lights are on, the radio, wind screen wipers, power windows ... add that all up and the size your alternator to generate at least that amount. anything else will just increase the rate at which you charge up your battery. So it make give you some ability to take away energy when breaking but i have found with my setup i don't really break all that much, i am typically only having the alternator charge when i am in neutral. Also you can only force so much current into your battery until it starts cooking. if you put more than 15v on the battery to try to force more current in it will just start to get damaged. Note: electric cars are more able to regeneratively break due to the high voltages and large battery packs.