new alternator not charging

[chris-pilling]

hello, im curious to know whats going wrong here! i have a new alternator, its actually a small nippon denso one bought new via ebay. i then changed the pully as i am running a tooth belt system. Now the original pully was alot smaller so im guessing its something along these lines? its charging rate at idle show just under 12volts which i know isnt enough and even when reved it doesnt increase? i seem to remember it dropped more? strange!

any ideas? could it be simply the increase in pully size thats cocked it up? if it needs altering then i'l have to use this one as its made for the car if you get me? could it be the rectifier? im not massively clued up on alternators and there gubbings

any ideas would be very welcome

cheers chris

[aquamini]

Hi Chris i have some old bicycle dynamo's you can fasten to your wheels so you can do away with your alternator i'll drop them off at the weekend,not clueded up either on alternators but i would think increasing pully size wouldn't reduce charging rate....just slow it down,i'll give you a bell tommorrow there's someone in Standish who deals in the nippon alternators he may be able to help Cheers Jon.

[mk1]

Altenators are more sensitive to revs than dynamos, I suspect that this problem is nothing more than a lack of revs due to the larger pulley. My racer Rltenator used to start showing a charge at about 3,500 rpm. The pulley on that was about 3" across.

[chris-pilling]

haha cheers Jon, my lemons have just about run out of charge. im guessing you ran the same system as i am doing Mark ask my pully is about 3inch the type bought from minispares?

iv had the alternator checked and it does charge but at low revs it also has a discharge!? its of a kabota tractor aparently and starts to charge at 700rpm (alternator revs) now if ive increase the pully size then obviously this will inturn increase the required rpm to start charging so say if its two thirds larger then it should start charging at 2100 rpm. however this is all relative to the size of the crank pully in comparison. so anything past that? im guessing it will be the same as what you said Mark? what alternator did you use?

something also confusing is that i have now noticed that the ignition light does not light up when i start the engine? but i have a power probe and if i give it a live feed then it lights up? now is this because of the fact its not charging? but if that where the case then shouldt it stay lit till it starts charging? the bloke who tested it says it must be a wiring problem but im prity sure the wiring is all ok. he also said if there is no charging light then it wont charge?!?

anybody any more ideas than me? voltage stabilizer on the back of the speedo???

[mascher]

On many alternators there is an IND, indicator connection that goes to the charging indicator (ignition light). If this connection isn't made the alternator regulator will not allow the voltage to rise to a charging level. If the bulb fails it will cause the same problems.

Kelley

[chris-pilling]

Hello Kelley, sorry i may sound stupid but what is IND short for?

[chris-pilling]

its ok, i have figured it out now. cheers