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Thread: Alternator question

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Posts: 1-7 of 7
2009-04-08 19:40:33
Alternator question
Ok so this may sound kinda weird but bear with me for a minute.
my oem alternator died on my way to work a few weeks ago.I had no money for a new one so i used the one that came on my det.After the install i left work.a few days later,my battery exploded.Yea,you read correctly,it blew up as in the neg terminal popped off and spewed acid everywhere.I put my new battery in and wen i checked the charging status of the alt it puts out 19.36 volts!!!So my question is,is there a difference between the jdm and usdm alternators,cuz if so,im gonna need a new oem.If not then i have a serious short somewhere.
2009-04-08 20:40:51
19.36 volts, while high, won't make your battery explode. If you ever have a professional-grade battery charger on, you'll notice a similar voltage. Batteries exploding typically is going to be from an unfused short somewhere. 'Tis the number one reason I tell people to never jump a blown fuse with a paper clip or something "for the time being". Last time I had a battery explode at the shop, our new guy left a ratchet with an extension on the battery, and it shorted the positive to the chassis.

The biggest difference in alternators you'll find isn't going to be different voltages. Pretty much everyone is a +12V system. Amperage however does vary. Some systems come with a 70amp alternator, some with 110amp or higher.

Check for shorts. Even if that isn't your issue, it's good to be certain on something like that. Any wires by the terminals look a little melty? Also, what battery did you have and how old was it? If you can't tell, I'm leaning toward something other than the alt.
2009-04-08 21:52:52
I am an idiot,and i apologize.Me and my coworker looked it up,and indeed japan uses a different electrical system,ie a much higher amperage.at the alt it had 21v,way too much for my12v batt,which leads me to beleive the stator may be bad as well.Anyways im going to get the us spec alt and go form there.There were no blown fuses or relays,and the battery, wires/terminals are new (and gold plated!woo).Im pretty sure the right alt will fix my problem.Thanks for your response tho,i appreciate the help.
2009-04-08 22:10:41
Yep, no problem. 21v from an alt is bad news. I'm still convinced Japan cars use the same 12v system. Amperage could be different though. Thats purely the alternator being built to the needs of it's intended car/engine. Glad you got it sorted out.
2009-04-08 22:54:30
Thanks man.And for the record,an optima red top makes a cool sound wen it pops.lol.i wish i took a pic,the terminal completly unseated itself
2009-04-08 23:16:38
Originally Posted by Power-Shift
Thanks man.And for the record,an optima red top makes a cool sound wen it pops.lol.i wish i took a pic,the terminal completly unseated itself

NICE! A+ work.
2009-04-09 02:59:50
As far as I know Miko sells JDM alternators from RR's, VE's, DE's, DET's. I'm not sure from which motor mine came from, but it's been working top notch!
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