# Amperage & Alternator question **URL:** \ **Category:** NYSpeed Automotive\ **Created:** [August 19, 2009, 11:58pm UTC](https://forums.speedlife.net/t/amperage-alternator-question/72359 "2009-08-19T23:58:11Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Toda\_Party](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/toda_party/32/7354_2.png) [@Toda\_Party](https://forums.speedlife.net/u/Toda_Party)\ **Post date:** [August 19, 2009, 11:58pm UTC](https://forums.speedlife.net/t/amperage-alternator-question/72359/1 "2009-08-19T23:58:11Z")
So I’m designing an air to water intercooling system. I don’t have the amperage of the electric water pump, the only info I could find was that it operates on 12v…whoop de do. [http://www.frozenboost.com/product\_info.php?cPath=212&products\_id=1001&osCsid=3dad192f9d598397ab6a92c8cc445592](http://www.frozenboost.com/product_info.php?cPath=212&products_id=1001&osCsid=3dad192f9d598397ab6a92c8cc445592) The fan is 12-15v with 3 amps. [http://www.frozenboost.com/product\_info.php?cPath=212&products\_id=1024&osCsid=3dad192f9d598397ab6a92c8cc445592](http://www.frozenboost.com/product_info.php?cPath=212&products_id=1024&osCsid=3dad192f9d598397ab6a92c8cc445592) my list of electrical items in the car are: ## Normal Car stuff ( headlights, radio, etc.) V1 Radar Detector Radiator Fan AC Fan My question is, Will the addition of the above mentioned pump and fan make any noticeable dent in my alternator output, for instance dimmed or flickering headlights, etc from too much current draw? Will I need to pick up a high output/heavy duty alternator? I know when people put together some crazy sound systems they do the heavy duty alternator thing… I’m thinking the small fan and the pump won’t really make a noticeable difference, but I figured i’d make sure… ---
**Author:** ![Cavi\_Mike](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/cavi_mike/32/5217_2.png) [@Cavi\_Mike](https://forums.speedlife.net/u/Cavi_Mike)\ **Post date:** [August 20, 2009, 3:58am UTC](https://forums.speedlife.net/t/amperage-alternator-question/72359/2 "2009-08-20T03:58:28Z")
You’ll be fine with the stock alternator, this setup is only going to draw maybe 10 more amps total. ---
**Author:** ![Jskrapper](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/jskrapper/32/7570_2.png) [@Jskrapper](https://forums.speedlife.net/u/Jskrapper)\ **Post date:** [August 20, 2009, 5:19am UTC](https://forums.speedlife.net/t/amperage-alternator-question/72359/3 "2009-08-20T05:19:14Z")
^^ agreed. If you feel that nervous yopu can either up the gauge of the cable running from the alt to the battery and redo the grounds. (i gained about 7 amps an half a volt at the battery doing that) or get a smaller pulley to OVERdrive the alt. Honestly, this pump will take less draw than the rear defroster, by a lot. I would just roll with what you have since it is at least 70 amps and the VR won’t let you go much higher. ---
**Author:** ![97FormulaWS-6](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/97formulaws-6/32/7384_2.png) [@97FormulaWS-6](https://forums.speedlife.net/u/97FormulaWS-6)\ **Post date:** [August 20, 2009, 5:49am UTC](https://forums.speedlife.net/t/amperage-alternator-question/72359/4 "2009-08-20T05:49:50Z")
Yea, you should be fine; I WOULD find out what size fuse you need to run with that thing though. That’ll give you a little better idea of the normal draw of the pump. ---
**Author:** ![Fry](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/fry/32/7284_2.png) [@Fry](https://forums.speedlife.net/u/Fry)\ **Post date:** [August 20, 2009, 5:58am UTC](https://forums.speedlife.net/t/amperage-alternator-question/72359/5 "2009-08-20T05:58:22Z")
From your link: > This pump is Bosch part number 0 392 022 002 [http://lmgtfy.com/?q=0+392+022+002+](http://lmgtfy.com/?q=0+392+022+002+) First link, click on Characteristic Curve. Looks like it draws about 3.5 amps fully loaded. You should be fine with a measily additional 6 amp draw on the system. :thankyou: ---
**Author:** ![Toda\_Party](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/toda_party/32/7354_2.png) [@Toda\_Party](https://forums.speedlife.net/u/Toda_Party)\ **Post date:** [August 20, 2009, 4:08pm UTC](https://forums.speedlife.net/t/amperage-alternator-question/72359/6 "2009-08-20T16:08:27Z")
word thanks guys. I suck w/ electricity ---
**Author:** ![Hass](https://avatars.discourse-cdn.com/v4/letter/h/51bf81/32.png) [@Hass](https://forums.speedlife.net/u/Hass)\ **Post date:** [August 20, 2009, 5:39pm UTC](https://forums.speedlife.net/t/amperage-alternator-question/72359/7 "2009-08-20T17:39:14Z")
Hum… How do you figure out how long devices will run with a given power supply? What formula is used? Been fucking ages since I did this, however my instructors would kill me for forgetting. ---
**Author:** ![travisn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/travisn/32/5046_2.png) [@travisn](https://forums.speedlife.net/u/travisn)\ **Post date:** [August 20, 2009, 6:23pm UTC](https://forums.speedlife.net/t/amperage-alternator-question/72359/8 "2009-08-20T18:23:40Z")
depends on how well they are built? ---
**Author:** ![Hass](https://avatars.discourse-cdn.com/v4/letter/h/51bf81/32.png) [@Hass](https://forums.speedlife.net/u/Hass)\ **Post date:** [August 20, 2009, 7:16pm UTC](https://forums.speedlife.net/t/amperage-alternator-question/72359/9 "2009-08-20T19:16:35Z")
> [@travisn](#): > > depends on how well they are built? If this was directed at me… huh? :s I know the aH of the battery, I know the Voltage of the Battery. I know the current draw of the item I’m placing on the line, and the voltage as well. Now discounting resistances, in a perfect world… what’s the equation? :X It’s not as simple as… 10aH battery, 12v. Item is a Dildo, which requires 5aH, @ 12v. 10/5 = 2. Dildo can run for 2 hours on 12v battery w/ 10aH capacity? Gotta be a formula for it somewhere ;\ ---
**Author:** ![travisn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/travisn/32/5046_2.png) [@travisn](https://forums.speedlife.net/u/travisn)\ **Post date:** [August 20, 2009, 7:31pm UTC](https://forums.speedlife.net/t/amperage-alternator-question/72359/10 "2009-08-20T19:31:28Z")
oh. sorry. lol. I thought you meant how long it will last. since you were talking about alternators I figured you meant an “endless” supply so I didnt take that into consideration. ---
**Author:** ![Hass](https://avatars.discourse-cdn.com/v4/letter/h/51bf81/32.png) [@Hass](https://forums.speedlife.net/u/Hass)\ **Post date:** [August 20, 2009, 7:34pm UTC](https://forums.speedlife.net/t/amperage-alternator-question/72359/11 "2009-08-20T19:34:38Z")
> [@travisn](#): > > oh. sorry. lol. I thought you meant how long it will last. since you were talking about alternators I figured you meant an “endless” supply so I didnt take that into consideration. Ohh noo 😛 But i figured out that the equation i used about is more or less correct, provided this ebay auction is correct, lol. [http://cgi.ebay.com/ebaymotors/BRAND-NEW-OPTIMA-BLUE-TOP-DUEL-PURPOSE-BATTERY\_W0QQcmdZViewItemQQ\_trksidZp3286Q2ec0Q2em14QQhashZitem1e5809a418QQitemZ130326045720QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories](http://cgi.ebay.com/ebaymotors/BRAND-NEW-OPTIMA-BLUE-TOP-DUEL-PURPOSE-BATTERY_W0QQcmdZViewItemQQ_trksidZp3286Q2ec0Q2em14QQhashZitem1e5809a418QQitemZ130326045720QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories) A.H. (amp hours) 55 RC (reserve capacity drawing 25 amps) 120 min. 25\*2=50, sooo. ya.