what would be a good alternator to use to keep battery fully charged while all accessories are on? electric fan pulls 18.5 amp,water pump 6 amp,fuel pump 5 amp and ignition box pulls about 3 amp at 2000rpm. with all accessories and head lights on the battery is pulled down to 11.3 volts after idling 10 minutes and you have to drive a few miles to get back to full charge. using a duralast 72 amp alt. going down the road it works fine,but stop and go it sucks. is there an alt. i can use that will keep bat. fully charged at idle with everything on?

Toyota mine holds 14.4 at idle look for a 89 90 4 runner

does that have an internal or external reg? how many amp?

I run a 85 amp Denso that uses a external reg...
that should be enough for you..... add up all of the
draw(head lights are about 14 amps) and then add about
15% more for the size alt you would need

looks like my draw would be 46amp + 15% would be 53amp. just called a local starter alt. shop,they have a 120amp denso with external reg. for $200 brand new. what do ya think?

internal, 60 amp, got mine fron autozone for about $45 fabed up the brackets

ok, i'll go take a look at what he's got and if something less than 120amp.

I run a powermaster 140...it makes 80 amps at idle. Runs everything and is overkill....but I like overkill. Only $160

Or check these out:

Summit Racing Alternators

I see where Eastwood ( the auto restoration folks) is selling a nice NEW alternator. $199.99 GM 1 wire style. Apparently catered toward street rods & cruisers. They have a nice video on their site explaning the benefits of it. Check it out before you buy. It may work for you.

rather than trying to explain here's a couple links you should read.
remote sensing
one wire / three wire

We run custom made ones from a local guy.

You take him a junk one or anyone for that matter.

And he gives you back a BEAST!!

They run about 75 bucks.

It keeps my race car at 14.5 at idle with a ton of stuff running.

I have also had them on my competition stereos, and they work well!

i would call some local shops and see how much to build you one.

First thing you need to know is how fast you are spinning your existing alternator @ idle. Crank pulley Dia. divided by the Alt. pulley dia. = pulley ratio. Pulley ratio X idle rpm = alt. rpm @ idle. You may not be spinning your existing alt. fast enough at idle, and installing a higher amp output alternator may not necessarily solve your problem. Which ever alt you buy, see if you can get it with an amp output curve. Most drag race alternators have a very fast rise time - lots of amps at low rpm's. What you are looking for is a combo ( alt.& pulley )that will cover your amp load @ idle - and no more. More than that is a waste of HP. BTW, most of the HP loss is in spinning the cooling fan, not in amps. It can be a real "catch 22" if you are trying to do double duty - street and strip. When you get the alternator spinning fast enough to cover all your accessories at idle, at 6500 engine rpm the alternator is spinning over 20K. The rotor usually doesn't last too long at those speeds. Some typical alternator numbers: Max speed for an alternator = 18,000 rpm. They usually reach max output around 6,000 rpm. Alternators perform best from 2,400 - 6,000 rpm with greatest efficiency around 2400 rpm. Sustained alt. speed of 14,000 to 18,000 wastes lots of HP. Also keep in mind that many of the high output ignition systems around these days are "happiest" at 14 volts. They aint high output at 12 - 13 volts.

This is in the tech archives. Pretty good info there.
http://www.moparts.org/Tech/Archive/elec/34.html

1 wire gm 140amp so far so good

I like the Denso because they can take alot of RPM.
The down side is the larger case sizes (larger amp units) are really deep so that makes them hard to mount on a big block in the stock location. I have a 130 Amp unit from a newer dodge truck. It is external regulated and I had to change the pulley to a v-belt pulley. My pulley ratio is about 2:1. I made a simple bracket to mount the alternator up by the intake next to the distrubitor, this location gives the alternator belt good contact with the pulley. Almost 1/2 the pulley is in contact with the belt, so far no belt squeeling has been noticed. As mentioned the power loss is mostly from spining the cooling fan of the alternator, but if it is putting out alot of current it needs the cooling so the alternator does not burn up.

looks like my ratio would be 2.3 and the idle rpm at 1000rpm would be 2300. thanks for the info,i'll check it out. how are the denso's at idle?

went to the alt/starter shop yesterday. the guy pulled out a denso 80 amp from a 4 runner,rebuilt. pulley is correct and should bolt up without to much trouble. he's looking for an internal reg. to mount inside and let me know. $125 total. what do ya think?