need help with 24volt charging

steven in Tn · Mar 18, 2015

went and had my alternator repaired and hooked it back up today the same way it was hooked up when i bought it, with one wire on the battery terminal of the alt. i am getting 24v to the alt but when i cranked it the amp gauge stays on zero. when i use the glow plugs it shows -30 so i guess the gauge is working correctly. there is two other wire there at the alt but have been cut and wasnt hooked up,but it originally had a generator on it. i forgot to take my volt meter is there anyway it could have been charging but not showing on the gauge?

Jim Guarino Agri-Services · Mar 18, 2015

From your photo, it appears that you have a single wire, self exciting alternator. If you had the alternator repaired, it looks like the repair shop did not try to clean anything up. What did they repair? Possible problems: oil on the slip rings/brushes, wrong regulator, bad diodes, wrong battery polarity.

What machine is this on?
Agri Services

Case450 · Mar 18, 2015

Man I wish I could help ya, but when I take my starters and alternators to the shop in town what rebuilds 'em for me, when they come back they look brand new all clean and nice.

Yours looks questionable.

Put the voltmeter to 'er and see if it's making power I'd guess.

AJ. · Mar 19, 2015

Your machine has two 12V batteries hooked up in series to make 24 volts,clip the negative lead of the volt meter to the negative cable,positive to the main positive cable,note the reading,start the engine and go to 1/2 or 3/4 throttle and check the reading,if the alternator is good the reading will have increased to over 26 volts or more,when the machine was converted they may have used a cable from the starter motor positive directly to the alternator and then the charge would not show on the ammeter,check it with the volt meter first and you will know what it's doing.
AJ

87nassaublue · Mar 19, 2015

Since you have a 1 wire connection to the BATT terminal on the alternator, you won't have a working idiot light or meter. You have a self exciting setup in your wiring so you'll need to check the output with a volt meter to know if it's working. I'm not familiar with that specific alternator, but they all work pretty much the same. I believe the R terminal would be the remote sense terminal if used. If hooked up that should be connected to the 24v source as close to the positive 24 volt post of your battery. The other terminal looks like an "L" or a "1". I Believe that is your "exciter terminal" which would be connected to your idiot light or your amp meter. That one would serve two purposes, to excite the alternator at start up and to indicate via the idiot light or gauge if the alternator is charging. I prefer to hook up all the terminals properly but many choose to try to run it with the one wire. It works but it's not nearly as reliable and you don't have a benefit of any charge indicator. Just my 2 cents.

steven in Tn · Mar 19, 2015

the pic above is before i cared it to the shop. i can see new parts in it and it looks like new now.
i will care volt meter with me and check it out.

steven in Tn · Mar 19, 2015

i get no output at all too the batterys or straight from the alternator with the single wire. not sure how to check it using the other terminals.

AJ. · Mar 20, 2015

When you connected the volt meter to the positive cable and the ground cable of the batteries the meter should show 24 volts,start the engine the meter reading should have increased to over 26 volts plus,you can do the same test at the alternator by connecting one test lead to the Bat + terminal and the other to good clean ground,if the voltage does not increase try exciting the alternator,use a jumper wire momentarily [tip it once]between the Bat + and the L terminal and see if the meter reading increases if it does not the alternator is not charging,what make and model is the alternator,there was no dash warning lights on that machine.
AJ

EricB · Mar 20, 2015

If your alternator previously had a self-excited regulator all you
needed was the one wire hook up but if they replaced the regulator
with the type that needs power to the terminals it will no longer
charge with only the one wire. The simplest way to check if it
charges (with the engine running) is to touch the back of the
bearing cap with a screw driver, if there is magnetism there it's
charging.

steven in Tn · Mar 21, 2015

thanks for the help guys, got it charging.
had to have another hot wire on the 1 terminal.

Bob · Mar 21, 2015

Pretty sure the "1" terminal is actually the "L" (lamp) or "I" (Ign) terminal.

Is power switched "off" to that terminal when the engine is shut down?

If NOT, you may find that the battery drains through the alternator overnight.

AJ. · Mar 22, 2015

So much for that been a one wire alternator,if it was a one wire it would be self exciting and not need the second wire,the 941 with the Prestolite alternator had the exciting power going through an engine oil pressure switch,there was power to one side of the switch,start the engine the switch closed and sent power to the alternator,stop the engine the switch open and the power is switched off,look around the engine for a switch,it will not have one if the OME was a generator unless it was added as the machine has a mechanical oil gauge,as your machine has a master switch you should switch it off for safety/security and as Bob said to save the battery when parking up,is your ammeter showing a charge now?.
AJ

steven in Tn · Mar 22, 2015

(quoted from post at 22:38:54 03/21/15) Pretty sure the "1" terminal is actually the "L" (lamp) or "I" (Ign) terminal.

Is power switched "off" to that terminal when the engine is shut down?

If NOT, you may find that the battery drains through the alternator overnight.

yes, there is no power to anything after u turn the master switch off.

aj, yes the gauge is working now

need help with 24volt charging

steven in Tn

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