Ronmar
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On the A1, the polarity protection box is called a LBCD or load and battery connection device if I recall correctly. The “AC “ wire on the regulator connects to the LBCD. The AC lead is actually a field sense wire which is a way to measure alternator load. The LBCD monitors alternator load with this wire and uses this information to disconnect a failed or badly depleted battery so you can complete the mission without burning up a really expensive Neihoff alt.Just saw your post. I have a 2007 A1 that the no charge light just came on. I’m wondering how you resolved your problem and if so share that with me. Checking the voltage on the two leads going to the regulator I have 24 V on the AC terminal and 0 V on the exciter terminal the one closest to the pulley. I jumper 24 V to the exciter terminal and disconnected the wire to the AC terminal alternator putting out correct voltage. Reconnected the wire to the AC terminal Alternator Stop pudding out power. Changed out the polarity protection box no help. Appreciate any pointers she could give. Thanks
A little history: In the A0, Some knucklehead specced a monster battery bank 2-1/2 times larger than the alternator can adequately charge, to meet some perceived military need. So what did they do in the A1, larger alt? Smaller Battery? Nope, they added the LBCD to disconnect the batt and feed it a trickle charge. They finally started in the right direction in the A1R with an alt(you guessed it) 2-1/2 times larger But they kept the LBCD system… You would think this would fix all the alt/batt issues, but it didn’t really as The larger alt was absolutely needed to deal with the introduction of AGM batteries as they require nearly double the acceptance charge current of the wet lead acids the A0 was designed with, so same basic problem was maintained.
Enough History So reconnect the AC wire as it is necessary. The Excite wire on the alt is what tells the alt it is OK to begin charging/providing power after the engine starts. it keeps the alt from trying to charge at low RPM while the starter is drawing hundreds of amps of current. That excite power comes from the de-energized contacts of relay K11 up in the power dist panel(PDP). When you turn on the main sw, K11 should energize, along with the oil loght in the dash annunciator panel. When you start the engine and oil pressure goes above 15PSI, the dash light goes out. That same signal de-energizes K11 and allows it to send 24V to the excite terminal on the regulator to bring the alt online… The first thing I would check is the K11 operation. It should also de-energize when the truck is shifted out of neutral as the neutral relay(K26) is where K11’s power comes from.