109A Alternator Upgrade Problems

erikmuntz

New Member
Joined
Jun 20, 2020
Messages
11
Location
California
All,

Swapped a 59A to 109A alternator today. In theory should charge much quicker. The problem is that it is barely charging at all; and today I lost power when driving and had to do a quick battery change to get home. I brought an extra battery out cause I thought something like that would happen.

I have the three wires coming from the alternator, brown w/ red, red from 10mm bolt. I also have a ground wire going from the grounding stud on the back going to the negative of the battery. Checked all connections and they seem fine. I'm going to pick up new red/brown connector tomorrow because that ones a little corroded but I don't think that's it.

The nut that holds the red wire to the battery is touching a piece of the frame just slightly, would that prevent it from charging?

When I reconnected the battery this afternoon after doing the swap I got a pretty good spark and something burned, but I checked all connections for everything and they all check out.

Any ideas and help would be much appreciated. Thanks!!

Erik
 
Unless that red wire happens to be a poorly colored ground wire, it, nor anything else metal on it, should touch any metal component in the Jeep. It could be shorting out and draining the battery faster than the alternator can recharge it. If it gets bad enough, it could start a fire (even with the car just sitting there) and should be taken care of immediately.

Take a picture of it if you're unsure.
 
Alright;

I found that the alternator was bad so got a new one in and installed it. Jeep fires right up but with both of my batteries will not charge above 9V with the alternator. The thing is the alternator is pushing power to the rest of the Jeep, and with all accessories on (light, air compressor, etc) it doesn't die. Even when I use the horn the battery will plummet in voltage but then immediately return to 9V.

My trouble shooting so far:
-the starter and the alternator are on the same fusable link. If it had been blown, in theory, the circuit would be open and wouldn't be able to start
-checked all connections and confirmed no open circuits
-cleaned and added electrical grease to as many of the connectors as possible.

I'm going to have my battery tested at the local Autozone; but I have two of the same type (Altima Red Tops) and have the same problem with both. Unlikely but possible I have two bad batteries.
Any ideas what else it could be if the battery isn't bad?
Thanks in advance,
Erik
 
Does your engine have a good ground strap to the body? Most auto parts stores will bench test an alternator if you bring it in.
Lastly and probably not ant help, I had a boat 5.0L alternator wired wrong by the previous owner and it did something similar to what you describe. I think the output went straight to ground.
 
Been driving around to trouble shoot (what better way) and was able to get to work today ~15 mins and back. Right when I pulled into my drive way my radio turned off, my idle RPMs spiked to 1500. Turned it off and tried to restart it; nothing. Click. Would love some advice from anyone who knows more about this than I. I've:

-tracked down the alternator wires, no bad or open circuit
-tested the batter, perfectly good
-ensured all other major circuits were closed, they were

pretty lost for an explanation on this one. any ideas? No ECU, butter bypass.