I have battery charging issue with my stock 88 10th ae, the battery(confirmed and tested) doesnt get charged, battery terminals measured at 12.88 volt at idle, it barely pass 13v at 4,000 rpm. If I measure from alternator “B” terminal to battery negative, I received 13.3v at idle and 13.4-13.5v at around 4,000 rpm. The normal charging voltage should be 14.2-14.6, anyways my 95 Accord charges perfectly fine at 13.5v at idle.
I will clean all the connection tmr and replace with my spare alternators and see if I can solve this issue.

If none of that works, I may have bad connection somewhere, if that’s the case, is it ok to connect “B” terminal from alternator straight to the battery? It seem 13.5 volt is ideal to generate the charge.

 

I would suspect the alternator before the wiring, so I would definitely try that before you change the wiring at all. It's also worth noting that the stock alternators on these cars don't exactly have a lot of output. When you say "stock", do you mean 100% stock? With an electric fan or even an upgraded stereo you can draw more than the alternator can keep up with. Bad grounds can also cause poor charging.

You can do that temporarily, but I would not recommend it. You're basically creating a straight connection with no fuse / breaker, which is not a good solution. If anything, get a big thick wire (I think stock is 8AWG, go to 4AWG or 2AWG) and do this as a test only. If you find it fixes the charging issue, turn the car off then replace the wire properly.

 

The cheapest thing you can try is cleaning your terminals and connections. I just rebuilt my power wiring harness, and there isn't much in between. Its almost a straight path. I replaced the battery terminals completely. Give it a clean and then check your resistances. Keep in mind that air is an insulator too, so if you have loose connections, that can play a factor.

Also measure from positive post to case ground on alternator for shortest path to show highest voltage. 13.3 is pretty low. If it's an original alternator and not a Chinese core job, I would try to rebuild it with a new voltage regulator, brushes, and bearings. That procedure is described in the FSM if I remember correctly.

 

Found out one of the connector wires was snapped off, cleaned the battery terminals and some of the connections, having my battery charged and will try a test run tmr.