My 1990 honda accord recently needed a electrical switch replaced for my ignition, my car is a manual transmission. A honda master technition gave me the part I needed off a 1991 honda accord automatic.
Came home plugged it in, started my car up twice to test it. Worked great, no problems, however later that night, I started my car to drive it home, let it run for about twnty minutes while I was talking with a friend, shut off my car for a moment and when I went back to start it, it would not turn over, I heard a ratatatat sound coming from behind my dashboard, my lights on the dash and the rest of the car are weak, so naturally I think low battery, yes, battery was almost dead, (alternator light was not on, and it's a new alternatot) so I charged battery up to full, tried to start, still no start and lights are still weak. Checked connections from ignition, all check out clear, checked fused and plugs. There was a sound coming from the area of the starter when it was attempted to be started, however I am not sure if weak lights would be an indicator of a bad starter, from past experieinces I have noticed you have full battery power even with a dead starter. Solenoid hasn't given me in problems, checked connections on battery, ground and main, clean, good connection. I am at a loss, thinking battery may be weak, but its only two years old, it has been drained and charged about 30 times in the last two years (forget lights on). ANyone have any ideas?

Put your volt meter on the battery only, try to start, when lights go dim, what is the voltage across the battery. Do you know how to do a voltage drop test, testing one wire or component at a time.

Was the alternator an OEM new or OEM rebuild, that's all I use on Hondas.

Unfortunately I don't have a volt meter, my lights are already dim before I start my car, I try turning it over and the lights almost shut off with that low of power. I took a light up tester, grounded it out and turned the car on and tested literally everything, from the main box, starter, alternator, all fuses. Ignition wiring. The light goes on for everything. The alternator was an OEM rebuild, I had that installed about 5 weeks ago. I would think that when I had my car running that the battery would have been charged by my alternator but I doubt that it is bad. Because my battery registers a full charge, even though lights are dimm. When I first checked it it was dead, well almost dead, I put a charger on it, and in 25 minutes it registered as fully charged. I am used to, (all the other times I have charged it up) it taking about an hour and a half to two hours on manual to charge

News update, I have checked the battery at autozone and they tell me that my battery is good. I went through checking all connections and fuse connections, my light tester came on. (btw the lights are always dim, not just when I am trying to start it). Tested the batter connections, I have good battery cables aparently. Tested the volt ohms on the ELD (electronic level something or other) I was getting power on the hot wire, tested the volt ohms on it, they don't match what was on the book, main is getting 2V when it should be getting 4v and the middle of the three pin plug gets nothing, continuity check reveals hot wire great, middle connector, barely registers.
By pure accident I left the pin connector off and noticed that with it disconnected I still have power to lights and everything, although the lights are still very dim and weak. So I think it's a safe bet to rule the ELD out and the readings I got would indicate either bad wiring or battery maybe,l however with it unplugged and the lights are still weak and still no start, then it is a safe bet that it doesn't have anything to do with what my problem is.

Without a volt meter and a voltage drop test, you are only going to be guessing, I am thinking that you must have heavy corrosion or a bad connection where you cannot see it, maybe inside the bottom of the fuse box under the hood or under the dash, you have to get a volt meter.

It only takes 300 milliamps to make a test light go full bright, its not a good tester in your case. An ohm (continuity) test is no good either, if a wire is frayed and it is only hanging on by one little thread, the ohm meter will say its perfect, but it won't carry enough amps to light up the lights or much of anything.

A small give a way is the dim lights, the light circuit is all prior to the ignition key, in military terms, its on the battery buss, you can turn the lights on without even putting the key in the ignition. Can you check the library for a wire diagram or buy a Haynes manual from Autozone, I am moving so my stuff is packed away already, sorry.

Okay, I tested continuity and all that, so there is no broken, but like you said there may be something hanging by a thread
I am now convinced that the devil is living in my car.
I started pulling wires and plugs off and checking them. And I cleaned my battery cables, which really didn't need to be cleaned, pulled those off and check them too, all OK.
Now however there were four plugs that I pulled, the green one that goes to the thermostat and the three others that were clustered around it next to my distributor. I was told that there should be a ground wire on my thermostat somewhere, didn't find one.
But the devil moved half way out, I got disgusted and gave up finally, snapped everything back together and sat in my car smokin a cig, when just for s and giggles I put my key in and turned my car on, walla! I had full bright lights.
Thinking great something is working, I tried to start it, my heart sank as when I tried to turn my engine over, my light went dim for a brief second like it normally does, but would not turn over, but I maintain strong lights, I'm thinking that maybe I have abad ground or power wire running from or through or into either my starter or the starter solenoid. Neither have given me warning signs before, although a few times my car did take a little longer to start. Can power for lights go through the starter or something like that. Its weird or is it most likely two separate issues.

It has to be a bad battery or battery wire connection, use a set of jumper cables on your own car in place of the battery cables, negative battery teminal to some engine metal piece and the pos battery terminal to the starter connection. The car won't start cause the fuses are not powered but the starter should rotate, maybe the starter is shorted internally, feel the real battery cables and see if one is really warm, turn the key and keep turning to allow a cable to heat up some, use a friend to hold the key in the start position.

I just reread, run another wire from pos battery terminal to the battery cable so the rest of the car can get power and maybe it will start, also is there more than one negative battery ground wire, you may wantto run a redundant ground to the fender or chassis.

If this still acts the same then maybe to battery post is broken internally??

Should I check thefuse that starts the car

Yes. Check all under hood and under dash fuses with a test light or multimeter.