Picture this, your Turbo 350 transmission goes out on your 1967 Nova SS. You think to yourself "Hey, I am a capable guy, I have seen that show Trucks, Muscle Car, American Hot Rod, and a video on YouTube that shows how to fix a transmission, I can easily fix it." So you go to O'reilly Auto Parts, buy an engine hoist, take a weekend to disconnect all the necessary hoses and parts, and remove your engine from the car. You look at the flywheel and think "Hey, I think this is going to be more complicated than I thought..." but you ignore that voice in your head, because you are competent...or so you think. You disconnect the driveshaft and, after a long struggle and a few banged knuckles, you finally get that transmission out of the car.
Now, you completely forgot that you needed to buy another hoist for the transmission (because, let's face it, trannys are heavy), and a transmission stand, so you make your way back to the auto parts store. Guess what my friend? They are out of transmission stands. So you buy the hoist and tell yourself you don't really need the stand anyway. You head back to your garage, remove the pan and realize you have no idea what you are looking at. There are gears and vacuum hoses and bolts everywhere. You do your best to tighten the bolts and inspect the gears, but you can't find anything wrong. You spend the remainder of the weekend putting the car back together, after wisely deciding to go to a mechanic.
On your way to the mechanics, your driveshaft disconnects, falls into a pot hole, slams the rearend backward and completely totals your Nova.
You think to yourself "If I had just gone to a mechanic in the first place...this would have never happened..."
TL; DR: go to a lawyer now, it's more expensive in the long run if you do something to screw up your case.
Even though it is a misdemeanor, you still need an attorney. So you pled not guilty - now what? Are you an experienced attorney? Do you know the rules of evidence? Do you know what hearsay is and the numerous exceptions to the hearsay rule? If you go it alone, you'll probably be facing some rookie DA but that DA will probably have had several trials under their belt. I know you don't have cash right now, but having a criminal record will cause you no amount of problems, including for employment. Just ask anyone on this site who cheir criminal record expunged
Mr. Gleason's answer perfectly put it all into perspective. At least, it should have. You do need an attorney, ESPECIALLY if you have evidence to prove you're not guilty. It's not as simple as giving something to the DA and getting the case dismissed. It should be that easy, but sadly is not. You do need to get an attorney to help. If you do not qualify for the public defender, then start looking around for private attorneys in your area. Many offer payment plans which should help fee-wise.
The above stated is advice only, and does not establish an attorney-client relationship.
What you are trying to do is represent yourself (sometimes called "pro per" or "pro se"). California law allows you to represent yourself if you choose to. However, it also requiers the judge to make sure that the trial is fair for pro per defendants. By pleading not guilty you are in essence requesting a trial. A trial is much more complicated then just presenting the evidence that you are innocent. The judge was likely looking out for you when he told you to go speak with an attorney before going to trial.
The best thing you can do is speak with an attorney about the specifics of your case.
Properly handled criminal law [especially a charge that would prohibit you from possessiing a gun for ten years if you were convicted, such as misdemeanor battery] is of the complexity of brain surgery [if it is fully and completely and properly handled], so if you needed brain surgery, would you pull out your Black and Decker and start auguring into your skull, or would you hire a brain surgeon? How you answer that determines whether you should get counsel or do this case yourself.
In general, I agree with the other attorneys posting above - it is usually a horrible idea to represent yourself. That said, the charge is really simple, and for many people hiring an attorney on a case like this may not be worth it. In many jurisdiction, especially with the new realignment law, there is only a very small chance of actually going to jail. So the real risk of doing the case yourself and loosing may only be a few hundred dollar fine (this charge can carry six months jail, so you probably need to find out how seriously it is treated in your jurisdiction). A competent lawyer will charge at least a few thousand dollars to take this case, and probably more if it goes to trial.
That said, there are potentially serious collateral consequences depending on what you plan to do in the future - a 242 conviction will make it illegal to own or possess a firearm. A conviction will also make it difficult for you to enter the military, or become a teacher or lawyer, for example. There may also be immigration consequences if you are a non-citizen.
You probably need to at least speak to an attorney to determine what the actual risks are to you.
There are serious consequences to the charge of battery. Not only jail time, but loss of firearm rights. The rules of evidence control how witness statements get into court so that the jury can even consider them. I would strongly advise you to seek counsel in this case. You likely need to hire an investigator to gather evidence on your behalf.
DA's Offices and the Police are under extreme budget constrictions. Don't expect this will go away without some hard work on your end.
I will keep my answer short. You need a lawyer. A good lawyer would be able to present evidence of your innocence to the prosecutor and hopefully have your case dismissed. Hire a lawyer, show your evidence and see what the lawyer recommends.