Tuning/Buzz Problems with 8 string...dont know what to do anymore

A dying battery won't affect tuning accuracy. on the lowest strings, attack from your right hand is key as well as string gauge. If you prefer lighter gauge strings you have to lighten up on pick attack or strings will boing out of tune temporarily. You can up gauges to circumvent this but the higher you go in gauge you change the tone a little bit, so it's just a balancing act on modifying technique and gauge/setup preference.

 

Always fret the 12th fret with the same pressure you typically use to play to set intonation. If you want to be super precise, lightly fret the 24th fret, if you have it, and adjust that as well... That will get you right on the money. There is nothing wrong with adjusting open notes a few cents lower to compensate for chords going out, many players do that

 

I seem to post the following advice quite often ...

You cannot use a clip-on tuner to set intonation, as a clip-on relies on vibrations in the headstock. When setting intonation you have to play high frets, in which case the strength of the vibration that reaches the headstock is lower.
Because the tuner relies on headstock vibration instead of what actually comes out of the pickups, it can pick up random instrument resonances.
Consider that when you play ar the 12th fret, even if you mute all the other strings, the portion of the played string between nut and 11th fret may be resonating with an obviously bizarre pitch.

It is slowly driving me crazy how clip-on tuners are marketed as, and increasingly considered, acceptable for general use. They are only suitable for quick, easy and rough tuning of open notes, and even then are problematic due to relying on vibration. We should tune what comes out of the pickups because that is the sound the guitar produces.
You need an in-cable tuner.
Cip-on tuners are convenient but sloppy things for players who never do setups.

Also, set action how it needs to be, intonation can always be corrected afterwards. Setting intonation is what corrects for errors caused by a change of action.

 

Hate to tell you the truth, but clip-on tuners are perfectly fine. However, I do agree that using a tuner to adjust intonation is the weirdest concept I've heard since a long time...

 

I've used clip ons to adjust intonation and even then double checked with a strobe tuner and it was perfectly fine. Clip on tuners work a lot better than you think.