Active guitar pickups (which includes piezo pickups) and all analog musical circuitry benefits from higher voltage. (The benefit is increased headroom). A fresh, regular “AA” battery produces 1.5 volts and that decreases as it loses its charge down to 1 volt where the device stops working. So, in general, if you’re about to record with regular batteries you’ll want to have a fresh charge to maximize headroom.
Unfortunately the “good” rechargeable batteries (NiMh) produce less than that: 1.2 volts. This means they will have less headroom. BUT as the battery runs out of charge it stays more consistent than the regular batteries
Conversely Alkaline rechargeable batteries start out at 1.5V when they are fresh and behave like the disposable ones .. they gradually fade down to 1 volt where the guitar pickup stops producing sound. So while they start at the right voltage they do wind up averaging somewhere close to 1.2%
This means if you are recording in a high-fidelity situation use the alkaline batteries but have a charger close at hand and swap them out very frequently and you’ll be better off than using disposable batteries. But if you’re on the road, and want more convenience then use the more-popular NiMh type.
Keep this in mind if you want to reap the benefits of the alkaline battery: Once an alkaline has used a third of its charge it is producing 1.2V just like the NiCh battery. Then it drops fast so if you want have the benefits of an alkaline battery you’ll have to keep it 75%+ charged. If you have a battery health indicator, that would usually mean when it drops from full to almost-full.
I found this great video that tests NiMh batteries (spoiler alert, Duracell and Ikea’s rechargeable “AA” batteries completely outperform all of the other brands).
Some other info — “AAA” “C” and “D” batteries all operate at 1.5V! they just have different capacities
Alkaline (Manganese-dioxide) and Zinc-Carbon are primary cells that start out with 1.5 volts and then fade down to 1 volt
NiMh is a secondary cell which gives it a nice and even curve. Here is an image showing this:
So if you’d like to get the absolute best fidelity from your recordings, go alkaline! and if you just want to play music and have a more reliable setup go with a Duracell rechargeable battery
(No sponsorship here, though I’ll probably set up an affiliate link in the future when I’m not feeling so lazy after researching this!)