From the now extinct Bronica website via the Wayback Machine:

Bronica Learning Center :: Batteries

Today, virtually everything man made that measures time uses an electronic timer. Small,
portable timers (watches, pacemakers,etc.) use batteries. All cameras have timers for shutters, and all modern cameras use electronic timers, and therefore, use batteries.

Batteries differ in size, shape and cell type. The type of cell, and its chemistry determines its voltage, voltage stability, useful temperature range, shelf life, and discharge character. When you're looking to put a battery in a Bronica, there are three available cell types

* silver oxide
* alkaline manganese dioxide
* or lithium cells

SILVER OXIDE

It is the recommended battery for all Bronica;ETR-Si, SQ-A, SQ-Ai, SQ-B, and GS-1

The silver oxide battery. It has excellent voltage stability, the best longevity, wide temperature latitude, good shelf life, and a predictable (and comfortable for the power requirements of a camera) discharge character.

ALKALINE MANGANESE DIOXIDE

Next is the alkaline manganese dioxide battery, known simply as the alkaline. It has good voltage stability, reasonable longevity, wide temperature latitude, good shelf life, and a predictable discharge character. It is also the least expensive cell, and works well in all Bronicas.

LITHIUM

The performance of lithiums vary greatly, as there are several types. They can be engineered for high amp draw, and lower shelf life; or low amp draw, but longer shelf life. They have the potential for the highest energy density per volume of any low cost cell, but the trade off has been made, in "consumer" applications, for long shelf life. This allows these cells to be terrific for hearing aids, and pacemakers....but poor for an intermittent high amp draw requirement like a
Bronica.


The following chart outlines the recommended cells for all of the recently manufactured Bronica cameras.
ETR-Si

Best: Silver Oxide 6V(544,PX-28)

Good: Alkaline 6V(544A, Etc.)

OK: Lithium 6V(544L)

SQ-A/SQ-B

Best: 4 Silver Oxide (MS-76)

Good: 4 Alkaline (MS-76A)

Forget it: Lithium

SQ-Ai with AE Finder

Best:
4 Silver Oxide (MS-76)

Good:
4 Alkaline (MS-76A)

Forget it:
Lithium

GS-1

Best:
Silver Oxide 6V(544,PX-28)

Good:
Alkaline 6V(544A, Etc.)

Forget it:
Lithium

* The AE Finders for the SQ-Ai cameras represent an unusual situation. The silver oxide, the tenacious cell that it is, allows there to be a brief period, when it is near exhaustion, where the low voltage threshold of the AE is skirted due to the power demand of the electromagnetic release mechanism. The result is insufficient voltage to
set the correct shutter speed in the Auto mode only. It can occur for a roll of film, or two...so the precaution has been issued to prevent this. This situation is not present in the older SQ-A, SQ-Am, SQ; or the ETR style cameras. It also doesn't affect the GS-1. Keep extra batteries in your camera case.
I have had trouble with Lithium batteries in both my Bronica and Mamiya cameras.