8AH Batteries          15AH Batteries     Battery Accessories      

About Connectors      About Loads     About Battery Chemistry

I offer two sizes of battery box, and with each size the choice of no battery, an SLA (lead-acid) battery, or a lithium battery (LiFePO4). The 8AH box is supplied with two output connectors, while the larger 15AH box comes with three switched outlets and optional USB charging port and optional 12volt cigarette lighter outlet capable of running your air pump or other 12v accessory.

The 8AH battery is appropriate for a single major load, such as a BixFish bait tank or a fishfinder. The 15AH battery can handle two major loads (i.e., fishfinder and BixFish bait tank), as well as powering the optional 12v outlet for intermittent use, such as an air pump, and the optional USB outlet.

15AH and 8Ah Batteries

8AH Batteries

8 AH Battery Pricing










Wired box, without battery


The box for the 8AH battery is truly waterproof, and conveniently holds 8AH or smaller SLA (lead-acid) or LiFePO4 12v batteries. Or it can be supplied with no battery in case you want to supply your own battery.

The maximum battery size that will fit in this box is 6-1/4″ x 4″ x 3-1/4″. If you intend to supply your own battery be sure to carefully check the dimensions.

The battery box comes with two outlets (one is switched, one is not), a lighted switch for the switched outlet, and mating connectors for the two outlets for you to use on your cables.

The box color may be orange as shown, or blue, depending on supply availablilty.

I assemble and wire these boxes to order, and they are easily customized. Contact me if you want something different.

15AH Batteries

15AH BatteryPricing




15AH LiFePO4






Wired box, without battery



Add 12 volt outlet to box



Add dual USB charging port to box


15AH batteries are assembled in what is commonly called a 30-cal plastic ammo box. These boxes are splashproof, but not waterproof.  They are a good fit to the battery, while allowing extra room for more connectors and switches, an optional USB charging port and 12 volt outlet.

The 15AH capacity is sufficient for a 7″ fishfinder and for a BixFish bait tank. A third outlet is available for nav lights or any other desired use. Mating connectors are included.

If you supply your own battery, maximum dimensions are 7-1/2″ x 4-1/2″ x 3-13/16″, including room for the battery tabs.

The standard configuration has 3 outlets. All are controlled by a master switch. One is wired directly to that master, while there is an additional switch off the master for each of the other two outlets.

Optional USB Dual Port Charging outlet, with voltmeter
Optional 12v Outlet

An optional USB Charging Port can be added to the 15AH battery box, allowing you to recharge your phone, or power one or two GoPro cameras. 

A 12v outlet can also be added, to supply power to accessories that use a car cigarette lighter type plug, such as your electic inflator.

Battery Accessories

Battery Accessories Pricing




SD21 Mating (male) connector



SD21 Cable male/female connector set



Battery charger, LiFePO4 and Lead Acid, 2A



Install connector on your charger



Connectors for the BixFish batteries are available. If you are buying a bait tank or transom pump, then the mating connector is supplied, and you don’t need to buy one. And one mating connector is supplied for each output on a battery you buy.

Dual Chemistry 2A Charger

You will need to put a mating connector on a charger if you a charger elsewhere. Remember: the charger must specifcally match the battery chemistry: LiFePO4, or Lead-Acid. A charger for one of these is not appropriate for the other. I offer a 2 amp charger that can be switched to either battery chemistry, and it is supplied with the mating connector wired. 

I can help you pick a charger, ranging from $10 to $30, depending on your desires and needs. If you order the charger and have it shipped to me, I will install a mating connector on it for the price shown, and then ship you the modified charger.

About Connectors

I use fully waterproof SD21 connectors on BixFish battery products. Wiring polarity is positive 12v to pin 1, and ground to pin2.  Instructions on how to wire this connector are shown in the video. With each battery box, I supply mating connectors for the outlets. If you are ordering a complete bait tank, or a transom pump, at the same time, I will wire the mating connector. Also, if you need a connector installed on your fishfinder or other item, I will wire the connector for you for free, if you are purchasing a battery at the same time. You will need to get the item to be modified to me in San Diego, by either shipping it or dropping it off locally.

As I make these batteries up to order, if you need something different in the way of connectors, don’t hesitate to ask.

About Loads

Fishfinder current increases with screen size

How long you can run on a full battery charge depends, of course, on the load on the battery. Unfortunately, it is sometimes difficult to find out what a given fishfinder, for example, actually needs.

The BixFish bait tank pump needs about 0.75amps, so an 8AH battery could be expected to power your tank for perhaps 10 hours (battery makers typically overstate battery capacity). 

A 4″ fishfinder such as the Garmin Striker 4 series consumes about 0.4A, while a 7″ Garmin Echomap might be more like 0.7-0.8 amps, while a typical 5″ finder will be somewhere in between. The best way to determine your current needs is to measure the current, often a difficult thing to do. 

When measuring the current for a fishfinder, make sure the sonar is actually, and the transducer is in water so it won’t overheat and be damaged by running it in the air.

About Battery Chemistry

LiFePO4 Voltage holds up better during discharge

LiFePO4 batteries (pronounced Lithium Phospate) are superior to lead acid batteries, but cost significantly more.

Weight: Typically 1/3rd to 1/2 the weight of a siilarly rated lead acid battery.

Size: somewhat smaller. The cells are about 1/3rd to 1/2 the size of similar capacity lead acid cells, but manufactures often waste much of that size advantage when packaging the battery to a familiar form factor.

Over the discharge cycle, the Lithium Phospate battery will on average have about 12% higher output voltage, because it maintains its output voltage while the lead acid voltage falls significantly more during the cycle. That translates into about 12% higher energy stored in the battery compared with a siimilarly rated lead acid battery. That means your fishfinder, which is a “constant energy” consumer, not a constant current consumer, will run about 12% longer on a given charge. For fishfinders, current *decreases* as voltage *increases*.

For bait tanks, the opposite is true: as voltage decreases during the discharge, current also decreases. More significantly, the pump slows down as well. Thus, a Lithium Phosphate battery will give a much steadier flow of water to the bait over the discharge cycle than will a lead acid battery, keeping the water in the tank turning over at a good rate. 

Conclusion: you can probably get by on a less expensive lead acid battery, but you will get better bait tank results and longer operation from an LiFePO4 battery of the same amp-hour rating.