Boat batteries are a pain in the ass.
They’re heavy, expensive, and sometimes confusing devices that are certainly nowhere close to the fun part of bass fishing. This all makes them very easy to ignore, but you really should not do that, because you’re not getting very far without one.
“When you go to purchase a battery, you have to have some knowledge of what you’re purchasing,”Tom Jones, who is a veteran mechanic and the Owner/Operator of Wake-Falls Marine in central North Carolina.
“Most of these associates that are selling for these folks, they don’t really know, they’re just a hired hand and they’re going to want to sell you the most expensive battery. That’s their job. There are so many people that end up with a deep cycle battery because it says ‘marine deep cycle’ and it is priced about 50 or 60 dollars more than a cranking battery. So they’re looking at the price and the size and they’re thinking ‘that’s better.’ Well it’s not better. It happens all the time. When people go to buy batteries, they get sold that deep cycle because it says marine on it. It’s not what you need for cranking.”
You don’t have to get a degree in electrical engineering to avoid situations like the all-too-common one Jones describes above, but you do need to know the basics of what you’re buying. There are multiple kinds of marine batteries, all with different applications, and each of those categories can contain batteries with different specs that may make them useless to you if you don’t know exactly what you need.
What is the difference between a cranking battery and a deep cycle battery?
There are two main types of marine batteries, which are designed for different purposes and can be easily confused. A cranking battery is designed to start your motor. It’s built with a larger number of thinner plates in order to release a larger amount of energy all at once. Starting your outboard requires a lot of energy, and you’ll notice the much larger number of amps a cranking battery can produce.
A deep cycle marine battery is designed with a smaller number of thicker plates to release smaller amounts of energy more steadily. This is more useful for powering your trolling motor, which draws small amounts of power over a long period of time. Deep cycle batteries and cranking batteries are not interchangeable. In addition to the performance differences, a deep cycle battery misused as a cranking battery will have a dramatically shortened lifespan.
“Most alternators, stators, and regulator rectifiers [on bass boats] are designed to put out somewhere between 16 and 30 amps. A cranking battery can take that abuse back at it for recharging. Whereas a deep cycle likes to be charged slowly and low. That’s why you see those on a trolling motor with an onboard charger of say two to ten amps. There are some 20 amps out there for the tournament guys that need to recharge quickly. But if you ask those guys, they’re probably going through batteries every two or three years. So it shortens the longevity when you’re constantly feeding it more amps than what it was designed to be recharged. So that’s the biggest difference,” says Jones.
What specs do I need to look for in a boat battery?
According to Jones, the most important thing when buying a battery is being sure that you’re matching the manufacturer’s recommendations. For a starter battery, you want to meet or exceed the recommended cold cranking amps for your particular motor.
Specifically, cold cranking amps (CCAs) measures the number of amps a battery can deliver over a thirty second time period while maintaining a voltage of at least 7.2 at 0 degrees celsius. You’ll also see marine cranking amps (MCAs) on starter batteries, which is the same measurement at 32 degrees celsius. CCAs are the most important measurement to know for your starter battery.
“Let’s just say for instance I have a Mercury 250 Verado. Their minimum spec is right at 1000 cold cranking cramps. So you want to either be there or above. If you’ve got a lot of electronics, you probably want to step it up,” says Jones.
Even though electronics are a slow, consistent power draw, you should never run them off your trolling motor batteries. Always run them off your starter battery or an extra battery. Connecting your electronics to your trolling motor battery(ies) can cause interference on the screen and will drain your trolling motor batteries, which are not being recharged.
“Most bass boats have some pretty big units both at the bow and on the helm, and bass boats don’t get run a lot. They go from spot to spot and they’re relying on that battery to supply all of that current. So a quality battery with a heavy CCA usually has more reserve capacity built in with it. That’s important to look at.”
Reserve capacity is a measure of how long a battery can sustain a constant power draw of a certain amount, usually 25 amps, before it is fully discharged. Think of it as the battery version of how large your gas tank is. This is the more important measurement when you start talking about constant power draws like your screens and trolling motor. If you know how much power your electrical systems draw, there are calculations based on reserve capacity that will give you a decent estimate of how long you can expect to have power.
Once you know what type of battery you need and what specs you need to meet or exceed, you’ve got to pick an actual product. A lot of marine batteries, especially at the lower end of the price scale, are pretty similar.
“I heard somewhere that there are only a couple manufacturers that make batteries for everybody, but they’re just kind of labeled differently,” explained Jones, who is a dealer for Deka Marine and has used them personally for years.
“I think Deka Marine is the best for the money. When I’m looking for a battery, I want a good handle, something that’s easy to get in and get out. I want it to be shaped to fit most battery trays. Its ease of use, how easy it is to get in and out of the boat. There are some that have rope handles, that’s just going to cause problems. A solid plastic handle, there are some that have a built-in handle that’s small, which is nice because it’s easy to carry, but when you’ve got to contort it, you can’t get to hands on that handle when you need to turn it 45 degrees to push it over into the corner. The strap handle that’s plastic seems to work best. You can get two hands on it. You can maneuver it around.”
Favorite Starting Battery: Deka Marine Master
Favorite: Deka Deep Cycle Battery
If you’re looking for something a little higher quality than the standard marine battery, Optima is very popular in the high-end bass boats for good reason.
“Optimas are a gel cell battery. It’s really good for a boat that gets beat up and bounced around because it’s less likely to have issues with the cells. It’s a rugged battery that’s designed to be jumped around and bounced and beat up. But you got to weigh that out with am I really bouncing this boat a lot. Am I seeing a lot of you know, turbulent water. Is it worth the extra money for that? Some people want the best of the best,” says Jones.
- 12-Volt, 750 Cold Cranking Amps, Size: 10 inches x 6 7/8 inches x 7 13/16 inches tall, Weight: 43.5 pounds, Dual SAE & 5/16 inches Stainless Steel Stud Posts. 55 Ah C20 capacity
- Optimal starting power even in bad weather
- Mountable in virtually any position. Works well as a boat battery or RV battery
- Fifteen times more resistant to vibration for durability
- Reserve capacity of 120 minutes for constant performance
- 12-Volt, 800 Cold Cranking Amps, Size: 10" x 6 7/8" x 7 13/16" tall, Weight: 38.4 pounds, Dual SAE & 5/16" Stainless Steel Stud Posts
Should you get lithium batteries for your boat?
One new technology in the world of marine batteries is the lithium battery. Lithium is very much in its infancy and its price tag is there to prove it, but the performance is undeniable.
“They’re coming a long way,” says Jones. “I think they’re awesome because they’re lightweight. For trolling motors especially, I think they’re really good because they can take way more cycles and they offer way more longevity. So weight plus longevity is awesome, but boy does it come with a price tag.”
For now, lithium is only an option to power your trolling motor, so don’t try to use one as a cranking battery.
“Right now it’s just for trolling motors. You’ve got to have a special charger to recharge a lithium, none of the manufacturers to my knowledge have a charging system built into them for a lithium battery so you don’t want to use one as a cranking battery.”
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