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Battery types suitable for kayak sounders
2:35PM 28th Aug 13

Battery types for sounders ( fish finders ) on fishing kayaks

Key points:

• Non-rechargeable lantern type batteries – no charger required

• Sealed Lead Acid (SLA) batteries – rechargeable, inexpensive, heavy

• Lithium batteries – rechargeable, lightweight, great for larger sounders, more expensive

Summary: non-rechargeable batteries can be a good option for those in remote locations, but are too expensive for routine use. Commonly available SLA (Sealed Lead Acid) rechargeable systems are affordable and will suit most kayak anglers looking to power small to medium sized electronics packages provided the batteries aren’t run flat and are recharged immediately. Lithium battery technology, especially lithium iron phosphate, will suit kayak anglers looking for significant weight savings, greater reliability, and/or are powering more advanced instrumentation with higher power demands.

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Fishing kayaks are becoming more sophisticated, and one area we’re seeing greater levels of investment is with electronics. It’s now not uncommon to see instruments from brands like Humminbird, Lowrance, and Garmin normally adorning large cabin boats and runabouts attached to kayak decks as anglers seek greater fish finding and navigation capability. No longer is it seen as crazy to fit high powered sounders to kayaks like Viking Kayaks Profish series. In fact most self-respecting fisho’s are constantly looking at ways they can afford the next upgrade.

One factor many need to consider is how to keep these modern fish finders and chart plotters powered. What kind of battery system is most appropriate for my kayak and the electronics I want to run? What is going to ultimately prove the most practical? The most significant factors we need to take into account are: the amount of current we need to supply, the weight of the battery system, how durable it is, and finally how much it will cost us in real terms.

The simplest of all systems is the disposable lantern battery. Connect two 6 volt batteries in series to get the 12 volts needed for the typical sounder and you have a non-rechargeable system that’s robust, uncomplicated, and won’t need recharging. This makes it an excellent option for those paddling and fishing in remote locations where facilities for running chargers are difficult or impossible to find. Since each battery pack is discarded once flat the system becomes expensive, hitting both the pocket and the environment hard.

The next most common system is to use SLA (Sealed Lead Acid) rechargeable batteries. These are not unlike the batteries used to start your car, but instead of having liquid electrolyte (acid) flooded around the internals it’s contained in a gel or glass fiber mat. This means SLA batteries won’t leak if tipped over, and in fact can be run on their side or even upside down if needed.

Like all battery systems they have their peculiarities that need to be taken into account:

1. They don’t like being run flat. In fact most don’t like having more than 40-50% of their charge used before being immediately and fully recharged.

2. They don’t like being charged too fast. Plug them into a normal car battery charger and you run the risk of popping their seals (causing them to leak) and creating bubbles on their plates that permanently reduces their capacity to hold a charge.

3. SLA batteries are reasonably heavy. Like a car battery they rely on the reactions between lead plates and the acid electrolyte, and lead is a heavy substance. In basic terms, the more lead present the more capacity the battery has, but the heavier it will be. The common12 volt 7 amp hour battery weighs 2.5kg while a 12 amp hour suitable for running larger instruments weighs around 3.9kg.

Though weight is a penalty, the big advantage of SLA battery systems is price. Batteries and chargers start at around $40 each depending on size, and if properly used and maintained will give several years of service. They’re also easily recycled so are a good option for the environmentally conscious.

Lithium technology is the latest rechargeable system to become a viable option for kayak anglers. In suitably sized batteries it commonly takes two forms:

1. Lithium cobalt oxide (similar to the batteries found in your cell phone) – these are very light weight for the amount of charge they hold, but can pose a serious fire risk if the case containing the battery components is damaged allowing exposure to air. They can also be fast-charged, but in the process they heat up making their removal from plastic kayaks during the process essential.

2. Lithium iron phosphate – slightly less energy dense than the LiCoO2 batteries above, they’re faster to charge than traditional SLA batteries, and more significantly pose a much smaller fire risk if damaged or not maintained appropriately. LiFePO batteries are the lithium batteries of choice for kayakers wanting light weight or a top performing installation for high drain instruments.

Lithium battery and charger systems are more expensive than traditional SLA systems (e.g. $320 for a 12 volt equivalent 10 amp hour LiFePO battery and charger) but offer some very significant advantages. Weight is reduced from 3.9kg to 1.7kg, and the capacity is more than double (remember SLA batteries shouldn’t be flattened more than 40-50%). Properly maintained lithium batteries also have a greater life expectancy than SLA batteries, lasting several times longer.

In summary:

• non-rechargeable batteries can be a good option for those in remote locations, but are too expensive for routine use.

• Commonly available SLA (Sealed Lead Acid) rechargeable systems are affordable and will suit most kayak anglers looking to power small to medium sized electronics packages provided the batteries aren’t run flat and are recharged immediately.

• Lithium battery technology, especially lithium iron phosphate, will suit kayak anglers looking for significant weight savings, greater reliability, and/or are powering more advanced instrumentation with higher power demands.

Looking for a new sounder but can’t decide which way to go? Want to find out which battery is best suited to your sounder, GPS, or Chart Plotter? Get in touch with local Viking Kayaks fishing specialist Stephen Tapp for more advice.

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