FPV Power - The Best Yak Batteries on the Market

7ah, 17.5ah, and 50ah FPV Kayak Power!

These batteries come in three flavours and for size and weight they cannot be beaten.  While there are certainly cheaper options, the benefits outweigh the costs in spades.  This can be a real deciding factor if your kayak is approaching its load rating and you need to shave off grams to get on the water, or equally important ensure your stability on the water.

First of all let's take a look at the specs for each battery:

7ah
Voltage: 7.5-12.6V 
Capacity: 7000 mAh 
Amp Draw: 10A 
Max Cycles: 1600 @ 1A discharge 90% 
DoD Dimensions: 110x80x50mm 
Weight: 455g 
Case: Waterproof hard case IP67 (waterproof only when lead is connected) 
Battery Management System: Built-in short circuit and over current protection with charging and discharging safety cutoff. 
Charger: 2A wall charger
RRP:  $135

17.5ah
Voltage: 7.5-12.6V 
Capacity: 17500 mAh 
Amp Draw: 10A 
Max Cycles: 4200 @ 1A discharge 90% 
DoD Dimensions: 130x80x70mm 
Weight: 915g 
Case: Waterproof hard case IP67 (waterproof only when lead is connected) 
Battery Management System: Built-in short circuit and over current protection with charging and discharging safety cutoff. 
Charger: 2A wall charger
RRP:  $235

50ah
Voltage: 12V 
Capacity: 50,000 mAh 
Amp Draw: 60A 
Max Cycles: 400-800 
Dimensions: 170x140x95mm 
Weight: 3.2kg 
Case: Waterproof hard case 
 Battery Management System: Built-in short circuit protection with charging and discharging safety cutoff. 
Charger: 10A wall charger
RRP:  $599

By comparison, an 18ah lithium battery from one of the major chain stores is $179 and weighs 2.6kg where the FPV Power costs $235 and weighs less than 1kg.  The store bought battery is 2.5 times heavier and you need to buy a charger separately.  Each FPV battery comes with a charger, so after you have bought a charger for the store bought battery the price will be relativelyo on par.  Better, lighter battery for much the same money.  What is left to think about?

Let's now look at a 50ah SLA/AGM.  The weights vary considerably between manufacturers and AGM/SLA because of the internal components.  An SLA/AGM batteries use dense internal materials significantly adding to the weight of the battery.  For pricing I did not use an online only store (like eBay) because some of these will use much cheaper imports that won't give you quite the performance.  Again going to one of the large battery chain stores they provide a 50ah SLA for $169.95.  Sounds a lot chaper right?  The short answer is yes, initially the price of these batteries is cheaper, but there are many other considerations to think about than just price.  Weight is definitely one of these.  The SLA in this example is 14.5kg, which is nearly FIVE TIMES the weight of the FPV-Power battery.

Lithium batteries require no maintenance over their lifespan, while SLA/AGM require some looking after.  Additionally, the life of a battery is measured in charge cycles not years.  So if they are not properly looked after this can significantly reduce the number of charge cycles the battery is capable of, or put another way, your battery will not last as long.  SLA/AGM also don't handle lots of input current well so they are slow to charge while the FPV-Power 50ah charges from dead flat in 5 hours using the 10amps/hr included charger.

Speaking of current, pulling more out of an SLA/AGM will significantly reduce the number of charge cycles it is capable of, again reducing its overall lifespan.  It is recommended that you do not use more than 50% of the total capacity of the battery, so in our example of the $169.95 battery above, you are only getting approximately 25 usable amps.  This could serioulsy impact your time on the water!

Now for the lithium, when you buy a 50ah you get 50amps of usable power because you can run a lithium effectively flat (or at least over 80% of their capacity).  There is another important aspect to this though, and that is current drain over time.  A lithium will maintain a much higher stable output over its use meaning it can power your electrics/electronics longer.  Over time an SLA/AGM will gradually lose output voltage and if your gear requires above a certain voltage to operate (most sounders do) then they will drop out sooner than they would using a lithium.

Here is a quick summary of the differences:

                                                                  Lithium                                       SLA/AGM
Cost                                                                                                                       X
Weight                                                            X
Capacity                                                         X
Depth of Discharge                                      X
Efficiency                                                       X
Lifespan                                                         X

Comparatively speaking, the lithium wins in every category but cost, but you need to consider that over time this may not hold true.  Lithiums offer significantly more charge cycles meaning you will be replacing an SLA/AGM sooner than you would a lithium.  This will be more true if they are not maintained correctly over time which will also reduce their lifespan.  Remembering that we should only run an SLA/AGM down to about 50%, to get the same run time you would need a 100ah to compete with the 50ah FPV battery.  These are not significantly more expensive than the 50ah example (coming in at between $225 and $250 at many retailers - keeping in mind you will also need to buy a charger), weight is an even bigger factor with these batteries coming in at about 25kg.  We are now talking about EIGHT TIMES heavier than the FPV!  Hypothetically a kayak with a load rating of 150kg will lose 1/6th of that to the battery alone, and that's a lot.

These batteries are available from many retailers including Freak Sports or from FPV directly.  Don't forget, if you are a Yak Hunter's Members Program Member, you will get a discount at some of the suppliers.  This alone could cover the cost of membership!
The 17.5ah

This is the 17.5ah battery in my hand.  You can see that they are quite a bit smaller than their counterparts.  You can also buy brackets for them for in hull installation so you don't need to worry about having them floating loose on the deck.  The batteries all come with a "pig's tail" for wiring them to your sounder or other electronics.
The 50ah

While larger than it's baby brother, the 50ah is still small in comparison to its SLA/AGM counterparts.  While it is also heavier, let's see you try to hold an SLA or AGM in one hand!
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