What is a True Deep Cycle Battery?

Having briefly touched on the topic of deep-cycle batteries in our article on dual-purpose batteries last month, now seems like a good time for a more in depth look at these often-unsung heroes of work and play.  Sort of like a janitor, you only notice them if they’re doing a poor job. These days deep-cycle batteries are used in so many applications, it’s no wonder the industry registers in the multi-billion-dollar range. From recreation like golf carts and RVs to heavy industry like forklifts and UPS systems, deep-cycle batteries are everywhere, keeping the world running. At this point, it’s safe to say we could not live without them.

The simplest definition of a deep-cycle battery is a battery that can be discharged constantly until it reaches the maximum depth of discharge recommended by the manufacturer and then recharged before the process is repeated again and again. A car battery could never be subjected to this type of application and last very long. But why?

Served on a Plate, or by a Plate

A true deep-cycle battery will differ greatly from most standard automotive batteries due to the composition of the individual plates inside the battery. Automotive batteries utilize sponge lead, lead that has gone through a special process so that it becomes like a sponge. Sponge lead has a lot more surface area which allows for energy to flow out of the battery more readily for cranking an engine. The downside of the material is that it’s weak and subject to rapid sulfation.

Most deep-cycle batteries are made with flat plates, or in some cases cylindrical tubes. If the battery is well made, these plates, thick with ample active material, are well cured so they’re neither brittle nor mushy. Curing time is critical to ensure long-life and resilience. Some manufacturers cut corners and the curing process is rushed which can lead to early failures. Remember Murphy’s Law. Fullriver plates undergo a 10-day curing period, one of the longest in the industry where the standard is 1-3 days.

A Tight Fit

After the plates are finished, they are ready to be installed in the battery case. For a typical flooded cell battery, they are simply set into place. But for an AGM battery, the glass mat material is intentionally bulky and must be compressed to fit into the case. Once the electrolyte is added to the cells, the glass mat expands, further wedging the plates into the cell housing. This greatly mitigates against the inherent vibration of applications like electric vehicles, or a pallet jack going down the road in the back of a semi-truck.


The next step in assembly is to connect each of the individual 2-volt cells in the battery together to whatever nominal voltage the battery is supposed to be. 3, 2-volt cells for 12 volts, 4 for 8 volts, 6 for 12 volts, and so on, ad infinitum. Most manufacturers accomplish this inter-cell connection by punching a hole between the plastic separators (partitions) that divide these cells, and basically bolting the cells together. This method has one serious short-coming, upward movement of the cell pack. If a battery bounces up and down, the cell connection is subjected to stress where the partition inhibits this movement, and a dropped cell is common. Instead of a 12-volt battery, you’re left with a 10- volt.   

Fullriver uses a method of cell interconnection called over-the-partition (OTP). Instead of punching through the plastic partition, the cell connections go over each partition. By linking each cell with OTP welds, if the cell pack wants to move upward, the inter-cell connections are not stressed by slamming into the plastic partition. That’s not to say the pack is free-floating, it’s just allowed some wiggle at these critical connection points.

The thing about battery cases…

The case of the battery is the next critical component we shall examine. It doesn’t sound very exciting, but you can be sure it matters more than you might first imagine. Have you ever been told not to put a battery on concrete? That’s not true anymore unless you have a battery that’s really old but was related to the type of case batteries used to be made with, rubber. Today, battery cases are made from a few different materials.

Many automotive and some deep-cycle batteries use polypropylene cases. To begin, PPO is not very puncture resistant. The lid on a PPO case is heat sealed to the top of the battery. Heat-sealing is problematic because it is vulnerable to failure when in hot environments. In the case (pun intended) of a valve-regulated battery this weakness effects the overall operation of the battery. The psi rating of the valves on top of the battery, which allow air and moisture to escape the battery, cannot be too high or there’s a risk of case failure, either by rupture or deformation. In turn, the lower psi setting of the valves allow them to open more often, which allows for more moisture to escape from the battery. When a sealed battery dries out, it’s game over.

Fullriver battery cases are made with ABS plastic. While that may not sound very sexy, ABS solves a lot of the problems inherent in PPO. First, the lid can be epoxy sealed to the case, which is much stronger. If you want to take the lid off an ABS case, get out your angle grinder, because it’s not going anywhere otherwise. This allows for, you guessed it, higher psi settings on the valves. The valves open less frequently and thereby retain more water for the life of the battery. Oh, yeah, and ABS is incredibly resistant to drops and punctures.

DoD: Dispatching Myths

It is all too common today to be reading on some forum or in the marketing literature of a “new battery technology” that deep-cycle batteries cannot be discharged more than 50% of their rated capacity. In other words, they would have you believe that a 100Ah battery is really only a 50Ah battery because one must never discharge below 50% (Gasp!) If you happen to own a battery and the manufacturer has stated not to discharge below 50%, by all means follow their advice. Generally, with most respectable manufacturers, they allow for discharging to at least 80%. Every Fullriver battery is life cycle tested to 100% DoD. Meaning, every battery Fullriver makes, is tested from day one to its full rated capacity, 100% DoD, until it finally gives up and quits.


We’ve examined some of the more critical parts to a true deep-cycle battery. However, there are so many other things that Fullriver does to ensure the highest quality, longest lasting deep-cycle battery that it’s just not practical to examine every one of them in fine detail. In passing, here’s a few of the other details worthy of mention. All Fullriver batteries in our DC Series have a 10-year design life. All our terminals in the DC Series are made of highly conductive brass to reduce heat/resistance.  Our batteries offer some of the highest cycle life in the industry. For longer life, and faster charging, we use 99.994% pure lead in every battery we make.

And that, in our experience, is what make a true deep-cycle battery. Attention to design details, rigorous manufacturing standards, and the best components. It’s not any one thing by itself, but the sum of its parts that makes it great. 

Sustainability, Reliability, or Both?

Fullriver believes at its core that lead-acid battery technology remains the most sustainable and reliable iteration of energy storage technology. Recently, much acclaim and ardor has surrounded lithium battery technology. At the same time, older battery technology has been dismissed out of hand as dying and irrelevant.  So much so, that one of the largest golf cart manufacturers has switched entirely to lithium for their carts.  According to Plato, knowledge is justified true belief. Today we will examine these technologies in terms of their reliability and sustainability to hopefully add knowledge to our belief.

Ease of Recycling-

Lithium: As it currently stands, lithium batteries are both very difficult to recycle and very expensive, with very few of the residual materials from this process able to be reused.  Current estimates are around 15-20% of a lithium battery is reclaimable.  It doesn’t require much insight to see what this means in the long-term, lots of landfill waste, and a constant quest to mine new materials from the earth.

Lead-Acid: It is well documented that one of the most recycled products is the lead-acid battery. Lead Acid battery recycling is one of the best examples of true circular economy. Very few products/materials outside maybe aluminum / steel are recycled at this level. Even everyday materials like paper, cardboard, and plastics have a long way to go to achieve a similar recycling success as lead batteries. Quite remarkable, as much as 99% of a lead-acid battery is recyclable. And not only is it readily recyclable, but a lead-acid battery is almost always recycled because of its inherent value. Lead-acid recycling is so valuable, a whole industry exists that continually seeks it out.

Consumption of Raw Materials-

Lithium: The raw materials in lithium batteries require intensive mining processes to obtain. Because much of these materials cannot be re-used, this mining will go on and on to satisfy the skyrocketing demand for lithium batteries. 

Lead-Acid: To produce a lead-acid battery still requires mining of raw materials, this demand is held in check by the abundance of recycled materials used to make today’s batteries. Up to 80% of the lead in a new battery can be of recycled origin. It is possible that the lead in new batteries today in some part has been in use for a hundred years.  

Energy Consumption-

Lithium: To produce a lithium battery it requires 450 kWh for every 1 kWh of capacity.

Lead-Acid: In stark contrast, it requires 150 kWh for every 1 kWh of capacity to produce a lead-acid battery.


Lithium: While the individual lithium cells themselves are very reliable, the layers of tiny electronic components like pcb’s, composed of diodes, resistors, and mosfets, are lithium’s pinch point. The failure of any one of these components, and it’s lights out for the battery. This is one reason that many mission-critical applications have not yet adopted lithium.  Even Nasa still uses a very pricey lead-acid type battery to this day (silver-zinc). Murphy’s Law is alive and well.

Lead-Acid: A good analogy to understand the reliability of lead-acid batteries can be borrowed from the appliances of yesteryear. Major appliances like refrigerators and washing machines had much longer lives than their modern counterparts. Even buying a top-tier brand appliance today seems to have only a nominal impact on the reliability. In contrast, a lead-acid battery has no electronic components, it simply does not need them to do its job. 


Lithium: In general lithium cells are advertised by their manufacturers to be capable of anywhere from 1000-2500 cycles at 100% DOD depending on the producer. While this accounts for individual cell performance, it does not take into account the overall pack reliability.

Lead-Acid: One of the oldest and mostly widely used battery technologies, great advancements are being made to increase the usable life of lead-acid batteries. New designs like the Fullriver EGL Series, cost 35-45% less than lithium batteries of comparable quality, while offering ~1,000 cycles at 100% DOD.


Lithium: The cost of a lithium battery was one of its first barriers to adoption. But lithium proponents argued that scale would translate to lowered costs. The opposite is true. With giants like Tesla increasing production by 80% in 2022, the cost for raw materials has increased by 15-20% in January of 2022 alone.

Lead-Acid: While it cannot be said that lead has remained stable, compared to lithium it is relatively stable. A robust recycling sector helps to buffer much of the potential for instability in cost. The cost of a lead-acid battery of reputable quality (cheaper is available, but quality may be sacrificed) is 35-70% less than that of a lithium battery from a reputable producer.

When broken down side-by-side, the truth is, lead-acid batteries may experience some displacement, but they will continue to be a valuable player in the future of energy. Lead-acid batteries exhibit immediate real-world upsides in the here and now. Batteries like the Fullriver EGL Series demonstrate lead-acid's constant improvement, promising at the very least, a multi-pronged approach to meeting the energy demand of the future in a safe, reliable, sustainable, and cost-effective manner.  

A Surprisingly Simple Winterizing Protocol

Ahh, the change of the seasons, leaves turn pretty colors and drop, temperatures begin their gradual slide toward winter, life slows down, and all the relics of fair weather are put away. Engines are stabilized with additives, water lines are filled with anti-freeze, and then there are the batteries. It is this time of year that our support emails and phones usually get an uptick in activity as concerned citizens write/call to make sure they’re doing everything right to protect their investments until spring returns. The usual caveat we add at the beginning of almost every article applies here as well: This advice only applies to Fullriver AGM and Gel batteries.

Spoiler Alert!

While we will talk about some of the factors to consider and delve into the “why” of our winterizing solution, there’s really no need to drag out the answer like some googled recipe that forces you to swipe past 50 ads before the big reveal of the ingredient list is unveiled. Here it is:

To properly store your battery for the winter, after fully charging the battery or set of batteries, remove the main negative cable from the pack, and set aside so that it cannot inadvertently come back into contact with the terminal during storage.

It is really that simple. Go have a pumpkin latte or something.

But, why?

The reason we can unhesitatingly recommend this approach is related to three factors, time, temperature, and internal resistance. Obviously, winter doesn’t last forever, even though it can seem that way in some places.  Even if it was 6-9 months of storage, if it’s cool weather the whole time, no problem. The second reason is related to this, several months spent in temps at or below 25°C/77°F will only have a nominal impact on the battery’s resting voltage. This is all true because of the low internal resistance of Fullriver batteries. Internal resistance is also referred to as self-discharge. Because of the purity of lead in our batteries, the rate of self-discharge at or below 25°C/77°F is very low.

This handy graph should offer more statistical assurance:


Just for the sake of thoroughness, some may be wondering if the battery can be stored for so long without charging, why disconnect the negative cable from the battery. This is due to parasitic draw. It would be very rare to find a vehicle in any form that doesn’t have some device, in RV’s it may be a carbon monoxide detector, in other vehicles it may be the vehicle computer, but they all have something that creates the tiniest draw on the battery, even when everything seems like it’s powered down. A long duration of parasitic draw over several months does more than just slowly bring the voltage down. The effect of a parasitic draw over long periods without recharging can permanently damage the plates of the battery, causing a permanent loss of capacity.

Battery Tender

Oh, yes, we get calls and emails about using battery tenders all the time. Unfortunately, we have seen many overcharge scenarios because of using such devices. They are a dime a dozen, and for one reason or other, they can be problematic. Since there is really no need to use them during winter storage, it is better to just forego their use and avoid any potential problems they may create.

What if it’s too cold?

For storing Fullriver batteries, there are very few places on earth, inhabited by people, that actually get cold enough to be a problem. Yes, -70 in Siberia is too cold, but anything above -40C/F should be fine. Fullriver batteries contain very little water, and if they are charged then actually freezing the batteries is a very low probability.  

So, bring on the cold, and don’t worry about your batteries for a few months. Once the temps improve, give the batteries a full charge and resume use as normal.  If you have questions, please leave us a comment below.

Explore the Boundless Waters with Fullriver AGM Batteries

Solace in Preparation

The passion with which a mariner hits the water is the substance of song and legend going back millennia. Such is the simple desire to reinvigorate by leaving the trials of life behind back on dry land. Your passion may lead you to the open sea, the glass of a pre-dawn lake, or flying up and down rivers. No matter your journey, you want the experience to lift you out of daily stresses, not create more. Doing this takes planning, attention to detail, and preparation.

Fullriver batteries stood head and shoulders above competitive products. They lasted longer, provided more power and withstood far greater user abuse than any other battery.

James Hortop, CEO of Merlin Equipment; United Kingdom

Fullriver knows how crucial all your investments are to leaving terra firma in confidence. With our batteries, you can stay out on the water for as long as it takes to catch all the fish, feel the wind on your face, and forget what drove you to seek aquatic solace in the first place.

Wake boarders in the Sand Hollow State Park Reservoir in Hurricane, Utah.

For our part, we want to help you enjoy the journey by providing the only application specific battery lines designed to perform dedicated functions for marine applications. 

The DC Series

The widest range of true deep cycle AGM batteries of any manufacturer. The DC Series battery line provides long lasting power to trolling motors, refrigerators, bubblers, ice makers, and a wide range of accessories that make your passion come to life. View product line

The FT Series

The widest range of thin-plate, pure lead AGM batteries available worldwide. Full Throttle is made to provide superior cranking power in extreme temperatures (-40°F to 125°F). FT Series batteries have the best discharge recovery of any starting battery on the market. This is good for those days where the fish may not be biting. You can stay out on the water just a little bit longer and keep the tunes rocking. View product line

A Take from Across the Pond

From powering medical equipment aboard ambulances to running sensitive electronics in covert surveillance vehicles and complete systems aboard ocean going yachts to front line main battle tanks, UK based Merlin Equipment have been the go-to provider for those whose lives and livelihoods depend on power.

With ever increasing power demands and expectations that everything should be “green,” the requirement for a dependable battery has become increasingly important. After extensive testing and experience, Merlin Equipment selected the Fullriver DC Series and Full Throttle Series as it’s trusted battery for these critical missions.

CEO of Merlin Equipment, James Hortop, commented, “Our testing showed that Fullriver batteries stood head and shoulders above competitive products. They lasted longer, provided more power (whether that was deep cycling ability or CCA) and withstood far greater user abuse than any other battery. As a company that only sells quality product, Fullriver was the only fit for our lead/acid needs”. James also added “As a company who also markets (and has developed its own) Lithium Ion range, when coupled with a quality battery management system, pure-lead AGM is actually our preferred choice over lithium in many cases - it is far more dependable, robust and predictable.”

A Fullriver DC Series battery are installed into a London metropolitan police vehicle.
A DC Series battery in a HM Coastguard vehicle installed by Merlin Equipment.
Mic Harrison, lead engineer for Merlin Equipment is installing Fullriver DC batteries into a Sunseeker yacht.
Mic Harrison, Lead Engineer for Merlin Equipment installs DC Series batteries into a Sunseeker luxury yacht.
A Fullriver DC Series battery are installed into a London metropolitan police vehicle.
A Fullriver DC Series battery is installed, by Merlin Equipment, into a London metropolitan police vehicle.
Merlin Equipment has recently installed four Fullriver DC series batteries in a Volvo police vehicle.

At Fullriver, we want to be the battery that lets you forget your troubles. No more stress of having your batteries die mid-season, or even mid-trip. No more forgetting whether or not your batteries need to be replaced. 

You planned hard to prepare the perfect excursion. You should get to enjoy every hour on the water stress free. Chase that setting sun like mariners of old whose tradition you are carrying on. Don’t just start your adventure. Follow it through to the end with application specific batteries from Fullriver.

Featured photo courtesy of Cameron Hotchkiss (@camhootch). Battery installation photos courtesy of Merlin Equipment.

An Overland Explorer and Filmmaker: Cameron Hotchkiss

In this interview, we take a deep dive into who is Cameron Hotchkiss (@camhootch). Then, we find out why Fullriver batteries are the perfect fit for his adventurous lifestyle.

You are a cinematographer and have your own business, Momentum Media Company. Can you tell me a little more about how you started creating content for businesses?

My background started off in skiing and mountain biking. That slowly trickled into the motorsports world. It was the perfect organic storm of people who wanted to connect and capture video. And I enjoyed doing those things anyway. I’ve been specializing in the outdoor and automotive world. And that’s what I’ve been doing for about seven years now. It’s been awesome!

Your Instagram content is awe inspiring; the photos that you capture are breathtaking! How did you get your start in photography?

Thank you! I’ve been doing it by myself. I originally went to Washington State University for film and marketing. But ended up dropping out and putting in the time and doing it all myself. I’m a YouTube graduate as I like to say. I started from the ground up and started shaking hands and working with people I wanted to work with.

The mountains, the rivers, the wildlife… It’s incredible! I’m very thankful to call it a job.

Cameron Hotchkiss

You’ve been to some beautiful places. Where is the most amazing place you’ve traveled to? And why?

That’s a tough one... Probably Alaska. I’ve been to Alaska on two different occasions. One was to film an ice climbing film, which was a ton of fun. The most recent trip was for Ultimate Adventure two years ago. We got to be in Alaska for about 20 days. Living in Spokane we don’t have access to mountains like that, being on the road, living out of an off-road vehicle for that amount of time, and being out in nature, is awesome. I’m not doing a great job at explaining the feeling, but the mountains, the rivers, the wildlife… it’s incredible. I’m very thankful to call it a job.

Cameron's van parked on a dirt road in the woods.
Cameron's companions camping in his van and preparing a meal in the woods.
Cameron's van parked in the desert ready for camping.

Having the Fullriver power system on the van makes it so much more comfortable and convenient... I don’t know how I would be able to do what I do without it!

Cameron Hotchkiss

How did Fullriver products make it into your daily lifestyle?

About three to four years ago, I bumped into Ian Blomgren (@the_utv_overlander) from Fullriver at Overland Expo and said I was from Spokane and he perked right up because he’s from Spokane. We were in Arizona, and he said, “What the heck are you doing all the way out here?” and I said the same to him. We just built a relationship from there, as you know Ian is a great dude. I had tons of questions regarding batteries and how to outfit my van. Ian immediately was like “We’ve got the right product for battery power."

You have a sprinter van that you’ve completely renovated to accommodate your camping lifestyle. What are some of the advantages of using Fullriver batteries in your van?

Honestly, having the Fullriver power system on the van makes it so much more comfortable and convenient. With me being a full-time media guy, when I’m done shooting Jeeps or whatever lifestyle like skiing or mountain biking doesn’t matter what it is, I’m able to go back to my vehicle dump footage, charge batteries, charge my fridge…I don’t know how I would be able to do what I do without it! It’s a lifesaver having those batteries on board for sure!

Okay. This question is just for fun. What’s the most daring thing that you’ve done?

In Alaska, filming the ice climbing film. A little backstory on the film, we had this idea of shooting ice climbing at night, so we lit up all the glaciers with different lighting. With that being said, we were leaving at about 7pm every night and hiking out to the glacier and then filming all night 'till about seven in the morning. So, we were tired, being out in the elements for that amount of time, and our sleeping schedule was wonky. We were on night five or six coming off the glacier and I lost my footing and slid down the side of the glacier. And the only thing that stopped me from going into a crevasse was that I had my camera backpack on, and I basically got wedged so I couldn’t go down in it. That was scary, I think overall that was my closest near-death experience. It’s always fun to tell people stories and get into what inspires them. I’m not an ice climber by any means, but got to tell Allan, the ice climbers’ story, and that’s something that he enjoys doing. I just like submersing myself in people’s lives and what they like to do and tell their story. These trips are so diverse - I learn a lot. When I did the Idaho BDR (back-country discovery route) with Ian this last year, I learned a ton. Even with being in motorsports for seven years, I’ve hadn’t shot something where I was living out of an ATV for ten days. It’s fun to figure out ways to be proficient in the back-country and stay safe, but also do my job well.

Cameron, it looks like you’ve done it all! You can be seen off-roading, camping, dirt biking, fishing, mountain climbing, skiing…What’s the next adventure on your list?

I recently picked up a dual sport motorcycle, and I’m hoping to check off some more BDR’s with my Pops - go make some memories with my Old Man. Get out in the woods and try to log some miles and some BDR’s on bikes. And I also have more BDR plans with Ian. There’s lots on the docket. So it should be fun!

Interviewed by: Alexis Moore

A New Battery with Double the Cycle Life - EGL Series

The battery world has developed with only small changes over a span of decades. Lead acid batteries have been around pretty much unchanged since 1859. Lithium batteries have been used commercially since 1991 and would be the latest major breakthrough. While we see small innovations in each of these technologies, we haven’t seen the gap close much between the two battery types… Until now.

The Gap Closes

Fullriver Battery has achieved something that is extremely uncommon in the world of battery manufacturing. We created a new battery technology that increases lead acid performance, life cycles, runtime, and reliability. This better matches the characteristics of lithium batteries. Most importantly, we did it without causing consumers to break the bank to get it. Presenting the Fullriver EGL Series Deep Cycle AGM.

The Fullriver EGL Series is the first lead acid battery that performs like lithium. We used a combination of a new plate design, venting system, new proprietary paste materials, and our military grade construction standards. This allows an EGL battery to maintain a run time within 5% of rated capacity for over 850 cycles. To put into perspective, 850 cycles is more than twice the expected life of most AGM batteries on the market today.

Improved Cycle Life, Improved Warranty

Even the best deep cycle lead acid batteries loses runtime as the battery cycles. Water is lost as the battery vents during charging and paste materials breakdown leading to corrosion. This lowers the available plate surface area able to hold charge. Because of these factors, the acid loses specific gravity as the battery ages. 

The good news is that Fullriver Battery addressed all these issues head on with the EGL Series. In perfect conditions, a premium AGM battery can reach up to 32,000 Ah. A perfectly maintained flooded battery can reach up to 41,000 Ah. The EGL Series can reach up to 93,000 Ah.

300-400 cycles and they're still at 100%.

Peter Miller - General Manager, Coast Cart

The EGL Series is a beast that continues to provide consistent run times throughout its life. This is why Fullriver is the only battery manufacturer to offer a 4-year warranty of any cycling battery on the market. Don't just take our word for it. Watch what Peter Miller from Coast Cart had to say about the EGL series below.

The EGL Series represents the first major leap in lead acid battery technology since the introduction of gel electrolyte in the 1930s and the invention of Absorbed Glass Mat (AGM) in 1972. This latest breakthrough is available exclusively through Fullriver Battery.

Featured photo courtesy of Cameron Hotchkiss (@camhootch).