Author: Wil Burlin

Fullriver Battery Review: DC400-6 Sealed AGM Battery

Fullriver Battery Review: DC400-6 Sealed AGM Battery

Fullriver Battery Review: DC400-6

  • 6V / 415ah capacity @ 20 hr. charge rate
  • Projected lifespan of 1250 cycles @ 50% depth of discharge
  • Convenient option for daily off-grid use
  • Ideal for occasional use in remote locations (like a vacation cabin or industrial site) due to maintenance-free nature

Fullriver makes our favorite Sealed AGM (Absorbent Glass Mat) battery on the market: the DC400-6, a 6V battery with 415 ah of capacity.

This battery is ideal in situations where the battery bank may go an extended period of time between charge cycles, like at a vacation cabin or a remote telecom site. It’s also a great option for daily off-grid use if you prefer to avoid the maintenance required of flooded batteries.

This Fullriver battery review will cover over the pros and cons of their DC400-6 Sealed AGM (Absorbent Glass Mat) battery in depth and explain some ideal use cases for AGM batteries.

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Price & Specs

  • Model: DC400-6
  • Price: $582.49 (as of 5/16/19)
  • Dimensions (LxWxH): 11.61 × 7.05 × 16.69 inches
  • Weight: 123.2 lbs
  • Nominal voltage: 6V
  • Cycling capacity @ 20 hour rate: 415 ah
  • Projected cycle life at 50% depth of discharge: ~1250 cycles

It’s worth noting that Fullriver carries a wide range of 2V, 6V and 12V AGM batteries. We chose to highlight the DC400-6 because it is our best-selling AGM battery with ideal charging characteristics to pair with a broad range of off-grid systems.

You might be better served with another option depending on the scope of your project. For example, 2V batteries work better for larger systems (more on that below). Check out our tips for sizing off-grid systems and chat with your system designer to find the best option for your project.



The main difference between flooded and sealed lead-acid batteries is that flooded batteries need routine maintenance to keep them in working condition. Every month or so, you need to refill flooded batteries with distilled water, which evaporates during the charge cycling process.

If you are the type of person who loves to get hands-on with DIY projects, you might enjoy the routine maintenance required to keep flooded batteries in good shape.

But most people don’t want their solar system to be the center of their entire life. If you’re the type of person who procrastinates taking your car to the shop for regular tune-ups, you will likely prefer the “set it and forget it” nature of sealed batteries, which don’t require any maintenance check-ups.

If you want a battery that just works without any extra hassle, the maintenance-free Fullriver AGM battery is our top pick.

No Off-Gassing

Flooded batteries emit a gas byproduct as a regular part of their operation. Off-gassing can be dangerous if it builds up in a poorly ventilated area.

For that reason, flooded batteries need to be installed away from living quarters in a well-ventilated enclosure, which can add to overall project costs.

Fullriver’s AGM battery is sealed, and it does not emit gas as part of the cycling process. This means that it can be safely installed indoors without fear of Hydrogen gas buildup.

Install in Any Configuration

Sealed AGM batteries are just that—sealed. You can install them on their side and they won’t leak.

Sealed AGM batteries won't leak, even if installed on their side.

For that reason, Fullriver’s AGM battery is a popular option in RV systems, where vibrations from the road can cause the fluid in the battery to slosh around. Where flooded batteries would spill, the Fullriver AGM stays sealed tight.

They are also more flexible for home installs. If you have a shed or a workshop and need to save floor space, the Fullrivers can be installed sideways without spilling or leaking. That extra bit of versatility is convenient as you plan out your system.

Quality Support & Reputation

Lastly, nobody likes buying from a company that makes it a headache to get support for their products.

We’ve stocked Fullriver for several years and have a great working relationship with them. In cases where our customers have had to contact Fullriver customer support, they’ve been quick and efficient at solving issues.

Generally, we’ve found their support team to be responsive and knowledgeable, which gives us peace of mind that questions and issues will be resolved quickly when they do pop up.


Higher Cost

At the time of publication, we sell Fullriver’s DC400-6 AGM battery for $583 apiece. That’s a fair bit more than a comparable flooded battery, the Crown CR430, which goes for $325 apiece.

Fullriver projects their batteries to last 1250 cycles at 50% Depth of Discharge (DoD), while the Crown CR430 is good for 1200 cycles at 50% DoD. (A cycle refers to the battery being drained and then recharged again—essentially, one day of use.)

Given the similarities in amp-hour capacity and cycle life, the performance of these batteries is fairly comparable. So why does the AGM cost more?

When I speak with clients, I like to be honest and call it what it is: a convenience upgrade. Flooded batteries require monthly maintenance checks, and there is the potential to come into contact with battery acid while refilling the water, which will burn your skin. AGM batteries are maintenance-free, so you never have to check up on them.

AGM batteries cost more to manufacture because the design is more complex, with the electrolyte suspended in a fiberglass mat, which prevents it from spilling. Essentially, you are paying a premium for the lack of maintenance and the right to forget about your solar system so you can get on with the rest of your life.

If you are the type of person who likes to get hands-on with DIY projects, by all means, opt for flooded batteries. They will deliver similar performance at a much lower cost, so long as you stay on top of a regular maintenance schedule.

Not Suitable for Large Systems

Most off-grid systems tend to be on the smaller side because batteries are quite expensive (the single most costly component of any off-grid system). Off-grid homes tend to take measures to cut down on energy usage, like using efficient appliances and forgoing central heat and A/C units, to get the most out of the battery bank.

Still, I occasionally work with people who need to build large off-grid systems. For these systems, we don’t use the Fullriver batteries because it is best practice to limit 6V battery banks to 2 strings of 8 batteries each (16 batteries total, or 38.4 kWh of storage).

We are limited to 8 batteries in a string because it matches the voltage requirements of the inverter (6V x 8 batteries = 48V string, which matches the nominal voltage of a 48V inverter).

And we don’t run more than 2 strings in parallel because it creates too much resistance between the battery strings. This leads to unbalanced charging and discharging across the strings, which will create uneven charge levels in the batteries.

This isn’t a knock against the Fullriver DC400-6 battery, it’s simply a limitation of the system design process. To solve this issue, we turn to 2V batteries so we can fit more batteries in a string (24 batteries on a 48V inverter).

For large off-grid systems, we turn to the Crown 2CRV1200 or Fullriver DC1150-2.

Ideal Application

Sealed AGM batteries are more convenient and less complex than flooded batteries. Unlike flooded batteries, there’s no threat of ruining your AGM batteries early by neglecting a regular maintenance schedule.

You’ll pay a premium to upgrade to the Fullriver DC400-6 battery, but the tradeoff is that you never have to deal with messy battery maintenance. For many people, ditching the burden of monthly check-ins is well worth the extra cost.

If that appeals to you, the Fullriver DC400-6 is our pick for our preferred sealed battery for daily off-grid use.

There’s another use case where this battery shines: systems that only see occasional use. If you have a hunting cabin that you visit once a month, sealed batteries are practically mandatory.

Flooded batteries will start to self-discharge and if they are not regularly cycled. They would quickly die if you tried to use them in a system where you would not have access to perform regular maintenance.

Sealed batteries have much slower self-discharge. They can sit dormant without upkeep for longer periods and better maintain a charge when you come to visit. That makes the Fullriver DC400-6 our recommended battery for remote systems such as a hunting cabin.

For more info, check out our solar battery guide linked below. If you’d like some help designing a system, feel free to call us at 1-800-472-1142 or request a quote on our website.

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Best Portable Solar Panels For RVs, Boats & Mobile Use (2019 Edition)

Best Portable Solar Panels For RVs, Boats & Mobile Use (2019 Edition)

Best Portable Solar Panels For RVs, Boats and Mobile Use

  • Solarland’s portable solar panels are ideal for RVs since they are warrantied for vibration.
  • Sunpower’s lightweight, flexible solar panels are great for camping.
  • Mission Solar makes the best solar panels for boats—they are rated to protect against corrosion from salt mist.

A big part of the appeal of going solar is the ability to generate electricity in places without access to power lines. This is especially important if you live your life on the road in an RV, boat, conversion van or tiny home.

Portable solar panels are often less cumbersome and easier to use than generators, which can be heavy, noisy, dirty, and need to be refueled regularly. Solar is often the most convenient solution for people who live in RVs, boats or tiny homes (or love to take road trips / travel frequently).

I’ve been in the solar industry since 1998 and have designed hundreds of mobile-ready solar electric systems in that time. More people seem to be taking to the mobile lifestyle lately, so I wanted to put together my assessment of the best portable solar panels for RVs, campers, boats and tiny homes.

If you’re building a system that needs to withstand the elements and survive life on the move, this guide is for you.

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What to consider when picking solar panels for mobile use


First things first: there’s really no reason you can’t use traditional solar panels for mobile use.

By “traditional,” I mean the full-sized panels you would install on the roof of a typical home or office. These are the most cost-effective option, and l would still recommend looking into them so long as you have the space to mount them.

The snag is that these panels are quite large: about 3.5 feet wide and 5.5 to 6.5 feet tall (depending on whether you choose 60-cell or 72-cell panels). These work great for tiny homes, but they don’t really fit on the top of a van, for example.

They also may not be warranted for use in a mobile application. Specifically, the warranty would not protect against damage from vibration, which could occur if you drive with panels mounted to your roof.

And let’s say you go camping and want to haul your system from the parking lot to leave it by your tent. Traditional full-sized panels are going to be a huge burden to lug around. I would strongly recommend opting for smaller, more portable solar panels in these cases.

Mounting Options

Panels should be built to handle high wind load, since you will likely be moving down the highway at high speeds.

Be sure to consider the space and structure available for mounting panels. Solarland offers a range of mounting brackets for this type of application, including simple Z-brackets for bolting a panel onto a flat surface, and specialty marine mounts that are designed for boats.

Marine Applications

Marine systems should be built in a dry space. Ideally, your panels should be mounted as far away from the water as possible.

Your battery bank enclosure needs to be built in a dry space. Enclosures aren’t water-tight (since the batteries need to be ventilated), so you should place it somewhere that will protect water from coming in contact with the electronic equipment.

If you plan to take your boat out in saltwater, look for panels that are IEC 61701 certified to prevent corrosion from salt mist.

Mobile-Ready Inverters & Power Centers

It is also crucial that the rest of your system components are mobile-ready. A major component is picking an inverter that is built for mobile use.

The key feature of mobile-ready inverters is neutral ground switching capability. This means that the inverter can plug into shore power and automatically switch so it is safely grounded.

This safety feature keeps your system grounded while on the road. But it can also remain properly grounded when you plug in your RV at a campsite, for example.

Magnum, Cotek and Outback sell inverters that are tailored for mobile use. We also sell pre-wired power centers that are configured in-house for use in mobile and marine applications:

3. Best Portable Solar Panels For RVs / Campers / Mobile Homes

Some RV customers like to use our large solar panels. This way they have a high voltage and high wattage output in a single panel. This is also the most cost-effective solution.

Standard solar panels with a traditional aluminum frame come in many sizes, ranging from 20 watts up to 360 watts. These gain wattage every year, and I would not be surprised to see a 375-watt solar panel by the end of 2019.

However, remember that these panels are usually not warrantied for protection against vibration, which might occur if you are driving down the highway at high speeds.

Instead, look to something like the Solarland 12V and 24V panels, which have a robust frame and are warrantied for mobile applications.

If you don’t need a large solar array, you might enjoy our flexible solar panels. We recommend the SunPower 50W and 100W flexible panels. These are very lightweight, and designed to be stored while driving and deployed once you arrive at your campsite.

I keep mine paired with a 50’ cable so that I can move it around the campsite and get it into the sun, while keeping my camper in the shade. These also fit nicely across my windshield, so I can collect solar energy while blocking the sun from heating up my camper.

My trusty SunPower 100W flexible solar panel in the windshield of my camper.

The flexible solar panels are limited to about 100 watts, so they are intended for portable and smaller uses. They have grommets in the corners so that you can quickly secure them using bungee cords or other appropriate tie downs.

Best Portable Solar Panels For Your Boat

Boats are more likely to use the larger framed type panels, as they have plenty of room to mount them. You can see this concept in action on the River Otter Waterway Cleanup Project (featured below), a marine system we designed for a client which utilizes full-sized panels.

Many of my customers that just boat around for a few hours a day like the flexible panels. They are just smaller, more portable, and get the small jobs taken care of with a lighter solar panel.

If you are going to be boating in salt water, you will want to choose a solar panel that is rated for salt air and corrosive environments.

We currently offer Mission Solar for these applications as their panels pass the IEC 61701 certification for protection against corrosion from salt mist.

When building a solar array on a boat, your choice of accessories matters more than the panels you choose.

This will primarily come into play when you are installing your power center—the enclosure that contains your charge controller, inverter and other necessary components.

These power centers need to be ventilated properly, meaning they aren’t water-resistant. They should be built in a place where they will remain dry at all times.

Hit the Road With Confidence

This should give you plenty to think about as you plan your mobile solar system. When you’re ready to finalize the design, give us a call at 1-800-472-1142 or request a consultation online.

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How to Size a Solar System: A Step-By-Step Walkthrough

How to Size a Solar System: A Step-By-Step Walkthrough

Once you have determined that a grid-tie solar system is the best option for your home, we want to help you size the system correctly. This article will teach you how to size a solar system that covers your energy use patterns, without over-sizing your PV array.

The process for sizing off-grid solar systems is different, due to the need to account for battery bank sizing. Click here for advice on how to size your off-grid solar system.

As a system designer, I follow a step-by-step process to size grid-tied systems that work with my client’s project constraints.

The first step is to figure out the main constraints on the project and using those restrictions as the starting point for the design. We can approach the project from one of three angles:

  • Budget constraints: Build a system within your target budget.
  • Space constraints: Build a system that is as space-efficient as possible.
  • Energy offset: Build a system that offsets a certain percentage of your energy usage.

I want to make sure I deliver a system that satisfies my client’s specs, but I also need to account for sizing factors that might not be immediately obvious to them.

Some common stumbling blocks that come up over and over again:

  • Local levels of sun exposure
  • Orientation of the array (facing and tilt angle)
  • Plans for future expansion
  • Product efficiency ratings
  • Natural degradation of performance over the life of the warranty

This article is intended to provide a step-by-step overview of the sizing process for grid-tied solar systems, taking the above restrictions into account.

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Sizing Grid-Tied PV Systems: Getting a Quick Estimate

First, gather the Kilowatt Hours (kWh) usage from your electric bill. We want to have all 12 months available so we can look at peaks and valleys in usage. Energy consumption spikes in the summer and winter with heavy use of your A/C and heating units. A full year of energy consumption data gives us the big-picture overview we need.

We also want to average the data from 12 months of bills to know your average monthly kWh usage. Grid-tied systems tend to overproduce in the summer with peak sun exposure.

If your utility provides a favorable net metering policy, the energy your system generates can be banked with the utility as credit to be used later. Not all utility companies do this; check with your local provider.

Next, we want to look up your sunlight hours per day, through a sun hours chart or the PV Watts Calculator (I will get to this in the next steps).

For a general estimate we can use this simple formula, then fine-tune as we get further into the design:

(Yearly kWh Usage ÷ 365 days ÷ average sun hours) x 1.15 efficiency factor = DC solar array size required.

If the solar array cannot face south, on the preferred angle, we need to adjust the system by adding more solar.

Here is an example. I live in New Mexico where the PV Watts Calculator says I have an average of 6.10 sunlight hours per day. That is a LOT, I know, but that is why I live here. I use 1000 kWh per month, or 12,000 kWh in a year. According to the formula:

(12,000 kWh ÷ 365 days ÷ 6.1 sun hours) x 1.15 = 6.2 kW DC solar system required

Fine-Tuning the Estimated System Design

When I am ready to make a solar system estimate as accurate as possible, I pull up the address on Google Maps. I check to see if I have any viable south facing options for a roof mount.

(Your solar system should point toward the equator, so if you live in the Southern Hemisphere, look for north-facing options instead.)

A roof mount is the simplest and most cost-effective solution. It costs less than other racks. Many times the slope of the roof is already set up for solar gain, and it keeps the solar panels close to the inverter and service panel. This is great for the efficiency and costs less in conduit and wire.

To learn more about the pros and cons of each mount type, read this article: Ground Mount vs. Roof-Mount Racking: What’s the Best Way To Mount My Solar Panels?

Customer Tom M. with his roof mounted system in Albuquerque, NM.

If a roof mount is not an option, I will look into the possibility of a ground mount or pole-mounted solution.

Once we know how much area we have for solar panels, and what angles and directions we will be working with, I get out the PV Watts Calculator and follow these steps.

How to Use the PVWatts Calculator

  1. Enter the address and hit the orange arrow to the right.
  2. Once you are on the System Info page, enter the DC system size from the previous section.
  3. Choose standard module.
  4. For array type, select “fixed” for roof mounts, or “open” for ground mounts.
  5. Leave the system losses at around 15%.
  6. Enter the slope of your roof in degrees, and the azimuth. Azimuth is the degrees relating to north and south, with north being zero and south being 180. (Click here to learn how to fine-tune your angle and azimuth values.)

Once all the info has been entered, click the arrow to the right and it will tell you how much power your system will put out on a monthly basis.

This is our step-by-step process for honing in on an accurately sized system. We provide this info because our audience is heavily inclined to DIY, and most people prefer to research at their own pace.

Once you’re ready, we do encourage you to schedule a free design consultation with us so that we can double check your sizing, find compatible products, and ensure the system works within your constraints (budget, build space and energy offset). You can also give us a call at 1-800-472-1142 for an immediate consultation.

Choosing Grid-Tie Solar Equipment

Once we know how big the solar system needs to be, we will cross-reference that with the amount of space available. If you are doing a ground mount, that is usually not a problem.

From my example above, I know I need a 6.2 kW DC system. I can multiply this number by 1,000 to confirm that I need 6,200 watts of solar panels.

My fastest resource is to go to our grid-tied solar packages and scroll down until I see something in this range. If the client expresses a desire to buy American-made panels, or needs certain features like individual panel monitoring, I take those choices into account.

Here are a few viable options I’d consider. Note that the imported panels are more cost-effective, so you get roughly 10% more production for the same price.

Grid-tie systems with American-made panels:

  • 6.2 kW system with 310W Mission Solar panels and SolarEdge Inverter / optimizers
  • 6.2 kW system with 310W Mission Solar panels and Enphase IQ7+ micro-inverters
  • 6.2 kW system with 310W Mission Solar panels and SMA central inverter

Grid-tie systems with imported panels:

  • 6.7 kW system with 335W Astronergy solar panels and SolarEdge inverter / optimizers
  • 6.7 kW system with 335W Astronergy solar panels and Enphase IQ7+ micro-inverters
  • 6.7 kW system with 335W Astronergy solar panels and SMA central inverter

If you’re having trouble deciding which products to buy, we’ve written articles covering that ground as well:

Of course, sometimes it’s easier to talk to someone with experience and have them walk you through the design process. The fastest way to get a thorough evaluation of your solar needs is to call us at 1-800-472-1142 and connect with one of our designers. We’d love to help you design the perfect grid-tied system for your needs.

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Lead-Acid Battery Comparison: Pros and Cons of Flooded, Sealed, AGM and Gel Batteries

Lead-Acid Battery Comparison: Pros and Cons of Flooded, Sealed, AGM and Gel Batteries

Lead-Acid Battery Breakdown: Flooded vs. Sealed

  • Flooded lead-acid batteries are most cost-effective option, but require regular upkeep
  • Sealed batteries (AGM and Gel) cost more but do not require regular maintenance
  • AGM batteries resist vibration and can handle higher charge/discharge rates
  • Gel batteries can withstand high temps and work best with slow, deep discharge

Batteries come in many shapes and sizes. In the solar industry, two battery chemistries work well for our purposes: lead-acid and lithium.

We’ve written an in-depth comparison of lead-acid vs. lithium batteries previously on this blog, but here are the Cliff’s Notes: lithium is the premium option, with a longer lifespan and fewer maintenance requirements. Lead-acid costs much less up front, but regular check-ins are required to keep the battery bank working properly.

This article will focus on the differences between the main lead-acid battery types used in the solar industry. You’ve got flooded lead-acid and sealed lead-acid batteries, and the latter group can be broken down into AGM (absorbent glass mat) and gel batteries.

Every battery type has a different purpose and use case, so let’s go over the pros and cons of each.

Flooded Lead-Acid Batteries

For many years, the flooded lead-acid battery has been the standard in the solar industry. This type of battery is also used in golf carts and forklifts. They are the most cost effective and longest lasting of the lead-acid batteries.

Flooded lead-acid batteries contain an electrolyte that is free to move around in the battery encasement. When charged, the battery acid and lead plates react to store electricity.

These batteries are meant to be mounted upright so that the electrolyte does not leak out of the caps on top. (Since sealed batteries are…well, sealed, you can mount them in any orientation without fear of them leaking. Not the same for flooded batteries.)

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While this is the most economic battery on the market, it will only reach its potential lifespan if they are maintained properly. The levels must be checked monthly and topped off with distilled water to ensure the longest possible lifespan.

Note: flooded lead-acid batteries release toxic hydrogen gas when charging. They need to be enclosed and vented to the outside to prevent this gas from being trapped and creating a hazardous environment.

Related Product: Crown CR430 6V Flooded Lead-Acid Battery

Sealed Lead-Acid Batteries

The sealed lead-acid batteries are very similar to the flooded version, but there is no access to the inside compartment. This means that you do not have to add distilled water. The electrolyte is sealed inside, and there is enough to allow the battery to live out a calculated number of cycles.

You sometimes see these referred to as VRLA (valve regulated lead-acid) batteries, because they have a small valve to allow for the escape of the gasses that occur during charging.

AGM (Absorbent Glass Mat) Batteries

Absorbent Glass Mat batteries are the most popular VRLA battery because they can work in a wide range of conditions. The electrolyte is suspended in a thin fiberglass mat that is situated between the lead plates. This allows the battery to be resistant to vibration, which makes them a great choice for RV and other mobile applications.

They can also be mounted in any orientation. It is common to see them mounted on their sides for convenient placement and wiring.

AGM batteries are more expensive than flooded lead-acid batteries, and they do not last quite as long. But for that extra price, you get the luxury of not having to maintain the batteries or deal with as much gas that is released during the charging phase.

They are perfect for mobile applications, places where leaked acid would be problematic, remote locations where maintenance will not be possible on a regular basis, and places where the batteries could be subject to extremely cold temperatures.

Related product: Fullriver 6V 415Ah AGM battery

Gel Batteries

Gel batteries are another VRLA battery very much like an AGM, but they use a thick paste that allows the magic to happen rather than the fiberglass mat.

The main difference between gel and AGM batteries is the charge rates. AGM batteries can handle higher charge and discharge rates than gel batteries.

Gel batteries are the most costly of the VRLA batteries, but excellent candidates for projects that need a very slow deep discharge. They also last a bit longer in hotter temperatures, so you might pick them if you are concerned about high ambient temperatures in the space where the batteries are enclosed.

Gel batteries are more expensive than other lead-acid battery types, so they are not ideal outside a handful of specific solar applications (very hot climates, mainly). The technology has been eclipsed by other battery types that have been developed more recently.

It is very common for people to mistake a Gel for an AGM, and this can affect the lifespan of the battery. Gel batteries are the most sensitive of the VRLA batteries, and It is critical that the correct charging parameters are used when you have a Gel battery in your application.

My Experience Living Off the Grid

When I first started living off the grid in 1996, I had never heard of a Gel or AGM battery. Everyone I knew that was exploring the off-grid lifestyle used the flooded golf cart batteries. Once I started working in the industry and doing more installations, I started seeing more battery options.

I quickly realized that the bigger flooded batteries called L-16s were the standard in most of our nicer installations. These are sometimes referred to as a forklift battery. While the cost per amp hour was similar to a golf cart battery, it became evident that the L-16s lasted longer. It was explained to me that the bigger the battery, the thicker the lead plates would be, therefore gaining a better lifespan.

About three years ago, my flooded batteries were at the end of their life, and I opted to get AGM batteries this time around. While I don’t really notice much performance difference, I am relieved to not have to crawl under my stairs to check water and maintain the batteries anymore. Even though my L-16s were in a sealed vented compartment, once in a while I would catch a whiff of something that must have been the hydrogen gas seeping out. I haven’t smelled that since, and it was worth every penny to make the switch.

For more advice on which battery type is best suited for your project, chat with one of our system designers or check out our Solar Battery Guide linked below.

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