When we first tested the EG4 LL-S Lithium Battery 48V 100Ah Server Rack Battery, it quickly became our benchmark for what a solid solar battery should look like. It offered great performance, smart communication features, and reliable customer support.
However, one year on from our first EG4 LL Battery Review, we’ve now put a ridiculous number of hours on these batteries. From testing various inverters and solar panels to powering our solar mini-split system in the garage throughout the year, we’ve discovered a bunch of new things we like about this battery, as well as a few thta we don’t.
So, does the hugely popular EG4 LL Server Rack Battery still hold up? Let’s find out.
As mentioned, we’ve put a lot of mileage on these units, and the EG4 LL Battery continues to impress. You can read our full review on the LL Battery if you want an in-depth overview on these batteries, but here’s a quick refresher if you don’t need all of that:
Each battery weighs in at 99 lbs, so they’re relatively easy to carry. That said, they’re server rack batteries, so they’re at their best when they’re stacked in a racked cabinet. EG4 offers a 6 Slot Enclosed Battery Cabinet and a 3 Slot Battery Rack, both with built-in wheels.
Each EG4 LL-S Battery has a storage capacity of 5,120Wh at 51.2 volts and 100-amp hours. The battery cells have long-lasting LiFePO₄ chemistry, with each battery rated for over 7,000 cycles at 80% depth of discharge (DoD). This means you can expect to get years of dependable performance out of them, even with heavy use.
In terms of scalability, you can parallel up to 64 of these batteries in a single system, giving you a total storage capacity of 327,680Wh, or 327.6kWh. This is more than enough power for a full home or a serious off-grid setup.
The metal battery housing is sturdy, the overall design is simple, and everything feels well put together. The LCD display screen is bright and user-friendly, showing battery voltage, state of charge, current, and more. All the essential connections are easy to access, with the breakers and terminals up front, communications and grounding on the sides, and side rails that allow the batteries to slide into a server rack cabinet with ease. All of this means installation is both clean and straightforward.
At the time of writing, you can pick up the EG4 LL Battery for about $1,279 through Signature Solar (with code: SOLARLABGET50). While the price of these batteries has gone up and down a bit throughout the past year, the current price of just over $1,200 is a very competitive for a 48V rack-mount lithium battery from a reputable brand.
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When we say these batteries have been in constant use over the past year, we mean it. We’ve used them to test various solar inverters, run our mini split system, and be the main power storage destination for our solar panel testing mount out in the backyard.
Despite that daily workload, the performance has remained rock-solid. Voltage levels, discharge rates, and amperage all remain consistent, and the storage capacity hasn’t degraded in any sort of noticeable way.
We’ve also run tests on the batteries themselves, specifically to check the idle drain and efficiency. The EG4 LL Battery’s idle draw is extremely low, which helps conserve stored energy when systems are off or idling. Efficiency remained at nearly 100%, with some of our testing showing it between the 95–97% range during intense charge and discharge tests.
Overall, they’re continuing to perform exactly how they did when we first got our hands on them. Again, we don’t just use these batteries for backup power during the occasional power outages, they’re used every single day, and for some pretty intense testing. In all liklihood, the average buyer isn't going to be nearly as hard on these solar batteries as we have been.
Honestly, the only slip up we’ve noticed after a full year of daily use is one of the display screens on a single EG4 battery. The screen still works, and it has only impacted one of the many LL Server Rack Batteries in our system, but there are now a few visible lines across the screen that make it more difficult to read at certain angles.
One of the main things that has stood out to us since our first review of this battery is how easy and flexible EG4 has made firmware updates. This is because EG4 enables firmware updates via two simple methods:
This is more than just a nice bonus, it’s a huge deal for long-term system compatibility. Firmware updates mean your batteries can communicate seamlessly with newer inverters, and other server rack battery models, like the less expensive EG4 LifePower4 V2 Battery.
We actually run this type of mixed battery setup ourselves, and the main server rack battery cabinet in our garage uses a mix of LL-S and LifePower4 batteries on the same inverter.
Thanks to them all being updated with the latest firmware, they work flawlessly together. That level of cross-generation compatibility is one of the many things we’ve found that gives EG4 an edge over server rack batteries from cheaper brands.
Since the first review of this battery, we also put EG4 and Signature Solar’s customer service to the test. To get a fair assessment, we anonymously mystery shopped Signature Solar, calling in under fake names and asking a range of tech questions about various EG4 products.
We did this several times, finding their team to be knowledgeable, patient, and genuinely helpful every single time we phoned them. Signature Solar is EG4’s main retailer and distributor, so it’s reassuring to know that you’ll get amazing after-purchase support if you pick up your EG4 LL-S Battery through them.
The impressive support stands out even more when you compare it to what you get from the other server rack battery brands we’ve tested, including Eco-Worthy, Vatrer Power, and Rich Solar.
While Eco-Worthy and Rich Solar each offer a customer support phone line, they don’t seem to have a ticket system, so it’s difficult to actually get a hold of anyone. Even email responses through these brands can be very slow.
Reliable customer support may seem unimportant when you’re first ordering a battery, but we can’t stress enough how valuable it can be if something goes wrong or you need clarification when you're setting your system up. If you go with an EG4 Battery, you know you’re getting premium support, especially if you order from somewhere like Signature Solar.
We covered all of the pros and cons for this battery in our original review, but we uncovered a few more things we liked after a full year of regular use. Here’s the main ones that stood out to us:
After a full year using these batteries almost every single day, each EG4 LL Battery still performs like new. The voltage stability, discharge consistency, and total capacity retention are all excellent. They've proven themselves to be dependable off-grid or backup power solutions that can handle continuous use without noticeable degradation.
Speaking of long-term usability, being able to update the firmware with your computer or via a free dongle is a game changer. It extends the lifespan of your investment by ensuring compatibility with future hardware. It’s also something you’re just not going to get when you order a cheaper server rack battery from a lesser-known brand.
We’ve tested the support for plenty of companies, including major brands like EcoFlow, and Signature Solar remains one of the best retailers in the business. Their techs know their stuff, and they stand behind EG4’s products with solid warranty coverage.
You also get American-based support, which means no language barriers or irregular hours of operation. Whether you’re buying a single battery or investing in a large-scale battery bank, having reliable support from a retailer that isn’t going to disappear overnight is hugely beneficial.
The option to parallel up to 64 of these batteries makes this system incredibly flexible for large and growing builds. Whether you’re running a small off-grid cabin or a full residential solar system, EG4’s LL series can be scaled to your needs.
We’ve always been huge fans of any solar equipment that can be scaled up, as it allows you to start small, then increase your output and storage capacity as your power needs and budget grow. It’s another huge plus for the EG4 LL-S Battery.
We also appreciate that EG4 offers 12V, 24V, and 48V versions of most of their lithium batteries. That makes upgrading or expanding older systems much easier, especially for users with low-voltage setups who don’t want to replace their inverter.
While this battery continues to impress us, it’s not without its flaws. Here’s a few of the little gripes we have:
As mentioned, one of our LL batteries developed minor lines across its LCD display. The display screen is still readable, but we’d like to see a more rugged screen, especially since this display is also used on the more expensive and higher capacity EG4 WallMount All-Weather Battery.
We picked up on this in our original review, but we wanted to point out again that the handles are awkward to use. They’re really difficult to grip without pinching your fingers, which is pretty annoying given we're talking about a 99-pound battery.
Other options, including the Rich Solar Alpha 5 Battery, have much better handle designs with side grips that lock halfway up.
For most users who rack their battery and then leave it in place for years at a time, this isn’t going to be a huge issue. However, if you’re someone who moves your batteries often, it’s noticeable and annoying.
As mentioned, you can find cheaper 48V lithium batteries from brands like Eco-Worthy, Vatrer Power, or RUiXU, but you’ll be trading long-term reliability and lasting customer service for lower prices.
For example, the Eco-Worthy 48V Server Rack Battery failed to shut down in freezing temperatures when we tested it. Even when we dropped it down to ice-cold temperatures, it continued to operate well below its rated BMS protection limit. This may sound like a bonus for those planning to run an off-grid setup in a cold climate, but it’s actually very unsafe for the battery and would undoubtedly impact its lifespan.
Meanwhile, the RUiXU Server Rack Batteries we tested were slow to restart after an overload and seemed to lack the robust safety protections you get with the EG4 models.
These budget options might work for small or temporary setups, but for a home backup power or off-grid solar system, you’re better off investing in something that is well-supported and built to last. Besides, these batteries are only $100 to $200 cheaper than the EG4, so you’re not actually saving that much when you spread the costs over the length of time these batteries should last.
After a year of heavy daily use, our opinion hasn’t changed: the EG4 LL 48V Server Rack Battery is still one of the best solar storage batteries on the market.
Between its proven durability, intelligent firmware system, excellent customer support, and fair price point, it’s hard to beat.
If you want to save a bit, you can always step down to the EG4 LifePower4, which offers similar performance but without the LCD screen. But for those building a long-term off-grid or backup power setup, the EG4 LL remains our go-to recommendation for server rack setups.
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