EG4 LL-S 48V 100Ah (SR-48-100-IN-01)

What these numbers mean for an off-grid build

The table above is what the manufacturer publishes. This section is what those figures imply once the unit is doing real work, worked from this row and from the 21 products in the same table. The arithmetic is shown so you can check it against your own design rather than take it on trust.

Usable energy, and how many you would need

Nameplate capacity is 5.12 kWh. Lithium iron phosphate tolerates deep cycling far better than lead acid, but nobody designs to empty: at a routine 80 percent depth of discharge this unit gives about 4.10 kWh per cycle, and at 90 percent about 4.61 kWh.

Put that against a load list. A modest off-grid cabin running perhaps 3 kWh a day would need roughly 2 of these to carry two days with no meaningful sun at 80 percent depth of discharge; a larger household at 6 kWh a day would need about 3. Those are starting brackets, not designs: cold reduces available capacity, and a bank that is never fully recharged behaves like a smaller one. Build the load list first in lesson four, then size the bank with the battery calculator.

How much power it can actually deliver

The published maximum continuous discharge is 100 A, which at 51 V nominal is roughly 5,120 W of continuous output from a single unit, a discharge rate of about 1.00C. That figure, not the energy capacity, is what decides whether one unit can feed your inverter at full tilt.

It matters most at startup. Well pumps, compressors, and power tools draw several times their running figure for a moment, and a bank that cannot supply the surge will either sag enough to fault the inverter or trip its own protection. If your inverter is rated above 5,120 W continuous, you need more than one of these in parallel, and the parallel arrangement has to be built so the units share current properly. Conductors and fusing on a bank this size are not a place to improvise: lesson six covers why direct-current faults behave differently, and the wire gauge calculator sizes the cable for the actual current and run length.

How fast it takes a charge

At the published maximum charge current of 100 A, a full recharge from empty takes on the order of 1.0 hours of uninterrupted charging, and absorbing that current at 51 V calls for something like 5,120 W of array delivering at full output. Real charging is slower than that, because the last stretch tapers by design and because an array rarely holds peak output for long.

The practical reading is about winter. In the worst month, the hours of usable sun are short, so a bank that theoretically recharges in a morning may take several days to recover from a deep discharge. That gap is what generators exist to close. The solar calculator will tell you what your own location can deliver in its worst month.

Cold, which is where lithium banks are lost

The published minimum charging temperature is 32 degrees Fahrenheit. Charging lithium iron phosphate below freezing plates lithium onto the anode and does permanent damage, which is why the number exists and why it applies to charging rather than to discharging.

This unit is not listed as heated, so in a cold climate it needs to live in conditioned space, or in an insulated enclosure with a heat source, or behind a battery management system that refuses charge until the cells are warm enough. If you are siting a bank in an unheated shed or a crawl space, check the design low for your location first: the site report gives it for any address, and lesson five covers the rest of the battery decision.

Life, and the only cost figure that matters

The published cycle life is 7,000 cycles at 80% depth of discharge. Cycled once a day that is roughly 19.2 years, though calendar ageing, temperature, and how often the bank is left part-charged all pull the real figure around.

Combining price with cycles gives the number worth comparing across chemistries: at the recorded price of $1,537, this unit works out at roughly $0.043 per usable kilowatt-hour cycled, before accounting for depth of discharge and losses. Sticker price flatters cheap batteries and cost per kilowatt-hour cycled does not, which is why lead acid can look inexpensive and rarely is.

Where it sits against its peers

At $300 per kilowatt-hour of nameplate capacity, this unit is 5 percent above the median for this table (median $286 per kWh across the 21 units listed). Prices move constantly, so treat the ratio as the signal and the absolute figure as a snapshot from the date recorded above. The price index tracks the market ranges over time.

The closest alternatives in this table

Sorted by the specification that defines the category, these are the units in the lifepo4 batteries table sitting nearest to EG4 LL-S 48V 100Ah (SR-48-100-IN-01) at 5.12 kWh. Comparing against near neighbors is more informative than comparing against the whole table, because it isolates the differences that are not simply size.

• EG4 LifePower4 V2 48V 100Ah (SR-48-100-LP4-IN-02) · 5.12 kWh, $287 per unit
• SOK SK48V100N 48V 100Ah Server Rack (3U, heated) · 5.12 kWh, $234 per unit
• Trophy Battery 48V100E-2UL · 5.12 kWh, $331 per unit
• Pytes V5 · 5.12 kWh, $283 per unit

The full table sorts on every column, which is the fastest way to see whether a difference in price is buying a difference in specification or only a difference in brand.

How this fits with the rest of the system

A battery is chosen against the inverter it feeds and the controller that charges it, not on its own. A single unit here supports an inverter up to roughly 5,120 W continuous; anything larger needs units in parallel, correctly arranged so they share current. Check the inverter's continuous rating and its surge rating against the bank rather than against the array, since the surge is what fails first. The inverter table lists both.

On the charging side, the controller's maximum output has to sit within what the battery management system will accept, and the array has to be able to deliver that current in the month when there is least sun. The controller table lists maximum charge current and array limits by system voltage, and the panel table gives the module figures the string design comes from.

Checking these figures against the datasheet yourself

Look for whether cycle life is quoted at 80 percent or 100 percent depth of discharge and at what temperature, because those conditions move the number a great deal. Check whether the maximum discharge figure is continuous or a short-duration peak. Check the minimum charge temperature separately from the minimum discharge temperature, since they differ and only one of them damages cells. And check whether the communication protocol is genuinely supported by your inverter rather than merely present on both.

Two conventions catch people out across every category. The first is that a specification quoted without its test conditions is not really a specification, so where a datasheet gives a number and no conditions, treat it as marketing until you find the conditions. The second is that model names persist across silent revisions, so a sheet downloaded three years ago may not describe the unit in the box. The price index and the observed prices above are dated for the same reason.

Installing it, and living with it afterwards

This is a 48 V-class unit, which in practice means a rack or wall-mounted installation, heavy cable between the bank and the inverter, and a serious main fuse close to the terminals. The advantage of the higher voltage is that every conductor in the system gets thinner and every fuse smaller for the same power, which is why most whole-house off-grid builds settle here. Whatever the voltage, secure the battery so it cannot move, keep terminals covered so nothing metal can bridge them, and keep tools and jewelry away from the top of the bank.

Set the charge parameters from this manufacturer's documentation rather than leaving the controller on its defaults, which are usually written for lead acid and are quietly damaging to lithium. Write the settings into your systems binder and check them again after any firmware update, because controllers sometimes revert and nothing announces it. Fit a shunt-based monitor so you are reading state of charge rather than guessing from voltage under load, and log a reading weekly for the first year so you learn what normal looks like on your own system.

Warranty, and what it is worth

The published warranty is 10 years. Off grid, the length of a warranty matters less than the mechanics of claiming on it: who pays freight on something heavy, whether a replacement ships before the failed unit is returned, whether the seller or the manufacturer handles the claim, and whether an owner installation voids anything.

Ask those questions before you buy rather than after a failure, and keep the purchase paperwork, serial numbers, and installation photographs with the systems binder. Where the unit is a single point of failure for something critical, the honest planning assumption is that a warranty replacement takes weeks, which is the argument for a spare or a second path rather than for a longer warranty. Lesson ten covers deciding which of those is worth paying for.

What separates one lithium battery from another

Once you are comparing units of similar capacity and voltage, the datasheet differences that matter are narrower than the marketing suggests. The cells themselves are made by a relatively small number of manufacturers, so a great deal of what you are buying is the battery management system, the enclosure, the terminals, and the company behind them.

The battery management system is the component that decides whether the pack protects itself sensibly. Look at whether it will refuse charge below freezing, how it balances cells, what it does when one cell drifts, and whether it can tell your inverter what it is doing rather than merely disconnecting when it has had enough. A pack that simply opens a contactor under stress is a pack that will drop your house without warning.

Communications matter more than they appear to. A battery that talks to the inverter over a supported protocol allows the charge profile to come from the battery rather than from a setting somebody typed in once, and it gives you a real state of charge instead of an inference from voltage. Confirm the protocol is genuinely supported by your specific inverter model, not merely listed by both.

Then look at the practical items: whether terminals are a sensible size for the cable you will actually use, whether the case can be mounted the way your space requires, whether the unit can be paralleled and how many, and what the manufacturer says about expanding a bank later with newer units. Mixing old and new packs is the classic expensive mistake, and some manufacturers handle it far better than others.

What the table cannot tell you

Every figure above comes from a published datasheet, and datasheets describe a unit under test conditions rather than in your building. They do not tell you how a manufacturer behaves when something fails inside the warranty period, whether spare parts will still be available in ten years, how the firmware behaves in an edge case, or whether the support line is answered by someone who knows the product. Those things decide as much of the ownership experience as the specifications do, and the place to learn them is from people running the equipment: the forum is a reasonable place to ask.

Nor does a datasheet describe the installation. Most off-grid equipment that disappoints its owner was undersized for the real load, wired with conductors chosen by eye, protected by fusing selected on price, or sited somewhere too hot, too cold, or too awkward to service. The equipment rarely fails on its own terms. Lesson six is the one to read before buying anything on this page, and the system planner puts the whole design together so the components are chosen against each other rather than one at a time.

Specifications here are recorded from the manufacturer datasheet or a primary retailer page on the date shown, with a confidence flag on every row. Manufacturers revise datasheets, and models are superseded without changing name. Check the current sheet before you spend money, and if you find a figure here that no longer matches the source, the corrections page is how to tell us; corrections are logged publicly rather than quietly edited. How this site researches sets out the rest.