Lithium vs Lead-Acid Battery for Solar: Which Should You Buy?

For a home solar system that is charged and discharged every day, buy lithium (LiFePO4). The reason is what the manufacturers rate each type for, not the price per battery. Hithium rate the HeroEE 16 at 90% depth of discharge for more than 8,000 cycles. LONG's own chart for the CWP200-12N lead-carbon battery shows about 900 cycles at 50% depth of discharge and about 250 if you drain it fully. Lead-acid still wins in three cases: a standby battery that sits charged and is rarely used, a battery that lives somewhere below 0 C in winter, and a small 12 V system where no lithium pack fits. The rest of this guide is the detail behind that answer, taken from the datasheets of the batteries we stock.

In this article

• What is the real difference between lithium and lead-acid?
• Why does the Ah on a lead-acid label not mean what you think?
• How many cycles does each battery really give?
• How much does each one weigh, and where does it go?
• Does your inverter need a different setting for lithium?
• When is lead-acid still the right choice?
• Which battery should you buy?
• FAQ

What is the real difference between lithium and lead-acid?

Both store DC and both connect to the same off-grid inverter. The difference is how much of the stored energy you may use, how many times, and how fast the battery accepts a charge. Lead-acid covers the tubular batteries most homes started with and the sealed VRLA types we sell, AGM and lead-carbon. They are 12 V blocks, so a 48 V bank is four in series. LiFePO4 packs come as one cabinet at 25.6 V or 51.2 V with the battery management system (BMS) built in, which is why the inverter can talk to them.

Spec from the datasheet	LONG CWP200-12N lead-carbon	LONG WPL200-12N AGM	Felicity LPBA 10 kWh	Hithium HeroEE 16
Chemistry	Lead-acid VRLA, cycle use	Lead-acid VRLA, standby use	LiFePO4	LiFePO4
Nominal voltage	12 V	12 V	51.2 V	51.2 V
Nameplate capacity	200 Ah at the 10 h rate	200 Ah at the 10 h rate	10.24 kWh	16 kWh, 314 Ah
Rated depth of discharge	Chart runs from 30% to 100%, cycles fall fast past 50%	Not rated for cycling	95%	90%
Cycle life	About 900 at 50% DOD, about 250 at 100% (chart, to 60% capacity)	Design life over 12 years on float (EUROBAT, 20 C)	6,000 or more at 25 C	More than 8,000 at 90% DOD and 100 A
Max charge current	60 A	60 A	180 A	100 A recommended, 200 A max
Charge temperature	-15 to 40 C	-15 to 40 C	0 to 55 C	0 to 40 C
Weight	68 kg each, 272 kg for a 48 V bank of four	68 kg each, 272 kg for four	82 kg	110 kg
Store price	$248 each, $992 for four	$220 each, $880 for four	$1,680	$1,950

Sources: LONG WPL200-12N and CWP200-12N datasheets, Felicity LPBA48200WG1 datasheet, Hithium HeroEE 16 datasheet, all linked from the product pages. Four 12 V 200 Ah blocks in series give a 48 V 200 Ah bank, which is 9.6 kWh of nameplate energy.

Why does the Ah on a lead-acid label not mean what you think?

A lead-acid battery is rated at a slow discharge. LONG print it on both sheets: 200 Ah is the 10-hour rate, drawn at 20 A. At the 5-hour rate (34 A) the same battery delivers 170 Ah, and at the 1-hour rate (120 A) only 120 Ah. Pull hard and 40% of the label disappears.

That matters because the loads that make you buy a battery are the big ones. A 48 V bank of four running a 2,000 W load pulls about 42 A before inverter losses, between the 5-hour and 1-hour columns on LONG's table, so you never see the 200 Ah. Hithium rate the HeroEE 16's cycle life at a continuous 100 A and allow 200 A, so the lithium label is the number you get.

Then there is the half you are told not to use. The lead-carbon chart shows cycles collapsing past 50% depth of discharge, so a 200 Ah lead-acid bank is run as a 100 Ah bank if you want it to last. The lithium packs are rated at 90% (Hithium) and 95% (Felicity). Compare prices on the energy each type is rated to give you, not on the nameplate.

How many cycles does each battery really give?

The cycle chart on the lead-carbon datasheet is the whole decision on one page. LONG test at the 5-hour rate, at 25 C, charging at 2.4 V per cell for 16 hours, and count cycles until capacity is down to 60%. The curves land at roughly 250 cycles at 100% depth of discharge, 550 at 80%, 900 at 50% and 1,800 at 30%. One cycle a day at 50% is about two and a half years.

Hithium rate the HeroEE 16 and HeroEE 8 at more than 8,000 cycles at 90% depth of discharge and 100 A, with the cell itself at 11,000. Felicity rate the LPBA wall battery at 6,000 cycles or more at 25 C. Roughly nine times the cycles of the lead-carbon battery, each going almost twice as deep. That is why both lithium brands print a warranty in years: 7 years on the HeroEE 16 page and on the Felicity LPBA datasheet.

The 16-hour charge in LONG's test condition is the other half. A lead-acid battery takes its last 20% slowly, at a fixed voltage, over hours. If your charging window is a few hours of generator or a short winter day, the bank is undercharged most days, and lead-acid left partly charged sulphates and loses capacity. The lithium packs charge at constant current until nearly full, which is what the 100 A and 180 A charge ratings mean in practice.

How much does each one weigh, and where does it go?

A 48 V lead-acid bank is four 68 kg blocks, 272 kg on a rack, with eight terminals to torque and three series links to keep tight. The HeroEE 16 is one 110 kg cabinet on wheels. The Felicity LPBA 10 kWh is 82 kg on the wall. Lithium expands by plugging in another identical unit, up to 16 HeroEE packs or 32 Felicity LPBA units in parallel. A four-block lead-acid bank cannot take a fifth block, and mixing old and new blocks in series is how banks die early. Sealed lead-acid does not need topping up, which is its one clear advantage over the flooded tubular type. Lithium packs are sealed too, with breaker, fuse and BMS inside.

Does your inverter need a different setting for lithium?

Yes, and it is a menu item, not a new inverter. On the Voltronic Axpert range the battery type is program 05. The VM III user manual lists AGM as the default, then Flooded, User-defined, and the lithium options (Pylontech, WECO, Soltaro, the LIb protocol and a general Lithium setting). A lithium type sets the charge current and the bulk, float and cut-off voltages automatically, and the manual tells you to fit the communication cable so the BMS takes over. The Axpert VM IV Twin 6 kW has a reserved BMS port for RS485, CAN bus or RS232, and Hithium list Voltronic among the compatible brands on the HeroEE datasheet.

Leave the inverter on AGM with a lithium pack connected and it charges and cuts off at lead-acid voltages. The BMS protects the pack, but you give away capacity and lose the state-of-charge reading. Battery equalisation (programs 30 and 31 on the VM III) exists for flooded and user-defined batteries and must stay off for lithium.

When is lead-acid still the right choice?

Lithium is the default for a battery that works every day. It is not the right buy in these cases:

• Standby power that is rarely used. A UPS for a shop, a lift, a pump that runs on battery a few times a year. The LONG WPL200-12N is built for this: float charging at 13.5 to 13.8 V and a design life of over 12 years at 20 C. A 6,000-cycle lithium pack sitting at 100% for years pays for cycles it never uses.
• A place that drops below 0 C. Hithium specify charging from 0 to 40 C, Felicity from 0 to 55 C. Below zero the BMS blocks charging, because lithium plating damages the cells. LONG rate both lead-acid types for charging from -15 C. An unheated cellar in a mountain village in January needs a heated battery room or lead-acid.
• A 12 V system. The smallest lithium pack we stock is the 25.6 V HeroEE 8. A 12 V inverter such as the Axpert VM II 1.2 kW takes a single 12 V block, so AGM or lead-carbon.
• An inverter with no lithium setting. An inverter that offers only AGM and Flooded can run lithium on user-defined voltages only if the battery maker approves it. Otherwise stay with lead-acid or change the inverter.
• A bank under about $900. Four AGM blocks are $880. If a $1,000 HeroEE 8 or a $1,680 Felicity is out of reach, a lead-acid bank works today, provided you size it at 50% depth of discharge and accept the cycle count above.

Which battery should you buy?

Your situation	Buy	Why
48 V home system cycled every day, whole-house loads	Hithium HeroEE 16, $1,950, or Felicity LPBF 15 kWh, $1,800	90% or 95% DOD, 8,000 or 6,000 cycles, 100 to 120 A charge, inverter communication
48 V system, essential loads only, wall space not floor space	Felicity LPBA 10 kWh, $1,680, or LPBA 8.7 kWh, $1,344	82 kg on the wall, expandable to 32 units
24 V system (Axpert VM III Twin 24 V class)	Hithium HeroEE 8, $1,000	25.6 V, 8 kWh, same 90% DOD and cycle rating as the 16
Standby or UPS, rarely discharged	LONG AGM 200 Ah, $220 per block	Float design life over 12 years, 1,600 A for 5 s
12 V system, freezing location, or budget under $900	LONG lead-carbon 200 Ah, $248 per block	Cycle-use VRLA, charges from -15 C, size it at 50% DOD

The battery voltage is set by the inverter, not by preference: see 12V vs 24V vs 48V: which battery voltage do you need?. Weighing a battery against the generator subscription? The numbers are in 16 kWh battery vs generator subscription.

Frequently asked questions

Is a 100 Ah lithium battery better than a 200 Ah lead-acid battery?

For daily use, usually yes. The lead-acid 200 Ah is a 10-hour-rate figure and the battery is run at 50% depth of discharge to reach a useful cycle count, while the lithium pack is rated at 90% or 95% and holds its capacity at high current. Compare rated depth of discharge and cycle life, not the Ah on the label.

Can I replace my lead-acid bank with lithium on the same inverter?

Usually, if the inverter has a lithium type in its menu and the battery maker lists it as compatible. On the Axpert range it is program 05 plus the BMS cable. Match the voltage class: a 48 V bank becomes a 51.2 V pack, a 24 V bank a 25.6 V pack. Never leave old lead-acid blocks in parallel with a lithium pack.

Can I charge a lithium battery in winter?

Above 0 C, yes. Hithium rate charging from 0 to 40 C and Felicity from 0 to 55 C. Below zero the BMS refuses the charge, so a pack in a room that freezes sits uncharged on the coldest mornings. Discharging is allowed down to -20 C on both.

How long does a lead-acid solar battery last?

It depends on how deep you cycle it. LONG's chart for the CWP200-12N shows about 900 cycles at 50% depth of discharge and about 250 at 100%, tested at 25 C to 60% remaining capacity. Heat and undercharging shorten that. Once a day at 50% is about two and a half years.

Are lead-carbon and AGM the same thing?

Both are sealed VRLA lead-acid, same size and weight in the LONG range, and both charge from -15 C. The difference is the job: LONG specify the WPL AGM for standby use (float 13.5 to 13.8 V, 12-year float design life) and the CWP lead-carbon for cycle use (cycle charge 14.4 to 15.0 V, with a cycle life chart). For a solar bank that discharges daily, choose the lead-carbon.