Frequently asked questions

A 12V LiFePO4 battery gives you roughly twice the usable energy, about a third of the weight, and up to ten times the cycle life of the lead-acid battery it replaces. You also charge it far faster and never top up water or worry about fumes.

LiFePO4, or lithium iron phosphate, is the chemistry used in almost all 12V leisure and marine lithium batteries. It is chosen over other lithium types because it is much safer, very stable, and lasts thousands of cycles. When people say a 12V lithium battery, they almost always mean LiFePO4.

No. Phones and laptops use energy dense chemistries like NMC that are less stable. Leisure and marine batteries use lithium iron phosphate, LiFePO4, which is far more stable, tolerates thousands of cycles, and is the safe choice for a 12V house bank.

Lead-acid should only be drawn down to about 50 percent before it wears out, so a 100Ah lead battery gives you around 500Wh of usable energy. A 100Ah lithium can be used to 80 to 90 percent, giving around 1,000 to 1,150Wh. In real terms one lithium battery does the work of two lead-acid batteries of the same rating.

Usually yes. Because lithium delivers far more of its rated capacity, you need roughly half the amp-hours of lead-acid for the same real usable energy. A 220Ah lead bank is matched by about 120Ah of lithium.

Work it in usable energy, not amp-hours. The tool does this for you: enter your battery and it shows the energy matched lithium and a same case drop-in. As a rule of thumb, a 100Ah lithium replaces a single Group 24, 27 or 31 lead-acid battery comfortably.

Often yes. Many lithium batteries are built to match the BCI Group 24, 27 and 31 footprints, so a same group lithium drops into the existing box. Always check the exact model dimensions, as some are a little taller or use different terminals. The tool shows a fit check with the real dimensions.

Physically it can be. Electrically it is not automatically plug and play. The case may fit, but you should check your charger, alternator and solar settings suit lithium. See the charging questions below.

Yes. A pair of 6V golf-cart batteries in series gives 12V at around 215 to 225Ah. A single 12V 200Ah lithium replaces them with a fraction of the weight, though a large 200Ah case can be a similar size to the two lead boxes. The tool flags this.

Usually not. The conversion is about your house or leisure bank. Most people keep a normal lead-acid starter battery, or fit a dedicated lithium start battery. Do not run your house lithium and your starter battery as one mixed bank.

Yes, but plan it. To parallel batteries safely they should be the same make, model and roughly the same age, and you should bring the new one to a similar state of charge before connecting. Mixing old and new, or different brands, can leave one battery doing more work than the rest.

It depends on your daily energy use and how many days of autonomy you want. Rather than guess, enter your current battery or your loads into the tool and it sizes the pack for you, including the right number of units.

Not always. Many mains and shore chargers with an AGM or gel profile already sit inside the lithium voltage window and work fine. A plain flooded or wet profile charges too high and can make the BMS cut off, and any desulfation or equalization mode should be turned off. A charger with a dedicated lithium profile is the safe choice.

Bulk and absorption sit around 14.2 to 14.6V, with float at or below 13.6V, or no float at all. Lead-acid often charges to 14.8 to 15.0V and holds a higher float, which is wrong for lithium.

Not directly. A standard alternator has the wrong charge profile, and a lithium battery can pull so much current that it overheats or damages the alternator. Fit a DC to DC charger, also called a B2B charger. It limits the current, applies the correct lithium profile, and protects the alternator.

Use an MPPT or PWM controller set to the lithium charge voltage, around 14.4V for a 12V pack, and turn float off. Solar is a great match for lithium because the fast charge captures more of a short sunny window.

Almost always yes, and lithium actually suits inverters because it holds voltage under load. Check the inverter low-voltage cutoff is not set so high that it shuts off while the lithium still has usable charge, and make sure the battery BMS continuous rating covers the inverter current.

Check them. Lithium can deliver much higher current than lead, so make sure your cable gauge is adequate and fit a correctly rated main fuse close to the battery. Undersized cable or fusing is a fire risk.

Fit a shunt based battery monitor on the negative lead. Lithium holds a flat voltage for most of its discharge, so you cannot judge charge from voltage alone the way you could with lead-acid.

The battery management system is built into the battery. It protects against over and under voltage, over current, short circuits and temperature limits, and balances the cells. Every quality lithium battery has one. Pick a battery whose BMS handles your maximum charge and discharge current.

No. Lithium batteries are sealed, so they can be mounted in any orientation and do not need venting, unlike flooded lead-acid. That often frees up where you can put them.

No, not safely. Charging LiFePO4 below 0C causes permanent damage, so the BMS blocks it. Discharging in the cold is fine. If you will charge in sub freezing conditions, choose a self heating battery or add a heater pad, and insulate the battery box.

A good BMS simply blocks charging below 0C, so the battery protects itself and you may see the charge current drop to zero. Charging a lithium cell below freezing without that protection causes lithium plating, which permanently reduces capacity. This is why self heating packs exist.

Yes. Lithium iron phosphate is the most stable common lithium chemistry and does not behave like the lithium in phones or laptops. It does not off gas like lead-acid and contains no acid to spill. The BMS adds further protection.

No. Never run lithium in parallel or series with lead-acid, and do not mix different makes, sizes or ages in one bank. They charge and discharge differently and one will damage the other.

Over time, usually yes. A lithium battery costs more up front but lasts 2,000 to 5,000 cycles and around ten years, against roughly 300 to 1,200 cycles and three to five years for lead-acid. The cost per cycle is far lower, and you often replace lead two or three times in the life of one lithium.

It varies with how hard you cycle the bank, but heavy users often see lithium pay for itself within a few years by not replacing lead-acid every three to five years. For light, occasional use the case is more about weight, capacity and convenience than pure payback.

Typically around ten years, or several thousand charge cycles, when charged correctly. Using the wrong charger profile is the main thing that shortens lithium life, which is why the install settings matter.

About 70 percent. A 100Ah lithium weighs roughly 11 to 14kg against 27 to 32kg for the lead-acid equivalent. For a campervan that is payload, and for a boat it is weight off the waterline.

It depends on budget and features. Budget brands cover the basics, value brands often add Bluetooth and self heating, and premium brands add the longest warranties and pro grade build. The tool gives you a best pick plus budget, premium and cold weather alternatives so you can compare.

One larger battery is simpler, with fewer connections and one BMS to manage. Several smaller ones can be easier to carry and fit in awkward spaces, and give some redundancy. The tool leans towards the fewest units that meet your needs to keep it simple.

Often the cells are a similar grade of LiFePO4, and the real differences are the BMS quality, the build, the support and the warranty. Budget brands can be excellent value. Premium brands charge more for longer warranties, higher BMS current ratings and proven support.

Most reputable 12V lithium batteries carry a 5 year warranty, with premium brands offering 7 to 11 years. A longer warranty is a reasonable proxy for how long the maker expects the pack to last, but always check what it actually covers.

Battery prices change daily. We show a price tier and band for orientation and send you to the retailer for the live price, so you never see a stale number.

Depending on your setup, a lithium aware mains charger or a DC to DC charger for alternator charging, a shunt battery monitor, correctly rated fuses and cable, and a heater pad or self heating battery if you charge in the cold.

The tool sizes your pack with a transparent engineering calculation, then matches it to real products from reputable brands. We earn an affiliate commission if you buy through our links, at no extra cost to you, but we recommend on engineering merit, not commission, and we always send you to the retailer for the live price.