Battery Equivalents and Replacements

Battery Tender 12V Lithium Iron Phosphate Batteries

Battery Tender 12V Lithium Iron Phosphate Batteries is group of several lithium, dual purpose, batteries. They are lightweight batteries, have large discharge currents, large number of charging cycles and have many other benefits when compared with similar lead-acid batteries. On the other hand, they must be charged with proper chargers and they cost more than corresponding lead-acid batteries.

Published: December 27, 2018.

battery tender lithium iron phosphate battery

Deltran Battery Tender Lithium Iron Phosphate (LiFePO4) batteries are designed to replace Flooded, AGM, and Gel cell lead-acid batteries in applications such as motorcycles, ATVs, utility vehicles, personal water crafts, scooters, dirt bikes, lawn mowers etc.

They can provide substantial starting/cranking currents and can replace starting or dual-purpose lead-acid batteries in such applications.

These batteries are advertised as being able to withstand 2000+ deep cycles at 80 percent depth of discharge, making them suitable replacements for deep cycle lead-acid batteries in marine, solar and other similar applications. Even half of that number ('only' 1000 recharging cycles) means almost three years of use on a daily basis. Hardly that any deep cycle lead-acid battery can withstand such use, perhaps only the top of the line, deep cycle lead-acid batteries can do that, but ... Even such lead-acid batteries must be charged using intelligent chargers and they also cost more than 'common' deep cycle batteries.

Note: these batteries do come with 3-years limited warranty. If used and charged properly, they will easily last more than that.

Since the Battery Tender Lithium Batteries are in most cases smaller than conventional lead-acid batteries, several foam spacers are included to fit into multiple size battery boxes. These batteries also feature 'Quad Terminal Configuration' and they can be mounted and operate in any position.

Also, they are much lighter than lead-acid batteries, leading to significant weight savings - keep that in mind on small boats, where lead-acid batteries are often used as weight for improving the stability of the boats.

Battery Tender 12V Lithium Iron Phosphate Batteries - Features and Specifications

Comparison of Battery Tender 12V Lithium Iron Phosphate Batteries is given in the following table:

Model BTL09A120C  BTL14A240C  BTL24A360C  BTL35A480C 
Photo lithium btl09a120c t  lithium btl14a240c t  lithium btl24a360c 1  lithium btl35a480c t 
Nominal Voltage 12 V 12 V 12 V 12 V
Cranking Amps 120 A 240 A 360 A 480 A
Relative Cranking Amps ~218 A/kg ~300 A/kg ~307 A/kg ~282 A/kg
 Lead Acid Battery Replacement Range 7 - 9 Ah 10 - 14 Ah 21 - 24 Ah 26 - 35 Ah
 Stored Energy 25.6 Wh 51.2 Wh 76.8 Wh 96 Wh
Relative Stored Energy ~46 Wh/kg ~64 Wh/kg ~65 Wh/kg ~56 Wh/kg
~2.1 Ah ~4.2 Ah ~6.4 Ah ~8 Ah
Maximum Charging Current 10 A 10 A 10 A 10 A
Dimensions (L x W x H) 4.21 x 2.2 x 3.35 inches
10.7 x 5.6 x 8.5 cm
5.27 x 2.55 x 3.62 inches
13.4 x 6.5 x 9.2 cm
6.49 x 3.38 x 5.11 inches
16.5 x 8.6 x 13 cm
6.49 x 3.38 x 5.11 inches
16.5 x 8.6 x 13 cm
 Weight 1.2 lbs (~0.55 kg) 1.76 lbs (~0.8 kg) 2.6 lbs (~1.17 kg) 3.75 lbs (~1.7 kg)
Operating Temperature 40 - 140°F
4 - 60°C
40 - 140°F
4 - 60°C 
 40 - 140°F
4 - 60°C
 40 - 140°F
4 - 60°C
Amazon Link Battery Tender BTL09A120C Lithium Iron Phosphate Battery Battery Tender BTL14A240C Lithium Iron Phosphate Battery Battery Tender BTL24A360C Lithium Iron Phosphate Battery Battery Tender BTL35A480C Lithium Iron Phosphate Battery

Note: Amazon affiliate links in the table open in the new windows. All information in this table come from official Battery Tender web site. Information over time change, so be sure to verify the data before you make purchase.

battery tender lithium chargerMaximum charging current of these batteries is 10 A. Since their actual capacity is 8 Ah or less, charging them with such current would charge them in less than one hour. Which is very fast.

However, such fast charging can, IMHO, shorten battery operating life if used on a daily basis.

These batteries can be even charged with classic lead-acid battery charger, as long as it doesn't use a high-voltage anti-sulfation charging mode and it stops charging when voltage reaches 14.8 V - IMHO preferably sooner, at 13.6 V, for example.

In order for these batteries to last, lithium battery charger is highly recommended, preferably lithium battery charger from Deltran (their batteries, hence their chargers), like Battery Tender 022-0198LI Lithium Junior Charger for Lithium Iron Phosphate Batteries (Amazon link, link opens in the new window), photo on the right.

This battery charger is used to fully charge and to maintain lithium iron phosphate batteries. It employs 5 steps charging method consisting of Qualification phase, Recovery phase, Bulk phase, Absorption phase and Float at 13.6 volts - very similar to lead-acid battery chargers, but NOT exactly the same.

To improve safety, charger comes with several very important safety features: spark proof, short circuit protection, reverse polarity protection, safety timer etc. Such safety features are not just marketing trick, they are there for good reason - batteries in general, especially lithium batteries can store large amounts of energy in small volume/mass. If something goes wrong, it can lead to fire, heat, explosion, damage, injuries or worse - hence, take these batteries and charges seriously ...

This charger comes with 5 year Warranty.

Weight Comparison

Relative stored energy in Deltran Battery Tender Lithium Iron Phosphate batteries could be better, when compared with RC (Remote Control) models/drones lithium ion batteries.

Note that lithium ion RC batteries are designed to be as light as possible, with energy capacities often well above 150 Wh/kg.

Battery Tender 12V lithium iron phosphate batteries have capacity in 45 - 65 Wh/kg range, which is far below 150 Wh/kg, but they are also more robust, have excellent starting currents and can tolerate more recharging cycles.

Top RC lithium ion batteries are also very expensive batteries.

'Relative Cranking Amps' of the Battery Tender 12 V Lithium Iron Phosphate batteries is in range of 220 - 310 Amps per one kilogram of the battery.

Relative stored energy and cranking amps of the most popular marine and automotive batteries is given in the following list:

optima d34m bluetop- Optima 35 RedTop, 44 Ah, 31.7 lbs (~14.4 kg), MCA 910 A - 36.6 Wh/kg, 63 A/kg

- Optima D35 YellowTop, 48 Ah, 36.4 lbs (~16.5 kg), MCA 770 A - 34.9 Wh/kg, 46 A/kg

- Optima D31M BlueTop, 75 Ah, 59.8 lbs (~27.1 kg), MCA 1125 A - 33.2 Wh/kg, 41 A/kg

- Exide XMC-31 MEGACYCLE AGM-200, 100 Ah, 71 lbs (~32.2 kg), 1110 A - 37.2 Wh/kg, 41 A/kg

- VMAXTANKS V35-857, 35 Ah, 25 lbs (~11.3 kg), 390 A - 37.1 Wh/kg, 34 A/kg

Note: this list contains deep cycle, dual purpose and starting batteries, which is clearly visible - deep cycle SLA batteries can provide 30-40 Amps/kg, dual purpose batteries can provide 40-50 Amps/kg, while starting batteries can easily provide 60 or more Amps per one kilogram of the battery.

Also, smaller AGM or Gel Cell SLA 7Ah/12V batteries weigh around 5.5-6 pounds (2.5-3 kg), while 21Ah/12V batteries weigh around 14-15 pounds (6.5-7 kg). These batteries have relative stored energy values between 28 and 38 Wh/kg.

Battery Tender 12 V Lithium Iron Phosphate batteries store 1.5 - 2 times more energy and can provide 4 - 8 times more cranking amps than the best AGM SLA batteries.

Maintenance and Storage

In order to prolong the battery life, don't store it in high temperatures and don't discharge them below 20%, or below 8V (under load).

Compared to lead-acid batteries, these batteries have less than 5% of the average lead-acid battery self-discharge rate and can be stored for much longer periods without maintenance, preferably charged at ~70%.

Other than that, these batteries are maintenance free - if they are regularly charged with lead-acid charger (no desulfation mode, charging cut-off voltage at max 14.8V), charging them from time to time with lithium charger is recommended.

Use as Starting/Cranking Battery

lithium btl24a360c 1A lithium battery’s cranking performance decreases as its temperature approaches freezing. These batteries will operate normally in temperatures down to 40°F (4°C) - some sites claim 0°F (-18°C), however, data in the table are taken from the official web site and official manuals.

When starting the engine during the cold weather, if the engine fails to start on the first try, a light load such as the headlights can be used to warm the battery.

The length of time it takes to warm the battery depends on the outside temperature. The colder the weather, the longer it will take to warm the battery sufficiently.

A good rule of thumb when the temperature is below freezing is to turn on the headlights for about 2-5 minutes, depending on the battery capacity, battery charge condition, types of lights (LED, incandescent), etc.

Of course, keeping the battery fully charged will improve starting in the cold weather.

Value given for the 'Lead Acid Battery Replacement Range' in the table is actually value for starting lead batteries. For deep cycling batteries things are little bit different.

Use as Deep Cycling Battery

lithium btl14a240c 1One of the reasons why these batteries are so popular is their number of recharging cycles, which makes them ideal batteries for solar and electric vehicle applications, as fish finder battery and similar.

IMHO, these batteries are not good as trolling batteries - largest of them, BTL35A480C battery, has (calculated) capacity of 'only' 8 Ah. Such battery can power small trolling motor (36 lbs of thrust, 30 A max current) for about 10-12 minutes (down to 20% discharge) - not much.

Connecting these batteries in parallel using power diodes or similar electronic circuitry to provide larger capacity is possible, but IMHO not recommended, unless you are ABSOLUTELY sure that you know what are you doing! In any case, it's your own responsibility!!!

Long story short:

- if you need lightweight starting battery in mild and warmer climate (up to 480 Amps), Battery Tender 12V Lithium Iron Phosphate Battery is excellent choice.

- if you need lightweight, high capacity, fish finder battery, these batteries are good choice. There are lithium batteries on the market which provide even more Wh/kg, but they also do cost more money.

- if you need trolling motor battery, these batteries are simply too small to provide enough power for longer period of time.

- if you need lightweight, general purpose battery for camping or fishing trips or other outdoor activities, consider these batteries; perhaps they are just what you need.

Be aware of limitations of equipment you have and that equipment will serve you well - it applies here, too :)