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12V | 24V lithium ion battery purchase handbook

Views: 576     Author: Site Editor     Publish Time: 2022-06-29      Origin: Site

12V | 24V LiFePo4 Battery Pack Purchase Guide



Do you have the following doubts:

1. Should I buy a 12V or 24V battery?

2. What is Usable capacity?

3. What is the maximum discharge current?

4. What do you need to know about Cell?

5. What is the maximum charging current?

6. How to calculate the number of cycles?

7. What is the depth of discharge of the battery pack?

8. What are the current capacities of 12V and 24V batteries?


1. Should I buy a 12V or 24V battery?


1.Before we think about the answer, ask yourself a question first, where do you plan to use the batteries? 

At home ? ourdoor ? mabe marine ? RV ? trailor ? or else?


2.Great ! Ask yourself 2nd question, how you use them?

Single use? or series? or parallel?


3.Maybe you'll use together with an inverter, right? what's the voltage of it's working platform? how about the maximum load?

12V inverter ? 24V inverter ? 1kw inverter ? 3kw  ? 5kw ? 8kw or more?


4.Now you've know you requied voltage, it's time to think about the only key factor, that is the load.

Batter should be chosen based on the voltage platform of your inverter,and be causion that the most BMS of the battery is 100Amp ( 1280 watt ), if your requied load is bigger than this , pls let us know and we will give you professional suggestion. 


2.  What is Usable capacity?


To keep things simple, in this Buyer’s Guide we’re only looking at 100Ah batteries. In other words, we’re comparing apples with different flavour apples, not apples and dragon fruit. Also, it’s worth noting that lithium-based batteries have a much greater usable capacity than their older-school lead-acid counterparts. Whereas an AGM/Gel deep cycle battery has a usable capacity of around 50 per cent (for decent brand batteries), decent lithium batteries will have around 90-95 per cent usable capacity.


Usually, for obtain better customer satisfaction, LITHTECH will strictly control the selection of cells. Before leaving the factory, we will test each battery pack to ensure that the actual capacity is 1%-2% higher than the rated capacity.


3. What is the maximum discharge current?


This relates to how hard you can drain the battery. For example, your 12-volt fridge will draw about five amps maximum when it’s running; a 1200W inverter will draw around 100 amps at full tilt; and your winch will draw 550-600 amps when working. So, if you’re not running a coffee machine, washing machine, portable aircon and an induction cooktop (yes, some people are!), then anything with more than a 50A draw will probably do you. You’ll only need to look at high-draw options (or running multiple batteries in parallel) if you really need to draw a lot of juice.  


4. What do you need to know about Cell?


Cell design has changed over the years. Older lithium batteries are made with 18650 style cylindrical cells that resemble AA batteries but are a bit thicker and longer. These cylindrical batteries are connected to create battery banks of 12.8V and 100Ah, and are held together with either plastic frames or, in the case of some cheaper ones, are just glued together. 

Nowadays, nearly all lithium batteries feature a ‘prismatic’ style cell arrangement, with four prismatic-shaped (rectangle-box shape) cells at 3.2V and 100Ah each, connected in series to give the nominal 12.8V we need to power our equipment.  

Prismatic cells are more stable and can take more of a beating than the old-style cylindrical cells and are therefore better suited to automotive use.


5. What is the maximum charging current?


Like maximum discharge current, most lithium batteries will have a maximum charge current listed. The rule of thumb here is the lower the number, the longer the battery will last, however some batteries on the market claim to be able to be charged at upwards of 100 amps. Take that number with a grain of salt.


6. How to calculate the number of cycles?



This is where the numbers get rather interesting. Simply put, the number of cycles the battery can undertake means the number of times it can be discharged and then recharged before it reaches the end of its useable life. For example, say you discharge your battery with the fridge and LED lights overnight, then recharge it the next day, that’s one cycle – the only difference here is the depth of discharge.

The average lithium battery is good for around 5000 cycles at 80 per cent Depth of Discharge (DoD). We’ll talk about DoD just below, and we’ll get back to that 5000 cycles when we talk about warranty.


7. What is the depth of discharge of the battery pack?



Depth of Discharge refers to how far you discharge the battery. For example, if you use 50 amp-hours (Ah) of a 100Ah battery, you’ve discharged it to 50 per cent Depth of Discharge (50% DoD). If you use, say, 80Ah of your 100Ah battery, you’ve discharged to 80% DoD.  

Where this is important is for the longevity of the battery over time. For example, if a battery has an 80% DoD rating of 5000 cycles, that means if you discharge it 80% every day, that battery should last for 5000 days (13.6 years) before it dies. It should be noted that the same battery might have a 50% DoD rating of 7000 cycles, so if you only discharge it to 50 per cent once per day, you should get around 5000 days (19.1 years) out of it.

The above examples are quite simplistic, and it should be noted that on some days you may run the batteries through several cycles when running inverters for coffee machines or cookers, or fans or lights, while on other days you may not cycle the battery at all.


8. What are the current capacities of 12V and 24V batteries?


12V  50Ah | 100AH | 120Ah | 150Ah | 200Ah | 300Ah

24V 100Ah | 200Ah








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