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FAQs

General Shipping & Return Batteries BMS Charging & Discharging

    1. The main difference in wiring batteries in series vs. parallel is the impact on the output voltage and the capacity of the battery system.
      Batteries wired in series will have their voltages added together. Batteries wired in parallel will have their capacity (measured in amp-hours) added together. However, the total available energy (measured in watt-hours) of the battery system with the same battery amount is always the same even with different connection methods.

      For example, wiring two 12V 100Ah batteries in series will set up a 24V (25.6V) 100 Ah battery system. Wiring the same two batteries in parallel will get a 12V (12.8V) 200Ah battery system. And both systems have a total available energy of 2560Wh (Wh = volts x amp-hours).

      Additionally, batteries wired in series and parallel should be identical batteries with the same voltage, capacity and BMS rating. Connecting different batteries may lead to problems that may damage them or even more severe outcomes.

    1. DEPTH OF DISCHARGE (DOD)
      The lithium iron phosphate (LiFePO4) batteries typically have a higher depth of discharge values. About 85% of the energy capacity can be drained before they need to be charged. Compared to lead-acid batteries, they can only be discharged up to 50%. Continuing to use the battery beyond that point will negatively affect its lifespan and effectiveness.

      95% EFFICIENCY
      The LiFePO4 batteries have an efficiency rating of over 95%, which means that for every 1000 watts of solar power absorbed by the batteries, over 950 watts are available for use. Compare this with lead-acid batteries with efficiency ratings of 80% to 85%, which means for every 1000 watts, only 800 to 850 watts are available for use.

      ENERGY DENSITY OR CAPACITY
      The LiFePO4 battery systems tend to have higher energy density values than lead-acid batteries. This means that they can store a higher amount of energy for the same size. Meanwhile, the LiFePO4 batteries are only 1/3 lightweight of lead-acid batteries, which makes it an easy choice when mounting or mobility is in consideration.

      LESS COST
      While lead-acid batteries may ostensibly be more affordable, the long-lasting life cycles and effectiveness of LiFePO4 batteries offset those costs. Considering you won’t have to replace a LiFePO4 battery as soon as you would have to replace a lead-acid one, they aren’t exactly more costly.

      4000+ CYCLES LIFESPAN
      Ampere Time LiFePO4 batteries can last for 4000+ cycles while the lead-acid batteries typically have only about 200~500 charge cycles, and the cycle time of Ampere Time LiFePO4 batteries is three-time longer than the lead-acid batteries.

General

Connection

    1. Yes, you can connect 2*12V batteries in series to build a 24V battery system.

    1. We do not suggest that you connect Ampere Time batteries with other brands’ batteries. Below are the detailed explanations why we don’t recommend connecting batteries from different brands. ① Batteries from different brands have different cells. Although they are all LiFePO4 cells, their charging and discharging are a little different. If the cells are different, there will be a little difference in battery pack capacity.
      ② The over-current capacity and protection provided by BMS from different brands are different. If the overcharge and over-discharge protection parameters are different, it will affect the voltage difference between batteries after being used in series.
      ③ The MOS withstand voltage values of the BMS from different brands are different.
      Some battery packs from other brands do not support series connections. If the withstand voltages of MOS are different, it may burn out the BMS after series connection.
      The premise of Connection
      To connect in series or /and parallel, batteries should meet the below conditions:
      a. identical batteries with the same battery capacity (Ah) and BMS (A);
      b. from the same brand (as lithium battery from different brands has their special BMS);
      c. purchased in near time (within one month).

Installation

Voltage & Capacity

    1. Most of our customers will use a multimeter to check the voltage of their Ampere Tim LiFePO4 batteries. And you could roughly estimate your battery's remaining power by its rest (open-circuit) voltage. Based on the characteristics of LiFePO4 batteries, the voltage measured by all LiFePO4 batteries during charging/discharging is not the real voltage of the battery.
      Therefore, after charging/discharging and disconnecting the battery from the power source, the voltage of the battery will gradually drop/increase to its real voltage.
      If you need to test the real voltage of the battery, please disconnect all the connections to the battery and test its voltage after putting it aside for over 30 mins. 
      Here take 12V 100Ah battery as an example, please refer to below SOC:
      Capacity---Voltage
      100%---13.5V
      99%---13.4V
      90%--- 13.3V
      70% --- 13.2V
      40% --- 13.1V
      30% --- 13.0V
      20% --- 12.9V
      10%---12.8V
      1% ---10.8V (recommend low voltage disconnect voltage)
      0% ---9.5V
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