LFP batteries XCAP background information

  • New batteries are not fully charged, but to about 40%, the so-called Storage Charge. In this condition LFP batteries can be stored for years, losing about 10% of their charge each year. The self-discharge is very low, about 1-2 % per month
  • So before you start using a new battery, it has to be charged to full. If you use an XCap LFP-charger, this state is indicated by the charging LED; when it turns from red to green. Using a dedicated LFP charger (CC/CV-type, end voltage 14.6V) is strongly recommended as most lead-acid chargers are not suitable.
  • A big advantage of LFP batteries over lead-acid (SLA) batteries is their very low internal resistance. Thus internal losses are much lower and voltage remains higher during heavy loads (starting). The downside is that a shortcircuit results in very high current. Each battery has a built-in protection against this (BMS), but it is recommended to use a 10A thermal fuse, or a circuit breaker, as close to the battery as possible.
  • Batteries used as a powersupply to instruments have moderate loads (1-3A). The voltage curve under load of a typical LFP-battery is depicted below. The curve starts at about 13.3V and gradually falls to about 11V; its slope is much more flat than that of a SLA battery. Below 11.5V the BMS can release the load at any moment without warning, so it is safe to switch batteries around 11V.
  • It is recommended to charge batteries after each flight; the next one might be unexpectedly long.
  • When the battery is not used for a long time (winterstop), the best way to store it, is with 40% charge and storage in in a cold, dry place. This is done by fully discharging the battery (leave the switch on) untill the BMS switches off and to charge the battery to 40%, depending on its capacity and the charging current.
  • If a LFP battery is treated according to these guidelines it will live very long: 2000 cycles or 10 years can be achieved in this way. This is at least 5 times longer than SLA batteries.
  • Compared to SLA, LFP offers another advantage: the capacity is independent of the load. The red and green curves are a 8Ah SLA under different loads: 0.4A and 5A. At 5A the capacity of a 8Ah drops to 6.1. The 8Ah LFP has the nearly the same capacity at any load. In general the useful energy of LFP is 150% of a comparable SLA.

Glider Pilot Shop is exclusive dealer for XCap-batteries in the Benelux. The four standard-size LFP batteries listed below have been added to our webshop as well as two types of LFP battery-chargers. However, if you need a different size or model or a customized version of the LFP-battery please contact us and we will prepare a proposal for your customized battery.

XCap LFP12-8 Avionics battery

  • Capacity: 7.7-8.3Ah @ 1A
  • Dimensions: 151 x 65 x 95 mm
  • Weight: 1.1 kg
  • Connection: 3/16” FASTON tab
  • Current: 8A cont/14A pulse
  • Charger: 14.6V CC/CV 2A

XCap LFP12-10 Avionics battery

  • Capacity: 9.6-10.3Ah @ 2A
  • Dimensions: 151 x 65 x 95 mm
  • Weight: 1.4 kg
  • Connection: 1/4” FASTON tab
  • Current: 10A cont/14A pulse
  • Charger: 14.6V CC/CV 2A or 3A

XCap LFP12-12 Avionics battery

  • Capacity: 11.8-12.2Ah @ 3A
  • Dimensions: 151 x 95 x 101 mm
  • Weight: 1.8 kg
  • Connection: M5 screw terminal
  • Current: 10A cont/20A pulse
  • Charger: 14.6V CC/CV 3A

XCap LFP12-19 Engine battery and light starting

  • Capacity: 18.8-19.3Ah @ 5A
  • Dimensions: 181 x 78 x 167 mm
  • Weight: 3.2 kg
  • Connection: hole 5.5 mm diameter
  • Current: 30A cont/80A pulse
  • Charger: 14.6V CC/CV 3A or 5A