With low energy density, heavy, inefficient discharge rate and non-ecofriendly features, lead acid battery is not satisfying as backup power for modern portable industry instruments. Thanks to high specific energy, light weigh, small size, long cycle life, high safety and consistent high-voltage, lithium battery pack have become the first choice to replace lead acid battery on industry instruments.1.Requirements of backup power for ground-penetrating radar tester:
Ground-penetrating radar testers require high working voltage, long working time and special environment temperature. Thus long lifetime domestic Bak lithium cell and combination of 6 series& 8 parallels can fulfill customers’ relevant parameter requirements. Concerning protection IC, 6 series Seiko hardware protection circuit+6 series charge balance circuit are able to achieve maximum over current of 25A , continuous discharge current of 8A and charge balance circuit of 300mA on finished lithium battery pack. Environmentally, top-grade white water-proof enclosure can attain water resistance.
2.Specific parameters of finished battery pack as follows:
- Model: 18650-6S8P/16Ah/22.2V
- Circuit Design Requirements
- single battery overcharge protection voltage: 4.35±0.25V
- single battery overcharge recovery voltage: 4.15±0.50V
- single battery over discharge protection voltage: 2.70±0.08V
- single battery over discharge recovery voltage: 3.00±0.10V
- Combined battery over current protection (10ms):30~35A
- Charge balance current: 300±50mA
- Charge balance voltage: 4.20±25mV
- Battery over heat protection (recoverable): 70±5?
- Finished battery can be protected from the harm of short circuit and reverse charge.
- Battery cycle life requirement: 500~1000 times (national charge and discharge standards)
- PCM: a protection circuit designed mainly for rechargeable lithium battery pack. Because of chemical characteristics of lithium battery, protection functions like smart capacity calculate, overcharge, over discharge, short circuit, over current, etc should be provided to avoid fire and explosion.
- Protection IC: constantly monitors cell’s overcharge, over discharge, short circuit, and over current to ensure cell’s safe, stable and efficient work.
- Charge balance module: used for balancing cell’s voltage differences during charging and strengthening cell’s voltage consistency to extend lifetime of finished battery.
- Temperature switch: mostly targeted for temperature protection. When battery’s temperature abnormally rises to 75?, temperature switch works for over heat protection whereas it can automatically restores a low temperature.
- 18650 lithium cell/18650/2000mAh/3.7V BAK cell (long lifetime cell).
- MOSFET: play the role of switch during circuit protection to guarantee load voltage can neither rise nor drop.
4.Diagram of backup power solution for ground-penetrating radar tester:
5.Picture of backup power for ground-penetrating radar tester: