SAFIERY UNIVERSITY
LITHIUM BATTERIES
INTELLIGENT DC to DC CHARGERS
This technical article is designed to give value to the reader through more knowledge of charging Lithium Batteries with a DC to DC Charger.
Great Charging from Vehicle and Solar
DC to DC Lithium Chargers supply:
- Up to 25A Charging from the vehicle
- Work with vehicles that have smart alternators
- Up to 360W of solar panel power transferred
- Operate at 96% efficiency.
Recovery of Lithium Batteries after Deep Discharge.
In early 2012, we had installed a well know brand DC to DC charger on 240 Ahrs of Lithium Batteries. After a deep discharge, the customer could not recover the batteries. We had to go out and purchase a very low current constant power supply of 1-2A to recover the batteries. After deep discussion with the battery manufacturers’ engineers, we understood the problem. It was not the batteries, but the DC to DC Charger.
When Lithium batteries have a deep discharge, the voltage will nose dive very fast and very deep. Once below about 8-9V, the BMS in the Lithium Battery will not allow it to be charged at a high charge rate.
Most DC to DC Chargers start up by “sensing the battery voltage”. The Lithium Battery BMS will show maybe 3-4V to the DC Charger. Those DC chargers may them want to thump through a medium or high output current to recover. The Lithium BMS will not allow this for safety reasons. Hey presto: an impasse with no recovery.
PROJECTA solved this problem with the new IDCL 25.
The Projecta team have addressed this in their IDC25L Lithium DC to DC Charger.
When in recovery mode, the charger starts with 2 levels of “soft start”.
Soft Start 1 Constant 1.25A if 2V< Battery Voltage <8V
Soft Start 2 Constant 6.25A if 8V< Battery Voltage <10V
Bulk 20A at 9-11Vdc input; 25A at 11-32Vdc input
Hey presto: full Lithium recovery!
Need a Bullet-proof Combination
Deep discharges can occur on a trip. It has happened to me several times.
- Recovery is vital
- Recovery has to be bullet-proof with little mucking around.
Charge efficiency
- PROJECTA IDC25L has a charge efficiency exceeding 94%
- Typical AGM Batteries are around 75% efficient. But as Lithium is close to 100%, you need a high efficiency charger to match them.
Charging from Solar is full 360W
- Some DC to DC Chargers have a solar rating that is less than the vehicle rating. But not PROJECTA IDC25L. It is 360W solar power charger!
Compact Design
- Only 123mm L 122mm W and 40mm high
- Fits into the engine bay of most 4WD
IP 67 RATING
- Waterproof and Dustproof to IP 67