There are two types of Lithium batteries, lithium ion and lithium polymer batteries. The chemistry is basically the same for both types of batteries, so are the charging methods. The lithium ion battery is easy to charge, especially if you have a variable DC power supply from Mastech. Mastech has a new line of switching power supplies that are improved to handle battery charging needs. By adding over-voltage protection, the new “EX” models like HY3010EX can handle the reverse voltage without damage. Original models like the “E” or “D” models, e.g. HY3010E or HY3010D, can be damaged by the batteries via reverse bias, if the customer is not careful.
Charging lithuim iron phosphate 3.2 volt cells is identical, but the constant voltage phase is limited to 3.65 volts.
The basic method is to charge at constant current (0.2 C to 0.7 C depending on manufacturer) until the charge current has dropped to 10% of the initial charge rate. To do so, you can set the voltage of the power supply to 4.2V (if you are charging single cell, or multiple of 4.2V if you have multiple cells in series), and set the current limit to the max charging current allowed by the battery or at a level you want. If your battery is sufficiently discharged, you will see CC light of the power supply is lit when battery is connected, indicating that power supply is charging at constant current mode. As the charging progresses, the voltage will climb to 4.2V and the current will start to decrease, and the “CV” light will be lit. The termination condition is the drop in charge current to 10%. The top charging voltage and the termination current varies slightly with the manufacturer. All the “EX” models of Mastech power supplies come with an OV (short for Over-voltage) adjustment knob (second knob from the left), for battery charging, typically you can set that to maximum position. Charging for multi-pack batteries is similar, you just need to change the voltage and current setting accordingly.
The charge cannot be terminated on a voltage. The capacity reached at 4.2 Volts per cell is only 40 to 70% of full capacity unless charged very slowly. For this reason you need to continue to charge until the current drops, and to terminate on the low current.
It is important to note that trickle charging is not acceptable for lithium batteries. The Li-ion chemistry cannot accept an overcharge without causing damage to the cell, possibly plating out lithium metal and becoming hazardous.
Charging Lithium ion batteries at slow rates
When the charge rate during the constant current phase is low, the charger process will spend less time during the constant voltage tail. If you charge below about 0.18 C, the cell is virtually full when the 4.2 volts is reached. This can be used as an alternative charge algorithm. Just charge below 0.18C constant current and terminate the charge when the voltage reaches 4.2 volts per cell.
We have added a new model of programmable DC power supply, model HY3005DP.
The output of this highly stable, high quality DC power supply is continuously adjustable at 0-32V DC and 0-5A.
With its full digital control and 5 memory settings, it’s extremely easy set up the output you want and repeat the settings you use regularly.
What’s more, you can use the USB interface and software that comes with the unit to program a waveform, essentially use this power supply as a simple arbitrary waveform generator.
The unit comes with very bright LED displays, providing accurate readout for the voltage and current values. This unit has toggle switch at the back that allows you to operate it in 110V AC or 220V AC.
We are pleased to announce the arrival of EX models, a new line of switching power supplies that have built-in over-voltage protection, over-current protection, and over-temperature protection. The EX models are best suited for the following applications:
battery charging for Lithium Polymer (LiPo), Lithium Ion, Lithium Manganese, A123 (LiFePO4), NiCd, NiMH, Lead Acid batteries (Flooded, Gel, AGM, SLA), etc.
as electroplating and anodizing rectifiers
electrolysis, hydrogen generator, fuel cell applications, etc.
DC motors, slot cars, aviation applications, etc.
with the over-voltage protection, you no longer need to worry about reverse EMF feeding back into the Mastech power supplies and damaging the power supplies. You can even accidentally hook up the battery with the wrong polarity, and the power supplies will be fine. If you turn off the power supply while the DC motoring is running, that’s fine too. In a nutshell, much more robust and much more versatile.
We also added HY3080EX, and HY30100EX, capable of outputting up to 80A and 100A respectively, excellent for applications that require large current like anodizing, electro-plating, and hydrogen gernators.
Finally we re-installed the forum for Mastech Power Supply again, after we had to shut down last time due to spammers. We apologize for the inconvenience, and hope to use the forum as tool to answer all technical questions. Please visit us at http://mastechpowersupply.com/forum to post any technical questions and get answers from our knowledgeable staff and expert users around the world.
We are pleased to announce the arrival of Mastech Variacs! We currently carry three models of Mastech Variacs, a 5KW or 5 KVA model, a 2KW or 2 KVA Variac, and a 500W or 500VA Variac. We also have two variations of the 5KVA and 2KVA variacs, using 110V AC input or 220V input.
Mastech Variacs are high quality variacs with voltmeter for easy setup, and with very wide range of ouput voltage: from 0V to 250V, to address a wide range of applictions. Please check them out here:
With these addition, we have not only dramatically increase the choices of linear power supplies, especially the higher current power supplies. HY6020E, with up to 60V in output voltage and 20A in output current, is one of the most powerful power supplies we carry so far.
