Our Design Partner, FMA Direct

Our in-house staff of engineers is constantly at work developing new products, and improving existing designs for the R/C industry, as well as commercial and military clientele.




1 Computer Controlled Integrated Full Power Balancing for Fast Charging
2 Unprecedented Accuracy
3 Liquid Crystal Display
4 Fuel Gauge Readout
5 Simple, easy to use one button user interface
6 Support for A123 chemistry included
7 PC Interface ready
8 Unparalleled Safety
9 Self Diagnostics
10 Storage Charge Mode
11 Safety Charge Mode
12 Support for long battery extensions
13 Cold Weather Mode


Full Power Balancing > Microcontroller-based, with integrated Full Power Balancing means one computer is in charge of all processes of charge and balancing. Full Power Balancing means higher balance current than competing brands of balancing chargers as well as external balancers. This equates to faster charging times. Integrated balancing makes the charger much smarter. The charger has the ability to prevent damage to the itself or to any battery. This improves safety, reliability, and longevity of charger and batteries.
Unprecedented Accuracy > Each Cellpro 4s is factory calibrated and capable of measuring cell voltages to within 10mV or less. Combine 1 and 2 above and it means you can safely charge good quality, high discharge rate lithium batteries (15C or higher discharge rated) at up to 3C charge rate without damaging the batteries, or as fast as 20 minute charge time. Don't try this with any other brand charger!
Liquid Crystal Display > The included Liquid Crystal Display (LCD) keeps you informed up to the second as charging progresses. Information about each cell's voltage, supply voltage, charge voltage, charge current, battery fuel level and charge mode are easily available at the touch of a button.
Fuel Gauge Readout > This original FMA feature calculates the percentage of battery capacity remaining in the battery pack connected to the charger. It displays within seconds after the battery pack is connected. But in the FMA charger, Fuel Gauging does a lot more than just displaying battery capacity. In AUTO modes (defined as 1C, 2C, or 3C), the charger utilizes Fuel Gauge information to automatically choose the optimum charge rate for the battery pack being charged.
Simple, easy to use one button interface > Cellpro 4s includes 3 AUTO modes (using Fuel Gauging technology), manual modes for setting any charge current (from 0.25A to 4A max), Storage Charge Mode, and A123 Mode (special mode for charging A123 brand or compatible batteries).
Support for A123 Chemistry Included > A123 batteries charge to a lower voltage (3.6V) than standard lithium batteries. FMA was the first company to introduce support for A123 batteries in our charger line. A123 is a promising technology with strong performance and safe operation. Although currently optimal for .40 size airplanes and higher, this type of battery is gaining acceptance in the R/C industry and is a good choice for many applications.
PC Interface Ready > The charger comes ready to support an interface to your PC. Using FMA's FUIM1 (PC interface module) and free Charger Viewer software, you are ready to utilize the GUI interface to watch all parameters of charging on your personal computer, print charge graphs, save files to your PC, or export to spreadsheet for evaluation and cataloging of battery performance over time.
Unparalleled Safety > FMA engineers consider safety as the number one priority when it comes to lithium batteries and chargers. Sophisticated computer algorithms continually monitor all aspects of the charge process to ensure complete safety during charging. We are so confident in the safety of the Cellpro 4s charger that we have no reservations about telling our customers it is safe to leave the batteries in your aircraft during charging. The Cellpro 4s is capable of properly determining if there is a problem in the wiring of a battery pack or if there are damaged cells within a battery pack. If the sum of the individual cell voltages within a battery pack do not equal the total voltage of the battery, the charger will not charge. So, if you wire your own packs or you are uncertain about the wiring of a battery, it is virtually impossible to damage the charger or the battery pack. This goes way beyond simple things like reverse polarity protection.
Self Diagnostices > The Cellpro 4s also includes self-diagnostics - through a series of SAFETY CODES, the charger can determine problems within the charger (internal faults) or problems with the battery pack, the wiring, or the power supply. The user guide includes important information about SAFETY CODES which can often enable the customer to diagnose and correct problems without returning the unit for service.
Storage Charge Mode > The safest, and best way to store lithium batteries during the off season is when they are at 50% charge capacity. The Storage Charge mode available in the Cellpro 4s makes this simple and accurate. First, discharge the battery pack. Then connect it to the charger, press and hold the MODE button until STORE mode is displayed, and release the button. The charger will use Fuel Gauging technology to charge the batteries to precisely 50% capacity and then stop.
Safety Charge Mode > In the event that one or more cells within a battery pack are damaged, the charger will automatically invoke Safety Charge mode. This could occur if the total pack voltage is low (the battery has been drained too low), or if one or more cells are below a safe operating voltage. The charger is capable of rejuvinating most of these battery packs safely and automatically.
Support for Long Battery Extensions > Because the Cellpro 4s charger is capable of reading resistance of individual cells and wiring, it can easily handle long wiring extensions up to 3 feet in length. This makes it extremely convenient to charge a battery pack which is burried deep inside an R/C aircraft. Don't try this with any other brand charger. You could end up with over-charged batteries or even worse, a fire!
Cold Weather Mode > Did you realize that charging lithium batteries in cold weather (below 50 deg F) can cause permanent damage to the battery? Yes, it is true. In fact, at temperatures approaching freezing, a single charge to 4.2v can actually cause complete loss of battery capacity. The damage is permanent and irreversible. For this reason, the Cellpro 4s charger monitors ambient temperature and reduces the full charge voltage to 4.1v per cell below 50 deg F, preventing damage to the batteries.