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.



I'm using Windows Vista or Windows 7 Pro 64-bit (or 32-bit). Do I have to have the FUIM2/FUIM3 connected to the USB device before connecting it to my computer? I ask because I keep getting "no driver found for your device."

1) Leave the FUIM2/FUIM3 disconnected from the Cellpro 4s and from your PC's USB port.
2) Launch the Cellpro 4s GOLD Viewer application.
3) Click the download USB driver link from the application window.
4) Pick the correct driver from the web page. If your device is FUIM2, use the Driver for Win Vista x32 or x64 bit. If it's the FUIM3, there's only one driver.
5) Follow the on screen instructions. If you have attempted to load the driver before, what might happen is an uninstall first. If you see that the program wants to uninstall the driver, let it. Then go back to the website and install it again.
6) Now launch the Viewer application again.
7) Plug the USB end of the interface into your USB port at this time. Win7 should tell you the driver is loaded now.
8) Plug the other end of the cable into the Cellpro 4s's PC port and apply power.
9) Click the firmware you wish to install, then choose Update Firmware.

FMA periodically announces firmware changes. How do I know if I should have the upgrades made to my charger?

FMA continually strives to improve firmware for our charging products. In general, upgrades range from minor bug fixes, to terminology, to new modes of operation. Most upgrades strive to improve the chargers' capability to handle older battery packs while still maintaining unprecendented safety. The only times a customer needs to consider a firmware upgrade is 1) if he feels the charger is being too discriminating in rejection of multiple battery packs that are presumably in good operating condition; or 2) a new mode is added that the customer might wish to have, such as the A123 charge mode that also includes the Storage Mode. For more information on upgrading your charger to A123 version, see the next FAQ. Lithium batteries do age. They do go bad. As cells in the battery begin to leak electrolyte or develop crystals that increase internal resistance, capacity variation between cells occurs. While the customer should trust the charger to tell him when a battery pack should be replaced, the decision is ultimately up to the customer. Newer firmware versions may handle older packs slightly better; allowing them to charge at a slow rate rather than erroring out with an ERROR or SAFETY code. This maximizes the customer's savings in lithium battery packs and is an added bonus in that it may permit more cycles before final demise.

I own one of the Cellpro 4s chargers that supports up to 3A charge rate. Can I send in my old unit to upgrade it to the new 4A version?

Unlike previous models of the Cellpro 4s charger, the new 4 AMP version does not support an upgrade path from the older models. In addition to firmware updates, the new 4 AMP version requires additional hardware improvements not supported by the older 3 AMP Cellpro 4s chargers.

I purchased the standard Cellpro 4s charger. Can I upgrade to the new A123 version?

If you have purchased a Cellpro charger from FMA Direct in the past and want to upgrade to the A123 code, you may send the charger back for upgrade. Please send the charger by postage paid to FMA, Inc. For a fee of $12 including return shipping (UPS Ground shipping in the continental U.S.) FMA will upgrade your existing Cellpro charger to the new A123 capable code.

Is it beneficial to use the CP4S-DPM Cellpro 4S Discharge Protection Module with the Brushless Power System 150 to protect the lithium batteries or does the speed control have accurate cut-off?

The short answer is that it is always beneficial to monitor the Lipo pack at the cell level using a DPM. The ESC does have a proper LVC but it can only monitor the pack voltage so it cannot detect if one of the cells is weaker than another.

The ESC determines the LVC when you first connect the battery pack. In this manner, it can determine the cell count and type of battery used to select the most appropriate cutoff voltage.

On smaller power systems like the Brushless Power System 150, the cost and added 0.3oz weight of using the Cellpro 4s DPM may deter many people from adding it to the system. On larger power systems that use more expensive battery packs, the choice for adding the Cellpro 4s DPM becomes more clear.

Please decipher the following description of a Cellpro pack rating. In particular (15C / 90%) & 15C, 11C/140 degrees. Thanks.

The old ratings method was seen as something like your first example; 15C / 90% It meant that at a 15C discharge rate (or 15 times the pack capacity C) you would still get 90% of the stated capacity. This older rating scheme focused on the capacity left in a pack at a high discharge rate and turned out not be be a critical factor in maintaining cycle life or longevity of the pack. In those days, most vendors (including FMA) had not documented the effects of temperature, cell balance, and discharge rate on the Lithium pack life span.

Today, the new rating scheme looks like this; Ratings: 15C , 11C/140°F , Cell Rating Spec

The first number, 15C, is the maximum discharge current that the cell will handle without puffing, catching on fire, or generally destroying itself.

The second numbers, 11C/140°F, means that the cell can truly be continuously discharged at 11C without loss of cycle life because it remains at or below 140°F. In a multiple cell pack, the inner cells will be about 10°F hotter or 150°F which is ok. The Rule-Of-Thumb is that this second set of numbers is about 70% of the highest C discharge rating without puffing. There are exceptions to this rule but it works for most manufacturers cells.

The last "Cell Rating Spec" is a hyperlink to the information in chart form that plots all the data taken during the cell qualification testing. As FMA is about to release many new cells from multiple manufacturers, the Cell Rating Spec will provide a consistent and more appropriate method for rating the discharge capabilities of Lithium cells.

When using a Cellpro DPM, you can re-enable the motor many times after the initial DPM shutdown and get a cell to go below 3.0v unloaded. Is this a problem?

According to our design spec, this behavior for the DPM is normal. Any single LiPo cell can be discharged to 2.5v under load without risk of damage. The reason all LiPo ESC manufacturers have raised this minimum is because they cannot "see" the individual cells. Cutting out at 3.0 or 3.1v per cell has become the norm to allow for pack imbalance. The Cellpro scheme is quite different because it bases the cutout on the lowest cell in the pack. Therefore, it will initially cutout around 3.0v, but as the unit is re-armed, it can take a cell as low as 2.5v. Only the weakest cell will go to 2.5v which is still within industry standard specs for cutout. It also gives customers the absolute longest run time with as many re-arms as possible without ever damaging the weakest cell.

Which balancing line is better for me; Cellpro or BalancePro HD?

It is better to understand what you want and be confident of your choices before ordering. The size of your plane often determines which line is best for you but there are also other factors to consider.

Although we used to think that the BalancePro HD to Cellpro Adapter (SVCPA1) would work at 10amps on the Cellpro packs, Engineering has recently reported that the maximum current level should not exceed 5amps or the white Cellpro node connector pins will get warm.

There are pros and cons to each choice of using either two 3-cell packs or one 6-cell pack. If you intend to fly smaller planes using a 3-cell pack, then the flexibility of combining two smaller packs is best but it adds the complexity of wiring the two packs in series to the ESC. If you only intend on flying a glow conversion, the simplicity of a single pack is best. A single 6-cell pack only requires one DPM (Discharge Protection Module) but also forces you to use the BalancePro HD line. The BalancePro HD 6s charger can charge up to a 3C or 10amp rate. The two 3-cell packs allow you to use the Cellpro line which does not require the use of a DPM.

Buying two Cellpro 4s chargers so that you can recharge both packs at the same time helps to negate some of the advantage of the BalancePro HD 10-amp charge rate and 6s capabilities. The Cellpro charger has a 3amp rate limit or you can use a BalancePro HD charger with the adapter for a 5amp rate limit.

The Cellpro line and charger is the most simple for 2s - 4s applications. It is literally plug-n-play and walk away. When you jump to 5s and 6s applications for glow conversions, the BalancePro HD line has its advantages for keeping a single pack and a higher charge rate up to 10amps. Both cell balancing lines provide the ultimate protection for safe Lithium charging.

Can I charge two Cellpro packs at the same time when they are wired in series?

You cannot use two Cellpro chargers at the same time when charging two packs wired in series unless you first disconnect one of the packs from the series adapter module.