This power pack earns its name tag from being:
- - Silent: little to no RFI even in close proximity to the KX3
- - Powerful: Provides enough power to drive KX3 to full 15W transmission
- - Compact, durable and water resistant
(Notes: Batteries shown are for illustration only. Batteries are not included. Build time of 1 to 3 days needed prior to shipping. Using the recommended (QTY 5) Keeppower 2300 mah, the pack is rated for about 42WH)
mediadogg Software expressesly cautions against transporting the "DIY" Croc and its components on an airplane.
This water resistant pack can serve as your main KX3 power source. Use it for days between charges. Or keep it plugged into the KX3 as an external source to the internal batteries that can give an instant boost to 15W as needed.
Due to the robust nature of this pack, it can be used for extended periods in CW transmission mode. It is rated for up to 50% duty cycle at 15W KX3 operation (approx 42W power to the KX3 is needed). Long periods of safe continuous operation can be obtained when operating the KX3 at 5 or 10W output.
The advantage of the "Croc" pack over raw unregulated litium battery packs, is that the entire capacity of the pack is available at any KX3 output power level, up to 15W.
DO NOT use the pack continuously for more than 45W ouput. DO NOT use unprotected lithium cells.
Internal Design
- - Options and features can be tailored to your specifications. Additional time for testing might be required.
- - The pack is comprised of a5S (5 cells in series)configuration of 3.7V lithium ion cells of size 18500 (18mm diameter x 50mm length nominal). Protexted cells are a few mm longer than regular 18500 cells, so the battery holders have been appropriately lengthened.
- - A 5S BMS is used to manage charging and discharging of the pack. Hence, the batteries may be charged either externally in parallel, or internally in series. In all cases, a genuine lithium ion battery charger must be used. For internal charging, the charger must supply no more than 21.3V at 1.5A regulated.
- - A 5A buck converter is used to regulate the pack output to between 14V and 15V. Displays are provided to monitor both the unregulated input and regulated output of the buck converter. Optionally, USB ports can be optionally provided.
- - The buck converter, USB ports and displays are shielded using copper tape, and a ferrite bead is placed on the output cable inside the pack case.
Usage Intructions
- - The pack must not be submered in water, or exposed to excessive moisture or heat.
- - The pack should ideally be fully charged prior to each major use.
- - Never plug the output cable into the charging port.
- - In the event the pack is shut down by the BMS due to reaching maximum temperature or discharge levels, the BMS must be awakened (reset), by simply plugging in the charger (maximum 21V @ 1A). It is best to allow the pack to cool down and rest after any use that causes the BMS to shut down the pack, and before recharging the batteries.
- - If for any reason the BMS cannot be reset, use of the pack must be discontinued until the cause is identified. Carefully remove and examine the batteries, and if not found to be physically damaged, charge them individually in an approved charger. This is the best way to validate battery condition and identify potentially defective cells. Defective cells must be takem out of service immediately and isolated before being discarded according to local standards. Whenever the individual cells are removed from the pack and subsequnetly re-inserted, the BMS must be reset by plugging in the series charger (21V at 1A regulated). DO NOT insert discharged batteries into the pack. They must be fully charged in an approved charger, prior to insertion.
Using the Trickle Charge Port
- Under no circumstances should anything be plugged in other than a specified Lithium Ion Charger for 5S configuration, maximum voltage 21.3V, maximum amperage 1A.
- A specified charger has circuitry that regulates voltage, current and time of charge.
- Monitor the battery pack and voltage meters frequently while charging. When the pack reaches 21V, the charger should be disconnected. A specified charger will also stop charging at this point.
(Note: a suitable AC wall charger is available that has been tested with the KX3 power wheel accessory.)
Limitations and Disclaimers
- - This is "DIY" product. I am your contracted build surrogate, not a manufacturer. There are no certifications express or implied.
- - Please adhere to all lithium battery usage guidelines in this document: DIY Power Pack Battery Usage Rules
- - Batteries are not included or supplied with this pack
- - Only "protected' lithium cells may be used in this pack
- - Recommended battery cells: Keeppower 18500 Protected (Model No.: P1850C3)
Charging the Pack
Using only a regulated charger designed for 5S Lithium ion battery packs (21 - 21.3V at 2A or less), plug the charger into the charging port of the Croc pack. If the BMS has put the pack into sleep mode due to reaching the discharge limit, the pack will be quickly awakened by the charger. The pack power switch must be in the "ON" position. The charger and BMS are both designed to terminate charging when the pack reaches the vicinity of 21V, and the charging current will drop to near zero. The pack may be charged concurrently with its use as a power source, however, it will continue to net discharge if the power drain is greater than about 20 watts.
