EGO Power+ Outdoor Power Tool Batteries have been around awhile, I found threads mentioning them as early as 2014 here on ES. Since I have a few, and they are suitable, I have decided to try them for a couple of ebike projects. To do this I am making mounts and connectors for them using 3D printing. The plan for this thread is to collect information on these batteries and their related DIY applications as well as share experience and designs for their use. We can also link to other threads that provide information or applications where they are used. This first posting will be updated from time to time with new links or other information. Posting #2 will be about my own initial plans and experience, others are welcome to add their own, the intention is for this to be a shared resource on the EGO Power+ battery experience.
Since the forum search is not suited for 3 character words perhaps the term "egopowerplus" should be included in all such threads. This term is used in the web URL of the products and should make a good search term.
There are many videos and articles with details on these packs, here I will summarize briefly:
The EGO Power+ batteries are 18650 cell based lithium battery packs with 14 series cells primarily used for outdoor power tools such as leaf blowers, string trimmers and lawnmowers. They come in several sizes with one, two or three cells in parallel, using either 2.0 or 2.5 amp hour high current cells. This produces packs with 2.0 to 7.5 amp hours. The packs have a built in battery management system that is potted for moisture resistance, and they are designed so that cooling air can be introduced to the pack. Each cell is wrapped in a phase change material to absorb heat and moderate the temperature of cells during charging and high current drain applications. Fully charged they are a little higher than the manufacturer's claimed 56 volts, but they behave as other 18650 cell packs with 14 high current cells in series, so the voltage soon drops to about 3.6 per cell under load delivering about 50 volts. They advertise 3 year pack warranties and are available through various hardware store chains as well as online. For many these make them locally available power sources.
Pack model numbers, Capacities (AH), Weights(kg) and Parallel Cell count
- BA1120 2.0 1.26 1P
- BA1400 2.5 1.26 1P
- BA2240 4.0 2.21 2P
- BA2800 5.0 2.21 2P
- BA4200 7.5 2.86 3P
There are four pins on the battery pack and chargers. They are labelled Negative (-), T, D, Positive (+). The power is present between the negative and positive terminals. From the T terminal to the Negative terminal there appears to be a thermistor that the chargers use. From the D to the Negative terminal there appears to be a one-wire Data protocol that chargers and tools use to communicate with the BMS.
It is reported that the cells in the 2.5, 5.0 and 7.5 AH units may be Samsung INR18650-25R. The cells are rated at up to 20A discharge.
Sanyo UR18650RX cells were found in a 2.0AH pack. These cells are rated at up to 20A discharge as well.
Some reports indicate that the main current does not flow through the BMS. This means it is important to set the proper low voltage cutoff in your controller (42V is 3.0V/cell), and it means that individual cells are not protected for low voltage. This is probably why tools use the third pin in the battery interface - to get better information from the BMS to shut down and protect the pack if any cell goes too low.
Theoretically a 1P pack can deliver up to 20A, a 2P pack up to 40A and a 3P pack up to 60A, at least in terms of cell current. These values would require that inter-cell wiring, pack wiring and pack connectors be able to handle these levels of current without excessive heating, which is not necessarily the case. We look to the manufacturer's applications to see what demands they consider normal for these batteries.
Tools such as the 21" self propelled mower reportedly have a 1000W motor, or about 20A at 50V. The Snow blower and trimmer/edger/pole saw power head reportedly have 2000W motors (40A) and two parallel packs or a 2P/3P pack (4.0AH and up) are recommended. There is some concern that the wiring in a 2P/3P pack may get warm at 40A. If 2 packs are used in parallel they should be at the same state of charge before being paralleled. Running a 1P pack (2.0AH/2.5AH) the max current should be limited to 20A due to cell ratings.
The manual states that after 30 days the battery discharges itself to the 30% storage level. This is a BMS function - the BMS has a clock/calendar chip, probably to trigger this activity. The manufacturer recommends fully charging the pack before storage, and storing them and the charger in a dry temperate environment such as the house. Some people report their packs don't seem to self discharge. Lithium batteries last best when stored in the 30-50% charge state region. The automatic self discharge takes some time to complete, warms the end of the pack with the LED, and the LED blinks green during this process according to the battery manual troubleshooting chart.
Battery Status Indicator
The Pushbutton / LED indicator on one end of the battery is used to determine battery status. Depressing it momentarily activates the display:
Green - OK, 15% more more charge
Flashing Green - Battery has not been used for about 30 days and is in the process of discharging to storage level (30-50%)
Red - Charge level is low, prepare to stop using this battery
Flashing Red - Charge level is very low, stop using and recharge
Orange - Battery is overheated (70C), allow it to cool
Flashing Orange - Battery has been overloaded, allow to cool and reduce load
Some teardown articles indicate that the phase change material was not present on the 7.5AH pack and speculate that it is not needed in this pack, with the lower current per cell due to 3 cells in parallel.
There may be some current drawn by some tools even when power is off. The best defense against this is to remove the packs from any tools when not in use. The pack BMS does not seem to be able to interrupt the output current path so the battery may not be protected against a connected load.
Links to EGO Power+ Battery Resources and Articles
https://electricbike-blog.com/2016/04/1 ... -go-wrong/