18v dual side-by-side battery adapter insert into 40v tools, compatible with Ryobi

This adapter allows for two 18-volt batteries to be used where a single 40-volt battery would go in many Ryobi tools. Both 18-volt batteries are required to be inserted to power the load.

This adapter is verified to be compatible with...

- RY40002 = String Trimmer/Power Head (Expand-It)
- RY40006 = String Trimmer/Power Head (Expand-It)
- RY40009 = String Trimmer/Power Head (Brushless)
- RY401021 = Lawn Mower 21in (impedes closing the battery door)
- RY402011 = String Trimmer/Power Head (Brushless)
- RY40220 = String Trimmer/Power Head (Expand-It)
- RY404012 = Blower 450 CFM, 120 MPH
- RY404013 = Blower 650 CFM, 160 MPH (Brushless)
- RY404015 or RY404150 = Blower/Vacuum 600CFM (impedes usage of the front adjustable handle)
- RY40405 = Vac Attack Cordless Battery Leaf Vacuum/Mulcher
- RY40405BTL = Vac Attack Leaf Vacuum/Mulcher
- RY40407 = Blower 550 CFM, 125 MPH Whisper Series (Brushless)
- RY40408 = Blower 525 CFM, 110 MPH
- RY40604 = Hedge Trimmer (Brushless)
- RY408013 = Snow Shovel
- RYi300BG = 40V 300-Watt Pure Sine Wave Power Source

Confirmed DO NOT USE any adapter in the following - - - - - - - - - - -

- Blower 730 CFM, 190 MPH Whisper Series (Brushless) or any blowers with a turbo/boost button, including RY404100 / RY404010

- Any 40V Mowers, including RY401140 / RY401014 / RY401130 / RY401210 / RY401220 / RY40HPLM

- Multi-battery 1800-Watt Portable Battery Power Station Inverter Generator, including RYi1802BT / RYi1802B6 / RYi818BT / RYi818BG

- Cordless String Trimmer 15" (Expand-It), including RY40205BTL

- - - - - - - - - - - The above are NOT compatible with any adapter, refunds will NOT be given!

- See my other listings on Etsy for 18v to 40v adapters that may be compatible

The Battery Management System (BMS) built into all Ryobi 18v batteries will still provide a safe low voltage cut-off when the batteries are used in series to power a 40v tool. You must use two 18v batteries of the same Ah rating (and same level of charge) for this adapter to operate. This adapter has been tested with all genuine Ryobi batteries up to 12Ah, but note with 3Ah or under you will be disappointed at the runtime.

With 8Ah or larger the tool is very heavy so consider using the corded version instead where you can place the batteries in a backpack or belt-pack...
https://www.etsy.com/de/listing/1623079509/18v-dual-battery-adapter-wired-to-40v
https://www.etsy.com/de/listing/1753896955/18v-quad-battery-adapter-wired-to-40v

This adapter certainly works electrically in any tool or fan, but may only fit mechanically in some due to clearance around the battery pack area.

As of 03/12/2025 the only version available is "with spacer plate" which fits in more tools.

Safety information...

When using any parts of this adapter to power a non-Ryobi device, or when using a non-Ryobi power source/battery to power a Ryobi tool, you assume all responsibility to ensure adequate starting (peak) and running Amps. Wires internally are all 14AWG. Melted connectors due to over-current, dirty battery contacts, bad battery conditions, etc. are not covered under warranty.

Never try to charge two 18v Ryobi Li-Ion batteries in series (such as putting this adapter in a 40v charger) as damage to the internal Battery Management System (BMS) or the charger is possible. The charger cannot communicate with the battery pack(s) extra pin(s) to get temperature or charge current, without this info the charger may assume the wrong data and create a fire hazard, so always charge the 18v batteries individually and in approved chargers.

All adapters have been tested, in a variety of tools, but assessing every possible battery pack's age, condition, and temperature is unreasonable, as such you assume all risks of fire or damage.

This is 3D printed with PETG (3-perimeter/20%-infill) for strength and heat resistance.

Ryobi batteries are NOT included! Ryobi tools are NOT included!

You can use this adapter instead of a Ryobi 40v battery with P/N...

- OP4015, OP4015A = 1.5Ah
- OP40201 = 2Ah
- OP4020A = 2Ah
- OP4026, OP40261 = 2.6Ah
- OP4030, OP40301 = 3Ah
- OP4040, OP40401 = 4Ah
- OP40404 = 4Ah
- OP4050, OP40501 = 5Ah
- OP40504 = 5Ah
- OP4050A = 5Ah
- OP40601 = 6Ah
- OP4060A = 6Ah
- OP4060A1 = 6Ah
- OP40602 = 6Ah
- OP40604 = 6Ah
- OP40605 = 6Ah High Capacity
- OP40752 = 7.5Ah
- OP40754 = 7.5Ah
- OP4080A = 8Ah
- OP40804 = 8Ah
- OP40125 = 12Ah
- OP4012A1 = 12Ah

This is not a Ryobi branded product, nor am I affiliated with Ryobi in any way. Ryobi is a registered trademark of Ryobi Limited and/or TTI. The use of Ryobi here is for identification of manufacturer compatible products and does not imply any affiliation or endorsement by the Ryobi brand owner. This product is designed to be compatible with Ryobi products. This is an aftermarket tool.

[This listing description last updated 06/02/2025]