The Rainmaker 18 Volt Lithium Ion Backpack Sprayer is a battery-powered sprayer with a 4 gallon tank that carries liquid on your back so you can apply herbicides, pesticides, or liquid fertilizer without manual pumping. It runs on a 18 volt removable, rechargeable lithium-ion battery. This page lists the specifications a carrying retailer publishes, explains where a battery backpack sprayer fits in a grow room or garden, and is honest about the maker-only details we could not source. It is an application tool, not a nutrient or a grow system.
What it is
The Rainmaker Lithium Ion Backpack Sprayer is a powered backpack sprayer: a 4 gallon tank worn on the shoulders and driven by an electric pump instead of a hand lever. The pump is powered by a removable and rechargeable lithium-ion battery pack (included). As the carrying retailer describes it, this is an all-purpose sprayer for herbicides, pesticides, liquid fertilizer, and many home applications that requires no manual pumping and is suited to large jobs. Because the pump does the work, you squeeze a trigger and the sprayer maintains pressure rather than needing you to keep priming a hand pump.
Specifications
| Type | Battery-powered backpack sprayer |
|---|---|
| Tank capacity | 4 gallons |
| Battery | 18 volt lithium-ion, removable and rechargeable (included) |
| Flow control | high and low speed flow rate switch |
| Nozzles | 3 different sprayer nozzles |
| Hose | 4 ft hose with an integrated filter |
| Trigger | trigger with a lock-on option for continuous spraying |
| Straps | padded shoulder straps |
| Weight | 10.95 lb (empty) |
| Dimensions | 14.4 in x 7.5 in x 26.5 in (L x W x H) |
| Manufacturer SKU | HGC708910 |
Every figure above is drawn from a carrying retailer’s product listing (BG Hydro), because the Rainmaker maker page was not reachable this session. The weight and dimensions are the retailer’s shipping-field values for the empty unit; a filled tank is heavier by the weight of the liquid.
Why choose it
- No manual pumping. The electric pump keeps the line pressurized, so the unit requires no manual pumping and is suited to large jobs — you are not stopping to re-prime a hand lever mid-row.
- Adjustable output. A high and low speed flow rate switch plus 3 different sprayer nozzles let you shift between a fine mist and a coarser stream for the job at hand.
- Continuous spraying. The trigger has a lock-on option for continuous spraying, handy when treating a large area without holding the trigger the whole time.
- Carry comfort. A 4 gallon tank on padded shoulder straps spreads the load for longer sessions than a handheld sprayer.
Best uses
- Foliar and surface applications. It is described as an all-purpose sprayer for herbicides, pesticides, and liquid fertilizer, so it suits foliar feeds, IPM sprays, and cleaning solutions applied by hand.
- Larger grow rooms and gardens. A 4 gallon tank covers more plants per fill than a small pump sprayer, cutting refill trips.
- Jobs where hand-pumping is the bottleneck. Because the battery pump maintains pressure, it is a better fit than a manual sprayer for repeated, sustained spraying.
Compatibility and handling
As a sprayer, this tool is medium-agnostic: it applies whatever compatible liquid you mix into the tank, so it works alongside soil, coco, or hydroponic setups rather than being tied to one. Match the solution to the job, and always follow the label on any chemical you spray.
- Liquids it is built for: herbicides, pesticides, liquid fertilizer, and many home applications.
- Filtration: an integrated filter on the line helps keep particulate out of the nozzle when spraying wettable or suspension mixes.
- Battery care: the pack is removable and rechargeable, so charge it off the unit and keep it topped up between sessions.
How it compares to a manual pump sprayer
This table contrasts the battery backpack format with a manual pump sprayer on the attributes we can source; it does not claim one is superior — the right choice depends on your job size and budget. Only the Rainmaker column carries sourced specs.
| Factor | Rainmaker 18V backpack | A manual pump backpack sprayer |
|---|---|---|
| Pressure source | 18 volt lithium-ion battery pump, no manual pumping | hand lever you pump to build pressure |
| Flow control | high/low speed switch plus 3 nozzles | varies by model |
| Tank | 4 gallons | varies by model |
| Best fit | sustained, repeated spraying over larger areas | occasional or small jobs, or where no charging is possible |
Frequently asked questions
How big is the tank? 4 gallons.
Does it need manual pumping? No — it is powered by a removable, rechargeable lithium-ion battery pack, so the pump maintains pressure for you.
What can I spray with it? Herbicides, pesticides, liquid fertilizer, and many home applications. Always follow the label of the product you are applying.
How many nozzles come with it? 3 different sprayer nozzles.
Who this is for — and who should skip it
Suited: growers and gardeners who spray foliar feeds, IPM products, or cleaning solutions over larger areas and want a 4 gallon battery sprayer that spares them the manual pumping of a hand unit.
Not for / its limits: it is an application tool, not a nutrient, additive, or grow system — it does not feed a crop on its own. For a very small plant count or an occasional spot spray a handheld or manual sprayer may be plenty, and a battery unit needs charging to work.
HELD (not stated because not sourced this session): the Rainmaker maker product page returned HTTP 403 to both the WAF-immune fetch and an anonymous fetch, so no manufacturer-tier value is stamped — every spec above traces to a carrying retailer’s listing. Also held: the spray pressure (PSI), the battery amp-hour rating and stated runtime in hours, the charge time, the warranty term (held per M-05), and the live retail price (the storefront price field is the source of truth at deploy). The “36/PL” in the product title is a distributor pallet pack code, not a maker specification, so its quantity interpretation is held rather than stated.
Ready to cover more ground per fill? Add to cart, or talk to a grower about matching a sprayer to your room size and spray program.
Sources
- BG Hydro — Rainmaker 18 Volt Lithium Ion Backpack Sprayer 4 Gallon (HTTP 200, carrying retailer, retrieved 2026-07-08; PRIMARY reachable source for all specs): tank 4 gallons; 18 volt lithium-ion removable/rechargeable battery (included); high and low speed flow rate switch; 3 different sprayer nozzles; 4 ft hose; integrated filter; padded shoulder straps; trigger lock-on; weight 10.95 lb; 14.4 x 7.5 x 26.5 in; SKU HGC708910: https://www.bghydro.com/catalog/product/view/_ignore_category/1/id/8656/s/rainmaker-18-volt-lithium-ion-backpack-sprayer-4-gallon/
- Garden Supply Guys — Rainmaker 18 Volt Lithium Ion Backpack Sprayer, 4 gal (HTTP 200, carrying retailer, retrieved 2026-07-08; corroborates tank, voltage, battery, flow switch, nozzles, hose, filter, straps, and lock-on trigger): https://www.gardensupplyguys.com/products/rainmaker-18-volt-lithium-ion-backpack-sprayer-4-gal
- Hawthorne Gardening Company — Rainmaker maker product page (attempted PRIMARY source; returned HTTP 403 to both the WAF-immune fetch and anonymous fetch this session, so specs were grounded to the carrying retailers above per M-07): https://www.hawthornegc.com/shop/product/rainmaker-battery-powered-18-volt-lithium-ion-backpack-sprayer
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