Company: Shimano Inc. · Country: Japan · Current battery: BT Master 11AH · Category: Portable batteries for electric reels
If you fish a Shimano ForceMaster or BeastMaster, the battery matters as much as the reel. Shimano’s own answer is the BT Master 11AH, a 14.4V lithium-ion pack released in April 2022. It replaced the long-running Denryokumaru (電力丸) series, which Shimano recalled in October 2023 over a fire risk.
This review covers the BT Master 11AH in detail, what you need to know about the recall, how US anglers power Shimano electrics, and where to buy.
Company overview
Shimano is headquartered in Sakai, Osaka, and makes the ForceMaster, BeastMaster and Plays/Plemio electric reels. For the reels themselves, see our Shimano Electric Reels review.
At a glance
| Current battery | BT Master 11AH (April 2022) |
| Voltage / capacity | 14.4V lithium-ion, 11Ah |
| Weight / size | 1,700 g · 90 × 180 × 120 mm |
| Japan MSRP | ¥78,000 before tax (street ¥53,000–¥70,000) |
| Recalled | Denryokumaru 5Ah, 7.5Ah, 8.8Ah, 10Ah (October 2023) |
| US availability | Not sold through Shimano’s US channel; JDM export sellers only |
BT Master 11AH
Specifications (Shimano manual and Japanese retailers)
| Chemistry | Lithium-ion (retailers say lithium-ion polymer) |
| Voltage | 14.4V DC nominal |
| Capacity | 11Ah (about 158 Wh) |
| Weight | 1,700 g (3.7 lb) |
| Size | 90 × 180 × 120 mm |
| Charger | Dedicated, 100–240V AC in, 16.8V DC / 1.5A out, 330 g |
| Charge time | about 10 hours standard (manual); retailers quote 5–8 hours |
| Operating range | Discharge −20 to +50 °C · charge 0 to +40 °C |
| Outputs | “Double joint”: run a reel and a fish finder at once |
| Water | Water-resistant with rubber pads; do not submerge |
| JAN | 4969363042996 |
What Shimano claims
– About 2× the discharge performance of the old Denryokumaru 10Ah under high-load retrieval
– About 20% more reel power than a lead battery
– About 70% lighter and 50% smaller than a sealed lead battery
Features: a power switch, an LED charge indicator and a dual connector that lets you run a reel and Shimano’s Tankenmaru CV-FISH fish finder from one battery. The manual says to give it an initial charge before first use, because a protection circuit may block output from a new pack.
Which reels? Shimano’s BeastMaster 9000 page recommends “a high-capacity battery (11Ah)”, and Tomo’s Tackle recommends the BT Master 11AH or equivalent for the BeastMaster 9000B. Japanese retailer Fujimori lists it for the MD3000, MD6000, BM6000, BM9000 and MD12000. The manual says it’s for Shimano electric reels and fish finders only.
Storage: store long term at 20–40% charge. That’s normal for lithium batteries and extends their life.
Air travel: carrying it by air needs pre-approval from the airline.
BT Master 11AH prices
| Seller | Price |
|---|---|
| Japan MSRP (Tsurisoku, Shimaya) | ¥78,000 before tax |
| Shimaya | ¥53,000 before tax (¥58,300 incl.) |
| Fujimori | ¥59,200 incl. tax |
| MonotaRO | ¥69,980 before tax |
| Blue Marlin (Yahoo Japan) | ¥69,800 |
| Fishingshop.kiwi (ships internationally) | about US$430 |
Why it’s hard to buy in the US: We didn’t find the BT Master at Shimano’s US channel or the usual JDM importers. Large lithium batteries are restricted for air freight, which makes them difficult to export from Japan. International sellers such as Fishingshop.kiwi list it, but check they can ship to you before ordering.
The Denryokumaru recall: what you need to know
If you own a Shimano Denryokumaru (電力丸) battery, stop using it.
- Recalled models: Denryokumaru 5Ah, 7.5Ah, 8.8Ah and 10Ah (lithium polymer), sold from March 2007 onward.
- Announced: October 16, 2023 (Shimano and Japan’s Consumer Affairs Agency).
- Reason: a manufacturing defect that can cause smoke or fire as the battery ages. The consumer agency’s record notes serious incidents involving smoke or fire.
- Remedy: a free exchange for a BT Master 11Ah. Owners are told to stop charging and using the battery. Japan hotline: 0120-070-505.
Buying used? Any Denryokumaru sold on eBay or auction sites is a recalled product. Don’t buy one.
How the old 10Ah performed: Japanese site TsuriHack tested the Denryokumaru 10Ah and found reel choice made a big difference. After 8 hours of deep dropping, a ForceMaster 800 left 3 of 5 bars, while a BeastMaster 2000EJ left 2. The lesson still applies: bigger reels draw more power, so size your battery to your reel.
Powering Shimano electrics in the US
Most US anglers don’t use a Shimano battery at all. The common options:
1. Boat power (hard-wired). Many deep droppers wire their reels to the boat’s batteries. From a Hull Truth thread on the BeastMaster 9000 (forum figures, not Shimano’s):
– Draw is about 5–7 A normally, 10–15 A under load and 25–30 A if the motor stalls
– Use 8 gauge wire minimum, 6 gauge preferred; 12 gauge “is not going to work well”
– Count the full circuit length (positive plus negative) when sizing wire
– The factory cords (about 6–8 ft) are meant to run straight to a battery
2. Portable 14.8V lithium packs. Several US brands sell packs for Shimano electrics, including Abyss (PAB-T9000, 14.8V 10Ah) and BatPower. See also Black Oak LED.
Images: BatPower
A voltage caution: Abyss notes that Shimano reels have voltage-sensitive protection circuits. Check that any third-party battery is approved for your Shimano model before using it, especially at 14.8V or above.
3. A 12V lithium or AGM battery in a dry box, with a proper fused lead. This is the budget route, but check the battery’s continuous-current rating against the reel’s peak draw.
Choosing a battery for your Shimano
| Your reel | Suggested power |
|---|---|
| ForceMaster (small to mid sizes) | 10–11Ah 14.4–14.8V pack (BT Master 11AH or an approved equivalent) |
| BeastMaster 9000 | BT Master 11AH or equivalent, or hard-wired boat power with 6–8 gauge wire |
| Several reels on one boat | Hard-wired boat circuits with a fuse per outlet |
Care and safety for any reel battery
- Charge with the correct charger only, and never charge a wet or damaged battery.
- Keep it out of standing water. The BT Master is water-resistant, not waterproof.
- Store at partial charge in a cool, dry place during the off season.
- Check cords and plugs for corrosion every trip.
- Retire any swollen, hot or damaged pack immediately.
Pros and cons
Pros
- Official Shimano battery matched to Shimano electrics
- 11Ah at 14.4V, enough for the BeastMaster 9000
- Dual output for a reel plus fish finder
- Much lighter and smaller than lead
- Free replacement for recalled Denryokumaru owners (in Japan)
Cons
- Hard to buy in the US; not in Shimano’s US channel
- Expensive (¥78,000 MSRP; about $430 exported)
- Heavy for a lithium pack at 1.7 kg
- Long charge time (about 10 hours per the manual)
- No published IP rating or cycle life
- The previous Denryokumaru series was recalled
Shimano vs. other reel batteries
| Battery | Voltage / capacity | Weight | Price |
|---|---|---|---|
| Shimano BT Master 11AH | 14.4V / 11Ah | 1,700 g | ¥78,000 MSRP |
| Daiwa Super Lithium 12000WP | 14.4V / 12Ah | 1,230 g | ¥78,000 MSRP (-C) |
| Abyss PAB-T9000 | 14.8V / 10Ah | 730 g | $299.99 |
| BatPower | 7.8Ah or 15Ah | not published | $179.99–$369.99 |
| Black Oak LED | 10Ah LiFePO4 | not listed here | $274.50–$343.13 |
Where to buy
- Japanese retailers: Shimaya, Fujimori, MonotaRO, Blue Marlin (Yahoo Japan). Most don’t ship lithium batteries abroad.
- International: Fishingshop.kiwi lists the BT Master 11AH at about US$430.
- US alternatives: Abyss Battery (Largo, FL), BatPower, Black Oak LED
- Reel dealers: Tomo’s Tackle (Salem, MA) sells the BeastMaster 9000B and recommends the BT Master 11AH or equivalent.
Verdict
The BT Master 11AH is a well-made official battery for Shimano electrics. It’s powerful enough for a BeastMaster 9000, has a dual output and is much lighter than lead. For US anglers, though, it’s expensive and hard to get. Most will be better off with hard-wired boat power or an approved US-made 14.8V lithium pack. If you still have a Denryokumaru, stop using it: it’s under recall.
Deep-Drop.com rating: Performance 4.5/5 · Build quality 4.5/5 · Value 3/5 · US availability 1.5/5
FAQ
What battery does Shimano make for electric reels?
The BT Master 11AH: 14.4V, 11Ah, 1.7 kg, released in April 2022.
Is the Shimano Denryokumaru recalled?
Yes. Shimano recalled the Denryokumaru 5Ah, 7.5Ah, 8.8Ah and 10Ah in October 2023 because of a fire risk. Stop using them.
What battery do I need for a BeastMaster 9000?
Shimano recommends a high-capacity (11Ah) battery, such as the BT Master 11AH or an equivalent. Many US anglers hard-wire the reel to boat power with 6–8 gauge wire.
Can I buy the BT Master 11AH in the US?
We didn’t find it in Shimano’s US channel. International sellers such as Fishingshop.kiwi list it at about $430.
Details were checked against Shimano’s BT Master 11AH manual, Shimano’s recall notice, Japan’s Consumer Affairs Agency, Japanese retailers, TsuriHack and The Hull Truth on September 26, 2026.