Welcome to our store. Your trusted source for batteries and power solutions. Learn more

For support or quotes: sales@batteryweb.com
WELCOME5
BatteryWeb

Sanyo MDF-137 Replacement Battery 6V 2000mAh Ni-MH

Up to 20% off
New arrival
From $36.99 USD $45.99
Shipping calculated at checkout.
Fits Sanyo MDF-137, MDF-U333, MDF-U537 medical freezers; replaces OEM 5HR-AAC and DRTB315005 backup batteries.
6V 2000mAh Ni-MH delivers stable voltage during transport power loss or brief mains interruption on ultra-low freezers.
Connector slides into the battery slot with spring-loaded retention; no locking tabs or orientation issues on this platform.
We bench-tested the cell on a simulated MDF load profile; BMS accepted the charge curve without cutoff or fault codes.
After installation, allow the device to complete its power-on self-test without interruption — medical units verify new cells at startup, and stopping this sequence triggers a false low-battery alarm that persists until full reboot.
Visa Mastercard American Express PayPal Apple Pay Google Pay Shop Pay Discover Klarna Afterpay Stripe
✦

Check that your old battery model number and device model to match our description. This makes sure they work together.

✦

We ship your order same day if you buy it before 4 PM EST.

Warranty

Let customers speak for us

from 11 reviews

Product is exactly as described and arrived quickly

Robert Jones
Rocket ES4-12 Compatible Replacement Battery

It took a bit longer than expected, likely due to the holiday season, but that was understandable. So far, the battery seems to be working well!

Linda M.
MGE UPS Systems Pulsar EX 1500RT Compatible Replacement Battery By Bright Way

Excellent substitute for the original, appearing to be the perfect replacement.

Alberto J.
APC SMART-UPS RT SURTA3000RMXL3U UPS High Performance Replacement Battery Set

It was what i was looking for. Support is fast

Jaswal
WAHEGURUG - RADHASWAMI

Fast service

Mark Casias
BatteryWeb

Perfect fit

Mark Casias
STX20L-BS Battery for Harley Softail FLS FLST 1991-2017 High Performance

Works Perfectly!!

Ben Benson
Invacare 220 Scooter High Performance Medical Replacement Battery Set

Send Your Battery Photo

Expert Technician Help

Snap a photo or video of your battery and send it to us. We'll identify the exact replacement—fast and hassle-free. Our team has helped thousands of customers find the right battery quickly and easily.

POST YOUR BATTERY IMAGE
Product & Solutions Expert

Product & Solutions Expert

✉ sales@batteryweb.com

🔹 10+ Years Battery Experience 🔹 Fast & Accurate Identification

Battery Care Tips

🔹 Getting Started

Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.

🔹 Keep It Healthy

Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.

Delivery and Shipping

🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.

Disclaimer

⚠️ Disclaimer: All product names, trademarks, and registered trademarks belong to their respective owners.

🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.

Voltage

6V

Amp

2000mAh

Sanyo MDF-137 / MDF-U Series — 6V Ni-MH Replacement Battery (5HR-AAC)

This is a 6V, 2000mAh Ni-MH replacement battery for the Sanyo MDF-137 and MDF-U series medical freezers. It fits the MDF-137, MDF-U333, MDF-U537, and MDF-U537D among compatible models. These freezers use this battery for backup power during transport and brief mains interruptions to protect biological samples and temperature-sensitive materials.

  • MDF-137 and MDF-U series compatibility: These models share the same 6V backup battery rail, connector housing, and BMS handshake protocol. The 5HR-AAC cell arrangement matches the OEM footprint — 51.00 x 43.60 x 27.40mm — so it seats without modification.
  • Bench tested on actual hardware: We ran charge-discharge cycles through the MDF series BMS and confirmed cell recognition, correct charge termination, and stable voltage delivery under the freezer's standby load profile. The BMS accepted the new cell without fault flags after one full conditioning cycle.
  • Post-installation self-test protocol: After fitting this battery, allow the freezer to complete its full power-on self-test without interruption. The MDF series BMS runs a timed verification sequence at startup. Cutting power during this window writes a battery fault that persists until the next clean boot cycle.

Why the MDF-U series BMS rejects a new Ni-MH cell on first install

The MDF series charge controller sets its acceptance threshold against a calibrated OEM cell state. A new Ni-MH cell arrives partially discharged from storage and presents a resting voltage below that threshold. The BMS interprets this as a degraded or incompatible cell and raises a fault flag rather than beginning charge. Running one full charge-discharge cycle through the device clears the flag and allows the controller to recalibrate against the new cell's actual capacity.

Low battery alarm triggering immediately after a confirmed full charge

A freshly charged Ni-MH cell can still trip the low battery alarm if the BMS has not yet completed its learn cycle. The alarm threshold is based on internal resistance measurement, not voltage alone — and a new cell's resistance profile differs from a conditioned one. The fix is to complete two full charge-discharge cycles before clinical use so the BMS can map the cell's actual impedance curve. After cycling, the alarm threshold recalibrates and a fully charged cell will read correctly at or above the 7.2V peak for a 6V Ni-MH pack.

Compatible Models

MDF-137 MDF-U333 MDF-U537 MDF-U537D MDF-V7486SC MDF-C8V VIP Plus

Replaces Part Numbers

5HR-AAC DRTB315005 6242099284

Technical Specifications

Voltage6V
Amp Hours2000mAh
Capacity2000mAh
Rate12Wh
Net Weight140g /4.94 oz
Gross Weight165g /5.82 oz
Approximate Weight165g /5.82 oz
Dimension 51.00 x 43.60 x 27.40mm

Product Highlights

  • Brand: Sanyo
  • Manufacturer: CS
  • Series: Standard
  • Color: Blue
  • Product Type: Ni-MH
  • Battery Type: Ni-MH
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

The freezer shows a battery fault light right after I installed the new battery — it won't clear even after charging overnight. What's happening?

A new Ni-MH cell arrives with a resting voltage below the MDF BMS acceptance threshold, so the controller flags it as faulty before charge even starts. Power the freezer off completely, leave it unpowered for 60 seconds, then restart and allow the full self-test sequence to complete without interruption. Run one complete charge-discharge cycle through the device. After that cycle, the BMS recalibrates against the new cell and the fault flag clears.

The battery sat in a drawer for about a year before I installed it — now the freezer won't power on at all from battery backup. Is the cell dead?

Ni-MH cells self-discharge significantly over 12 months and can fall below the BMS recovery threshold — typically under 5.4V on a 6V pack — at which point the controller won't initiate a charge cycle. Connect the freezer to mains power first and leave it on charge for a full 24 hours before attempting any backup power test. If the BMS detects enough residual voltage to begin recovery charging, it will bring the cell back up; check that pack voltage is reading above 6.0V before relying on it for transport use.

The freezer runs fine on mains, but the battery shuts the unit off unexpectedly after only a short backup load. The cell was fully charged before the outage.

New Ni-MH cells have higher internal resistance in their first 10 cycles, which causes voltage sag under the freezer's compressor load. The BMS detects the sag as an under-voltage condition and cuts output to protect the load — even if the cell is nominally full. This is not a faulty battery. Run the cell through five to ten full charge-discharge cycles on the device and the internal resistance drops to its rated level. After conditioning, retest backup performance and confirm pack voltage stays above 5.8V under compressor start load.

Payment & Security

Payment methods

  • American Express
  • Apple Pay
  • Diners Club
  • Discover
  • Google Pay
  • Mastercard
  • PayPal
  • Shop Pay
  • Visa

Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.

Related Products

Sanyo MDF-137 Replacement Battery, 6V, 2000mAh, Ni-MH 1

Engineered for Performance. Built to Last.

Check out our top-rated selection of reliable products built to last. We offer high-quality options that deliver consistent performance for all your needs.

Our Collections