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Streamlight SL-20X 6V Replacement Battery 5000mAh Ni-MH

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New arrival
From $80.99 USD $99.99
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Fits Streamlight SL-20X flashlight, replaces OEM part numbers 20170 and 41B038AF00101.
6V Ni-MH pack delivers 5000mAh capacity; maintains voltage stability under the xenon lamp's high current draw.
Cylindrical cell configuration slides into the SL-20X battery tube with spring contact at the base.
We bench tested this pack on the SL-20X driver; BMS held steady voltage throughout discharge without early cutoff.
On first install, run the flashlight in standard mode for one full cycle before switching to turbo mode.
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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.

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⚠️ 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

5000mAh

Streamlight SL-20X Series — 6V Ni-MH Replacement Battery (20170)

This 6V 5000mAh Ni-MH battery pack replaces the original rechargeable cell in the Streamlight SL-20X, SL-20, and SL-20S flashlights. It fits the high-intensity xenon lamp models used by law enforcement, search and rescue, and industrial crews. Voltage and capacity match the OEM spec exactly — 6V, 5000mAh, 30Wh.

  • SL-20X platform fit: The SL-20X, SL-20, and SL-20S all share the same cylindrical battery housing, 6V nominal voltage rail, and spring-contact terminals — so one pack covers the full family without modification.
  • Bench tested on actual hardware: We ran this pack through full charge and discharge cycles on the SL-20X. The Ni-MH cells held voltage at the xenon lamp's draw without triggering early cutoff, and the pack reached rated capacity within two conditioning cycles.
  • Multi-cell pack handling: This pack contains matched cells from the same production batch. If you are replacing only one battery in a two-flashlight setup, do not mix this pack with a partially depleted original — mismatched cell ages under high xenon draw will cause the weaker pack to drop voltage first and degrade faster.

Why the SL-20X dims before the low-battery indicator triggers

The SL-20X drives a xenon bulb directly from the battery pack with no active regulation stage. As cell voltage drops under load, the lamp draws less current and output falls visibly — before the battery reaches its rated cutoff voltage. This is a characteristic of direct-drive xenon circuits, not a fault with the pack. A freshly charged 6V Ni-MH pack at full capacity will hold the lamp at full brightness significantly longer than a degraded cell operating at the same nominal voltage.

Battery cycling rapidly through modes near end of charge

If the SL-20X appears to flicker or the driver steps output up and down near the end of a discharge, the pack voltage is dipping below the threshold needed to sustain the xenon load. The lamp's current draw momentarily pulls voltage down, the light dims, current demand drops, voltage recovers, and the cycle repeats. Switch to a lower output mode immediately — this stops the cycling and lets the remaining charge discharge cleanly. Recharge when resting pack voltage falls to 5.4V or below.

Compatible Models

SL-20X SL20 SL20S SL20X 20X1701 ML500 ML5000 N38AF001A RX1019 Mini Stinger

Replaces Part Numbers

20170 41B038AF00101

Technical Specifications

Voltage6V
Amp Hours5000mAh
Capacity5000mAh
Rate30Wh
Net Weight464g /16.37 oz
Gross Weight644g /22.72 oz
Approximate Weight644g /22.72 oz
Dimension 183.90 x 32.20 x 32.20mm

Product Highlights

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

Frequently Asked Questions

My SL-20X is noticeably dimmer right out of the charger — why isn't it back to full brightness after a full charge?

Ni-MH packs that have been deeply depleted or left discharged for extended periods often need two to three full charge-discharge conditioning cycles before reaching rated capacity. The cells recover incrementally, not all at once on the first charge. Run the flashlight to cutoff, recharge fully, and repeat — brightness should return to normal by the third cycle. If it does not, check charger output voltage at the contacts; it should read at least 7.2V under no load.

One of my two SL-20X flashlights is draining much faster than the other after fitting the same new battery — what's causing the imbalance?

This happens when one flashlight still has the original aged pack while the other has the new 5000mAh replacement. The older cells have higher internal resistance, so they shed voltage faster under the xenon draw, giving noticeably shorter run time. The two packs are no longer matched in state-of-health, so direct comparison feels like the new one is underperforming — it is not. Replace the second pack with a unit from the same batch and the run times will align.

The SL-20X flickers for a few seconds when I first switch it on with a freshly charged battery — is something wrong with the pack?

This is usually a contact issue, not a cell fault. The spring terminals inside the SL-20X tail cap oxidise over time, and a thin oxide layer creates enough resistance to cause a momentary voltage drop at the high inrush current of the xenon lamp strike. Clean the tail cap spring contacts and the battery pack end caps with a pencil eraser or fine abrasive, then reassemble. If flickering stops after the first few seconds and output stabilises, the cells are fine — the contact surfaces needed cleaning.

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