To charge the EN-EL15 inside the Nikon D750 is impossible because the camera body lacks the charge controller circuit that would accept power from a USB cable and route it into the cell. The side port handles data only, no LED blinks, no icon appears, and the percentage on the top LCD stays put. That single hardware fact rules out every in-body workaround you might have read about online.
This guide explains why that tempting USB trick will never work, then walks through which Nikon chargers, third-party options, and field solutions actually keep a D750 shooting.
Why the D750 Will Not Charge Through Its Own Body
The USB port on the side of the D750 looks like it should pull double duty as a charging input, especially if you have used a newer phone or a Z-series mirrorless camera. Plug a standard USB cable in, and the camera responds as a device, not a charger. No battery icon appears, no charging LED blinks, and the percentage on the top LCD stays frozen wherever you left it.
The Hardware Reason Charging Fails
Inside the D750 body, the power management circuit pulls energy from the EN-EL15 and routes it to the sensor, processor, and LCD, never the other direction. No charge controller IC sits on the mainboard to negotiate power delivery from an upstream source, so even a high-wattage USB-PD wall brick cannot push current into the cell.
This design is baked into the PCB layout and would require a physical board swap to fix, which is why no firmware update, menu toggle, or service menu has unlocked the feature.
What You Actually See When You Try
Plug the camera into a computer, and it mounts as a mass-storage or MTP device for image transfer. Plug it into a wall adapter, and nothing happens, because the body simply does not request a charge handshake. The EN-EL15 contacts on the bottom of the cell sit dormant against the camera’s internal terminals until you pull the battery out and drop it into a dedicated charger.
That hands-off resting behavior is exactly why a purpose-built charger matters more than leaving the cell clipped inside the body.
The Official Charger and the Battery Generations It Supports
Nikon’s MH-25a is the wall charger built for the D750, and it remains the safest path for routine charging. It ships in the box with most new D750 kits, accepts 100-240V input through a folding AC plug, and ends a full charge with a steady green LED.
EN-EL15 Compatibility Across Generations
The original EN-EL15 shipped with early D750 bodies, and the MH-25a charges it without issue. Later EN-EL15a and EN-EL15b cells fit the same slot in the camera and the same cradle in the charger, so a fresh purchase of either generation drops into your existing workflow. The newer cells carry updated identification chips, but those chips are read by the camera body, not by the charger, so charging behavior stays identical across all three generations.
Charge Time and What the Lights Mean
A depleted EN-EL15 takes roughly two hours and thirty-five minutes to reach full on the MH-25a. A slow orange blink indicates active charging, and the LED switches to a steady green when the cell crosses about 90 percent capacity. The last ten percent trickles in slowly to protect cell longevity, which is why the green light often arrives a few minutes before the cell is technically at 100 percent.
The slow, protective trickle also explains why copycat chargers can feel temptingly fast while quietly shaving years off a battery.
| Battery Model | Shipped With | Charges on MH-25a | Camera Compatibility Notes |
|---|---|---|---|
| EN-EL15 | Original D750, D810, D7100 | Yes | Fully supported, no firmware caveats |
| EN-EL15a | D750 (later production), D7200, D810A | Yes | Identical fit and charge behavior |
| EN-EL15b | Z 6, Z 7, D780 | Yes | Works in D750, supports in-camera charging on Z bodies |
| EN-EL15c | Z 5, Z 6II, Z 7II | Yes | Backward compatible, higher capacity |
Third-Party Chargers Worth Trusting and the Ones to Skip
Aftermarket chargers have come a long way since the early days of bargain-bin knockoffs, and several brands now build reliable EN-EL15 chargers that match the MH-25a’s output at a third of the price. The trick is knowing which ones carry the right safety circuitry and which ones are little more than a plastic shell around a cheap transformer.
Brands With a Track Record
Watson, Wasabi Power, and RavPower all produce dual-bay chargers that accept every EN-EL15 generation. These units typically include overcharge protection, a clear per-channel LED indicator, and the same polarity contacts as Nikon’s first-party cradle. Charging speed lands within five to ten minutes of the MH-25a, and the included car adapter on some kits makes them a strong value for travel.
Red Flags in Cheap Knockoffs
Cut-price no-name chargers often skip voltage regulation, ship with mismatched battery plates, and lack any meaningful warranty. Symptoms of a bad unit include a battery that feels warm to the touch after a short charge, a charger LED that never turns green, and a cell that loses capacity noticeably faster across a few dozen cycles.
Look for an EN-EL15 label printed directly on the plastic, a stated 8.4V output, and reviews that specifically mention the D750 before committing.
Even a trustworthy third-party charger still expects a wall outlet, which quickly falls apart once the nearest plug is miles behind you.
Buy a charger that lists the exact EN-EL15 model on the box and provides a written warranty of at least twelve months. That single habit eliminates most of the duds before they reach your kit bag.
Travel and Field Charging When the Wall Is Far Away
On a multi-day shoot, the wall outlet is rarely where you need it. The MH-25a accepts the same 100-240V input worldwide, so a cheap plug adapter is often all you need overseas, but road trips and backcountry sessions call for a different approach.
Vehicle and Power-Bank Options
A 12V car adapter rated for the MH-25a lets you top up between locations on long drives, and most USB power banks can power the MH-25a indirectly through a small inverter. The inverter route adds bulk, though, so a dedicated DC coupler makes more sense for backpack kits that already carry a power bank.
Tethered Studio Charging With the EP-5B
Pairing the EP-5B DC coupler with an EH-5b or EH-5c AC adapter transforms the D750 into a tethered studio camera drawing power straight from the wall outlet. The EN-EL15 stays in the bag, the camera runs indefinitely, and timelapse or tethered capture sessions no longer depend on battery swaps. This setup weighs more than a spare cell, but for studio work it removes the single biggest source of mid-shoot interruptions.
Reading the LED and Solving Common Charging Glitches
The MH-25a’s indicator light speaks a simple dialect, and learning it saves a trip to the service center. Most charging issues trace back to contact problems, dead cells, or a power strip that quietly tripped off.
Quick Blinks and Steady Glows
A rapidly blinking red light usually points to a poor connection between the battery plate and the charger’s terminals. Reseat the cell, clean the contacts with a dry microfiber cloth, and confirm the plate is fully clipped into the cradle. A steady green glow means the charge cycle completed normally, even if you pulled the battery early.
When Nothing Lights Up
A dark charger with a plugged-in battery often means a dead cell or a tripped breaker on the power strip. Try a different outlet first, then test the cell in the camera body to confirm it still holds any charge at all. If the D750 refuses to power on after a full charge cycle, clean the in-body contacts with a dry cloth and confirm the MH-25a LED actually turned green before reinserting the battery.
Habits That Keep the EN-EL15 Healthy Over Years of Use
Lithium-ion chemistry rewards gentle treatment, and a few small habits can easily double the useful life of an EN-EL15 cell. The same practices also reduce the risk of showing up to a shoot with a battery that suddenly refuses to hold a charge.
Partial Top-Ups Beat Deep Discharges
Charging the EN-EL15 before it drops below twenty percent causes less stress on the cells than running it flat and refilling from empty. Partial cycles keep the internal resistance lower over time, which translates to more consistent burst rates during high-speed shooting. A top-up during lunch often matters more than a single overnight charge once a week.
Storage Charge and Heat Avoidance
Store spare batteries at roughly half charge in a cool, dry place, and never leave the D750 in a hot car after a shoot. Heat accelerates capacity loss far faster than cycling does, and a battery cooked at 140°F on a summer day can lose ten percent of its capacity in a single afternoon.
Label each spare with the date you bought it and rotate them so every cell sees similar usage, which prevents one battery from silently aging faster than the rest of the set.
- Top up early: Recharge at twenty percent rather than running to empty.
- Store at half charge: About fifty percent is the ideal storage level for lithium-ion cells.
- Avoid heat: Remove batteries from the camera between sessions in warm environments.
- Rotate the set: Number each cell and cycle through them to keep wear even.
- Update firmware: A current D750 firmware version improves battery telemetry accuracy.
- Inspect contacts: Wipe battery and charger contacts every quarter to prevent resistance buildup.
The Bottom Line
The D750 does not charge its battery in the body, and no workaround will change that, so the MH-25a remains the most reliable path to a full EN-EL15. Build a small charging kit around the official cradle, add a trusted third-party dual charger for travel, and treat your cells with partial top-ups and cool storage to stretch their lifespan across years of shoots.
FAQ
Can I charge my Nikon D750 battery inside the camera?
No. The D750 lacks the internal charging circuitry required to charge the EN-EL15 while it is mounted in the body, so the battery must be removed and placed in an external charger like the MH-25a. No firmware update or menu setting changes this hardware limitation.
Does the Nikon D750 support USB charging?
The D750’s USB port is wired for data transfer only, which means it cannot negotiate power delivery or push charge into the EN-EL15. Connecting the camera to a wall adapter or power bank through USB produces no charging icon and no change in battery level.
How do I charge my Nikon D750 battery without the original charger?
Trusted third-party chargers from Watson, Wasabi Power, or RavPower accept the EN-EL15 and its newer variants, often include a car adapter, and cost less than Nikon’s MH-25a. Confirm the listing specifies EN-EL15 compatibility, a regulated 8.4V output, and at least a one-year warranty before buying.
Which Nikon batteries are compatible with the D750?
The D750 accepts the original EN-EL15, the EN-EL15a, the EN-EL15b, and the EN-EL15c, all of which fit the same battery slot and charge on the MH-25a. Newer cells such as the EN-EL15b and EN-EL15c enable in-camera charging on Z-series bodies but behave identically inside the D750.
Is there a firmware update that enables in-camera charging for the D750?
Nikon has never released a firmware update enabling in-camera charging on the D750, and none is planned because the charge controller circuitry is absent from the mainboard. Any future firmware release focuses on metering, autofocus, and lens compatibility rather than power input.
How long does it take to fully charge an EN-EL15 battery?
A depleted EN-EL15 typically takes about two hours and thirty-five minutes to reach a full charge on the MH-25a, signaled by a steady green LED once the indicator stops blinking. Third-party chargers usually finish within five to ten minutes of that mark.
