Short answer: it fits and it works, but on an EOS R8 a 750mAh battery is emergency power rather than main power. The R8 is a full-frame body, and its finder, sensor readout and in-camera processing all draw more than the APS-C bodies in the same family, so the same battery typically lasts noticeably less time in the R8 than in an R50 or a 200D II. Treating it as the battery that lives in the bag just in case is sensible; treating it as your only spare invites trouble at the worst moment.
That conclusion needs no measurement. It follows from the power structure of the body, which is worth breaking down.
Where the R8 spends its power
The first draw is the finder. The R8 uses an electronic finder, so as soon as the camera is on and you are framing, either the screen or the eyecup is refreshing continuously. That draw depends on brightness setting and refresh rate, and it is a constant item that runs even at idle. A DSLR can let the sensor and screen rest while you use the optical finder; a mirrorless body has no such option.
The second is sensor readout. A full-frame sensor has a larger photosensitive area, and its readout circuitry moves more data per unit of time, which raises draw. The R8 uses an electronic first-curtain shutter, so the sensor takes part in the exposure as well, which makes the cost of each press higher than on a body with a mechanical shutter.
The third is in-camera processing and wireless. Focus computation, stabilization coordination and Wi-Fi or Bluetooth standby all stack on top of baseline draw. Switching these off in the menu saves something, but the saving is far smaller than the capacity difference.
How the 750mAh fits the R8
One premise first: a Canon original LP-E17 is about 1040mAh / 7.5Wh, while the 750mAh is the smallest of three self-defined tiers and is not equivalent to it. Estimating time by capacity ratio is crude but effective: 750 against 1040 is a little over seven tenths of an original battery.
| Use case | What 750mAh roughly covers | Advice |
|---|---|---|
| Indoor setups, product shots, a few dozen frames | Usually enough, even with margin | Fine to carry |
| Half-day street work, mostly screen framing | Tight; a second battery is often needed | Make it the second battery, not the first |
| All-day location work, bursts, 4K clips | Not enough; it is a mid-session top-up | Do not plan it as the primary |
| Cold outdoor work | Usable capacity shrinks further | Keep it inside a pocket, emergency only |
Note that the table gives range judgments, not precise figures. With the same battery, leaving Wi-Fi on or off, setting screen brightness a few steps higher, or using the eyecup instead of the screen can change the result considerably. The body manual and your own shooting rhythm are more reliable guides.
Where the 750mAh is the right choice
There is one role it fills well: you already have a large battery as primary and want a light, cheap top-up you do not have to worry about. The R8 is not a heavy body, and a 750mAh in a small bag adds almost nothing, which suits outings of an hour and a few dozen frames.
The other is overnight standby. If you leave the camera on a tripod waiting for a particular moment, with most of that time spent idle, the low duty cycle does not demand much total capacity, and a 750mAh will drain more slowly than you might expect.
Conversely, if your pattern is one battery for the whole trip, the 750mAh should not be on the shortlist at all; the 950mAh version is the easier choice.
A more sensible pairing
For R8 users, a sound arrangement is one large battery as primary plus one or two 750mAh batteries as top-ups. The primary covers the first half, the 750mAh covers the wrap-up and the unexpected, which keeps total weight under control without loading all the risk onto a small battery. For how many batteries are enough, the scenario estimates in the capacity and compatibility guide are a good starting point.
Two power-saving actions cost nothing and are worth taking: switch off wireless functions you are not using, and drop finder brightness one step. Both pay off more on the R8 than on a DSLR, because they address constant draw. One more note: neither the 750mAh nor the 950mAh has a USB-C charging port, so topping up an R8 on the road still means carrying the LC-E17 dock charger or a third-party charger with PD support. Direct charging exists only in the T series.
FAQ
Will a 750mAh battery damage the R8?
No. The LP-E17 voltage spec is fixed, and the body identifies a battery by voltage and communication rather than capacity. A 750mAh simply holds less and cannot damage the body through being small. The premise is a battery from a legitimate source with a working protection board.
Why does the same 750mAh last longer on an R50?
Because the R50 is an APS-C body with less sensor readout and lower overall draw than the full-frame R8. With less consumption, the same capacity naturally lasts longer. This is why battery runtime was never a property of the battery alone.
Roughly how many shots will the R8 get from a 750mAh?
There is no single answer; it depends on framing method, burst ratio, wireless settings and temperature. A reasonable expectation is clearly fewer than the same battery gives on an APS-C body, in the “enough for an emergency, not enough as a primary” range. Build a baseline on your own body with the three-step method rather than borrowing someone else’s number.
Do two 750mAh batteries equal one original battery?
In capacity, close; in experience, not equivalent. Two batteries mean one swap mid-session, and that swap tends to land at the least convenient moment. The discharge plateaus also differ. If the budget allows, one 950mAh plus one 750mAh is usually a better combination than two 750mAh batteries.