I've done the external 2S battery mod almost a year ago, I soldered up an XT30 plug right to the plus and minus on where the original battery used to be connected to.

Now I want to do something different, I want to connect a LiFe to it.
At first I wanted to connect a 2S LiFe, but it would make it 5V when depleted, and I heard that these goggles' video quality suffers when running at low voltage, which is basically guaranteed to be at with a LiFe.

So my question is, what's the operating range of the EV800D? because I'm thinking that maybe it's better to run a 3s LiFe instead, with a range of 10.95V - 7.5V.

I do not think most goggles will like to go below 6.8 to 7 volts as they start giving low battery alarms and eventually switch off.

(02-Jul-2021, 04:43 AM)kafie1980 Wrote: I do not think most goggles will like to go below 6.8 to 7 volts as they start giving low battery alarms and eventually switch off.

Yep, that's why I want to know if the EV800D supports 10.95V, because I do know that a normal 3S lipo is not recommended because it shortens the lifespan, and so what about a LiFe

Only way to know is by using a adjustable power supply and powering up the goggles to see how it behaves.

Some lipo charges have the ability to output custom voltage or current and could be used to test this.

(02-Jul-2021, 11:59 AM)kafie1980 Wrote: Only way to know is by using a adjustable power supply and powering up the goggles to see how it behaves.

Some lipo charges have the ability to output custom voltage or current and could be used to test this.

I can use my M6D to power them directly, but I don't want to accidentally fry or damage the goggles

The M6D has a Power mode function:
-set Battery Type to Power
-set Voltage
-set Max Current

If you set the current to a safe max limit such as 2 amps it should be safe enough. Besides the goggles will only draw as much as it requires. If the current is not sufficient then bump the Max current by 1 amps at a time. Don’t push it more than 5amps.

Else just make your LiFe pack and hope it just works

(02-Jul-2021, 03:16 PM)kafie1980 Wrote: The M6D has a Power mode function:
-set Battery Type to Power
-set Voltage
-set Max Current

If you set the current to a safe max limit such as 2 amps it should be safe enough. Besides the goggles will only draw as much as it requires. If the current is not sufficient then bump the Max current by 1 amps at a time. Don’t push it more than 5amps.

Else just make your LiFe pack and hope it just works

I think you misunderstood me, I know how to use the M6D, but I don't want to just dial a voltage and see if it fries the goggles or not,
obviously the goggles can handle 2s Li-ion, but if there's a data sheet or someone who is knowledgeable about the circuitry who can tell me that I won't damage the goggles overtime or something I'll prefer that.
Unless I know I won't destroy the goggles I think I won't connect the 3S LiFe pack ><

A LiFe cell has a NOMINAL voltage of 3.3V. A fully charged LiFe cell is 3.6V, and a fully depleted LiFe cell is 2.5V.

A 3S LiFe pack cannot exceed more than 10.8V and a when depleted will be at 7.5V.

When I asked you to test with the M6D as a controlled power supply I expected you to remain within the 7.5-10.8V range and try to sense how many amps it would require to keep the goggles powered up.

Why would there be a chance to burn your goggles if you stay within this range?

The EV800d can accept 3S Lipo voltage which is 12.6V. You are already within the safe range with 3S LiFe pack at its upper limit of 10.8V.

(03-Jul-2021, 10:45 AM)kafie1980 Wrote: A LiFe cell has a NOMINAL voltage of 3.3V. A fully charged LiFe cell is 3.6V, and a fully depleted LiFe cell is 2.5V.

A 3S LiFe pack cannot exceed more than 10.8V and a when depleted will be at 7.5V.

When I asked you to test with the M6D as a controlled power supply I expected you to remain within the 7.5-10.8V range and try to sense how many amps it would require to keep the goggles powered up.

Why would there be a chance to burn your goggles if you stay within this range?

The EV800d can accept 3S Lipo voltage which is 12.6V. You are already within the safe range with 3S LiFe pack at its upper limit of 10.8V.

The EV800D can accept 3s Lipo in it's charging port because it goes through some kind of a BMS, I'm asking about the internal battery as I'll be plugging the 3s LiFe directly to where the stock 2s plugs into.
The maximum voltage of LiFePo4 is actually 3.65V, and that's what I'm worried about, because if the EV800D is shipped with a 2s Lipo, I think the maximum voltage may be near 8.4V~ and I'd like to just verify somehow that it could work with 10.95V.

About powering the unit with the M6D, if the unit is only able to handle 2s Lipo, when trying anything 8.4V I will be in danger of damaging the goggles, won't I?
as far as I know it has nothing to do with amp draw? because that really isn't an issue, or is there something here that I'm missing?

by the way, here's one thread that I saw that got me the information about 2s vs 3s, and where it goes, just so you'll know where I got that infomation
https://intofpv.com/t-ev800d-battery-upgrade

there's