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Charging an Eco Flow with external battery

TDave00

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Dec 8, 2023
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Nashville, TN
I bought an Eco Flow Delta 2 and I want to connect a small external 48v battery through the XT60 solar input to increase capacity. I'm concerned about the amperage from the battery being too high and thus damaging the mppt of the Eco Flow. I've read that using a regular xt60 (vs an xt60i) connector will cause the Delta 2 to limit the current to 8 amps, which would keep me below the 500w input of the Delta 2.
I'm trying to keep from using a voltage converter to limit voltage and current, which is what most diy videos I've watched are suggesting.
Thoughts?
 
I tried a 36V external battery connect to one of the two 500W 11-60V 15A mppt inputs in my Delta 2 max. It charges at 500W for a moment then shows 0 watts of solar input. So I don't think a 48V will do what you are hoping for. However a 24V battery works great and I get around 380W of input from each mppt.

Using xt60i to ring terminal cable. The Delta 2 (max) will limit its input to 15A. The Delta 2 draws the current from the external battery. It's not pushed from the battery.
 
I tried a 36V external battery connect to one of the two 500W 11-60V 15A mppt inputs in my Delta 2 max. It charges at 500W for a moment then shows 0 watts of solar input. So I don't think a 48V will do what you are hoping for. However a 24V battery works great and I get around 380W of input from each mppt.

Using xt60i to ring terminal cable. The Delta 2 (max) will limit its input to 15A. The Delta 2 draws the current from the external battery. It's not pushed from the battery.
From a spec perspective that doesn’t compute since the charge controller takes up to 60v. I’m not doubting your real world experience, just suspecting some other factor was at play that made your 24v battery work but not the 36v… But regardless - yeah just get an xt60i so the DM doesn’t artificially limit itself. Plenty of options to buy them on Amazon and elsewhere…
 
From a spec perspective that doesn’t compute since the charge controller takes up to 60v. I’m not doubting your real world experience, just suspecting some other factor was at play that made your 24v battery work but not the 36v…
My EcoFlow Delta Mini works at 36v, but I haven't tried it at any higher voltages.

But yes, as other have said, you can plug anything you want into your PV input on your Power Station as long as you are 100% sure that you will not exceed the devices maximum allowable voltage input.

I have a 36V 5kWh battery system connected 24/7 to my EcoFLow.
 
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I tried a 36V external battery connect to one of the two 500W 11-60V 15A mppt inputs in my Delta 2 max. It charges at 500W for a moment then shows 0 watts of solar input. So I don't think a 48V will do what you are hoping for. However a 24V battery works great and I get around 380W of input from each mppt.

Using xt60i to ring terminal cable. The Delta 2 (max) will limit its input to 15A. The Delta 2 draws the current from the external battery. It's not pushed from the battery.
36v x 15a = 540w
24v x 15a = 360w
It's seems the 36v battery charging at 15 amps was putting you over the 500w limit. That's probably why charging stopped. I bet if you charge at 36v with the regular xt60 connector the Delta 2 will limit charging to 8 amps and max out at 288w. Thoughts?
 
Picked up a Delta 2 last month. Can charge all day at 12v with a 8 amp limit. Haven't had the chance to try it on my 24v pack yet.
The 8 amp limit seems to be strict as it sat exactly at 96 watts the whole time.
 
36v x 15a = 540w
24v x 15a = 360w
It's seems the 36v battery charging at 15 amps was putting you over the 500w limit. That's probably why charging stopped. I bet if you charge at 36v with the regular xt60 connector the Delta 2 will limit charging to 8 amps and max out at 288w. Thoughts?
Yeah, but it seems like a pretty inefficient way to handle what it deems to be "too much" power coming in though.

If the unit says it can handle 36V @ 15A it should be able to take in 36V @ 15A, no matter what.

I shouldn't have to artificially limit the current coming in to satisfy some weird unwritten rule.

@Brucey maybe you could try a buck converter to limit a 36V input to EXACTLY 33.3V (the theoretical max input with no overage; 33.3V X 15A = 500W) to see if it would work?
 
Yeah, but it seems like a pretty inefficient way to handle what it deems to be "too much" power coming in though.

If the unit says it can handle 36V @ 15A it should be able to take in 36V @ 15A, no matter what.

I shouldn't have to artificially limit the current coming in to satisfy some weird unwritten rule.

@Brucey maybe you could try a buck converter to limit a 36V input to EXACTLY 33.3V (the theoretical max input with no overage; 33.3V X 15A = 500W) to see if it would work?
The Delta 2 solar charger takes up to 60v @15A.
 
Picked up a Delta 2 last month. Can charge all day at 12v with a 8 amp limit. Haven't had the chance to try it on my 24v pack yet.
The 8 amp limit seems to be strict as it sat exactly at 96 watts the whole time.
Are you using an XT60 or XT60i connector? The 8 amp limit should only apply with the XT60.
 
Just took a look at the connectors I used for a solar cable and battery connection cable with ring terminals I made a few weeks ago.
They came from Amazonian jungle market and are marked XT60H-F. Cost was 7 bucks for 10 pcs.
 
Just took a look at the connectors I used for a solar cable and battery connection cable with ring terminals I made a few weeks ago.
They came from Amazonian jungle market and are marked XT60H-F. Cost was 7 bucks for 10 pcs.
yeah without an XT60i, the Delta 2 assumes it’s connected to the car cigarette charging adapter and artificially limits itself to 8amps.
 
Yeah, but it seems like a pretty inefficient way to handle what it deems to be "too much" power coming in though.

If the unit says it can handle 36V @ 15A it should be able to take in 36V @ 15A, no matter what.

I shouldn't have to artificially limit the current coming in to satisfy some weird unwritten rule.

@Brucey maybe you could try a buck converter to limit a 36V input to EXACTLY 33.3V (the theoretical max input with no overage; 33.3V X 15A = 500W) to see if it would work?
The specs are 60/15/500 (v/a/w). I'm assuming if you go over any of those it will cut off charging.
 
Mine came today and to my surprise it's an Eco Flow 1300 (not the Delta 2). I guess I misread the description on Lowe's website..again. This unit is 65/10/400 so I guess I'm gonna have to buy an additional 36v/10a converter. Sucks
 
As long as the voltage is with spec the amperage draw will be determined by the mppt of the ecoflow.
Right now I'm looking for a dc to dc booster to fit the delta pro. Something over 100vdc so I can charge off a server rack when the sun Is done for the day.
 
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I just ordered the Bluetti AC 180 ($649 with their $350 off coupon). Gonna return the Eco Flow 1300. (This is the second Eco Flow I've returned in the last few weeks... They sent me an external battery the first time instead of the main unit.).
The Bluetti has a 60/10/500w mppt like the Delta 2, which I thought I was ordering. I saw hobotech go up to 60v in the solar input on the AC 180 so I'm confident my 48v external battery will work fine, and it was $120 cheaper than the Eco Flow 1300 with better features. The Bluetti also uses lifepo4 instead of lithium 18650's, so more cycle life. I'm guessing that's why the warranty is 5 years vs the 2 years Eco Flow offers.
 
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As long as the voltage is with spec the amperage draw will be determined by the mppt of the ecoflow.
Right now I'm looking for a dc to dc booster to fit the delta pro. Something over 100vdc so I can charge off a server rack when the sun Is done for the day.
Voltage converters to me don't really ever make sense unless you're doing it in a mobile application where your source is an alternator.
Otherwise you're going to be having a lot of losses.

You would be better off running two 48V rack batteries at 96V rather than trying to bost the 48V to 100V.
 
I just ordered the Bluetti AC 180 ($649 with their $350 off coupon). Gonna return the Eco Flow 1300. (This is the second Eco Flow I've returned in the last few weeks... They sent me an external battery the first time instead of the main unit.).
The Bluetti has a 60/10/500w mppt like the Delta 2, which I thought I was ordering. I saw hobotech go up to 60v in the solar input on the AC 180 so I'm confident my 48v external battery will work fine, and it was $120 cheaper than the Eco Flow 1300 with better features. The Bluetti also uses lifepo4 instead of lithium 18650's, so more cycle life. I'm guessing that's why the warranty is 5 years vs the 2 years Eco Flow offers.
I have also in the past heard of people with problems with Bluetti products as well with their inputs.
But I wish you luck.
 
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