The BRAT Beta Program

[brad.midnite]

The manual is a work in progress certainly. We've been calling it a 'quick start' internally.

I am happy that 'the obvious' did exactly what you expected it might.

Edit: To elaborate further...

If you're using a flooded profile Auto-EQ/Manual-EQ can function. I may need to modify the code to provide an error pattern on the LEDs if Auto-EQ is ON but the profile doesn't support EQ. In writing this I realize there's no error message for this.

If you attempt a manual-EQ with a sealed battery profile selected, an error code will be displayed. What happens is all four LEDs will blink three times then the Float LED will display ON for a few seconds. All of the error code patterns work in this fashion, the 4 LEDs blink then a code is displayed. The idea being that a table in the manual will be provided to provide guidance/troubleshooting when the user does something illegal/a problem is detected.

If instead, a flooded profile is programmed as you have done, and you hold the push-button for 2 seconds, all four LEDs will light in sequence, chasing from left-to-right. This is an acknowledgement for the request of a manual EQ. If you want to cancel the request, whether it's currently EQing or not, you can hold the push-button for 2 seconds again, this will cause the LEDs to chase from right to left. This acknowledges the request to cancel a manual-EQ was acknowledged. If it was EQing when you cancelled, it will drop down to Float, if not, it will continue as usual in Bulk/Absorb.

I'm aware there are dissenting opinions (specific to solar/wind) whether an attempt to EQ should begin immediately or only begin after successful completion of absorb. Currently, in the beta units, it only EQs after absorb has completed, but you can request at any-time. I hope to add some compile-time logic so that we can provide either alternative based on the prevailing concensus of our customers as we ramp up to production. This decision is important and somewhat arbitrary because wind/solar can be flaky in terms of power available at any given moment. The Brat is designed to give up after its been unable to maintain EQ setpoint for 10 minutes. In which case it will fall back to float and attempt to finish the remaining EQ time the next day. In that way, it has retry days as does The Classic, but it's fixed to 1 day of retry time. My thinking in doing this was to avoid customer's batteries sitting at some arbitrary voltage above absorb for potentially a full day (i.e., just below EQ). If I modify the code to attempt to drive the battery voltage straight to EQ without completing a normal absorb cycle, it's a lot harder to 'give up' if there's not enough power available currently to bring the voltage up to EQ.

Long story short, thank you for joining the Beta list and providing feedback. I hope that together we can mold The Brat into a better, popular product.

-Brad

[onanparts]

The manual is a work in progress certainly. We've been calling it a 'quick start' internally.

I am happy that 'the obvious' did exactly what you expected it might.

-Brad

Yup! The EQ worked as designed. 

The singing BRAT looked interesting on boB's graph. I think he forwarded that to you also?

[onanparts]

This was actually recorded with my phone held against that big resistor.

[Doug]

Stopping EQ seems like a useful feature.
https://www.dropbox.com/s/lxc0mz55vxtens0/10-293-1%20REV%20P3%20The%20Brat%20Quick%20Start%201-29-15%2023.pdf?dl=0 Here is an update to the manual (Quick Start Guide) that describes stopping an EQ
See pages 9 and 10.

Doug

[TomW]

I wondered if anybody actually looked at attachments. 

I like this much better than the first or the original. 

[onanparts]

Discharged my 12V battery on the BRAT output side down to about 50% DOD. When first connected it was under 10% DOD so straight to absorb then float. No problem with the 600W resistor as the current was very low.

BUT!......Oh boy....had a Fluke clamp style current meter on the input side today while testing. 43 AMPS. Lets see....at 53 volts that's about....2279 Watts! Resistor got hot real fast. This test lasted all of 3-4 seconds before flipping the input breaker!

BRAT was also pushing about 43 AMPS on the output side during this time. BRAT did not release it's magic smoke.

Conclusion: Me thinks I just stick to the designed PV input.

Or....I could try this resistor....Good for 1000 AMPS+. Or not! 

[brad.midnite]

Likely it was at 100% duty cycle trying to bring up the battery to absorb voltage. This means you were getting 43 Amp pulses all along, just time-divided. It's a weighted average between 0 Amps and 43 Amps. If it's operating at 10% duty-cycle that's 4.3 Amps. If it was at 50%, that's 21.5 on average. The Brat currently does not current limit if you over-size your PV array.

[candh]

Is the beta testing over? Are there any opinions about it yet?

[BobWhite]

 

Am I on the list? Joking with ya! Ryan i did send an email, keep me informed.
Walt

[BobWhite]

I did recieve a brat and set it up at 24 volts and very happy with its performance.
Im alittle confused with the readings im getting though
Im getting 35.9 volts from the panel at .69 amps  when i hook the same panel to the classic 150 I get  28.3 at 8.5 amps. Can anyone help me understand that?
Walt

[Westbranch]

BW, 2 quick questions, you don't have the BRAT listed in your  sig line...  which panel is it? 
You do mean that you are using only 1 panel to run the comparison, right?

[BobWhite]

thank you westbranch!
I ran just one at a time of the MX60s.

Suncase MX 60                                      235
Module power Pmax, W                      235
Rated voltage Vmpp, V                       29.8
Rated current Impp, A                         7.88
Open circuit voltage Voc, V                37.0
Short circuit current Isc, A                  8.45
Maximum system voltage, V               600

Module efficiency %                           14.0
Cell efficiency %                                 16.1
Max series fuse rating A                     15

When I say one at a time I only hooked one panel to the Brat and then hooked the same panel to the classic only measuring the voltage and current as they were operating in a absorb state of charge, and then I hooked up another single panel and ran my test again until I did all four panels one at a time. I had to do the test in absorb as I do keep my batteries up and within a few minuets the brat was in absorb so I forced the classic into absorb to be on the same playing field.

I will update my sig line, i have made a few changes since I posted it.
Again thank you!
Walt

[brad.midnite]

I did recieve a brat and set it up at 24 volts and very happy with its performance.
Im alittle confused with the readings im getting though
Im getting 35.9 volts from the panel at .69 amps  when i hook the same panel to the classic 150 I get  28.3 at 8.5 amps. Can anyone help me understand that?
Walt

Hi Bob. Given the panel specs you posted it's apparent The Brat is running at very light duty cycles, which would be consistent with near-full batteries. I suspect the difference is the absorb voltage setpoints of The Brat vs The Classic. Let me know if you find different.

Thanks for the feedback btw.
-Brad

[BobWhite]

Brad, I believe you hit the nail on the head! Ill start by putting some heavy loads and bring the batteries down this weekend and take readings again on the BRAT,  I don't like to load them up when I can't keep an eye on what is happening.

Thank you Brad! I will get back to you.
Walt 

[Halfcrazy]

Kim and Walter should be in touch any day now to finish filling the Beta requests. If you do not hear from Kim by weeks end please email her kim@midnitesolar.com