MPP Solar 1012 vs DIY Milk Crate

[undercrust]

I'm looking to build a version of the Milk Crate all-in-one, but I'm having a hard time finding an MPP Solar 1012LV that would ship to Canada for a reasonable price.

For the battery, I'm planning a DIY LiFePO4 based one EVE 280K cells and a Daly 120A BMS with Bluetooth.

As far as I can tell, the main benefit of the MPP Solar AIO is that it's really easy to wire and a known good quality. It's ~C$750 from Azimuth Solar (not in stock), ~C$650 (assuming no import duties) from Watts247, or C$570 from eBay (shipped from Taiwan).

The @Will Prowse Milk Crate v2 system I've been using as a baseline for the plan has lead me to these parts:

Giandel 12V 1200W PS Inverter - C$150
Renogy Rover MPPT 150v | 40A - C$150 (https://a.co/d/6RD7JsI)
DROK Adjustable 0-24V DC 20A Power Supply - C$50 (https://a.co/d/hpRRhcD)

So, as far as I can tell from the Milk Crate v1 video, I could wire the output of that DROK power supply to the Renogy MPPT PV inputs, and achieve nearly 480W of input wattage (24V x 20A), and allow the MPPT to step down the voltage and charge the battery. So for a little bit more effort, I could save $200+, and get even faster plug-in AC charging than the MPP Solar AIO unit's 20A?

Questions:
1) Am I missing some major detail here regarding the comparison between the parts and the AIO unit that is critical to the comparison?

2) Why does @Will Prowse wire the power supply to the MPPT charger in v1 of the Milk Crate, but then wire directly to the battery in v2?

3) Seriously, what am I missing here??

Thanks in advance everyone! Any insight is appreciated!

 

[Willow1]

I'm looking to build a version of the Milk Crate all-in-one, but I'm having a hard time finding an MPP Solar 1012LV that would ship to Canada for a reasonable price.

For the battery, I'm planning a DIY LiFePO4 based one EVE 280K cells and a Daly 120A BMS with Bluetooth.

As far as I can tell, the main benefit of the MPP Solar AIO is that it's really easy to wire and a known good quality. It's ~C$750 from Azimuth Solar (not in stock), ~C$650 (assuming no import duties) from Watts247, or C$570 from eBay (shipped from Taiwan).

The @Will Prowse Milk Crate v2 system I've been using as a baseline for the plan has lead me to these parts:

Giandel 12V 1200W PS Inverter - C$150
Renogy Rover MPPT 150v | 40A - C$150 (https://a.co/d/6RD7JsI)
DROK Adjustable 0-24V DC 20A Power Supply - C$50 (https://a.co/d/hpRRhcD)

So, as far as I can tell from the Milk Crate v1 video, I could wire the output of that DROK power supply to the Renogy MPPT PV inputs, and achieve nearly 480W of input wattage (24V x 20A), and allow the MPPT to step down the voltage and charge the battery. So for a little bit more effort, I could save $200+, and get even faster plug-in AC charging than the MPP Solar AIO unit's 20A?

Questions:
1) Am I missing some major detail here regarding the comparison between the parts and the AIO unit that is critical to the comparison?

2) Why does @Will Prowse wire the power supply to the MPPT charger in v1 of the Milk Crate, but then wire directly to the battery in v2?

3) Seriously, what am I missing here??

Thanks in advance everyone! Any insight is appreciated!

Im doing the same thing, but on a larger scale, and installing it into a large flight chest that's on wheels... 2 big 200a Renogy batteries, Renogy 3000w inverter, 400w solar and 40A Renogy MPPT...
I've just asked the same question as I'd watched the same thing in the first video, with the AC-DC charger wired direct into the MPPT, then to the battery in the second...??‍

How did you get on with yours?

So far I've spent £2500 and I'm still a battery and 200w of pv solar short...! ??‍?
It should run a small building site once I'm done though....?

Regards
Shaun

 

[undercrust]

Im doing the same thing, but on a larger scale, and installing it into a large flight chest that's on wheels... 2 big 200a Renogy batteries, Renogy 3000w inverter, 400w solar and 40A Renogy MPPT...
I've just asked the same question as I'd watched the same thing in the first video, with the AC-DC charger wired direct into the MPPT, then to the battery in the second...??‍

How did you get on with yours?

So far I've spent £2500 and I'm still a battery and 200w of pv solar short...! ??‍?
It should run a small building site once I'm done though....?

Regards
Shaun

I actually think I figured out the answer to this one, at least the theory since I don't have the parts to test the practical yet.

Two main reasons (that I stand to be corrected on by someone with more practical experience):

1) An MPPT charge controller isn't the best equipped for "processing" the input waveform (?) of the PSU voltage. Because the MPPT system is used to processing a different waveform from solar panels, it's either inefficient at tracking the PSU power input, or I've read reports of the charge controller just throwing errors.

The "solution" on this one (again, I stand to be corrected) is that a PWM charge controller might be better equipped for handling the PSU because the PSU voltage output is more "friendly" to the PWM waveform type.

(I'm still learning proper terminology here, so I'd really appreciate someone translating that into correct terms)

2) The charging profile for LiFePO4 batteries is pretty darn simple, and really needs just the "bulk" phase for the battery to fairly quickly get up to ~95% capacity (which is a healthy upper limit for the battery cells anyways). A power supply set to 14.4v - 14.6v (3.6v - 3.65v per cell) will deliver a constant current (CC) and gradually raise the voltage of the battery.

The following stage would normally be constant voltage (CV) which keeps the voltage high and gradually decreases the amperage.


Since my setup is going to be a simple 12v system based on the EVE LF280K cells, I wanted to have a reliable fast-charging plug-in option, and the cells are capable of accepting an enormous input amperage safely...the 0.5C charge rate they measure cycle capacity with would be 140 amps, so my limitation would be at my 120A BMS, not the cells themselves. I wound up following the advice of this video that compares a number of charger options and I've got the fourth option (what appears to be a modified 75 amp server power supply) on the way from AliExpress.

I think your Renogy 200Ah batteries might have a 200A BMS, but practically speaking, that 50A or 75A solution might be a good one for you too. If the AliExpress thing isn't within your comfort zone, the expensive but very well made option would be the AIMS 75A bench power supply that @Will Prowse recommends on his website.

For what it's worth, that channel has some great videos that talk about battery charging in the context of top balancing that really helped me understand the process more clearly.

 

[hicke]

Hi guys!

I'm building a crate powerstation as well. ?My question is:

Could the power supply be replaced by a battery charger like the Victron Blue Smart IP65?

Also, in order to know soc, do I need a shunt?

Thanks for your time,

Henric

 

[mikefitz]

The power supply, DROK, as an Input to a MPPT solar controller, or directly too the battery is a really bad idea. It had poor current limit control, poor user control over voltage, and are are very unreliable units, ( they have been known to set on fire).
A quality AC battery charger like the Victron IP 22, will correctly charge the batteries with the default settings, and also via the app indicate the battery status. Far better than a Renogy Rover, that needs care in setting up user values , and the Rover may have calibration errors and its indication of charge state is totally incorrect.
Why spend $100s on a battery and then attempt to charge with a $40 power supply.

Other points raised.
A shunt based battery monitor , correctly set up , will accurately indicate battery status, the Victron Smart shunt or BMV 712 also have many useful functions, for example 30 days history.

Charge voltage, the charge voltaged of 14.4 to 14.6 are not really reeded. A voltage of 13.8 volts will get the battery to over 98 % SOC.

Victron default values of 14.2 volts charge and 13.5 volts float is a useful guide to charge volts.

Charging with a power supply at constant voltage does not allow control of absorbtion period or charge termination. Unless user intervention, it will continue to will apply high charge volts to a full battery , causing undue stress and perhaps reducing battery life.
If you are using a power supply set to a moderate voltage, say 13.7 or 13.8 volts.

A PWM solar controller is essentially a switch that connects the panel to the battery. The panel is 'pulled down' to just over battery volts and the current is limited by the panel. Some power supplies may be unhappy connected to a PWM controler. A MPPT controller may work with a power supply but may, as part of the maximum power process, 'short circuit' the solar input.
To sumerise, some power supplies and controller could have issues.

 

[hicke]

Thanks!
In order to have AC passthrough and use AC without battery when plugged in and in case there is a utility failure, switch over and use the battery. How would one do that?