rin67630
Solar Enthusiast
Hmm... they have different voltage presets on board, they cannot deliver different voltages at the same time.
Making best use of buck/boost DC/DC converters
- Thread starter Sverige
- Start date
Sverige
A Brit in Sweden
Yep, I spotted that after posting so had already edited my post before I saw your comment. At first glance I took the solder pads on the back of the board to be multiple outputs, which would be very nice but alas as you said, they’re just solder pads to select the output voltage.
Sverige
A Brit in Sweden
So I went ahead and did the test to see how the total power consumption of the 3 converters I’m going to be using was affected by two alternative connection topologies. In both cases the input voltage was 14V and the load devices were the same, as listed further up this thread.
Case 1: Daisy chain - each converter takes its supply from the output of the previous one and the current to each load is passing through the prior converters. So the conversions are from 14V to 12V, from 12V to 9V and from 9V to 5V. Total power consumption in this case was 7.2W
Case 2: Parallel - each converter takes its supply directly from the 14V supply, so the conversions each makes are 14V - 12V, 14V-9V and 14V-5V. The current reaching the loads only passes through one converter in this case. Total power consumption was 6.5W.
So there’s a clear winner, parallel connection is significantly more efficient and @snoobler wins the trophy for correctly predicting this in post #2 of this thread. Here, @snoobler, put it on your virtual mantelpiece! ?
I went a little further and progressively connected the loads in each case and the numbers are below. Loads were added in the order written. It’s quite clear that it’s as the further downstream converters have their loads applied that the power consumption increment rises in the Daisy chain arrangement (compared to parallel), because the current they’re pulling is passing through multiple converters.
Case 1 Daisy chain: 12V 3.85W, 9V 1.65W, 5V 1.65W
Case 2 Parallel: 12V 3.80W*, 9V 1.45W, 5V 1.25W
* Even with no loads applied to the 9V and 5V converters, the 12V device pulls less power in case 2 as it doesn’t see the quiescent current of the others.
While I have my test rig set up, I may try varying the supply voltage to see how the overall power consumption is affected if the supply rail is 24V DC instead of 14V. These converters seem to do an admirable job of keeping the output voltage the same, even if the input is varied. This test will only be done using the parallel connection case, as it’s clear that’s the best way to use these converters
Case 1: Daisy chain - each converter takes its supply from the output of the previous one and the current to each load is passing through the prior converters. So the conversions are from 14V to 12V, from 12V to 9V and from 9V to 5V. Total power consumption in this case was 7.2W
Case 2: Parallel - each converter takes its supply directly from the 14V supply, so the conversions each makes are 14V - 12V, 14V-9V and 14V-5V. The current reaching the loads only passes through one converter in this case. Total power consumption was 6.5W.
So there’s a clear winner, parallel connection is significantly more efficient and @snoobler wins the trophy for correctly predicting this in post #2 of this thread. Here, @snoobler, put it on your virtual mantelpiece! ?
I went a little further and progressively connected the loads in each case and the numbers are below. Loads were added in the order written. It’s quite clear that it’s as the further downstream converters have their loads applied that the power consumption increment rises in the Daisy chain arrangement (compared to parallel), because the current they’re pulling is passing through multiple converters.
Case 1 Daisy chain: 12V 3.85W, 9V 1.65W, 5V 1.65W
Case 2 Parallel: 12V 3.80W*, 9V 1.45W, 5V 1.25W
* Even with no loads applied to the 9V and 5V converters, the 12V device pulls less power in case 2 as it doesn’t see the quiescent current of the others.
While I have my test rig set up, I may try varying the supply voltage to see how the overall power consumption is affected if the supply rail is 24V DC instead of 14V. These converters seem to do an admirable job of keeping the output voltage the same, even if the input is varied. This test will only be done using the parallel connection case, as it’s clear that’s the best way to use these converters
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rin67630
Solar Enthusiast
Did you test with the 12V devices directly connected to the battery?
Sverige
A Brit in Sweden
No, I won’t be doing that. I won’t risk taking out my only wifi router which I need to use all day.
rin67630
Solar Enthusiast
I am doing that since years.
There is currently nothing inside the Wi-Fi router that would have required 12V, so you can be sure to 100% that your device has a already buck converter inside to generate the 5V requested by the logic and the USB socket, and even a second one to generate 3,3V.
Sverige
A Brit in Sweden
Haha, well ok - let me tell you a story about this!
I read your reply earlier, thought to myself “rather you than me!” and sat firm in my conviction that I would not be risking my precious router by applying the wrong DC voltage to it.... And then I began to wonder - maybe the manual provides a spec on the acceptable input voltage range, so I checked it. 5V 1A said the manual!
Now this made no sense to me, as I just knew I’d been running it from a 12v mains “wall wart” prior to today’s testing... Nope! Checked that, 5V DC it had printed on it
So here I am, Mr “Won’t risk the router by using a different voltage” and I’ve already wrongly put 12V across a 5V device earlier today!!
I did feel a bit foolish.?
?
rin67630
Solar Enthusiast
rin67630
Solar Enthusiast
Hi Sverige,
have you got skills in soldiering and would you feel comfortable in setting up a programming environment?
If yes, I am currently working on my ESP8266 controller program to retrofit real MPPT functionalty to many <10A cheap solar controller modules that only provide manual power point trimming.
My current DIY system provides a full graphical battery monitoring, tracking, statistics.
While I am on the way and have a few digital outputs left over, I could provide control for two additional buck converters with enable function,
so I could also remote/programm-switch these power outputs to reduce power when not in use.
The current bill of material will be:
- your small pseudo-MPPT solar controler (cannot be a PWM-module) e.g.
MPPT solar controller battery charging board
- a Wemos ESP8266 WiFi enabled microcontroller
- an INA226 I2C bidirectional current/power monitoring sensor
- 1 to 3 or more buck converters with enable input
- alternatively, if you prefer to switch AC a 2 Relays board
- 6x4cm or bigger prototyping board
- a few resistors, wires, screw-terminals and a small industrial junction box.
n.b: I am not affiliated with Aliexpress and do not even recommend them, but their shop provides almost every device's pictures and details to describe what's requested.
Stay tuned, I'm on my way...
Sverige
A Brit in Sweden
Looks like really interesting stuff, but I’ve got to be honest, I don’t think I have the time to take on a project like this. I’m not overestimating what’s involved, just that I’m over committed in other areas of my life right now, and need to dedicate my time to catching up on those. Sorry.
burtaverde
New Member
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- Jan 11, 2021
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Hello there, i'm looking into a few buck converter solutions and was wondering which one your preferred between the two you proposed. The usb charging one (https://www.aliexpress.com/item/32923862878.html) or the one with variable out (https://www.aliexpress.com/item/32729546380.html). Currently working with the mp1854 and its efficiency is a bit of a disapointment (way better than the lm2596 tho). Can't really get more than 1A for extended time without it requiring cooling.
rin67630
Solar Enthusiast
I love the red "fine" modules because they provide an USB port, but they are not adjustable.
The second green modules are perfect up to 1,5A, they have a very low quiescent current, are efficient for low and high voltages and stand higher current. Beside that, they have preset voltages. They are the best i have found so far in the mini-range (20W). You can go for them in confidence (I order them by ten pieces)
Anyhow I would recommend to glue a heatsink on the back.
you can have a look at my Powerpoint summary here...
The second green modules are perfect up to 1,5A, they have a very low quiescent current, are efficient for low and high voltages and stand higher current. Beside that, they have preset voltages. They are the best i have found so far in the mini-range (20W). You can go for them in confidence (I order them by ten pieces)
Anyhow I would recommend to glue a heatsink on the back.
you can have a look at my Powerpoint summary here...
burtaverde
New Member
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awesome, thanks for the information. I'm thinking the fine for phone charging and the others for basically everything else. I see the green is the MP2315 from the pp. Do you happen to know which chip is used on the red fine?
rin67630
Solar Enthusiast
The red modules stages a chip marked AGCK.
But to exclusively charge a phone or a tablet, you have a better choice:
https://www.aliexpress.com/item/33004519270.html
This one provides QC2.0 functionality. I tested it and it is really great.
I don't use it in my designs because I also need a fixed 5V to feed my ESP8266 and the QC voltage could harm it.
burtaverde
New Member
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hmm interesting. Could be a good future upgrade to play with. QC is nice, but so device dependent that i'd rather have a more basic 5v that just works with everything. It'll be practical to have one device that just works in most applications. That being said, i'll see if the red gets all my devices charging at 1-2A, cuz the basic 500ma would be too slow.
PS: if you're interested, i believe these could be the chips in the REDs: https://www.mouser.ca/ProductDetail...-MPS/MP2315GJ-Z?qs=QEkzKklKf2QEN5VKd%2Br2GQ==
PS: if you're interested, i believe these could be the chips in the REDs: https://www.mouser.ca/ProductDetail...-MPS/MP2315GJ-Z?qs=QEkzKklKf2QEN5VKd%2Br2GQ==
rin67630
Solar Enthusiast
So the red "fine" modules and the green are staging the same efficient chip.
The "QC" device delivers also a sound 5V 2A without QC.
burtaverde
New Member
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that explains why they're good, altough it's nice that the Red have over voltage protection. Idk if i'd trust it, but it's nice that they at least thought about it. I'll probably add a crowbar to blow the fuse if it goes over 6V, just in case it's feeling special one day.
It also has input voltage polarity protection, which is appreciated, although might go around it to increase efficiency since i don't plan on putting my wires in the wrong direction.
burtaverde
New Member
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Well got some good news and some bad news. The good is that i recieved them (both the "Fine" usb and the small green one). The bad is that i don't see a big efficiency improvement over the MP1584 stuff. It might be slightly more efficient, but since it's about half the size (on the green one) there's less area to dissipate heat so i'd consider them about equal, if not slightly worse. Now i don't have the equipment to precisely measure temperature, but that's my experience with them.
That being said, we may not receive exactly the same stuff since china is known for its amazing QC.
One interesting new buck converter i noticed is the mini560, which should be around the same size, but can handle 5A (officially at least)
rin67630
Solar Enthusiast
The HW613 becomes interesting at 12V 2A from 18V. The MP1584 at 15W begins to throttle, the HW613 runs happy and the heatsink shows 36°C only. I tested both with the same heatsink on the backside.
The red "fine" and the mini560 are 5V only...
burtaverde
New Member
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i see, i've only tested dropping from 11V-13V to 5.2V since that will be my main use (0.2 is still within USB spec, but compensates for drop under load). Maybe i should get a laser temperature reader since the chip on the HW613 is hard to measure with other devices.
