Boost Converter issues

E

Ethen Braughton

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Mar 21, 2018
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I have a 3s 16p pack. I received a DC to DC boost converter today, plug in 12.3v dc input manually adjust to 12.6v before I attach the 3s pack. As soon as I plug in the 3s pack the boost converter LED screen turns off and I can hear a small repetitive click from the unit. No magic smoke. The dc power supply is a 3A power supply. Not really sure what to do, brand new unit. MY question, Is the battery trying to draw too much current as soon as I hook it up to the converter? All this is done without a load on the batteries.

DC-DC boost specs
Features:
Cutting Size: 67.5mm x 41.5mm
Input Voltage: DC 3~35V
Input current: 9A (Max.)
Output Voltage: 3.5V~35V ( Adjustable,Boost, output voltage>= input voltage)
Output Current: 6A (Max.)
Output power: 65W, 100W( input and output voltage >20V)
Output Ripple: 40mV (TYP)
Display Color: Red
Voltage Meter Error: 0.1V
Measure Range:4~40V(for measure accurately, please ensure that the input voltage>4V)
Conversion efficiency: 96% (Max.)
Anti-reverse protection:None(please pay attention to the positive and negative)
A key switch input and output voltage green light: measuring the output voltage
Red light: measuring the input voltage long press the switch for more than 1 second then release, the voltmeter shutdown.


image_kkbmjj.jpg
 
In most cases, the output voltage needs to be about 1V or more for it to work as intended.

Altho, not sure why the led screen would of turned off. that is odd :s
 
The unit does not have current limiting and what is happening is the battery pack is trying to draw more than 3A, effectively looking like a short and the clicking is the unit trying to draw as much as possible from the power supply. You need a boost with current limiting (two of the blue adjustable resistors) if your charging a pack from a fixed voltage power supply.
 
Ahhh, that makes sense :) Not so odd now. I've learned something new!

You could put a resistive load in series with the battery to make sure the charger unit is working. This would reduce the amount of current flowing. An example would be a filament style light bulb or a DC motor.
 
completelycharged said:
The unit does not have current limiting and what is happening is the battery pack is trying to draw more than 3A, effectively looking like a short and the clicking is the unit trying to draw as much as possible from the power supply. You need a boost with current limiting (two of the blue adjustable resistors) if your charging a pack from a fixed voltage power supply.
Click to expand...

I thought that might be it, If I put a diode on the output with that keep the battery from back drawing?Any DIY suggestions to make this work?I have lots of resistors sitting around.
 
You could put a diode, or 2, to keep backwards flow. But there's really not any point to it. Also, diodes have voltage drop, so you'd have to account for that. The meter would say one thing, but the battery would get less.
 
Korishan said:
Ahhh, that makes sense :) Not so odd now. I've learned something new!

You could put a resistive load in series with the battery to make sure the charger unit is working. This would reduce the amount of current flowing. An example would be a filament style light bulb or a DC motor.
Click to expand...


Even when I connect a 6v 4a solar panel to the boost converterinput, as soon as I connect the batteries the boost controller turns off. I know the boost controller works because everything but the battery works on the load end. Using a diode on the output won't work because then the charger wont know anything is connected.I am stubborn and don't want to buy another unit, determined to find a way to make this work.

Okay so my 3s battery has a large enough capacity that it draws more amps than the boost converter is rated for while its charging. I guess my question is how do I limit the amount of current the batteries are trying to draw while charging? Without going and buying another unit with current limiting.
 
Ethen Braughton said:
Okay so my 3s battery has a large enough capacity that it draws more amps than the boost converter is rated for while its charging. I guess my question is how do I limit the amount of current the batteries are trying to draw while charging? Without going and buying another unit with current limiting.
Click to expand...

I said to put a resistive load in series with the battery like a filament light bulb or a set of resistors. That will limit the current, but let the voltage through.
 
UPDATE: 4 diodes in parallel did the job, since its a boost converter I can adjust the output voltage accordingly. Thanks guys for the inspiration.

Uhg, the diodes prevented back draw to boost converter, but then the power supply didn't supply any current, because it didn't sense a load.
The whole purpose of this project is to take 6.5v from my little solar panel and step it up to 12.2-12.6v for the 3s 16p pack. Can anybody recommend an alternative module for this task? It didn't seem this complicated when I started (famous last words). Or should I just wire the small panels in series and not use a boost converter? I wanted a mid size power bank for traveling purposes. Powered by what I have at the time, a few 6v .5A solar cells in parallel connected to boost converter.

Korishan how do I wire the resistors in series with the battery?
 
Boost converters are less efficient than buck converters, I'd recommend a buck converter with current limit, and set the current limit such that the max output is less than the max output of the solar panels (e.g. 24W solar panel then at 12.6V less than 1.7A). Still not ideal because it may try and pull more current than available if the solar panels aren't at peak power, but better than what you have now.
 
Ethen Braughton said:
Korishan how do I wire the resistors in series with the battery?
Click to expand...

Just like you wire anything else in series. Power -> Resistor -> Load -> Return to Power
 
If you stay with "6V" input from your panels, you need a converter which says it's a "boost" type.
"Boost" = takes the input voltage and makes it higher at the output
"Buck" = takes the input & reduces it at the output.
The circuits inside are different & yes this typically changes the efficiency.

However, the problem is this converter seems to only be doing what it's designed to, eg take any voltage in & draw hard on that to get as much current as it can out the output terminals.
It's probably doing a bit of a cycle (the tick sounds) where it pulls so much current from the source supply, it drops voltage below the minimum for this converter, the converter stops, the voltage climbs again, the converter starts again, then pulls voltage down again, etc, etc.

You need an MPPT type solar controller & put your panels in series to get a higher voltage in. An MPPT unit will sense the voltage on the input & adjust how much it's pulling dynamically to avoid the above cycling.
 
Redpacket said:
If you stay with "6V" input from your panels, you need a converter which says it's a "boost" type.
"Boost" = takes the input voltage and makes it higher at the output
"Buck" = takes the input & reduces it at the output.
The circuits inside are different & yes this typically changes the efficiency.

However, the problem is this converter seems to only be doing what it's designed to, eg take any voltage in & draw hard on that to get as much current as it can out the output terminals.
It's probably doing a bit of a cycle (the tick sounds) where it pulls so much current from the source supply, it drops voltage below the minimum for this converter, the converter stops, the voltage climbs again, the converter starts again, then pulls voltage down again, etc, etc.

You need an MPPT type solar controller & put your panels in series to get a higher voltage in. An MPPT unit will sense the voltage on the input & adjust how much it's pulling dynamically to avoid the above cycling.
Click to expand...

I stated I'm using a boost to BOOST 6v to 12v. I don't know why BUCK got brought up or the assumption I didn't know the difference. Honestly It doesn't even look like you attempted to answer my question.
 
You mentioned going with the panels in series instead and stepping down the voltage I believe, so I brought up that if you're buying a new DC-DC with current limiting, it might be a better idea to go with step down since it's more efficient.
 
Ethen Braughton said:
I stated I'm using a boost to BOOST 6v to 12v. I don't know why BUCK got brought up or the assumption I didn't know the difference. Honestly It doesn't even look like you attempted to answer my question.
Click to expand...

Wasn't particularly directing the boost buck info at you but another post.
Think I did answer the bit about why is it making "a small repetitive click" and suggest an answer for get your setup working better with an MPPT type device?
Just trying to help.
 
Thanks, the two 6,5v panels in series will give me plenty of voltage for a 3s pack NO BUCK NEEDED. I do have a buck converter that I use with any dc source over 13v. I know this seems complicated and impractical but I'm trying to develop this system to where it fits in my molly pack. I can't take a 100w solar panel 10 miles into the woods. Sorry If I sounded frustrated, can you recommend a small mppt module for 3s lipo? I can't believe how complicated this is.
 
floydR said:
https://www.ebay.com/itm/1pc-12V-MP...929196?hash=item3f826a122c:g:6~MAAOSwqeZZcawg
not sure if the mppt s good or not but sounds like what you want.
Click to expand...

Good find - that one looks like is is actually MPPT not just PWM - it has an inductor (see "large" gray box like thing, PWM units don't have inductors).
With MPPT it'll get the best out of the panels in any conditions, definitely worth the few $ cost.

Only trick is you'd need 3x 6V panels in series for it to work, it needs a few V in more than the battery out voltage.

Tempted to get one this end for a small garden light project I'm planning!
 
The whole issue this thread was about was the boost you had tried to draw too much current since it was constant voltage only, and hence loaded the panels too much and shut off. That's that MPPT is for, it will throttle down the current when the panel voltage drops below the MPPT set voltage.
 
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