Hey guys,
Having an issue with this unit
Voltage going in is 1000mAh 3.7, out is 12V
current required is only 0.001 amp
the unit heats up significantly and auto shuts off to protoect itself
i have measured current with multimeter and it only says 0.01ma
why is this overheating the unit i thought you could pull 1.2amp through it?
Hi Jesse,
This unit can certainly manage those conditions (if the output current is indeed 0.001 Amp). Pololu have some of the highest standards we’ve seen with electrical testing - and this unit being one of their own would have been well tested across that range.
Checkout the efficiency graphs on the product page.
With that said, if the unit has been taken outside that range be it by accident or otherwise, @12V it can only manage around 300-400mA before it can’t self cool fast enough to overcome the heat losses involved.
my fuse had blown in the multimeter im pulling 250ma and the unit heats up after 2-4 mins of constant draw. however i think im getting resenance issues as the 3.7v -> 12v -> 240v both are switching regulators im trying to figure out if i need to use a capacitor in between however i tried this and still have the issue.
250ma and the unit heats up after 2-4 mins of constant draw
Entirely normal at that power. While 250mA is well within the safe operating zone, if going outside the recommended range then this unit will get so hot it would burn to touch, and will continue to heat until failure.
thats the thing, it burns to touch and the light turns on and off once it over heats which is what it should be doing. it just doesnt make sense that its doing this.
Hi Jessie,
I’m about to make some assumptions as there is little information to go on - perhaps you are “seeing” 250mA output power, but in reality the target device wants more. This would lead to thermal runaway within the regulator and limit the output power to something less than actual, in this case 250mA. While you are using 3.7V, the efficiency graph depicts @3.3V 250mA as the top-end limit of this regulator. From there the the device will not be able to self cool and will turn into a small scale heater, followed by an ineffective paperweight!
This is a Pololu part, designed and rigorously tested across it’s entire rated range of use. Stepping outside that zone isn’t a great idea. Might be worth taking a step back, revisit what the target device current draw is under normal operating conditions (not with regulators on the cusp of failure) and then reconsider how you are going to get the project back on track.
Either way, 250mA is right on the brink of use for this device - I wouldn’t trust those readings until you can get a clear picture of what’s going on downstream with this device out of the picture.
hahaha wow yes i totally over looked the graph. that seems correct. i will try it with an external wall power supply at the normal 12 and see what its actual current draw is.
should i be able to use this one?
im trying to work out the math it handles 3.3v around 750ma and a little higher due to the battery running 3.3v> anyway
i have a 12v source and the current is 0.15amp so 150ma at 12v
so it should require roughly 600ma at 3.3v
Pololu 12V Step-Up Voltage Regulator U3V50F12
Hi Jesse,
Something to bear in mind as well is that if you check out the efficiency graphs on the product page, you can see that the efficiency of the converter drops drastically with an increased output current draw. That product should be fine with 3.7 Vin. The best approach though is definitely to use a robust power supply like a wall wart, and measure the actual current draw for your project, then create a power supply which will suit (allowing for a good safety margin).
i have a 12v source and the current is 0.15amp so 150ma at 12v
Bear in mind U3V50F12 efficiency drops off quickly. Let’s hedge on worst case scenario; 70%. You’ve checked the current of the target device @12V and measured 0.15A. That’s about 1.8W
With an efficiency of 70%, the step-up regulator would consume around 2.57W (1.8W out, 0.77W heat loss). @3.7V that’s around 778mA which will exceed the recommended limit of the U3V50F12
Coming back to my earlier advice on a different forum topic of yours; stepping up from 3.7V to 12V at any sizable current draw is a stretch. Perhaps reconsider the use of the single cell LiPo; lots of options which vary from a 5V USB PowerPack, or a 7.4V two-cell LiPo pack to name a few.
If i replace it with something like this - Polymer Lithium Ion Battery - 1000mAh 7.4v
I’m assuming i need to use an expensive charger too due to it being a duel cell unit.
I’m assuming i need to use an expensive charger too due to it being a duel cell unit.
Yep - cell balancing a multicell LiPo is very important, which dedicated LiPo chargers achieve.
If you have an important use case around size and that’s why you’re focused on the single cell LiPo’s then perhaps step up the voltage twice. Not ideal from an engineering point of view, however, you can take advantage of keeping both step-ups within a very efficient range.
im now having over heating issues again. using the small step up
however im converting 7.4v to 12v current is 0.20
same as wallport and its overheating
im thinking it has something to do with the resonance between the step up and the inverter can a capacitor fix this?
Hi Jessie,
If I have the numbers right, the target device is now using 2.4W of energy (12V x 0.20A). @7.4V the U3V12F12 has an efficiency of around 85%; so the net power requirement would be around 2.76W (2.4W x 1.15).
If that’s the case then everything checks out from a power perspective and it is unusual that the U3V12F12 is overheating. It could be resonance, it might also be due to the device being damaged given how it’s been taken out of spec a number of times. I don’t have the answer for you on this one - if you can’t solve it locally then perhaps touch base with Pololu directly?
It run fine at 0.14amp at the 7.4v but when i step the current up to the 0.2 it overheats.
Kinda odd anyway.
i have order a 14.8v battery and your step down converter which will produce the 5v need for my arduino while still being able to run my lights from the it can take anywhere from 5v - 32v input. hopefully the step down converter would easily be able to handle an arduino running at 5v.
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