Buck converters

[Penn]

I notice when most people build mods they tend to connect batteries in series to get higher voltage. I know a step up buck converter increases voltage and the boards aren't much bigger that AA batteries. So what I would like to know is what advantages/disadvantages are there in batteries in series instead of stepping up the voltage?

I would think connecting batteries in parallel would make sense to get longer life but does a step up actually chew up more usage since it is "cycling" volts. (cycling is my term, don't know the correct wording)

 

[Chip_]

I notice when most people build mods they tend to connect batteries in series to get higher voltage. I know a step up buck converter increases voltage and the boards aren't much bigger that AA batteries. So what I would like to know is what advantages/disadvantages are there in batteries in series instead of stepping up the voltage?

I would think connecting batteries in parallel would make sense to get longer life but does a step up actually chew up more usage since it is "cycling" volts. (cycling is my term, don't know the correct wording)

Well I can't speak for others, but, I am not particularly impressed with the buck converters.

1. Buck converters allow a much smaller footprint for your e-cig. ( 1 battery makes for a small container).

I don't want itsy bitsy containers, cause, they are always falling over on my desk. I want something with a larger bottom, so that my e-cigs don't fall over on the desk.

2. Cost: those darn little buck converter PCB's (populated) cost bigger bucks, then just a simple Linear regulator. I like simple regulators, so I need more batteries in series. Those linear regulators are EL-CHEAPO too!.

In summary, for me that is, I am not impressed with the buckeroooos. I like larger footprints.

 

[Penn]

Maybe my wording was wrong. I saw a few $2 boards (not pcb) that were listed as step up buck converters which what I was just reading seems to be the wrong name since buck is just simply a step down regulator.

Even so, the crux of the question you answered, you want something bigger. I'm considering attempting 2 projects, one would be small but longer lasting and the other bigger with possible variable voltage.

 

[Chip_]

Maybe my wording was wrong. I saw a few $2 boards (not pcb) that were listed as step up buck converters which what I was just reading seems to be the wrong name since buck is just simply a step down regulator.

Even so, the crux of the question you answered, you want something bigger. I'm considering attempting 2 projects, one would be small but longer lasting and the other bigger with possible variable voltage.

Actually you where right the first time They are called Buck-Boost converters. At any rate it is still a switching regulator.
Where did you see a Buck-Boost PCB for $2.00??? I have never heard of such a thing, at least at the power levels we are looking at
for E-Cigs.

 

[Penn]

Ebay. They come from china. Here is one.

Edit - Okay, not $2 but $2.47, lol.

 

[Chip_]

Ebay. They come from china. Here is one.

Edit - Okay, not $2 but $2.47, lol.

Well Holy moly, thats a great bargain. By the way, it looks like a Boost converter to me, i.e. Step up. If it were a buck-boost then the output would be adjustable down to zero volts.

Still it looks like a great deal, except that it comes direct from China - that worries me. I hate chinese electronics. I have been in electronics since 1977. And for the last 15 years or so, I am seeing electronic failures coming from chinese components, of which, I had not seen in the previous years. Those sneaky Chinese made-electronics, seem to be using tricks and gimmicks, (substandard) to get the components to work for a few months then wammmooo they fail.

 

[Relayer1974]

So what I would like to know is what advantages/disadvantages are there in batteries in series instead of stepping up the voltage?

I would think connecting batteries in parallel would make sense to get longer life but does a step up actually chew up more usage since it is "cycling" volts. (cycling is my term, don't know the correct wording)

Here's the TL;DR version: If you look at some PBusardo reviews, he gets slightly more time on some devices with 2x18350 vs 1x18650. Your mileage my vary. Plus, if all you have is 18350s handy, you're still in business.

While batteries in parallel provide double the capacity, tube-shaped APVs rarely, if ever, are going to be able to accept a parallel setup. They usually offer the 1x18650/18500 and 2x18350 in series options. What the 18350 option does for you is puts a lower amp drain on the batteries in a VV/VW mod vs an 18650. Lower drain can result in getting closer to the actual mAh rating. Higher drain tends to cut the practical mAh available down a bit. Also, buck/boost chips are usually more efficient when bucking than boosting at a particular output voltage, adding to the energy savings.

So yeah, there are a lot of variables and conditional statements, and they change from device to device.

 

[Penn]

I appreciate the input Relayer. I'm thinking the tube-shaped aspect doesn't apply since I won't be using a tube if I go ahead with my thoughts. I'm under the impression and electronic device won't be able to tell I have 2 batteries in parallel since it sees the pack as just one battery.

I'm not going for high voltage output (maybe 5 at most but usually I like between 3.5 and 4). Initially I am thinking of going simple but long lasting. Eventually I may upgrade to include adjustable variable voltage. Part of what I was considering is how to compensate for a single battery or parallel dropping below my desired max.

So I guess the real question, what is more efficient - boosting just a few volts or bucking down to the desired volts?

 

[Relayer1974]

If you're using two 3.7 lithium cells in parallel, a boost or buck/boost would be necessary. You'd have the advantage of massive capacity (around 6000mAh with beefy 18650s) and a voltage range from just above battery to at least six volts. You'd easily get the most vape time out of this setup. The disadvantage is that there are less boosters and boost/bucks out there than there are buck converters. Boost converters are harder to find in amp ratings over 3A. Buck converters with 6A or 10A capacities are easy to find.

I like using 4xAA or AAA NiMH cells, so I like boards that are buck/boost, because my battery voltage sits right in the middle of one and two lithium cells. I have this one on the way. It doesn't care about input voltage (within its rated range), so I'm expecting it to be good for 3.6 and 4.8 NiMH, 3.7 or 7.4 lithium, 5V USB and 12V car power.

 

[Dudeman1975]

Ok so I have a question to add I have a passthrough for my car and I have to plug a converter in to get to the 5v of a USB plug then convert again with the passthrough to the output to the 5v 510 or ego or whatever why not just a 12v plug with a buck installed and variable from there then try a 6 ohm coil at 12v

 

[dr g]

that could work though 6 ohm coils are not too common

 

[Penn]

Why use a 6 ohm coil? If you are bucking down you could just go to the desired volt for a common coil.

 

[Relayer1974]

This is what I built out of that buck/boost board. It works like a boss in my truck.

 

[dr g]

what is 13.9?

 

[Dudeman1975]

nice exactly what i meant