Charge circuitry basics and differences

[interestingfellow]

I'm no IEEE, but know enough to get in trouble. I have started looking into building in a charge circuit, and still have a lot to look for/through.

I just wanted to ask the experienced vapers here about what they might know.

A very basic charger (or charge circuit) just controls the amount of voltage and current going into a battery.
From there, some have a nice LED to show charge status, and some are smart enough to cut off automatically.
Even smarter chargers will check the battery first, and trickle charge it to the required minimum V to then charge normally.

Seems fairly straight forward.
So, why is it then, that you can't use a lip charger for a liion, or lmn batter? what about the chargers' characteristics makes it different from one type of chemistry to another (or is it the above mentioned facts)?



The reason I ask, is that I started looking into different diy charging circuits, and the design will say (somewhere) "not for xxxx type of battery". Here, look: Scott Henion DIY Lipo charger > Did you build it? - RC Groups (the link to the actual design is at the bottom of the first post there)

I'm thinking, why not just change the voltage and amperage, and re-purpose it? Then it could be for whichever type of battery you set it up for. Once set for the right V & I, something like this could be good for a single cell, or even a set/pack of LiFePo4's or LiMnNi's???? yes? no? gth?

 

[BuzzKill]

Li-Ions have a very specific charge cycle and are sensitive to over voltage , the SMART charger for Li-ion uses a special IC that controls the charge time and the cycling during that time , see this one http://ww1.microchip.com/downloads/en/DeviceDoc/DS21699B.pdf

other chemistry's have their own requirements as well

 

[interestingfellow]

Hmm.
SO, there are algorythmic cylces for optimal (or not explosive) charging, depending on chemistry?
Last time I messed with this sort of thing was 18 years ago with NiCads in my RC cars.

The search continues...

 

[BuzzKill]

Yes there are , goto battery University all the info is there , Google it

 

[interestingfellow]

i've been attending off and on for the last week.
haven't gradimacated yet

 

[BuzzKill]

That is the best most accurate info I have found yet on the web ! these people KNOW their stuff for sure .

 

[VWFringe]

in reading charger reviews on candle power forums i've seen where they actually can notice and correct design flaws, so that's better, or faster info than battery university

i wanted to put a charging circuit inside, so people could just plug it in, but that would only allow me to charge at a rate of 250-450 mAh, so it would take a whole day for an 18650...better for myself to buy a tenergy 2-channel (newer cc/cv model for $14), and make a pig-tail so i can clip onto the charger, and plug the other end into my vape

li-ion batteries, as you've read on the university, require a different charging method, but there ARE chips readily available and cheap which can automatically recognize and adjust for li-ion and ni-mh (not sure about li-po)

also, candle power forums has threads that show these guys making their own, using the cheap ones for a housing

 

[WillyB]

in reading charger reviews on candle power forums i've seen where they actually can notice and correct design flaws, so that's better, or faster info than battery university

i wanted to put a charging circuit inside, so people could just plug it in, but that would only allow me to charge at a rate of 250-450 mAh, so it would take a whole day for an 18650...

That's not exactly correct. An 18650 isn't drained completely, far from it, when vaping. I like many others don't vape my cells 'empty', actually the protection circuit won't allow it.

When I notice a vapor/performance drop, it's time to switch cells or recharge. Checking my cell's voltages at that time it looks like about 20% of the original charge has been actually used. Folks who claim 'days of of vaping' with an 18650 obviously have no problem with vaping at ~3.3 some volts. Not for me.

The main advantage of a built-in charge circuit is not to replace a standalone charger but to be able to keep the cell topped off if a USB port is available. And at the end of the day what difference does it really make though, as 450mA will fully charge my cell overnight.

 

[VWFringe]

i think a normal/full charge takes over 8 hours at 250 mah, and i shouldn't have exaggerated by saying it would take all day, but that's what i meant

i can't find any usb charging circuits that would allow use while charging, but i'm not sure if that's because it interupts the charging circuit as it tries to monitor the battery - being able to top off would be nice if you could use it at same time

there's a guy named Cottonpicker on candle power forums who makes usb chargers that use true cc/cv - i thought of approaching him to do a custom one - be nice to have automatic polarity protection and different voltages, be nice to be able to plug in any power tip that would fit and have it just work regardless of the polarity of the tip, and i think it's possible using the newer chips. but it was hoping for something like that that made me shelve using USB, (and that i thought it won't work while charging)

i just can't fit some of the bigger passive components into an e-cig mod to allow charging at higher rates

 

[WillyB]

i think a normal/full charge takes over 8 hours at 250 mah, and i shouldn't have exaggerated by saying it would take all day, but that's what i meant

i can't find any usb charging circuits that would allow use while charging, but i'm not sure if that's because it interupts the charging circuit as it tries to monitor the battery - being able to top off would be nice if you could use it at same time

Why do you say that? Many folks have mods with USB charging in them, which is the most convenient as USB power sources are everywhere. It does limit you to about ~400mA though.

Here's my old, used and abused, pumper from well over a year ago with that little, claimed 400mA EBay charger.

The hardest part for me was soldering on the mini-USB connector. I only used the two ends. You can't see but there are couple fine wires, one to the live side of the fire switch, the other up to the pos batt post. Been vaping while charging the whole time. About the only issue it seems to charge up the cell a bit low, ~4.12V. But that's basically a non-issue compared to the convenience, and technically that should extend the cell's longevity.

It needs a little refurb as the the kill switch is acting up and after dropping (for about the tenth time) the charging circuit is loose.

Never had any problems. Leave it sit and the charging LED goes out (there is no 'done' LED like on e-cig chargers). Take a few drags and it lights up again.


It seems you may be over thinking this. I've beat this thing to death and have had zero problems. Maybe I'm missing something... who knows?

As far as charge rates many folks use these.

It's been reported that these output lower than their claimed 500mA, and I assume that's a total output figure not per slot.

 

[VWFringe]

i definitely am over-thinking this,

TR-001 has problems terminating (but a lot of people don't seem to notice since they're good Li-Ion users and don't leave them unattended, pulling them as soon as they go green - I don't know that my sister's kids will be good about this, so i went with another model, Tenergy's 2-Channel).

i have to read more about about the smaller USB charging circuits i guess

 

[WillyB]

Is this the charger?

FWIW those Tenergy cells should be excellent for our use. In the latest shoot out I saw they perform as well or even a tad better than the more expensive AW2600 Li-Ions.

This charger is said to be one of the best, doing all things correctly.

4Sevens 26650 Battery Charger - 4sevens-store

It does have a small anomaly that the manufacturer is aware of and claims will be addressed. If contact with the battery terminals, or power is interrupted it goes into the 1A output even if originally set for 0.5A.

 

[interestingfellow]

wow, step away for a minute and miss a lot!

 

[VWFringe]

yep, that's the charger

got them today - took 4.5 hours to charge 2 18650's that were pretty low (~2.7-3v)