spencer
Enlightened
I have no idea. Even if it does increase or decrease it will only be by a couple percent. I wouldn't worry about a couple percent and I definitely wouldn't use more than 1xLi-ion(4.2V)
switching regulators are a lot more complicatedAh, too bad. 6-8 sub-C's is starting to get pretty bulky. I guess I will set them aside for some future project. Thanks for the info.
So, back to the 18650 approach. I had found this pre-built board:
http://www.batteryspace.com/dc-dcregulatormodulefrom60-84vdcto5vdc1ampmax.aspx
Why does it appear to be so big and full of stuff, when the circuit you described is just a little IC and 1-2 capacitors?
I was just reading about that - it does seem a little weak. And as tempted as I am by this one-stop shopping, pre-engineered system, I think I am going to give the LM22672 a whirl. Webench is quoting 90-95% efficiency between 6-8.4V and from 0.2-1A, so I'm hoping I can do much better than my last attempt. Anyway, this is for fun, so easier is not necessarily better! Thanks again.the new Mintyboost can deliver 400+ mA. Better than the 200+ mA of the old versions, but still not that good.
I'm looking for a device that charges the small lithium batteries in portable electronics from 18650 standard cells. I've searched high and low for such a thing, but never found one that does exactly that. There a AA-powered things that don't work very well, and large packs that cost $100+ and are intended for laptops and portable dvd players, but no simple thing that will charge a cell phone or iPod from an 18650.
This one comes close, but I don't get the impression the cells are removable - a fatal law for a flashaholic.
http://www.goldengadgets.com/1-watt-led-flashlight-2200mah-usb-power-charger.html
So has anybody found anything better? If not, can somebody build this? I know I'm not the only one who would purchase such a device.
Well, since we're both DIYers, here's my two cents...
Ditch the charger altogether. The LiIon->USB->LiIon conversion is bound to waste a significant amount of power.
Crack open the gadget whose runtime you want to increase, get at its cell and put a tiny three-terminal switch across the cell output before it gets to the monitoring circuit. To the other pin of the switch attach one of the two wires leading to a suitable connector (I'm in love with JST ones available at DX for this sort of job - they are small, unobtrusive and easy to use). The other wire, you just connect in parallel to the existing cell.
This way you have a gadget that works fine off its own cell, but to which you can connect any other LiIon cell via JST connector, flip the switch and have it use the external cell directly - no power lost in conversion.
This obviously won't do if you don't want an external cell hanging from your device (or in a holder attached somehow to said device); on the other hand, you can attach any LiIon at all - 14500 from a flashlight, prismatic cell from any trashed gadget, big fat LiPo leftover from the RC plane that you nosedived on concrete...
Depending on the device, it might work fine off a 4xNiMH battery too (3xNiMH won't do for a LiIon-powered gadget; it'll think the cell phone battery is empty almost immediately due to voltage incompatibilities).
I am using this more than a year for iphone. Can accept bare (unprotected) 18650 only.
Wow, that looks interesting, never saw it at DX/KD.... any tip where it can be acquired?
Hi! I want one or two )) what should I do?Bought it directly from China at that time, PM me if you want.
Here is the one from deal extreme i got, but it took like three weeks to get here but what are you going to do when there is free shipping involved?
http://www.dealextreme.com/details.dx/sku.18883
This looks like a not bad charger. Reasonable price and would be able to boost my cellphone battery way better than my 1 x AA cell phone charger (good way to drain a few AAs though). I use my Nokia N85 as an E-Book reader while camping or away for a few days and the more charging options the better. I have a reasonable number of 18650 cells (one of my lights runs from 8 x IMR 18650 cells) so I could take 4 spares for my 18650 lights and/or recharging my cellphone.
Does this charger put out enough oomph to charge a cell phone to full? Or at least to 80% or more? I'd like to be able to ram 1000mA into the phone and get a decent charge in a short time.
I got a 3 chargers. ( 1 left only )
Charger & plugs $20
Pouch $5 (Tight fit the charger only, not the plugs)
Ship $4, additional $3 for tracking.
No battery included.
Please PM me if you are interested.