Hi All,
I have a few projects lined up that I want to do, trying to figure out if it is cost effective. looking for input and suggestions.
Project 1: Battery pack for x2 16ft Cool White LED lights running at 12v 2.40 amps = 57.6watts hours, I am looking to run the lights for 3 hours for SUP.
Project 2: Same as above but for a kayak.
Project 3: Cpap battery backup for 16 hours for camping. its 24v @ 3.75amp hour or 90w, I am figuring the amp hour will at least be half since this is for a heated humidifier and heated hose I won't be using these while camping. so maybe 1.875 amp hour ?
Tools for the job = Limited.
* I will need to get a new 60w solder iron
* different gauge wires, I most likely have this.
* 16850 salvaged unprotected cells, recharging and discharging to calculate mah from salvaged laptop batteries. Was looking at this for the charging system and maybe discharge test as well
http://goo.gl/AqEX3s paired with this
http://goo.gl/q49ITR to calculate the discharge rate using a 1amp load. to build the charging system is cheap as I have spare PC PSU I can use, the discharge test a bit more expensive looking to do a few batteries at a time.
* Pretty sure I am going to need to get a SKYRC iMAX B6 and watch out for the knock off clones as well.
* better solder
* pretty much unlimited supply of used laptop batteries, talked to a E waste recycling center, they collect a few 100 pounds a month, I have 40 packs now to dismantle.
* some way to balance the batteries, BMS, individual charging
* buck or boost converter, I will need to either step up / down to 12v 2.4 amp for the LED project and step up or down 24v roughly 2amp for the CPAP project.
* lipo firebag, I know the risks of lipos even more so with unprotected cells. most of the work is done outside, or next to the front door for a quick toss.
* could I salvage a BMS from one of the dismantled laptop batteries ?
I am going to be spending about $40 as it is just to get the charger and most likely another $20 - 30 for remaining supplies. Is it even worth it ? do I just by RC packs and be done with it ? I know I will still need a charger. Once I invest in the initial setup building my own packs might be worth it. figuring I can get at least 1500mah out of used cells taking them down to the 2.7v area.
I know soldering the batteries is a risk as well since I won't be tack welding. 60w iron is recommended ? when pulling packs out of laptops maybe it is best to try and keep the tabs on the cells.
salvaging the cells from laptops packs, I have sparked a few nothing happened other then the spark, the pack was tossed outside after, is there a major risk from a quick spark ? I know shorts are a issue. I am guessing if anything is going to happen the battery is going to get hot before thermal runaway happens.
on to the project specs.
Project 1 & 2 are pretty much the same, just one is a SUP the other a Kayak. I know there are already pre done kits for $200+
*building the battery or buying it ? if building I was thinking of just a simple 16850 battery holder and load them in like you do the do AA batteries, depending on mah I can get from the cells I will need between 10-14, then when I am done I individually charge each cell, I am hoping this eliminates the need for balancing.
Step up or step down ? to keep things simple it would be nice if I can just do 3.7 high mah pack and step it up to 12v using a protected boost converter, really looking for input here,
I know I could just run the LED strip off a straight pack, but now I am pushing 16.8 volts to the strip, and they really did not like it when I was pushing 20v
wires and strip started to get to hot. then everything will have to go into a waterproof box with a waterproof DC barrel connector.
Project 3 CPAP battery backup, ResMed S10 elite 24v @ 90w or 3.75amp max, looking for 16 hours run time 2 8hr nights. I am figuring it will run at 1.8ap to 2amp, have not tested yet, this would be with the heated hose and humidifier off .
build or buy a pack ? if can salvage cells that are at 1500mah I will need about 22, or 32 if at 1000mah, again I would like to do the style of a battery holder, but this might add to the weight and build and may not be feasible, so if I build a pack it would need a balance system or BMS. again is it best to Step up or step down, I will need to have some sort of discharge protection, think of taking the cells down to 2.7v
looking for suggestions, thanks for the comments and help.