Thursday, July 30, 2015
lithium battery pack
so I got my fancy lithium battery assembled
here is what it looks like all done
did that to make it easy to carry
I got 8 LiPO4 10AH pouch cells
the manufacturing website http://www.bestgopower.com/battery-overview/pouch-cell.html
shipping cost almost $100 and took almost 2 months to get, so it is about $200 total
put them into a 4 cell pack that ends up 20AH at about 13V
I put power pole connectors on each set of 2 parallel cells,
made 2 matching connector sets, one puts them all in parallel in order to balance the voltage of the cells, I did not have to put an external connector on that one, but it will get me a 3.2V battery at 80AH and I do have a few things that will run on that low of voltage
I will likely need to use that connector at least every 6 charge cycles for cell balancing, but so far they are all at the same voltage with no drifting
the other connector puts them in series to get the 13V at 20AH to run most of my hardware and to charge them.
seems to work quite well
I charge them with solar (it limits the current by its nature) and use a DC to DC switcher to limit the charge voltage
http://www.amazon.com/DROK-Converter-1-2-32V-Laptop-Regulator/dp/B00C9UUFHC
have it set to float charge at 13.3V
the current solar is a 100W, but have a 20W one for portable use
so far I have been watching the voltage closely so I don't over discharge them,
over discharging these batteries will kill them forever almost instantly
but will soon will build a low voltage alarm so I don't mess them up
will set it to 12.9V with a delay to deal with transmit current on the radio dropping the battery voltage
as far as the physical mounting of them,
I left the clear plastic on the cells so that the cases are insulated (will help them not corrode)
I used 2 sided sticky foam tape to give them some space to expand if they need to
then I taped the outside so they can't go anywhere and lined the inside of the metal box I keep them in with tape as well
I took a circuit board and cut slots in it for the cells tabs to go through
you can see the poor solder joints through the tape I put to insulate connections (60W is not enough power to solder that large of wires to the cells )
going to redo the solder joints soon now that I have a way higher power soldering iron
I would likely never build this setup again,
quite hard to solder them and was worried about melting the plastic in them
and when I charge them I get radio interference, sounds like a loose connection,
so maybe I have a cold solder joint... or could just be the nature of the batteries
if I did it again, would get batteries that I can just bolt connections to, like these
http://www.electriccarpartscompany.com/-NEW-ENERGY-br-4000-CHARGE-CYCLES--20-AH_c_138.html
also don't have to worry about potential cell expansion with time like you have to with the pouch batteries
but maybe I should have just got something off this pace
http://www.electriccarpartscompany.com/-CUSTOM-12-VOLT-PACKS_c_182.html
overall I am happy with what I did,
the max continuous discharge is 60A with peak of 75A
that will more than double power my radio setup that I plan on running with it
will be adding an external box with fuses so the battery does not get hurt if I mess up,
but have not built it yet as it works now and I have been short on time
some motivations for wanting the lithium batteries is the potential life they have,
all my lead acid batteries are getting old, the lead acid batteries don't last that long anyway...
and the lithium are very light weight my setup is only 5 pounds
picked the LiPO4 over the Lithium ion because the voltage of the LiPO4 matches the radio hardware voltage requirements better than the lithium ion, and they likely have longer life, and tend not to light on fire randomly
my setup is lighter than premade options that I could have gone with
the other advantage i have is that I get perfect cell balancing.(with connecting them in parallel )
it is the least loss system for cell balancing I could find, and works even if I only charge to 80% (or whatever I prefer to charge to), most setups requite you charge to 100% for the cells to balance (because they shunt the extra voltage), and I kind of want the longer life of never charging past 90% (but still want the ability to go to 100% if I need to)
here is what it looks like all done
I got 8 LiPO4 10AH pouch cells
the manufacturing website http://www.bestgopower.com/battery-overview/pouch-cell.html
shipping cost almost $100 and took almost 2 months to get, so it is about $200 total
put them into a 4 cell pack that ends up 20AH at about 13V
I put power pole connectors on each set of 2 parallel cells,
made 2 matching connector sets, one puts them all in parallel in order to balance the voltage of the cells, I did not have to put an external connector on that one, but it will get me a 3.2V battery at 80AH and I do have a few things that will run on that low of voltage
I will likely need to use that connector at least every 6 charge cycles for cell balancing, but so far they are all at the same voltage with no drifting
the other connector puts them in series to get the 13V at 20AH to run most of my hardware and to charge them.
seems to work quite well
I charge them with solar (it limits the current by its nature) and use a DC to DC switcher to limit the charge voltage
http://www.amazon.com/DROK-Converter-1-2-32V-Laptop-Regulator/dp/B00C9UUFHC
have it set to float charge at 13.3V
the current solar is a 100W, but have a 20W one for portable use
so far I have been watching the voltage closely so I don't over discharge them,
over discharging these batteries will kill them forever almost instantly
but will soon will build a low voltage alarm so I don't mess them up
will set it to 12.9V with a delay to deal with transmit current on the radio dropping the battery voltage
as far as the physical mounting of them,
I left the clear plastic on the cells so that the cases are insulated (will help them not corrode)
I used 2 sided sticky foam tape to give them some space to expand if they need to
I took a circuit board and cut slots in it for the cells tabs to go through
you can see the poor solder joints through the tape I put to insulate connections (60W is not enough power to solder that large of wires to the cells )
I would likely never build this setup again,
quite hard to solder them and was worried about melting the plastic in them
and when I charge them I get radio interference, sounds like a loose connection,
so maybe I have a cold solder joint... or could just be the nature of the batteries
if I did it again, would get batteries that I can just bolt connections to, like these
http://www.electriccarpartscompany.com/-NEW-ENERGY-br-4000-CHARGE-CYCLES--20-AH_c_138.html
also don't have to worry about potential cell expansion with time like you have to with the pouch batteries
but maybe I should have just got something off this pace
http://www.electriccarpartscompany.com/-CUSTOM-12-VOLT-PACKS_c_182.html
overall I am happy with what I did,
the max continuous discharge is 60A with peak of 75A
that will more than double power my radio setup that I plan on running with it
will be adding an external box with fuses so the battery does not get hurt if I mess up,
but have not built it yet as it works now and I have been short on time
some motivations for wanting the lithium batteries is the potential life they have,
all my lead acid batteries are getting old, the lead acid batteries don't last that long anyway...
and the lithium are very light weight my setup is only 5 pounds
picked the LiPO4 over the Lithium ion because the voltage of the LiPO4 matches the radio hardware voltage requirements better than the lithium ion, and they likely have longer life, and tend not to light on fire randomly
my setup is lighter than premade options that I could have gone with
the other advantage i have is that I get perfect cell balancing.(with connecting them in parallel )
it is the least loss system for cell balancing I could find, and works even if I only charge to 80% (or whatever I prefer to charge to), most setups requite you charge to 100% for the cells to balance (because they shunt the extra voltage), and I kind of want the longer life of never charging past 90% (but still want the ability to go to 100% if I need to)
