12v 4Ah Battery under 1 lb
12v 4Ah Battery under 1 lb
(OP)
Afternoon,
I would like to start off saying I havent been on this site very long but our team is in need of help. I am part of a team that is launching a weather balloon up to 100000ft. The issue we are running into is that we need a 12v 4Ah battery that weighs under 1 pound, our overall weight limit is about 3 lbs. Is this a possible thing to do ? or is it not viable, I have been doing alot of research into it via supercap batteries and so forth but considering we are running low on time I could use some help.
Thank you!
I would like to start off saying I havent been on this site very long but our team is in need of help. I am part of a team that is launching a weather balloon up to 100000ft. The issue we are running into is that we need a 12v 4Ah battery that weighs under 1 pound, our overall weight limit is about 3 lbs. Is this a possible thing to do ? or is it not viable, I have been doing alot of research into it via supercap batteries and so forth but considering we are running low on time I could use some help.
Thank you!
RE: 12v 4Ah Battery under 1 lb
http://www.a123systems.com/lithium-ion-cells-26650...
The voltage out of these cells remains constant at 3 to 3.3 volts until only less than 5% of the charge is left then quickly fall to about 2V when about 1% of the charge is left.
The one issue is that they need to be kept above -30C or you can't get the energy out. So, you will have to insulate them some, and make projections of flight-time, thermal mass, heat loss, etc to determine how much insulation you will need.
I'm assuming your using them for a one-way trip, so balancing circuits, charge monitoring, over-current protection circuits heater-circuits for low temperature operation can all be skipped. These cells have a very, very low internal impedance, so you will not need any super caps. These four cells alone would be enough for a single short crank to start a car.
This size and chemistry-type battery cells are used in some Dewalt power tools packs. You can find them on eBay.
If you are actually making a product, then you might contact me as I work at a company that uses these to make aircraft battery packs. Sorry - I'm not allowed to give out samples.
RE: 12v 4Ah Battery under 1 lb
but you can get them with over 5Ah capacity https://www.ebay.com/sch/i.html?_from=R40&_trk...
TTFN (ta ta for now)
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RE: 12v 4Ah Battery under 1 lb
Keith Cress
kcress - http://www.flaminsystems.com
RE: 12v 4Ah Battery under 1 lb
Another thought is to dispense with the 12v requirement and use a little DC-DC converter with fewer cells. You'd still need the same energy, in fact a bit more, so the A-hour spec would be adjusted as required.
RE: 12v 4Ah Battery under 1 lb
RE: 12v 4Ah Battery under 1 lb
LG
Panasonic
or
Sony
The LG 18650 MJ1 3500 is 3500mA.
Sanyo purportedly just came out with 4250mA but you should be suspicious of a company stating a value considerably higher than everyone else in a physics-constrained product that is years mature.
Keith Cress
kcress - http://www.flaminsystems.com
RE: 12v 4Ah Battery under 1 lb
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: 12v 4Ah Battery under 1 lb
Your ebay link pulled up mostly Ultra Fire brand batteries. Not so sure that is a good name for a battery with all of the battery fires happening.. Lol
RE: 12v 4Ah Battery under 1 lb
Better double-check the ambient temperature at 100,000 feet (likely below -40°) versus the effect of such low temperatures on the battery capacity. I suspect that this may be an issue worth considering.
If it is, then think about adding insulation and maybe a source of heat (e.g. paraffin wax with a phase change) as such solution may (?) be lighter than extra batteries. Even the waste heat from the electrical load may need to be conserved within the thermal envelope. Solar gain might assist. A thermal analysis may be required. Or include a temperature sensor or two within the battery and payload, and record or transmit the data so you'll know if is, or isn't, a problem.
RE: 12v 4Ah Battery under 1 lb
Another issue is altitude. Some electronics have pretty low altitude limits.
UltraFire seems to be considered one of the most successful battery re-wrapping scammers.
Keith Cress
kcress - http://www.flaminsystems.com
RE: 12v 4Ah Battery under 1 lb
RE: 12v 4Ah Battery under 1 lb
RE: 12v 4Ah Battery under 1 lb
Dan - Owner
http://www.Hi-TecDesigns.com
RE: 12v 4Ah Battery under 1 lb
I think space temp is around -270C. You won't technically be in space at that altitude but almost.