I was Thinking of running 3 18650's in series with another 3 in parallel for a bicycle light pack to extend runtime. Will this cause a problem with cells discharging into each other with different voltage levels in parrelel? Also is there any battery carriers like 2-10 AA packs made for the 18650's.
18650 Battery pack question.
- Thread starter bryan24
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Citivolus
Enlightened
The laptop battery pack I ripped apart last week had exactly this configuration, with the pairs welded to each other (3 pairs in series). To be more concise, don't do it as two sets of a series of 3, do it as a series of 3 pairs.
You'll need a balancing charger, though, to ensure that each pair is getting properly charged.
You'll need a balancing charger, though, to ensure that each pair is getting properly charged.
All commercially made 18650 packs, whether Lithium Cobalt, Lithium Manganese, Lithium Nano Iron Phosphate, etc. all have cell balancing, and protection against over-charge/discharge. The parallel configuration will auto-balance the cells in parallel with each other, but not one set in series with other sets in series.
mdocod
Flashaholic
Hello LuxLuthor,
Your response is misleading IMO. While true for consumer devices that come with Li-Ion cells, there are an enormous number of "bare" (device-less) Li-Ion packs being sold on the market that have no provisions for balancing built in, and an enormous number of chargers that are are single channel outputs designed for li-ion pack charging with no balancing.
Eric
Your response is misleading IMO. While true for consumer devices that come with Li-Ion cells, there are an enormous number of "bare" (device-less) Li-Ion packs being sold on the market that have no provisions for balancing built in, and an enormous number of chargers that are are single channel outputs designed for li-ion pack charging with no balancing.
Eric
I didn't just mention "balancing," but OK, no problem...since mdocod says so, don't anyone bother worrying about over-discharging over-charging or balancing your cells. If you have any problems, just contact mdocod. :shakehead
OK what I'm trying to do is get the series voltage of 3*18650's (11.1v) and double the Amp-hr with another 3 in a parallel circuit. The constraints are the shark board being a set input limit of 11.5v.
I was thinking of using a sort of bridge rectifier circuit (4 diodes) to make sure no over discharging into each battery cell (the parallel part). So 3 batteries in series at each ac input leg of the bridge and the outputs at the DC legs. This would make things unnessarily complicated if there is no worries of shorts (over discharge) between the parallel batteries. This would also produce a voltage drop across the diodes for each side .7v*2 (1.4v).
The real objective is to double the Amp-Hr while staying under 11.5v.
I was thinking of using a sort of bridge rectifier circuit (4 diodes) to make sure no over discharging into each battery cell (the parallel part). So 3 batteries in series at each ac input leg of the bridge and the outputs at the DC legs. This would make things unnessarily complicated if there is no worries of shorts (over discharge) between the parallel batteries. This would also produce a voltage drop across the diodes for each side .7v*2 (1.4v).
The real objective is to double the Amp-Hr while staying under 11.5v.
Jarl
Flashlight Enthusiast
Bear in mind that 3 fully charged 18650's comes in at 3x4.2=12.6V.
