LiPo's in parallel
12-02-2011, 05:47 PM
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LiPo's in parallel
I have been searching for information on the limiting factors for wiring LiPo's in parallel, to no avail.
Basically, I want to wire up to four (4) same brand, type, capacitybatteriestogether in parallel for my Senior Telemaster. Thunder Power 6G 3300, 6S
My electric motor will consume up to 59 Amps max, and Iplanto use a 77A speed control, but in reality I am assuming a continuous consumption of 25 Amps.
Am I misguided here? Can you wire more than 2 LiPo battery packs in parallel?
Maybe my problem has to do with weak understanding of advanced LiPo usage.
My project is to fit a Senior Telemaster with this much capacity to get between 1 and 2 hours of flight time. I picked this setup because the combined weight allows me to get as much capacity as possible for the least weight addition.
Any recommendations on how to accomplish this?
Any recommendations on how to accomplish this?
12-02-2011, 06:10 PM
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RE: LiPo's in parallel
Any number of (same series cell) packs can be hooked in parallel for high capacity. This helps , maybe. http://www.scriptasylum.com/rc_speed/lipo.html
12-06-2011, 09:06 AM
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RE: LiPo's in parallel
Yep no problem at all. Take a look over at Hobby Lobby they make a slick system for hooking up multiple parallel and/or series connections.
http://www.hobby-lobby.com/parallel_...ueryId=2418420
http://www.hobby-lobby.com/series_mo...ueryId=2418420
Of course they are out of stock [
] But you get the idea, all you do is solder your esc to one of the sets of holes on the board, and simply plug in your packs and you are good to go.
I used them in one of my P-38s, used EIGHT 3S3700 packs, 4 to a side, wired in parallel and series connections to give me 6S2P7400 on each side.
http://www.hobby-lobby.com/parallel_...ueryId=2418420
http://www.hobby-lobby.com/series_mo...ueryId=2418420
Of course they are out of stock [
] But you get the idea, all you do is solder your esc to one of the sets of holes on the board, and simply plug in your packs and you are good to go.I used them in one of my P-38s, used EIGHT 3S3700 packs, 4 to a side, wired in parallel and series connections to give me 6S2P7400 on each side.
12-18-2011, 09:49 PM
#4
Senior Member
RE: LiPo's in parallel
If the parallel cells are exactly the same chemistry - - and they were fully charged to the same voltage independently.
Under discharge, they will remain balanced unless and until they are discharged to an unsafe level. When reasonable discharge rates exist, the cells will stay in balance. A defective cell may discharge
the good cells. You can even charge them in parallel, as long as you used a safe charging current. Usually the limit is whatever 1C rate that applies to the lowest capacity cell.
The safe max current capability will reduce as lower capacity cells energy storage is exhausted.
there are some caveats, in that dissimilar cells will usually have differing internal resistance, which makes a difference in current capability.
At high discharge rates, lead length differences may have an effect.
In an ideal environment for protecting the cells, current limiting devices should be used between each cell. Automotive fuses may be a low cost possibility. Unfortunately this is often not practical in higher current usage, unless a complex and pricy power control scheme is used. (Yes you can buy such things)
Under discharge, they will remain balanced unless and until they are discharged to an unsafe level. When reasonable discharge rates exist, the cells will stay in balance. A defective cell may discharge
the good cells. You can even charge them in parallel, as long as you used a safe charging current. Usually the limit is whatever 1C rate that applies to the lowest capacity cell.
The safe max current capability will reduce as lower capacity cells energy storage is exhausted.
there are some caveats, in that dissimilar cells will usually have differing internal resistance, which makes a difference in current capability.
At high discharge rates, lead length differences may have an effect.
In an ideal environment for protecting the cells, current limiting devices should be used between each cell. Automotive fuses may be a low cost possibility. Unfortunately this is often not practical in higher current usage, unless a complex and pricy power control scheme is used. (Yes you can buy such things)
12-20-2011, 11:47 PM
#5
Senior Member
RE: LiPo's in parallel
Just remember that adding more cells increases weight, and will likely change balance. There is a limit if it's to get off the ground and fly well.
