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Dual Lipo problem

Old 09-20-2009, 07:12 PM
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speedbird01
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Default Dual Lipo problem

Have 2 separate 2100 mah Lipos on an extra 300 50cc. Each goes through separate regulator (part of each switch) and then into its own battery port on a JR 921 rx. The two battery packs are not the same brand. After say three 12 min fights, one battery is down to ~7.9v or so and the other has not gone down, ie reads ~8.35v. Recharging, one pack takes ~400ma and the other with about ~50 ma. What is going on here ? I fear if I continue to fly, one pack will go too low and the other pack won't supply current at that time and the plane could go down. Any ideas on what is the CAUSE (not the solution), which is probably to get A123s.

Old 09-20-2009, 07:29 PM
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rcairflr
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Default RE: Dual Lipo problem

This is typical of Lipos running through regulators. The voltage out of the regulator on one is just slightly higher than the other and causing one battery to be drawn down and the other only slightly drawn down.
Old 09-20-2009, 08:44 PM
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speedbird01
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Default RE: Dual Lipo problem

thanks rcair. I am changing regulators around and see if the other pack then depletes faster.

However, the $64m question is, will the second pack kick in and produce current if the first gets too low to support a current load request, thereby avoiding a brownout....
Old 09-20-2009, 09:27 PM
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JOHNS3D
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Default RE: Dual Lipo problem

have seen this problem too...thats why i just used one li-ion fromeco 5200 mah with a regulator in my 50cc Extra...enough to fly like a month and enough power. Less space and weight.
Old 09-20-2009, 09:35 PM
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T Erickson
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Default RE: Dual Lipo problem

If you can adjust the regs within .01 volt of each other, it wont be a problem. Otherwise use a batt share or something along those lines. I use a wolverine switch and they draw down equally. Do some research on whatever you use, they don't all allow simultaneous draw. I like having redundant batteries. T.
Old 09-21-2009, 12:28 AM
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bgold
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Default RE: Dual Lipo problem

Get a Fromeco Wolverine switch and cure your problems
Old 09-21-2009, 10:48 PM
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camss69
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Default RE: Dual Lipo problem


ORIGINAL: T Erickson

If you can adjust the regs within .01 volt of each other, it wont be a problem. Otherwise use a batt share or something along those lines. I use a wolverine switch and they draw down equally. Do some research on whatever you use, they don't all allow simultaneous draw. I like having redundant batteries. T.
Yep.

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