Thread: New Product ESR / IR Meter fo Lipos
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Old Jun 18, 2011, 06:52 PM
jjmouris is offline
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Needs to do 52 legs !!
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Verenigd Koninkrijk, Fareham
Joined Aug 2008
7,290 Posts
Hello Wayne,

Lucky to find this great thread thanks to a post from Wim on the dutch forums. Very good of him and of you for creating this device and the amazing support. Was a great read so far!

A little bit of background on myself and what i spend my time with. Ever heard of the FAI class F5B ? It's some crazy people who insist on pulling way to many amps out of those poor little lipo's for short periods at a time and making our planes go from 100 to 300kph in less then 3 second while going strait up. It's addicting, what can i say. We regularly pull around 100C for about 2 seconds out of around 500 grams worth of Lipo. We generally only discharge the pack down to ~50% charge state. To throw in some more typical numbers, 5KW is about where most competitors are at now, on 5S 3300mah that would be around 300A at 16.5V under load or 3.3V/cell.

I think you can already see how important it is for us to have good cells, make sure out packs are in good health and possibly controll the temperature of the pack. I say that last thing a bit hesitantly as i have been avoiding flying in cold weather (sub 5 deg C) and generally don't bother preheating the packs when i do fly. This means i get less power on the first climb but then the power seems to be very constant for the other remaining 10-12 climbs. In the past this effect was much worse and it would take nearly 5 climbs for the power to level out.

In terms of wear on the packs. I have had no trouble abusing packs like this for more then one flying season and usualy when a new generation comes out the next year, the old ones get moved to the dust collection area anyway. But i do fear that we might get a bit less power nearer the end of the year and an injection of a fresh pack into the mix can have some ''unexpected'' results where suddenly more power is to hand. This is where people run out of their energy allowance as we fly with a total energy limiting device (1750W.min).

Many people have the SM Unilog with a 400A sensor in use and it has a nice 16hz recording feature with some spare slots;
http://www.sm-modellbau.de/

I was wondering about maybe seeing if we could somehow connect your unit to a Unilog and run a pack through on a ''tester unit'' to simulate a flight and see how the pack temperature really effects the IR of the pack.

Would love to hear your thoughts on the above and in general. Also i am probably wanting to buy a unit from you.

Kind regards, Joe
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