Kokam 1200 and Triton - what's going on?

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Eddie Bauer - 25 Aug 2003 20:58 GMT

Hi,

Just got delivery of my first lipo's - 2x 1200 HD kokams which I will
be using on a pico stick slow flyer. I've bought a triton to charge
them on. When delivered they are supposed to hold 50% capacity so I
put them on a 0.6A charge, 7.4v with time limit 80 minutes, figuerd
this should do it. Problem was that the charge current started at
0.1A, then after a few minutes went up to 0.2A then finally 0.3A where
it sat for the duration of the charge. What gives? After 80 minutes
the batteries had only taken 400mA.

I set the charger to charge at 0.6A and it only gave out 0.3A ! That's
not very nice is it? So what's going on? I read somewhere that lipo's
"draw" their own current from the charge, winding down the current as
full charge is approached but should this happen so soon ? is the
problem that it's the pack's first charge?

All help is graciously appreciated.

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123@abc.com - 26 Aug 2003 00:37 GMT

>Hi,
>
[quoted text clipped - 14 lines]
>
>All help is graciously appreciated.

Basically, a LiPoly charger applies a voltage of 4.2V per cell to the
pack. The charger will also limit the current to whatever you set
(normally 1C). As the pack charges, the voltage rises until it hits
the 4.2V/cell limit. At that point, the current decreases slowly to
zero. If your pack did not draw the current that you set, it was
probably more like 80% charged. At that point, the charger has
reached the voltage limit and the current is decreasing.

There are several things you need to know about LiPolys before you
attempt to charge and use them. Please see
http://pgoelz.com/piccolo_faq.html#70

This page is aimed at Piccolo pilots but applies to any LiPolys. Pay
particular attention to cell balance and maximum and minimum "never
exceed" voltages.

Paul

Reply to this Message

Eddie Bauer - 27 Aug 2003 22:52 GMT

> >Hi,
> >
[quoted text clipped - 32 lines]
>
> Paul

Thanks. I actually knew all that and have done all the pre-requisite
reading. The problem is that the Triton is not putting out the amps I
want, even from a fully depleted pack. From what I've read the
designers of the triton have been a little too careful and have
hardcoded the current limit to something like 0.3C which is crazy. I
think the user should be able to decide how much current should be put
into the pack up until the 4.2V limit is reached.

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Model Forum / Radio Controlled / Helicopters / August 2003

Kokam 1200 and Triton - what's going on?