I Charger 308 Discharge Limit

[philtea]

Hi All
Just joined this great forum
I am building a discharger for my I charger 308 duo to use in channel regenerative mode.
In the settings it only allows me to go to max 30 amp discharge for input or output.
This is verified on page 20 of the manual as max allowable but on page 38 it clearly shows a screen shot in regenerative to channel with a 40 amp limit set
Am I missing something as I would like to be able to have a higher discharge limit.

[Slyster]

Are you discharging into deep cycles? I wouldn't go any higher if that's the case.. generally they only like 1/10thC... or around 10A charge. My 4010 goes to 40A... not sure about my 308 I'll try it next time I use it.

[philtea]

I'm discharging in "channel regenerative mode" and using halogens for now using channel 2 as the output to the bulbs.
I was looking in the specs and it lists a 30A limit for "extra dishcharge" but this is when a load is put between the pack and the input channel
and shows Maximum regenerative discharge power capacity as 800w
The internal discharge limit can be set to 30A (I don't use this too much heat)
Seems strange they would limit a discharge to bulbs or resistors to 30A

[RedOctobyr]

The limit is 30A. I think that was a bad screenshot in the manual, maybe from when they were previously developing the 4010Duo.

Each channel's electronics can't handle more than 30A of current flow.

From the Duos thread on RCGroups, when doing a discharge from one channel into resistors on another channel, one user built a powerful resistor setup (actually using a modified hair dryer, pretty cool, IMHO). Link:

http://www.rcgroups.com/forums/showthread.php?t=2123395

He found that the most discharge wattage he could reach was about 650W from the 6S LiPos. This didn't make much sense until we realized that 650W "into" one channel (from the LiPos), and 650W "out" of the other channel (into the resistive load) is 1300W, which is the charger's total wattage limit.

So even wattage simply being transferred between channels apparently counts towards the 1300W limit, it's not just a limit of what you can draw from the power source.

800W of regenerative discharge presumably applies not when discharging into resistors on the other channel, but when discharging into your power source, like deep-cycles. And that's a lot of watts to put into even deep cycles.

The internal discharge limit, when expressed in amps, doesn't really tell the whole story. 3A from a 1S pack is only about 12W of heat to dissipate. But 3A from a 6S pack is about 75W of heat. If you discharge on both channels, you can dissipate 120W within the charger. About 30A on 1S, much less on higher cell-counts (about 5A on 6S).

Are you trying to load-test batteries or something? "Even" 30A is pretty significant if you're just trying to bring them down to storage voltage, etc. It's more than most other chargers on the market can do, with the exception of the 406 and 4010Duos.

[philtea]

Hi RedOctobyr
Thanks for the research,It really cleared things up I am just using 3s packs right now but I have quite a few and sometimes need to discharge if the weather turns bad.I was hoping to do them in a shorter time as I don't like leaving them unattended.
I got my mistake about the internal discharger after posting
I didn't realize using an external load would have such an affect on the charger
but it makes sense now.
Thanks for the link I had been looking for some info like this

[Slyster]

With a good charger, why not field charge in 12 mins? Now you need only two packs... save money... and never need to discharge.

[philtea]

Good point Slyter
I might just do that Also a good idea when I get Into bigger more expensive packs.
A deep cycle would be handy as well
Guess I could do the math and use the car battery for a bit,nice you can set input parameters so you don't run it down too far.