Duratrax Onyx 230 charger question

[Coelacanth]

These are a popular, common charger so I figure someone here has the answer to this question. I recently picked up an almost-new 230 and was surprised at how complicated the manual was. By comparison, my Onyx 200 is a very simple deal, just connect, charge, and it auto-switches to trickle charge when peak charge is detected.

With the 230, I did my first charge on a 6-cell 4200 mAh NiMH pack. Of course, it wasn't listed in one of the 8 default choices. This meant I had to "program" the 230 to give it a proper 60-minute charge at 4.2A. (The battery was first completely discharged with the 4 auto bulbs thing.)

At any rate, I noticed around 48 - 50-ish minutes, the battery pack was getting quite warm. Since the manual states to disconnect the battery if "it gets too hot" (whatever "too hot" means), I gave it another 2 or 3 minutes and finally pulled the plug. I thought this was a charger that does peak detection and will switch to trickle afterwards. The LCD was showing the battery at only 3800 or so mAh.

My question might be foolish. I just assumed that a pack that's getting that warm is reaching it's peak, and I figured the charger would switch to trickle. Isn't that the case with this charger? Or should I just have disconnected the battery, waited for it to cool, then reconnected it for the final 8 minutes? The last thing I want to do is damage an almost-new battery pack.

Thanks!

[Jay Dub]

I am not familiar with this charger, however with out a temp probe the charger has no idea how hot the battery gets. Also, I assume that if you "program" the charger for 60 min. @ 4.2 ah it propably locks out the peak function, and will charge it for as long as you determine at the amperage you determine. I would assume that you can adjust the amperage and just let it "peak". Or is this not the case? -Jeff

[Coelacanth]

I am not familiar with this charger, however with out a temp probe the charger has no idea how hot the battery gets. Also, I assume that if you "program" the charger for 60 min. @ 4.2 ah it propably locks out the peak function, and will charge it for as long as you determine at the amperage you determine. I would assume that you can adjust the amperage and just let it "peak". Or is this not the case? -Jeff

I'm not really sure about the peak function being locked out with the manual battery charge programming, the manual is 15 pages long and that part of the manual is pretty confusing. It seems you HAVE to program your battery, there's no mention of just plugging in any old battery and "setting & forgetting it".

With the Onyx 200, you only have to choose between 6 or 7 cells and you're ready to charge. LED lights indicate the level of charge, and it auto-trickles when it senses the battery is peaked. I think the 200 manual is a single fold-over sheet.

[Jay Dub]

Well, I read through the manual, and it seems straight forward enough. It doesn't appear that there is any sort of lockout function (which is available on some chargers btw). It appears to me that if the batteries were getting too hot, you might need to look at your peak detection voltage. This setting depends on the type of cells (look on some racing forums to determine the proper care for the type of cell you have) in your pack. Usually between 4-6mv is good for a NiHm. You can also (which you should propably do anyways) try charging the pack starting with a low 3mv peak detection, and work your way up (3mv, 4mv, 5mv, etc.) on successive charges until the battery reaches a comfortable temp when peaking. Looks like a good charger to me. I would start with charger profile "0" then change your capacity, and peak mv per cell "mv/c". -Jeff

[Coelacanth]

Thanks Jeff, the peak detection voltage was set by the previous owner to 5 mV, which seemed like it was in the normal range (3 to 7 was suggested by the manual for NiMH's).

[JK Racing]

for NiMh, drop to 3mV. I love my 230, but I only charge Lipo on it now, I set up 2 profiles, one for "small" batteries, one for "large" batteries (talking MaH, not physical size)

[Jay Dub]

Yes, sounds like a normal range. BUT, each and every type of NiMh cell requires a different charge profile. (this is why I hate NiMh's) So your particular cell type may need 3mv per cell, and your buddies might need 7mv. -Jeff

[Coelacanth]

Well, I figured it out, and indeed, the manual I downloaded completely omits mentioning how to select auto-trickle. Here is what the manual says about the trickle charge settings:

Press > to find the TRICKLE charge current screen. This is the amount of trickle charge current that will be applied only to NiCd or NiMH batteries after peak charge has ended. The charger will automatically set this value based on the fast charge current setting divided by 20. This setting can be manually changed if desired. Setting this to “0mA” effectively turns this feature off. For “A”, “AA”, “AAA” size Tx or Rx batteries, it is not recommended to set the trickle current to larger than 50mA. Trickle charge is never applied to lithium batteries.

Wha...? So, this part tells you that the 'correct charge current' will be automatically chosen, and in my situation, "200" was there. You can disable trickle charge completely by choosing "0".

Here's the interesting thing...near the beginning of the manual where they show the default 10 battery programs, the first program (Battery 0) shows this feature set to "Auto".

I found by pressing through all the settings for trickle charge that there was a setting for "Auto"!

Now why the hell doesn't the manual point that option out, right in the Trickle Charge Current screen???

[Jay Dub]

Ok, their programming tree isn't very good. But what does the trickle being on have to do with the batteries being hot? Are you saying that the battery peaked, and was just trickling when you pulled it off? That shouldn't account for the hot battery. I might get it slightly warm, but never hot. It sounded from your original post that you pulled the battery while it was still peak charging? -Jeff

[Coelacanth]

Ok, their programming tree isn't very good. But what does the trickle being on have to do with the batteries being hot? Are you saying that the battery peaked, and was just trickling when you pulled it off? That shouldn't account for the hot battery. I might get it slightly warm, but never hot. It sounded from your original post that you pulled the battery while it was still peak charging? -Jeff

Right, I think I had to pull the battery before it finished the normal charge, before it even went to trickle. As you said before, maybe the detection voltage that was set to 5 mV might've been too high, I have since changed it to 3 mV but haven't had a chance to discharge the battery and re-test. We have 2 feet of snow turning to slush with freezing rain today and there's just nowhere to test-drive the Galaxy.

My point was that the manual's description of how to set auto-trickle is completely lacking. It doesn't even say how to choose the setting, though it's obviously there in the options if you scroll through them, and the little table showing the default battery settings shows "Auto" for battery 0.

[Jay Dub]

Point taken. Next time you try to charge the pack use the 3mv setting and see what happens. I seem to remember that we used to use 3mv/c for NiMh's when I last used them. Too much more than that and they would get too hot. -Jeff