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id0l
12-15-2004, 06:31 AM
I have read through the battery faq but cannot find an answer. I just picked up a 9.6v 1800mAh custom pack (NiMH) and was wondering what the correct charge mode is for it, 0DV or -DV (delta voltage?). I believe all NiCDs are supposed to be charged with a -DV setting, but what about NiMHs? If someone can explain what the difference is between the two modes, it would help much to satisfy my curiosity. And if anybody has any recommended amp settings for the current adjust, I'd like to hear them (for NiCD and NiMH). :)

I also do not understand why trickle-charging (slow-charging) doesn't seem to do anything. I can leave a pack slow-charging all day and it won't have enough juice to even fire a shot. I'm using an Apex U+ Digital Charger/Discharger.

AustinWolv
12-15-2004, 08:25 AM
What does the instruction manual to your charger say? ;) Not sure what 0DV charge mode is, so can't comment on that. NiMH packs usually benefit from using 0.02-0.03v voltage drop for the peak voltage detection, whereas NiCd packs use much higher values, like 0.08-0.13v. That only applies if your charger has adjustable peak voltage detection. I would hazard a guess that you are correct in that the 0DV is being designated on that charger as the NiMH charging mode.

Charge that pack in the 2.5-3A range. Higher current than that will result in some extra heat that the pack doesn't need to see.

Trickle-charging is extremely low current rate, meant to keep your pack peaked after it has been fully-charged. Thus, it would take a loooooooong time to charge a pack that way that was discharged.

id0l
12-15-2004, 08:31 AM
What does the instruction manual to your charger say? ;)

LOL, well if I received one with it, I could tell ya. :p

All I got was a crappy peice of paper, mostly in Japanese, with a little engrish thrown in.

I seem to always get gyped on the manuals.

I believe it does have peak detection, along with MOSFET technology. I don't really know what this means, but it sounds nice. :D

Agrovale
12-15-2004, 08:41 AM
0DV is for NiMh packs as Wolv surmised. NiCds prefer a -DV in the 10-20mV per cell range.

id0l
12-15-2004, 08:50 AM
Is there anything special you have to do to new packs to get them to reach peak capacity/voltage/etc.? I'm having to cycle charge this battery to get the capacity to increase. It's been about 5 or 6 cycles and I'm reaching 1000mAh out of 1800mAh (it increases every D-C cycle). Have been charging between 1A-3A (started with 1A, have now increased to 3A).

This 10A discharge gets my batteries pretty darn hot as well. Last thing I need to do is fry a new battery.

AustinWolv
12-15-2004, 09:40 AM
10A discharge is nothing for a battery. For reference, those kinds of packs can see 20-30A discharge rate for R/C applications. Once a pack gets pretty hot like that, best to let it cool down though, so don't cycle the pack again right away.

CALI
12-15-2004, 10:27 AM
I had all kinds of batteries before and never had a problem charging it. As far as in the RC world, I've used Li Poly to Nimh etc. I've also used different chargers from trickle chargers to digital once similar to yours. I have a table of battery discharge/charge rates that I can let you copy for reference (all types). Also, buy yourself a Triton charger and this should fix your problem since you can just set it to auto...done. Hope this helps...

Marimba
12-15-2004, 12:19 PM
You should be able to charge your NIMh pack at 2x (2c) the rated capacity, or in this case 3.6 amps. I have found however, that charge rates higher than 3.0 amps tend to heat NiMh packs to beyond 120 degrees. Overheating your NiMh pack will shorten the lifespan of the battery. I would just stick to 3.0 amps. NiMh batteries do not need to be discharged, but the first charge you charge them with should be at 1/10 if the rated capacity to help them reach full capacity later on. If you are having trouble getting your battery to take a full charge, cycle it a few times by charging, then shooting off a few thousand bbs until the gun starts to slow down, then repeat the whole process. You could then discharge the battery using your chargers auto-discharge setting. Then recharge the battery while monitoring the mah applied to the battery with the charger to give you the most accurate idea of the state of your battery. Cali is correct in recommending a Great Planes Triton charger. AustinWolv recommended one to me when I was first beginning in Airsoft and, although expensive, it is one of the best Airsoft purchases I have made. It gives you complete control over the care of all battery types. Just out of curiosity, where did you source your battery from? Some companies use high-quality cells, and some do not. There is a possibility that you have one bad cell in your battery pack. That would keep your pack from charging beyond 1000 mah.

Good luck,
Marimba

id0l
12-15-2004, 04:18 PM
I got a custom pack from DrGonzo, at www.airsoftplayers.com/gonzo

Marimba
12-15-2004, 09:28 PM
From what I have read, those battery packs are good quality. So, bring your pack out to the game on Sunday, I can discharge-charge it to see what kind of capacity it has. Have you discharged the pack to less than 0.85v per cell (6.80v)? It is possible to cause a cell to reverse by discharging to too low a voltage. Try this as well: Set the delta V sensitivity on the charger to 0.01v, slow charge the pack at 150mah for 14-16 hours, discharge the pack at 1800mah for 1 hour, then fast charge at 1.8 amps for 1hour and 10 mins. Monitor the mah applied to the battery. I do not know what kind of read-out the Apex charger has, but I assume that it has a function to monitor the amount of mah applied to the battery. (That is where you are coming up with the pack charging up to 1000mah?) Does the charger also show the amount of mah discharged from the battery? If you wish to get really crazy about your batteries you could go to the extreme of purchasing individually matched batteries then building your own battery packs using Deans jumper bars and Deans connectors. You will find there is a lot of variation in the charge-discharge capacity of what are supposed to be identical batteries. The rated mah of a given battery is really just the average of many of the same type. I have found batteries that didn't live up to their rated mah, and some that will charge to well beyond rated capacity. In the R/C racing world finding the best batteries you can is an ongoing never-ending search. I think it is kind of funny that people will spend lots of money upgrading their Airsoft guns, but not think that good batteries are important to good performance. What good are upgrades if you don't have adequate power to use them? (I am learning that the hard way.) I recently up graded my G36, and now 8.4v minis will only run my gun for a short time. I had to order a 9.6v 3300 mah battery. Can't wait till it arrives.

-Marimba

AustinWolv
12-16-2004, 06:41 AM
In the R/C racing world finding the best batteries you can is an ongoing never-ending search. I think it is kind of funny that people will spend lots of money upgrading their Airsoft guns, but not think that good batteries are important to good performance. What good are upgrades if you don't have adequate power to use them? The voltage output and capacity for R/C racing far exceeds anything what is needed in Airsoft. For example, there is no way in hell a serious R/C racer would use packs from onlybatterypacks.com, yet many Airsoft players buy from that site and use those packs just fine. A pack with .02 more volt rating can be seen on the track, but does it really make that much of a difference for our guns that the full-auto burst is going to zap the guy anyway? The main concern for having good packs is a reasonable discharge rate for the pack and that the cells hold the capacity that they are rated to hold.
The only setups that truly need top-of-the-line cells are the ultra-high ROF setups that the Japanese like to have......something like 1200+ RPM.

The hottest cells out there simply aren't needed for Airsoft use.


I recently up graded my G36, and now 8.4v minis will only run my gun for a short time. That is a lack of capacity, not really related to cell quality.

The DJGonzo packs are quite good. He doesn't throw in any random cells he can get like some of the other battery pack assemblers out there.

id0l
12-16-2004, 03:26 PM
I am not and have not been impressed with my charger at all. I do not even think it has adjustable delta V, etc. If it does, then I can't figure out how to use it...the only paper that came with the charger tells you only the very basics to get you started. If I can't get it to charge correctly I will definatly bring it out on Sunday as it is my only battery...

edit: Strange, it charges up to about 1300mAh, then shuts off. If I press charge again it will go up another ~100mAh, then shut off. If I repeat this I can get it to charge completely. I don't know if my charger is on the fritz, if it's detecting false peaks, or what, but I've never had this problem before.

Marimba
12-16-2004, 05:08 PM
AustinWolv, you are correct in all of your comments. I was not trying to say that the battery packs from DJGonzo were poor quality, (everything I have read or seen about them suggests they are excellent) just to point out there does exist a difference in different brands and quality of individual cells. I was suggesting that it does make sense to seek out the highest quality cells possible. True, Airsoft does not require the same type of high discharge rate per cell that R/C racing does, but R/C batteries are matched for cell discharge rate and individual cell capacity. I believe that all Airsofters could benefit from good quality batteries. Who wouldn't want a 2000mah battery that could actually charge up to 2600mah?

-Marimba

AustinWolv
12-16-2004, 05:13 PM
Who wouldn't want a 2000mah battery that could actually charge up to 2600mah? The average player who cannot afford the "hotter" cells. ;) I'm right along with you that having a great battery pack is highly desirable, but I'd just like to point out to some of the new players that unlike the R/C racing world, you don't need the hottest pack you can afford.

id0l, if you have the charger I think you have, it does not have some of the features that we're discussing. However, it is a good charger, but is more of a plug 'n' play charger. Should still work fine for your usage. Bring it along on Sunday, and we can take a look.

id0l
12-16-2004, 09:44 PM
id0l, if you have the charger I think you have, it does not have some of the features that we're discussing. However, it is a good charger, but is more of a plug 'n' play charger. Should still work fine for your usage. Bring it along on Sunday, and we can take a look.

Most definatly. As I said before I can keep pressing the charge button after it stops and it will eventually charge the battery to full...however it kept going even beyond 1900mAh, so maybe this is not a good idea. I don't even know if it's working. I will find out tonight.

Also, the only adjustable thing on it is the DV setting and the amp rate...hehe.