NICAD Charging and Discharging
 

Hi,

So i have received my shiny new etronix 4 way charger and 350w hobbyking power supply. I currently have nicad batteries as im not yet confident enough to go lipo. Can i ask what a good regimen is for charging and discharging? Ive read up some info on it but im not entirely sure whats best. The batteries i have are all 7.2v 1300's, the charger supports discharging in 0.1v and 0.a increments.

Cheers,

Is that a sport pack? If so, I would charge at rate no more than 1C (1.3A) to ensure all 6 cells charge fully. You might want to invest in NiMH if you don't want to try Lipo. NiMH is easier to use especially for sport pack (shotgun setup).


I still have my side-by-sides I put together from pre-2000 that still works very well. 3 of my chassis have the sub-c cutouts so use NiCd's on them. :D Those can handle much higher charge rate as I can balance the cells individually after use. For discharging I use the bulb discharger and don't know off hand what amp it was..but for sport packs be very careful on the discharging as you can't balance the cells. You might kill the the weak cell unknowingly.

http://www.rctech.net/forum/albums/t...?dl=1443907668

Hi,

No they are just the cadnica regular 1300mah packs. Regimen wise should they be discharged before every charge? My charger has the option to discharge then charge afterwards? Discharge option i can select 0.1a and 0.1v increments, not sure what to discharge it down to. Charging wise again not sure what to charge at, i can select 0.1a and 0.1v increments...

I see. The primary reason why I discharge my NiCD is to balance the 6 cells on my side by side... But you can't do this on a sports pack, nor is there a reliable way to balance-discharge using just my charger.

I think most people damage their sports packs due to fast charge rate and over charging more than anything. The other cause is people discharging too low using those 'conditioners' that just plugs into the battery connector wiring.

So for sure your charge rate should be no more than 1.3A. For discharge I would not go too low as you have no way to monitor the weakest cell. Most Tamiya ESC's cut-off around 4V-4.5V for your reference, so you might want to start with like 5V cut off before your charge cycle. GL

No worries.... I have set it to 1A and it's on 00364 @ 23 minutes, Does the 00364 mean the amount of mah it has charged it by? If so i presume when it hits 1300 then it's fully charged?

Per your screen:

NiCd is your chemistry
1.0A charge rate
9.10v is the current peak voltage
CHG (status charging)
17:20 17min 20 sec (run time)
271 mAh charged so far..

Depending on how much charge your pack had, it might stop sooner or over the 1300mAh but don't worry about it too much. Battery should be warm to the touch.

If the charger stops (peaks) before the pack is warm to the touch, then you have a bad battery. One or more of the cells has high resistance and you can try reviving it by re-charging it at the same rate, or if that continues to fail, you will want to reduce the charge rate to sub 0.5A and charge over night.

Ok cool...

Ok so it got to 48 mins and about 700mah before it displayed full. Can i ask:

• How does it know what the peak charge is?
• If i discharge this now to then re-cycle should i leave it a while between or straight away?
• What discharge settings would you advise? I have attached pictures of the display...

NiCD has this peak voltage signature when it reaches the peak that your charger will detect. Unlike old timer or temperature based chargers, it is much more accurate to determine when the battery has reached its full charge level.

Honestly I would just run the pack in your vehicle a few times vs doing the charge/discharge cycle. You will not get the full power out of your battery the first 5-10 cycles, but after that you should get the potential max output out of them.

Since I don't discharge my NiCd sport packs on my chargers, someone else can chime in on the discharge setting. I will say to be very careful with this because as I mentioned many times already, these chargers can not detect the weak cell in your sports pack; it is relying on the voltage sum of the 6 cells.

Ok, i really appreciate your time, im pretty new to this as you can tell ;)

No worries, this is a test pack at the moment as i dont want to commit my new ones when im still learning, plus i want them to have the best cycle's from new and prolong life etc...

I'll drain this on my stock 540 motor, i was under the impression it would need discharging more than just when my motor stops? i'll try a 0.5mah charge and see if it goes any further.

Cheers,

No problem. Btw, discharging the battery until your motor stops is TOO LOW.. it can damage the cells.

You will want to stop around 5V range before you start your next charge cycle. Most ESC's will cut-out around 4-4.5V running NiCd/NiMH while the motor is pulling power. That means the pack when stable is around 5V-5.2V (0.83v+ per cell) at the lowest point of charge remaining. Some cells can handle lower voltage, but sport packs tend to use not so high quality cells.

NiCad really old school. One thing with NiCad, they hold a memory on amps. Nimh doesn't have memory you can discharge them to 0v. NiCad's .75amps lowest. Both NiCad & NiMh you cant discharge at 1amp. NiCads can be charge at 10% mah capacity.

Lipo's another type chemistry completely different fro NiCad's and NiMh.

NiCd's are old school, but learning about the different chemistry is cool stuff.
You don't take for granted one chemistry over the other, kind of.. knowing the good/bad of each. :)

I still use my NiCd's and NiMH almost on a daily basis. Only on the weekends do I run Lipo as I don't feel like waiting for them to charge each time. I have a couple NiCd/NiMh packs charged at all times and just peak them week nights before use.

NiCad going back in the '80's, when I started the hobby, with T.A. RC10. '90's the beginning of NiMh. less then 10 years lipo's, started with aircraft. NiCads low in mah(2000-2200mah), good for messing around on street and bashing. Lipo's more constant power, longer Time, charge up anytime, as long as it doesnt go lower than 3v, I set my ESC for cut-off at 3.2v on 2cell lipo's. Just remember Manufacture say 3v, when you run them down to 3v, its the average of cells you run. Running down to 3v, one of the cells may be at 2.95v or lower, may get a low voltage error on charger.

I trashed the nicads. The only Nimh I use for the nitro Starter box. Lipos on my Model aircraft first, the my RC cars.

Have Fun!!