Noob NiMH First Charge.
 

Hi everyone,

I've just got my first packs of NiMH batteries. Been out of R/C for a while and last batteries I used were NiCd.

I just have a few questions before my first charge as I would like these to last a while. They are Intellect 4200's and my charger is a Swallow EQ.

I've just taken it out of the box, connected it up to the charger, and what now? Do I:

1. Discharge it first, then charge it? Or
2. Put it on charge straight away?

If it's the first option, what rate do I discharge at, and what rate do I charge at for the first charge?
If it's the 2nd option, what rate do I charge it at?

I m guessing for the first charge I will need to do a trickle charge for about 15 hours?

Also, after the initial first charge, what rate do I charge these at? How often do I need to do a full discharge/charge? How often do I do a trickle charge?

Sorry for all the questions but the last charger I used was plug it in, turn the dial, that's it.

Thanks in advance :)

Ill trickle charge the first charge to peak it out nice... 15 hours at 1amp or .05amp (half amp) sounds ok.

When you quick charge them I like doing mine at 3.5amps. But you could go 3amps thru 4amps quick charge. Your soppos to discharge the pack everytime you run it low to help keep the cells matched.

I'm sure you could get better info tho

I dont like to discharge Nimh packs. Most manufacturers dont recommend it either. They also dont recommend trickle charging.
I get the best performance from my IB4200s by charging at 4 amps, stop running as soon as it slows down, and charge at .2 amps for 24 hours once every 4 cycles. The slow charge allows the cells to balance at the peak, instead of at full discharge. Some like to balance at full discharge, but I think if they are balanced at full charge they perform better. Think about it this way, the cells may not be exactly 4200mah each. If one is 4250mah, and another is 4150, then when you balance them at full discharge, then charge them at 3 or 4 amps, the one cell that is 4150 will reach max charge sooner, then while the other is still charging that cell will get a slight overcharge. It may be a small amount, but over time that cell will lose more and more capacity from slight overcharging, then it gets worse and worse. On the other hand, if you balance them with a slow charge for 24 hours, they all get a full charge without the possibility of overcharge. At such a slow rate they can bleed off any extra charge as heat.
These cells are really ok with whatever, except overcharging and over-discharging. They dont have memory like Nicd, so unless you prefer to balance them by discharge, then there is no need to do it.

Cool thanks I'll keep the tips in mind.

It's all so confusing...

lol, sounds like everyone has their own way.

SMC website

only change i would make is charge at 5 amps instead of 6

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To maintain the performance level of these cells please follow the tips below.

Before the first charge: The cells have been stored with a small amount of charge in them to help maintain the highest possible capacity. All new generation sub-c cells self discharge fairly fast. Not all cells self discharge at the same rate so it's important to place them on a discharge tray that will bring all the cells down equally. If your tray has a cutoff, set it at .90 volts. Trays with no cutoffs that bring the cells down to zero volts can be used but it's important to not keep the pack discharged at zero volts too long. As soon as the all the lights are off on the trays with no cutoff, you must then start charging your pack since leaving the cells at zero volts for an extended period of time will result in a drop of capacity. The pack will perform at its best after it has been run once, as the cells tend to be unbalanced after being stored with charge.

Charging: Use a high quality peak detection charger. Use a 6 amp linear charge with the peak detect (voltage threshold) set at .005(5mv) per cell. A 4 cell pack would be set at .02(20mv) and a 6 cell pack at .03(30mv). If you own a temperature gun we like the packs to peak around 140 degrees Fahrenheit.

After the race: For maximum performance it's important to discharge the pack after a race. Discharge at 30-35 amps down to .90v per cell. This means 3.60v for a 4 cell pack and 5.40v for a 6 cell. Prior to charging the pack back up you should follow the traying method described above.

More than once per day: You can use your pack more than once per day. This will make the runtime drop slightly, but in most types of racing there is runtime to spare. Make sure to let the pack cool down for a period of 2 hours in between charges. Repeat the traying method described above prior to charging the pack back up.

Storage: After you have finished using your pack and you want to store it, we recommend you wait until the pack is cool then put 600 seconds of charge back into the pack. For long term storage (3 weeks or more) you should discharge/tray the pack then put 600 seconds of charge back once every 3 to 4 weeks. This will keep the cells from self discharging too low and keep the capacity as high as possible.

^^^^ I always ask the seller I'm buying from what they recommend - some say nothing special needed, others tell you to run a breakin period with them. They should know best....

+1 for blue i use the smc method as well i have seen great results from it

Yah I would listen to BlueB44, you need to discharge for max life and performance.....:deathstar

Thanks for all the help guys, I did my first charge this weekend.

Started off abit weird. I took it out of the pack. Set it to a Discharge > Charge cycle. It finished in about 5 minutes.

Thought it was abit weird.

So I pulled it out, plugged it into the car, and sure enough nothing.

So I put it into the charger. Set it to 4.2A (4200mah cells) and that finished charging in about 11 minutes.

Thought that was abit weird. Put it back into the car, there was enough charge in it for me to drive around for a bit.

Then after that. I set it to 3 Charge > Discharge cycles. That took more than 12 hours to do!

And now everything seems to be working fine. Charging at 4.2A takes about 50 minutes.

I may have damaged that battery... I m not sure, but yea, live and learn.

Thanks everyone for your help.

That 11 min charge was prob a false peak which are common, next time check the batt and if its not hot, just charge it again, you may have to do this a few times.

Watch how hot they get when charging. If they are getting so hot you can't hold them, stop and let them cool a little, then go back to charging. Getting really hot can damage them.

Ahh, so what's the deal with this 'false peak'? Any reason why it does that?

Also, on my Swallow EQ charger, there is a number in the top right corner. What is this number?

On the bottom right it shows the voltage, what is the purpose of this indicator?

Thanks.

I'm guessing but were you on AC when you had the probs? The peak the charger is looking for to terminate the charge on is only a few mv. If something else somewhere in your house thats connected to the same circuit turned on or was turned off, that can be enough to cause the false peak. I had a lot probs with false peaking until I moved the charger to a diff room that was on a diff electrical circuit in the house. My probs were only at high charge rates at the max or near max charge rate charger would run at. Lower charge rates this is not as much of an issue.

False peaks can also be caused by voltage spikes from the utility company.

I can't find a good pic of the charger when its on, so I have no idea what the number is. The voltage is either the input voltage to the charger or the volatge across the battery while its charging.

Cool, makes sense, the charger is in a one of 4 outlet. I didn't damage the battery by doing that did I?

Here is a pic I took before. I've got the charger doing a discharge>charge cycle.
Charging at 1.0A and discharging at 1.0A over 3 cycles, this is a brand new battery and doesn't seem to have false peaked or anything.

I just dont knowwhat the top right and bottom right numbers are.

Top number is mah. and the bottom number is the battery voltage.

False peaks won't hurt the battery, they are more of a pain than anything. IMO

I don't know. It just doesn't sound right to discharge so much on a NEW cell.

If it doesn't hold a charge just keep trying to wake it up. Stop the discharge intill you get a GOOD FULL peak. After a good full runtime with the car. Then do the whole discharge thing.