I had to charge my Robitronic Power Stick Pack 7.2 V Ni-MH once more. Since I’m a total beginner at this and I don’t use my R/C car as often as I would like to, I always forget how to configure my charger correctly.

So I had to look for detailed information on the web. The most understandable message I found at this link, post #3:

I have an IMAX charger also. Go into Program – SAVE

> Save a new program (01) with your battery as NimH type.
> Set voltage to 7.2V
> Set capacity to 3000mAH
> Set charge to 3.0A (3.0A for 3000mAH, 4.0A for 4000mAH, 1.8A for 1800maH and so on – as a rule of thumb for the right charge current, just take off the zeros and use a decimal point!)
> Set discharge to 1.0A

Took me a fair amount of searching to find all these but works great. I set up two programs, one for my 1800mAH and 1 for my 4700mAH

You can now use your program to cycle, discharge/charge the battery or just charge.

Good luck!

I also wrote an email to the manufacturer, Robitronic, asking pretty much the same questions. Let’s see if they answer me.

30.12.2016 – Update #1

I haven’t received any answers from Robitronic yet. I’m afraid I have asked too many detailed questions, probably no one at Robitronic will have time to answer them.

Meanwhile I have been researching the internet and I have found another source of useful information. Proper care and feeding of NiMH battery. It still is pretty general but informative.

Also I have discovered that there is not a definite and unique way to measure the state of charge of a NiMH battery. Probably the easiest one to use is the voltage method. A good answer to my question, I found on this forum: How do I test NIMH battery packs?

In conclusion, since I wasn’t able to find complete instructions regarding the charging of my batteries, I decided to proceed as follows:

• Charge with 4.0 A
• I’ll discharge the battery by using the car, since discharging through the charger wears the battery, takes a long time and no fun.
• Every fifth charge I’ll do a smoother charge with 1.0 A

Through my research I understood that, sadly, there is not an exact way of charging the batteries: I have seen many advices, but no black on white instructions. Therefore I decided to create my own “recipe” and stick to it. I’m pretty confident that I’ll be able to keep my batteries safe (as long as I use them!).

The one thing I’m not happy with yet is the charger, which I discovered being a copy of a very well known product: the SKYRC B6AC V2. I should buy the original one instead as the one I’m using now hasn’t got a good construction quality and it hangs every now and then. I’m therefore not sure it is working properly.

And, maybe, in the future I could even consider in switching to LiPo batteries.

08.01.2017 – Update #2

Robitronic finally answered to my email! So good! 🙂 Here below the answer they sent me (in German).

grundsätzlich sollten die NiMh Akkus nicht lange entladen liegen bleiben.
Der Akku lebt von den Lade- und Enladevorgängen.
Im schlimmsten Fall kann eine Zelle defekt werden und somit den ganzen Akku unbrauchbar machen.

Wenn ein Akku wenig Kapazität hat mehrere Lade-Entladevorgänge durchführen und prüfen ob sich der Akku erholt.
Die Ladung kann mit 4A oder auch mit 1A erfolgen.
Entladestrom wenn möglich auch hoch mit 4A.

Das Ladegerät Fullpower B6SAC sollte so eine Cycle Ladefunktion bieten.

Beim neuen Akku erst mal mit 400mA 12-14 Stunden laden.

Wenn auch nach mehreren Ladungen die Kapazität sich nicht erholt ist der Akku leider defekt.

So, for those who don’t understand German, a quick translation.

Don’t keep your battery fully discharged for a long time

They do confirm that the battery shouldn’t be left empty for a longer period of time as one of the cells  could wear out and make the whole battery unusable.

Loss of capacity: how may I try to restore my battery capacity?

In cases where the battery shows a loss of capacity you may try to load it and unload it multiple times in order to restore the original  capacity. The charging could be performed with 4A as well as 1 A,  they advise to unload the battery with the same A used during the charging.

How to charge a brand new battery?

For a brand new battery of 4000 mAh capacity, the first charge should be performed at 400 mA for 12 – 14 hours.

Although I had already tried different things with my battery, I’m happy with the answer they gave me, as they answered all of my questions. 🙂

And I also have one more news! I bought the new charger… and it should arrive the coming week! As soon as it arrives I’ll charge my battery and see if it behaves differently from my old one!