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  just Stampede, Traxxas,
  to now include other
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  enthusiastically promote
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     Take a look through
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  coming...
  - Tony

  StampedeProject.com

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Battery Charging

There is a whole geeky-ness to this battery thing which I will avoid in this article.  There are better articles that get into the mathematics and charger recommendations of batteries and charger than what I am willing to discuss.  I will attempt to greatly over simplify this for everyone who just wants to focus on fun rather than charging rates and delta peaks.

Good general article to read
RC Central - Focuses on the MRC Super Brain 959 charger but good general charging info and this Dream Models site

Charge Rate - Usually specified in amps, this is the rate of "juice" the battery sees per a period of time.  Think the rate of water difference between a garden hose and fire hose.  More water in a given time going on the fire.  Same with the battery, the higher the charge rate the more power the battery sees, and the faster it will charge.  To save you the calculation on a standard 6-cell battery pack - the recommended rate is 2-3 amps on a broken-in battery.  Be careful on specifying to high of a rate, slower is normally better and will extend the life you your battery and a .05 rate is great if you are patient enough for an overnight charge.  The default setting on my MRC Superbrain charger is 2 amps.

Peak - The peak specifies how much further the charger "overcharges" the battery after it is fully charged.  Peaking the battery will increase its punch, but will shorten the life of the battery if it is set to high.  My Peak Racing Power Maxx batteries specify a maximum peak of 48 mv. However to be on the safe side, I would go with the general recommendation for all NiMH 6 cell packs - 30 mv,

New Battery Conditioning and Old Battery Re-conditioning - A new battery, just like anything else, needs to be broken in to establish and set it maximum peak on the battery.  There is one and only one way to do this, slow overnight charging.  Set you charger on the lowest non-trickle amp rate setting (probably .05) with a delta peak per the following: 

For NiCad batteries, the delta peak voltage should be set to 10mV multiplied by the number of cells in the pack, or 50mV, whichever is lower. For most NiCad packs, this means that the 50mV setting should be used.

For NiMH batteries, the delta peak voltage should be set to 5mV multiplied by the number of cells in the pack. So a 6 cell NiMH battery pack should use a delta peak voltage setting of 30mV

Go play and discharge the batteries completely (until the RC car's wheels stops rotating on a flat surface).  The wheels will still spin at this point if you pick up the rear of the car.

Allow battery to cool to room temperature.

Then repeat follow the above procedure three times for each battery.

Your battery peak should now be set and your battery broken in and your can now use a more rapid charge rate so your batteries will charge in about 30-40 minutes.

Batteries - Broken In

Your battery peak should now be set and your battery broken in and your can now use a more rapid charge rate so your batteries will charge in about 30-40 minutes.  Now you can let that fancy charger do its job.

MRC Super Brain - At around $50 the MRC SuperBrain is probably the best charger value on the market.  It will charge pretty much any RC battery you will ever buy except the LiPoly, automatically detect the cell count and capacity of the battery and stop charging when the battery has peaked, all with a push of just one button.   

I have heard a number of people say that the MRC false peaks on occasion, I have found this to be true in two circumstances, first when the charger has in its second or third charge in a row and becomes too hot, or because I didn't allow the batteries to cool enough prior to a re-charge.  On Mis-Behavin's site he suggests a false peaking remedy for the first generation SuperBrains, but I have it on good information that all the Superbrains less than four years old have already had this issue resolved during manufacturering.  One issue that does seem to be a little bit of a problem when charging batteries in succession is that the charger does heat up. Many people will simply wire in a Radio Shack 110V fan into the charger and mount it on top to keep the charger cool during these high use times.  What I did that seems to work pretty well is remove all the secondary vent covers.  These are the pieces on the inside that don't allow you to see directly into the charger. Removing all these little covers greatly cooled the charger and eliminated any problems I have experienced with the charger overheating.

Keeping in mind this a really good charger, fantastic even for the price, there is one other little issue that slightly annoys me.  I would like full control of setting the delta peak instead the .5 increments provided.  As an example a 3300 should be charged to a delta of 3.3 but on the MRC you can either choose 3.0 or 3.5.  Yes I know it isn't much of a difference, but annoying never the less.

Overall I have had my charger since I started this hobby, well over 3 years ago, and have been very happy with it's charge times, and battery care.  I still have 3 year old batteries that perform outstanding due to the SuperBrain's ability to not overcharge my NiMH batteries (very key).

The New SuperBrain Charger will also charge LiPoly batterys and promises to remedy some of these minor complaints.