KE4QPF

The transfer is now completed from Rockcrawler.com

Please post your comments at will.

KE4QPF

Hey guys... new here...

For Christmas, I got my first New Bright R/C. The Monster Truck. Unfortunately, the battery that came with the thing totally sucked, so I went to RadioShack and did some modding as follows, and yes, I'm pretty darn good at soldering stuff...

Take 8 rechargeable NiMH AA-cell batteries and hook them up in a series so that the poles face like this:

+ - + - + - + - + - + - + - + -



To help with this, use two 4 AA-cell battery holders (MOD #: 270-391) from any RadioShack, glue them down with a hot melt glue gun to the radio receiver cage (one on one side, one on the other, when lifting the body off) and solder one black and one red wire together, then send the other two down to the battery compartment below through the hole you'll see light coming through near the negative terminal on the bottom of the truck. Bend back the terminals to reveal the wells to which you'll be able to pool up some solder and attach the red side (+) of one battery holder and the black side (-) to the other. Make sure you do this correctly, or poof, it's dead! This will enable you to continue to power the truck off using the switch on the bottom of the unit. By going to any electronics store, you should be able to fnd any additional wires and/or tools you'll need for the soldering process, and every RadioShack definitely has what you'll need in both tools/wires/batteries, etc.

Depending on what capacity of mAh batteries you use, the longer the truck will run. I've experienced a good 5+ hours of run time using this method. I got my batteries from the ULTRA PRO photo battery line from CompUSA which are rated at 2700mAH (TigerDirect.com/COMPUSA.com MOD #: ULT40153)...



...thus giving me nearly 26 watts of available power to the truck... the same rating as a Craftsman C3 drill battery. Making sure you have a good charger (TigerDirect.com/COMPUSA.com MOD #: ULT40033)...



...will ensure you have several successful outings with your truck.

Should you wish to get adventurous, you can add tail lights (RS MOD #: 276-209)...



...which will need a separate 12V automotive switch to shut them on and off from your power plant if you go this route. It looks really good trimmed up with (RS MOD #: 276-080)...



...chrome LED holders. I would not advise using any old 12V bulb because they'll drain the batteries quickly, and I would advise against using any LEDs that need to be connected in a series to make 12V, or cannot handle voltage drain or they'll turn off as soon as you run the motors. I used the Harbor Freight Tools Nitrous line LED strip (MOD #: 98409-1VGA)...



...and found it will just shut off when the motors turn on due to the amps being pulled causing a voltage drop. I'm thinking 2 more AA cells in series will fix this problem.

EDIT: THEY DID!!!

The 2.2V white LEDs from RadioShack (MOD #: 276-017)...

DON'T BUY THESE!!!:



...hooked up in series caused the truck's motors and lights to stutter, and I immediately had to pull them out resorting to "Grave Digger" headlights with the red LEDs I mentioned above. I have not experimented with adding 2 extra AA cells yet to make 12V, so I wouldn't advise doing it just yet with these types of LEDs, just the ones I mentioned as they have the right resistance and voltage variability ratings.

EDIT: AS MENTIONED, WORKED FINE!

Now let's say I want to up the voltage to 12V to negate this voltage drop when the motors are running???? If I add the additional 2 batteries in series to get this thing up to 12V, will it harm the motors which are obviously getting an undervolt issue since the LEDs will shut off at voltages below 9V? I have no clue how the motors are rated, nor have I really played with any other R/C car before. I just really need to know before I blow this thing through the roof.

EDIT: NO PROBLEMS AFTER 1 HOUR OF RUN TIME.

Once again, THANK YOU!!!

EDITED TO ADD PICS OF COMPONENT ITEMS.

KE4QPF

Posted December 29, 2008 06:44 PM

Don't really have a clue. They are the stock ones that come OEM right out of the box. I'm assuming it would be the same front servo-back motor set up as I found with the other cars/trucks/crawlers I found on this site. There have been no mods done to the motors since I cracked open the box on Christmas day.

texx

HELLO .. KE4QPF ..

These mods will follow ..

KE4QPF

Posted December 29, 2008 06:55 PM

But if they run between 4.5-6V, why the 9.6V OEM battery? Is that to factor in receiver drain? You'd think the motors would handle at least 9.6V to keep from blowing!?!? They're getting almost 12V under no load right now with the NiMH AA batteries fully charged.

KE4QPF

KE4QPF

KE4QPF

Posted December 30, 2008 12:01 AM Looks like the only problem you had was keeping it from running over your camera.

KE4QPF

KE4QPF

Posted December 30, 2008 03:38 PM

Thanks to your encouragement and help, some additional power plant work to boost it to 12.0V, and a minor soldering iron 'splatter burn', my Monster Truck is completed...













Thanks to you all for the advice!

KE4QPF

Posted December 30, 2008 04:36 PM

Thanks for the kudos on my wire work. I work for the local cable co. down here, so it's a force of habit in everything I do. I got the idea for the blue glow from all of the rice burners down here in South Florida running the neon lights under their cars. These LEDs are meant for just that purpose, however, I don't think they are as much of a PITA as a full neon kit. I just couldn't imagine how I'd get that transformer bolted onto the bottom, so I made due . It does make it stand out, dontcha think??? That's why I had to ask about boosting the 9.6V setup to 12.0V. When running the motors under load, the friggin' blue light kept going off because I ran the thing below 9V. It works much better now. At least it stays on, although it does dim a tad when running. I had this thing out in the street and had an ice cream truck clock it while doing a drag race. He told me it got up to about 10MPH, and that was after running it for about 30 mins. Not too shabby. As for the video of it, I'll have to wait until nightfall so you can see the blue streak!

Posted December 30, 2008 04:51 PM

I went back and edited my original post so those who want to see what components they'll need have visuals.

KE4QPF

Posted December 30, 2008 05:54 PM

The chrome holders are only US$1.49 each on RadioShack.com. Obviously, you don't have Bush in charge over there, so your money has to be worth gobs more than mine. RadioShack does international orders, so you should be able to place an order with no problem on delivery to the UK. I thought there were "RadHacks" in the Queen's Dominion!?!? I like how you rigged the flashers. Now you need to progress. If you're that handy with a soldering iron, for the love of God, find a good electronics store. I'm sure your imagination will take that thing places you've never expected.

KE4QPF

KE4QPF

Posted December 31, 2008 10:39 AM

It only spins the back wheels. Front wheels are servo controlled for steering.

KE4QPF

Posted December 31, 2008 10:59 AM

KE4QPF

Posted December 31, 2008 11:36 AM

KE4QPF

Posted December 31, 2008 12:56 PM

KE4QPF

Posted December 31, 2008 01:25 PM

KE4QPF

Posted December 31, 2008 01:57 PM

KE4QPF

Posted December 31, 2008 02:29 PM

KE4QPF

Posted December 31, 2008 03:13 PM

No problem. Thanks for your kind words!

Each 4-pack of AA batteries was US$14.99, and it was basically becuase I'm an impatient arse who couldn't wait for mail order and wanted the MAX capacity I could find for NiMH. The charger was US$29.99 and came with 4 in it. All links have now been added to the original post regarding the build components. Please keep in mind that the truck WILL RUN on 8 AA cell batteries to make the 9.6V. My issue came with adding the 12V lights on as LEDs will not operate when the voltage drops below their diodes' threshholds... they just shut off.

Most 12V LEDs will operate at 9V with no problem. Unfortunately, the motors inside the unit for steering and drive train caused the voltage to drop below 9V, thus requiring me to add the additional 2 AA cells in series. Just remember, if you hook them up parallel, you add to the overall mAh by adding the mAh rating of each cell together for your total, and if you hook them up in series you'll add to the overall voltage by adding the voltage rating of each cell together for your total. Hence 10 AA cell batteries @ 1.2V = 12VDC.

I went with the highest mAh rating I could find for AA cells since I needed the series to increase the voltage and didn't want to have to double up (mainly for weight reasons) to increase the mAh. Yes, I did get it to run a long time, but unfortunately, not for 10 hours as I previously thought it would... 3 hours was all I got with flat out flooring the accelerator, but it's still better than the quoted 15 mins. I got out of the New Bright pack. So basically I increased the run time by 12x. The truck ran at an average of 10MPH when drag racing the ice cream truck down my block.

The main reason for using these types of batteries is because with NiMH packs, if one cell dies, you're screwed, the whole pack is crap. With a good multi-cell charger (one that constantly monitors each cell's charge level and determines if it needs discharged and rebuilt), and the ability to swap poor performing or dead cells, your investment will last a hell of a lot longer and you'll find yourself spending less in the long run as you'll be ditching twice as many battery packs as you will individual cells. all it takes is for one cell in a pack to reverse polarity (which is pretty common in cheaper cell builds), and the whole pack is smoke.

KE4QPF

Posted December 31, 2008 03:20 PM

I think it's done from the standpoint that most of the beating on a monster truck would be up front... crushing cars, big-headed posters' "my hobby build is better than your toy build" cars, etc. If the front tires are off the ground, they perform no function spinning and eating the batteries.

So with that said, if you're jumping cars and stuff and have the front wheels of the ground a lot, the 4x4 is worthless to you... 2x4 is perfect. It places the power to the back of the truck where you'll need it most. If you're looking to road-off the thing, then 4x4 is the answer for you.

KE4QPF

Posted December 31, 2008 03:40 PM

KE4QPF

Posted December 31, 2008 04:48 PM

Update on the Harbor Freight Tools Nitrous "Blue Streak" LED light. I just upgraded the thin clear cable that came with it (probably 28-32 AWG) to some of the colored hookup cable (20 AWG) I used for the rest of the truck on the lighting hookups (RS MOD #: 278-1222), and now the light doesn't dim nearly as much as it did after upping the voltage to 12.0VDC. IT PAYS TO USE GOOD CABLE!!! Take it from the Edison vs. Tesla days... Tesla's AC won out due to DC cable needing to be of very high gauge to transfer power over significant distances... an expensive proposition when making power distribution for the masses.

KE4QPF

Posted December 31, 2008 04:55 PM


I don't really know what kind of motor it has in the read-end. When I looked into the cage, it was a huge silver can motor. I tried popping the latches to pull the cage off , but they snapped off in my hands. After doing this, I figured the thing would flop open easily, but the rake on the back has 2 screws that hold the whole thing together and the seams might be friction welded?!?! It did not want to come apart. The wires running from the motor are much thicker than the cable I used for the lights and I'd approximate it at about 16-18 AWG.