rzingsheim

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I have built a 1/6th scale G I Joe jeep with 4 wheel drive from some of the drive train components from a Crawler King. I did it with leaf springs to keep it as scale as possible. I even have a G I Joe trailer that I converted to leaf springs. I am looking to replace the Duratrax 7.2V 4200 mAh NiMH battery with something a little lighter and with longer run time. Can I use a 2 cell 7.4V Li Po? Any recommendations? I am not looking to do serious rock crawling, more scale WWII Jeep performance. I don't think I need a high C rating?, just good power and long run time. If I had a clue how to post pictures, I would. It turned out very nice.

SyCo_VeNoM

to post pictures
1 Make sure they are on your PC, and you know where they are
2 Look under the text field when typing in a post, and click upload picture. Personally I use the"Click here to upload images and files" option as the BETA one has messed up a bit on me.
3 Select the pictures one for each line if using the right upload option(or if using the beta I think you can just mass select them)
4 Press upload
5 Wait till upload is complete, and press done to close the upload window (this is WAY more important then it should be as if you don't the pictures end up in some spatial anomaly never to be seen)
6 Finish your post, and hit ok



Now to the battery yes you can use a 2S lipo, and if the battery box is the same as the wheely king(99% sure they are just the CC's is in the front) there are a pile of low cost lipos that would do the job.
Only thing is as I'm guessing its brushed (and possibly the EN-1 ESC) you will need a lipo LVA, but those are pretty cheap at $4 or so on ebay all day.
Batteries that fit in my WK's box
http://hobbyking.com/hobbyking/store...dProduct=14976 if you cut the spot where the wires come out to be a little bigger it would fit perfect, but that isn't needed as the door will close as is.

And unbelievably http://hobbyking.com/hobbyking/store...dProduct=14991 BUT this was a EXTREMELY tight fit(and kinda hard to get out), and would require a bit of cutting of the door for the wires to allow the door to close. I'll be honest I didn't even think I could squeeze it into the battery box(definitely couldn't close the door).

I'd go with my 1st rec of the 2. Also any lipo with the dimensions of the 1st should work.

rzingsheim

My Feedback: (4)

Thanks for the info. I'm not using the battery box so anything about the size of the original battery should work. Is there any danger of running the lipos to low? Some people have talked about some kind of cut off? I won't be running this real hard and I'm thinking if I'm careful I shouldn't have a problem. Also I'm going to give attaching photos a shot in a few days.

SyCo_VeNoM

Yes if they go under 3 volts per cell might as well throw em out as they are dangerous to charge, and could burst into flames which need a class D(or is it C) fire extinguisher to put out as water will only make it more violent.
Most lipo chargers will display an error to keep the user safe if they are over discharged.

Which is why I said get a lipo Low Voltage Alarm they are dirt cheap(like I said $4-5), and plug in the balance port of the battery they will start an alarm if ANY cell hits around 3.3 volts where low voltage cutoffs only trigger off total pack voltage. The alarm won't cut the power like a cutoff will, but trust me the alarm is LOUD, and annoying you will want to stop running one it starts, and it can be heard from pretty far away

The Real Dogman

I have a different perspective.

I have a few batts that were over discharged to the point my Hitec 4X charger would not charge or recognize them,,,, Until I set it for the next lowest cell, in other words if I accidentally overdischarge my 3s batt I set the charger for 2s and use the appropriate adapter. I only charge the 3s set 2s longe enough to get the bat up to the minimum the charger looks for on 3s so up to at least 9.4-9.6 volts, then I set the charger back to 3s and it charges fine. I also use those batts on a regular basis which means I probably have over 30 charges on them since the "tickle charge" to bring up to 9.6vlts. This does not always work, in those cases I will use a different charger to just get a little voltage. If you need help with that I can discuss further with you. You don't always have to buy new batts, at least you can save a few.

I must warn you tho, Always charge in a proper lipo bag!! Its just responsible hobbying. And always watch them while charging, be sure they dont get too hot!!

SyCo_VeNoM

So you cannot agree with playing safe with lipos?

I will admit it all matters how far you over discharge em...

If its .1-.3 volts you MIGHT be able to resurrect the pack(I wouldn't charge that pack in the house though). As you used 3S I'm guessing you used it in a brushless application where there is a LVC which probably was set too low, and the packs were out of balance, but still cut off before damage was done.

He wants to use it on a brushed rig with no LVC where he could run it to empty with no warning. There is a HUGE difference in .1-.2 volts under on a unbalanced cell or running a cell 1-2 volts down. Also if you look at the discharge rates of lipos its EXTREMELY easy to over discharge em on brushed crawler where you won't see the hit in power as readily as a brushless RC cause yu are not going full blast most times.

Personally I prefer to play it safe, and not play russian roulette as the device to monitor the batteries costs a whole whopping $4 to warn you, and keep them from over discharging...
And the advise I give will reflect playing it safe specially to someone new to the battery tech.
Now if you have been into it a while, or like taking risk go right ahead and do what could rupture a cell I've only talked to a guy who lost their houses in lipo fire on the board in the past due to them igniting while charging from now following proper safety precautions. Also talked to one that started his kitchen on fire, but he was able to put it out before it spread , and did real damage.

The Real Dogman

I ask that you respect the OP and clean up this thread for him!

SyCo_VeNoM

Won't argue about the bag I charge mine in the bag, and that sits in a US army ammo can I picked up cheap.
Saw a guy on youtube test out the ammo can with a lipo he purposely set off, and the ammo can was still able to be picked up bare handed as it barely broke 100 degrees before the fire got smothered out due to lack of air. I use the can cause where I charge there is no way in hell I would ever make it out in time if it started to rupture so I can just slam the lid.

Well as for assuming the 3S on brushless I was basing it on standard 540 can turns. I guess if its like a 55t motor or higher you could use 3S, but from experience 27T motors will die a fast death.

As for why I said about your post it wasn't due to insecurity, or you ruffling feathers(you seem more butt hurt in all honesty from your reply), from reading it you just say you over discharged batteries, and it was ok to recharge them, but never how far you went(so one can only assume if everything isn't presented). You also say you cannot agree with my post which means you disagree with the whole thing like having a LVA or LVC as you mentioned NOTHING about them in your post vs saying you disagree with my view on when the battery goes under 3volts a cell. Honestly reading your post sounds like your saying no you don't need any detection, and over discharging them is fine with no reference to how far you went down as you can just pop them on a different battery mode to resurrected them(that is how I would read it if I was new to lipos and didn't read anything else). You also don't state how many times you did it, and that you could damage the battery.

As for the two people I mentioned you are correct they got over confident cause they knew what they were doing, didn't play it safe, and made a huge mistake that cost one their house, and the other a kitchen set.
I think the one charged a 2S as a 3S or something stupid cause he didn't bother looking at the screen, and left it unattended. Other plugged the battery in to charge while in his truck on the kitchen table, and fell asleep to wake up to the table on fire as the battery melted clean through his vehicle(think those 2 were from about 3 years ago when the board had way more people on it).

So like I said its nothing about being insecure its about telling people proper lipo safety that are diving into them so accidents don't happen.

Side note I don't mind when people disagree with me, or prove me wrong as it gives me another angle to look at something that I can use in the future. There have been times people have proven me wrong, or told me why they disagreed, and guess what my views have changed a bit.

Edit: to clarify a point a little bit

rzingsheim

My Feedback: (4)

OK... How about getting back on track. I appreciate the concerns regarding Li Pos and their dangers. While I'm new to ground vehicles, I have been flying R C planes for many years and the fleet includes 7 electrics with Li Pos. I charge with a Hitec X4 multi charger. Regarding the Jeep, it's weight is 8 lbs 7.5 oz including battery. I don't know if this is heavy or not. Again, I'm not rock crawling with it, just driving it around like a WWII Jeep. One of the reasons to possibly switch to Li Pos is some weight saving. The NiMH I mentioned earlier weighs 15.4 oz. These "solid" car packs seem really heavy compaired to flight packs for planes. If there is another solution, maybe lighter NiMH types, I'd be interested in that info as well. If I can gain some longer run time ( more mah? ) that would be great as well. I have read some coments that switching to LiPos made there vehicles faster and more tork. The last thing I need is more speed. I'm trying to run it at a max speed of about 7.5 mph, which being that it is 1/6th scale, equates to 45mph which is about it for a full size WWII Jeep. Most of the driving will be in the 2-3 mph range.
One other concern. I have done some test running around on the lawn and after 5 min. or so the speed control heat sink feels pretty warm to the touch. Is this normal?
Thanks.

SyCo_VeNoM

Ok sorry bout the lipo safety thing its hard to tell what experience people have. Would have really helped if you said that so the info could have been tailored

As for temps it should be able to handle 155F temps, but I don't like to go past being able to touch it without burning my hand temps. You could use an IR Temp gauge to check what it hits at various points, if too hot gear down.
Motor can hit 170F after that you risk destroying the magnets.

If you go lipo the speed increase won't be much, just it would seem faster as the pack will hold its voltage higher longer. If you ever looked at the voltage curves of a NiMh, and Lipo you would notice they start off almost the same (I think its .2volts difference) but the NiMh starts to drop off immediately, and linearly where the LiPo will stay up and just plummet when it gets near 3V a cell. To offset the heat that will be generated from a lipo you could gear it down 2-4 teeth as according to tower stock its a 21t pinion.

As for lighter NiMh's from my experience they only get heavier I've had NiMh's in a lot of different capacities, and the 5000mah's weight difference from a 3800mah pack was quite noticeable in comparison to a 3800mah pack, and a 2200mah pack. It also would vary by brands, but I doubt by much as there are only a handful of actual battery cell manufacturers.

rzingsheim

My Feedback: (4)

OK, This will be my first attampt to post a picture. Cross your fingers! If this works I'll send more.

rzingsheim

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Some more shots of with the driver and General Omar Bradley.

SyCo_VeNoM

Looks damn nice
Curious how it looks underneath. Those tires, and rims look perfect.
Were they modified off the original?

rzingsheim

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Some shots of the drivetrain.

rzingsheim

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Some trailer shots.

rzingsheim

My Feedback: (4)

The last. One shot off road. One under the hood. I like to keep things neet and tidy.

The Real Dogman

CrawlerKing!! Great choice for your drive train!!

SyCo_VeNoM

The underneath pic answered my turn radius question I was typing in. It looked extremely limited in the 1st pic, but I can see its way more than I would have guessed.

That's some damn nice work, and that thing is pretty damn huge.

rzingsheim

My Feedback: (4)

Thanks for the positive feedback. Regarding the rims and tires, I ground out the outer hub area, leaving the center intact, from the Crawler King ( C/K )wheels so they would mate up to the C/K axels. I then ground away the center of G I Joe wheels leaving some overlap. The area in the center of each wheel with the raised area with 5 lug nuts is C/K the rest is G I Joe. I aligned them so they would run true and tacked them with C A, than layed in a fair amount of Aeropoxy on the back side for strength. It's a white 2 part aircraft epoxy that gets hard enough to tap and thread. On the outside, after the Aeropoxy hardned (24 hrs) I filled in the joint with regular epoxy so the two pieces would look like one wheel once it was painted. It turned out very well and so far in tests they have held up perfectly and it still uses the C/K nut to mount the wheels if I need to remove them. The wheels are G I Joe. I soaped them up to remove them for paint and did the same for remounting.

SyCo_VeNoM

Honestly man stop trying to start a fight.

I said check the temps, and the upper limit ESC's can take cause its after 5 minutes. If he said it was after 15 minutes I would have said its fine.
Personally I would still gear it down 2 teeth and test.

But I forgot you are the all knowing expert, and its where you make a living go on ahead I'll back completely off answering any questions from now on and just comment on how cool it looks.

rzingsheim

My Feedback: (4)

The turning radius on grass or dirt is about 8 ft. On hard surface maybe more like 10. I could have gotten more but it would require too many mods. I believe a real jeep of that era had a turning radius of around 36 ft. which would be 6ft scale so I'm not too far off.

SyCo_VeNoM

Damn that is a lot of work, but it paid off in the end with a cool looking ride.
I've always sucked at finishing touches like that.

Will agree with Dogman on the weight not being a big issue we have a guy from Russia that occasionally posts that made a WW2 truck(seriously it was a spectacle) from scratch out of steel tubing, and sheet metal the WK tranny was able to push that no problems. I think that weighed quite a bit more than your rig too.

The Real Dogman

Geezus, really, I said I was not saying you we're uneducated. Get over it, this guy has a legit thread with a killer build. I was trying to get passed the crap. Stop bringing the personal crap into it!! I am sorry for my part in it as i cant stand it. In fact, once you have had a chance to read this, I am going back to delete anything I may have wrote that you might be sensitive about and clean up this guys thread! I would think you would do the same and move on!!

i build crawlers and scalers as a means of income, so I would say without bragging this is an area I do know a bit about. And too much time has been spent on this rhetoric.

sorry rzingshiem, hopefully we can get this crap cleaned up for you real soon!! Killer jeep!!

rzingsheim

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The Jeep and trailer I got seperatly on E-Bay. Just search for "G I Joe Jeep". The jeep is from Hasbro and it will have 2002 or 2003 year stamped on a cross member on the bottom of the frame. It comes with posable ( they pivot ) front wheels. The frame is removable with screws which helps. You'll have to grind away the molded-in axels from the frame but it's pretty strait forward. When you remove the front axel you will have to reattach the front bumper as it gets seperated then you remove the axel. There are usually 5 to 10 on E-Bay at all times. There are several versions. Most don't have the canvas top. Some have mud color paint to simulate mud on the tires and body. Some are in desert tan with lots of fuel cans. Try to find one that is as complete as possible but not necessarily in the box. A word of warning. The more "minty"it is the more it costs. The one I used was displayed and out of the box but was never played with. I think I paid around $100.00 for it. Some guys are asking 2 and 3 times that but if you are patient and keep checking you can usually get a deal. There are original Hasbro jeeps from the 60's but they are not scale at all. I doubt they would work very well. There are some by "21'st Centery" that look good too, I just don't have experiance with them.
As far as the trailer goes Hasbro never reissued them so the only choice are the 60's models which I also got on E-Bay, same site as the jeeps. Fortunatly they are pretty good looking. The only thing I changed were the axel, spring, wheel, and tire set up and the actual mounting for the hitch. Almost all the ones you see will have the hitch "eye bolt" broken off or missing. I used a ball link and rod from parts of the axel controll arm suspension from the C/K chassis for the hitch eye bolt. See previous pictures. I also added safety chains. I bought a second "parts missing jeep" to get the rear axel wheels and tires so they would match the newer ones. The originals were one piece plastic. I had to cut the axel in half and widen it by sliding the axel rods in a brass tube. I repainted it drab olive from a spray bomb and replaced the red "tail and running light" stickers.
The leaf springs shackels and mounts for the jeep and trailer were also from E-Bay.

The Real Dogman

Nice! And yes ebay is a great source. I am currently watching a few!! You did a great job piecing together an excellent example and rc-ifying it! Got any video of it yet?