What Lipo ?
 

Greetings

I'll be running a Lehner 1940/6 9918,combo in a SuperGMaxx, singlespeed, don't know the weight yet. This unit will be used only at the local track. Speed runs are not on the agenda. Well maybe once or twice.I must buy batteries either NIMH or Lipo. I am leaning towards lipo, for weight and runtime reasons. With Lipo I will need charger, power supply and packs. Keep it safe.

Thanks in advance for your advice ,recomendations, and links? :P:

Heres a pic.

4s Lipo would be my choice. I use the Kokam 3200 cells. If you only race for 5 minutes, these work quite well. I don't use any type of voltage cutoff device, but I only run for 5 minutes also. These are available at Tower hobbies, along with the astroflight lithium charger. They also make packs with a cutoff built in, along with the ability to quick charge. For longer runtime and safe running, a pair of the 6400 mah 2s scorpion packs in series would be pretty sweet. This is slightly heavier than 12 cells, but with 6400 mah of power and 120 continuous amp draw capabilities, the performace would be very nice(better than 14 nimh cells).
Sweet truck, by the way! I have a similar truck, but I use the towerless vbs and a custom rear skid to use the extension on the chassis(no wing on my truck, either).

Mike

Mike

Our qualifiers are 5min, mains 10min, I'll be in the same class as the nitro boys. These packsbalance pro intrigue me. I am concerned about both cutoff and cell balance. Mike I'd like to use the G Maxx extension but have not figured out the skid thing. How did you do it? Are the packs with the cutoff built in the scorpion packs? Have you got a link to the Astro flight? Is this it?Astro flight

Thanks

I used the g-maxx front skidplate, a stock rear skidplate and the UE rear skidplate to make the custom skid(used these to line up the chassis braces with the ext. length and get the hole locations for the rear bulkless). I basically drilled the UE mount holes into the g-maxx skid and cut away the excess material on the outside.

The scorpion packs have the voltage cutoff built in. The scorpion charger allows quick charging as well(astroflight doesn't). That is indeed the astroflight charger I use.
The 6400mah packs will get you through the 10 minute mains. You should lap the nitro guys if you can drive well enough.

How would you wire the scorpion packs? Looks like a few more wires than I am used to? Will I be able to get 6v to the servo's?
Would the balance pro packs work with a voltage cutoff wired in line?:C: With the skids I imagine you had to counter sink the new mounting holes? Would a bench grinder/dremel work for removing the extra material? Yeah some driving skill would be helpful I am sure!:L:

The balance pro packs would work as well, but the advantage of the scorpion system is the fast charge and built in balancing/charge/discharge cutoff. I would use a series connector from the controller(as described in the "how to program your BK controller" post stuck at the top of the brushless forum.
I did have to countersink the new mounting holes. And a bench grinder/dremel would work fine(this is what I used, as I did not have the mill when I did it).

You are the man!;)

I thought the gmaxx extension came with the bottom skid. Or am I missing something.

It does come with the skid. Unfortunately, the Gmaxx skid does not match up with the UE VBS.

OKay. I understand now thanks papa. I was confused for a second. I thought I messed something. Sure enough I did. By the way. I like the looks of you ride so far. Keep up the good work.

Just an FYI - if you have a speed controller with lipo cutoff or a seperate device for LVC, you should get the BalancePro packs. They are cheaper by about $10-$20 per pack and they are the same technology as the Scorpions, minus the LVC.
I use the BalancePro 2s 6400 in my Brushless Jato and rely on the cutoff from the MGM controller. Considering I haven't been in a race longer than 5 minutes, it hasn't been a problem at all.
I do plan on running two of these packs in series to power either my 1/8th buggy or my MGT.

I like the sound of a LVC, the 9918 does not have one. I thought there might be a way to wire one in. However scorpion packs may be simpler.

Hey Mike. On the scorpion packs. Do you use a y-connector between the esc and batteries and a y-conn to the reciever? Or. Do you use only one batteryto determine cut off? Hey Batfish. Do you use the kokam fast charger? If so, how do you like it?

You can get FMA's LVC device that will work with up to 4-cells of lipo: https://www.fmadirect.com/site/detai...989&section=35

Yes, I use the BalancePro fast charger (it's the only one approved for use with the batteries) and I think it works just great. I can't charge my pack at the full 3C that they're capable of since it's a 6400 pack and the charger won't go to 19 Amps :) . It does, however charge the pack to over 80% in about 20-25 minutes, although I can't completely verify that since I haven't run it down to 6v yet either.

The new SkyVolt system from FMA looks great for high-voltage applications, but I don't have a need for high-voltage in racing. You can, however, get a 6s3p 9600 for only about $1,000 ;)

I have question. On lipos like batfish just posted the 6s3p. I know what the 9600 stands for. what does the 6s 3p stand for. I would guess 6s is like the number of individaul cells in the pack. The 3p I guess is like 3 cells in parrellal form to get the 9600. Does that mean there are 18 lipo cells in that one battery?

After looking at the scorion manual it seems like the speed control connects directly to the battery. Then there is a 3pin plug from the batterry that connects to the channel 2 slot on the receiver. It sounds like when running two packs in a series we would have to have some sort of a Y connector between both lipo packs and the speed control and then another Y connector betwwen the packs and channel 2 on the receiver. Is my thinking correct so far? :C:



@Cool this is a good thread on the lipo nomenclature lipo

Yes, papa, your thinking is correct.

For a grand total of 3 wiring harness:

1. deans series for power
2. 3pin for voltage monitoring battery slot on esc
3. 3pin for signal information to esc slot 2

urrgghhhhh...........:C: :eek:

lots of wires for safety's sake(and to protect the investment)!
I don't use the cutoffs. I just stop running immediately when the performance drops. It has worked so far, but a LVC is definately a good idea.

Getting it right the first time is sort of my philosophy. With such a significant investment, I hate the idea of screwwing it up. Risk Reduction...

Mike you have a reputation of being VERY accomodating. I don't like the idea of asking, but, for a price, would / could you make up these said wiring harness' for those of us with less than stellar wiring skills :o

Additionaly I have zero experiance with power supplies. Any comments in that arena would be most helpful.

Of course I could wire up the needed harnesses. The needed y connectors are actually an off the shelf product, with the series connector for the controller being the only real soldering that would be needed.
For a power supply, I do carry a 25 amp(more than enough!) power supply, which I use myself, for about $130. There are a few power supplies that would also work, but your "do it right the first time" philosophy tells me you want more than "just enough".

Mike, when I pull the trigger on the lipo I'll touch base with you about the off the shelf stuff and the series connector for the controller. Do you carry or can you get the Scorpion set up? Is a UBEC needed or a good idea?

With respect to the power supply and what is impotant to me:

1. Safety
2. Performance
3. Reliability

If I have to spend a few more bucks now to avoid the need for something different in a year or so, I'd do it. Can these things power up more than one device? What is needed to get power from a car batterry? In the past I have just taken enough charged packs with me to play for a few hours. I won't be getting to many $200 packs so I'll want to charge when a wall plug is not available.

Thank you mike and papa. You answered my main question perfectly and based on yours and batfish's opinions, i am going to get the fma setups when i can afford it

Hey Papa,
I am not sure, but looking at your first pic it looks like you might have your front upper arms on backwards. I know because I did that myself!:p

The more cutout looking edge is supposed to face front -- setting the upper pillowball back farther and behind the centerline of the cvd. More caster that way and more stable handling, but not as quick.

So far I've also not been using LVC on my lipos, just stopping as soon as performance drops. Seems to work ok as the drop is above the lowest voltage the cells are supposed to go. I use 2 x 2s2p TP6000.

Stanard...Good Eyes, I am aware of the issue with my front upper arms. I snapped a few quick shots right after the mock up. I did not put in the shims on the hinge pins either, no locktite anywhere yet. I 've got to work on the stobe integrated limiter mounts in the rear, to accomodate the DD wingmount. Also gotta go back and switch in th UE Hardened steel idlers. Whew! It's comin' together but a long way to go.;)

Mike or anyone, for that matter, would you tell me more about the power supply you use? Have you got a link?

When monting lipo in/ on a Gmaxx chassis, what is the best way to safely protect the packs from flying debris,impact and other possible damage.I've seen the Associated battery cups, any other methods or techniques?

I use a 25A power supply I bought at my local Radio Shack, but I believe Mike can get you something just right for what you need at a good price.

I don't have a G-Maxx chassis, but my XXX-4 buggy has the cutouts for nimh/nicd cells. I cut a piece of lexan (.040 from Parma, part number 10422) to cover the holes so I can set my lipo pack on it and not have to worry about rocks/debris hitting the cells from underneath.

According to FMA,you don't use a y-harness to connect the LVC wires when using multiple scorpion packs in series.

They have a standard response e-mail explaining the connections,you basically just daisy chain the LVC wires from the 2 packs together.So one pack plugs into the ESC,the other into the reciever and the 2 packs just plug together.(no additional wiring needed).This was my understanding from their e-mail anyway.

If you send them an e-mail asking how to connect the LVC wires when using multiple Scorpion packs in series then they'll send you the standard response so you can check that i haven't misunderstood.

I was confused by their reponse at first because in many pics of the packs you can only see one LVC wire but if you look at the manual there appears to be 2,one to the ESC and one to the reciever,as you said.

You only need one y-harness not three.(deans harness to connect power wires in series)

Gustav, you got it correct with the LVC wires and RX wires. Basically, if one of the packs hits LVC before the other one, it will still cut the throttle.
I think one of the RX wires for the battery is covered by shrinkwrap, and it isn't just a wire coming out.

Now I am confused. The best illustration that I saw was in the support section at FMA SUPPORT it is under the review heading RC Car Action - Scorpion product review. They go in to detail in a photo captioned " What's with all the plugs?" It shows four plugs exiting the batttery pack. I just went back and read it again. What do you think?

Of the four connectors, one is for charging only,2 are for the LVC,and the the other for discharge(power wires you're going to connect to the esc in series with your second pack.

For the LVC wires(small 3 pin connectors),you'll connect one to your esc from pack A,another from pack B to the reciever.Then pack A and pack B will connect together via the remaining 2 LVC wires.(you can't get it wrong because you have 1 male and 1 female LVC (small 3 pin connector) on each pack.

Gustav I follow what you are saying. The statement above throws me for a loop though. Any chances of forwarding or attaching FMA's standard response?

Unfortunately,i deleted their e-mail a while ago.(it just said what you already understand though)

I just saw the photo in the link you posted.It looks like the other LVC wire isn't under shrink wrap,it can be unplugged from the pack,that's why it isn't shown in some of the other photos.(mystery solved i think)

Yes, having some packs in hand would help. I think some photos don't show the wire because it is a esc wire, and the only show the receiver wire. There I go thinking again. :C: If I recall from another thread you have ordered or are going to puchase these packs real soon, trying to get a UK delivery. UHH... let me know how it go's Doctor.:D It'd be nice if someone else was on the cutting edge.

As you can see i edited my last post when i saw the photo.confusing eh?:L: (i edited before you posted but you musn't have been out of the thread and back in the mean time so you got the origional)

Sorry about that.

Your'e right it is just the esc wire that plugs into the pack isn't it.I should have realised that,oh well i get there in the end.

Yeah,i hope to get the Skyvolt packs and go 8s with a lehner 2240/12 and a BK 36150.I'd be fairly unsuitable for racing,but i suppose i could race that setup if i dial out some power,i'd get good runtimes aswell.Silly amount of power really.
The only thing is the cost is a bit crazy,i need to give it some thought.

Let us know how you like the scorpions if you get them,give a little review.

Stunning truck by the way!

Gustav - I think we are in agreement now. The connector is inside the shrinkwrap, but there IS an extension (lol).

Yes, i managed to grasp this incredibly difficult concept eventually:L:

thanks,where were you when we needed you! lol

Well if it does not blow up pooof:eek: and the truck does what I ask it to do I'll be Happy. Thanks gentelman!:cool:

Well, I found this thread about, running Scorpion Packs in a series, on another forum. Apparently the moderator works for FMA Direct.

Also, please check out these power supplies , which one do you think would be the most versatile?