ordered lipo!

[supermaxx4190]

hey guys,

i just ordered a 2s and 3s kokam 3200 lipo pack from tower to power my 10L supermaxx. I also ordered some batt cups to mount them like promod did. to go along with this i bought some komodos with the traxxas wheels. after some calculations, im almost positive my truck will be around 9lbs rtr (its 11.5 now!) lipo is going to save 1.5 lbs and komodos will be about 1 lb less than my 23mm velos with bowties. i raced last night and did very good with my heavy weight truck. i was neck and neck with a very dialed revo in the a main and we battled the whole race. 10 ft. from the coil on the last lap i hit a pvc pipe that someone had knocked loose and ripped (yes ripped) a lower racer x arm off my truck. (my truck being 11.5 lbs didnt help that crash). i had to use a stock traxxas serov for the main and i could barely turn. my hitec quit during practice. i did TQ in the quals though. my truck is finally dialed in and i could run very consistant lines. cant wait to try lipos out next week...i hope i get them in time.

PS. what voltage should i set my triton for for a 2s and 3s pack...(7.4 and 11.1??) thanks

[squeeforever]

ouch! thats gotta be a costly mistake. the komodoes shave 1 lbs of the truck? set the charger for 18.5 volts if you charge them both at the same time (not sure what the specs are on the triton)

[supermaxx4190]

yeah, it wasnt pretty. yes, komodos on sportmaxx wheels shave off about 1 lb from my 40 series bowties on velos

[supermaxx4190]

so i just charge them at their voltage (7.4 and 11.1). i will be chargin 1 pack at a time. when should i stop running them? will i notise a sudden "dump" in power, or will it go down slowly? thanks guys

[Batfish]

If your ESC doesn't have built-in support for low voltage cut-off (LVC) when using lipo batteries, it would be a smart idea to purchase a specific LVC device. Kokam/FMA sells one. Just search for "low voltage cut-off" and "Kokam FMA" at your favorite shop, or check in with Mike to see if he can help you there. Expect to pay just short of $20 for that device.

I would personally not chance running lipo without LVC, either through the ESC or a specific device. Lipo battery packs are too expensive to ruin one just because you ran too long. A lipo that has been over-discharged may never re-charge to it's original capacity, and in extreme cases may not re-charge at all.

Cut them off at 2.8V per cell, or better yet 3.0V per cell to be safe when discharging/running.

Also, on the Triton charging - make sure you set for 1C charging (3.2A, in this case), and use the temperature probe. I don't have a Triton and have never used one so I can't help much more than that. I do, however, charge my lipo packs with the ICE charger, which defaults to a peak/max of 4.2V per cell when charging. I also set the max temp at 90F, even though the danger zone is well above 120F. I want to be absolutely safe with them. When the temp outside is over 90F, I will adjust accordingly, but I don't expect to set the temp any higher than 110F with the lipo packs.

Gotta keep it safe and responsible :)

[Rcbros]

I got some Komodos sitting here. Track sad no after the first race lol.

LMK :P :D


So how much did the lipo set cost you.

[supermaxx4190]

Originally posted by Batfish

Gotta keep it safe and responsible :)

i hear ya man! i have been very spectical on buying lipos for that reason. i dont think mike runs a low voltage cutoff. i would need one for a 5s pack and i dont think kokam makes one. the only setting i have on my triton is 7.4,11.1, and 14.8 volts. i can only charge at 2.5 amps. i will be buying the new multiplex charger soon. anyc hance you could find a link to a 5s voltage cutoff? thanks

EDIT: i found this...http://www2.towerhobbies.com/cgi-bin...&I=LXJDJ0&P=7. i think this only goes to 4s, but im not sure. anyone know if this will work with a 5s pack? thanks

[Batfish]

That one has an 18V limit for input, so it's unfortunately no good for 5s.
I did find this product, but it seems to be in the UK only:
http://www.modelhelicopters.co.uk/ac...d_Lithium.html

Look down the page for JG011 and JG012. They go up to 45V, so that should suffice. You can even look at the manual for JG011 with a link on that page.

Mike - this may be something you can look into carrying, if it does what it says.

Hope this helps!

[supermaxx4190]

hey batfish, i just talked to the enginner of the LVC and he said i could connect it to only my 2s pack and that would cut my throttle when that pack hits 6 volt which means if my other pack is at the same charge state as the 2s, they will all be at about 3 volts per cell. i am going to need a special LVC which they are going to make for me when i order it. it has something to do with the spikes of amps in cars, so i think he is going to program it a little different.

BTW mike, kokam is not planing on making any bigger compasity cells, but are coming out with a new line that will have up to a 3p6s built from 3200 cells . its a whole new line and you will have to use a special charger and voltage cutoff device that moniters each cell. sounds cool but expensive.

mike, do you use any voltage cutoff device?

[Serum]

Nifty little device!!

[starscream]

Hey supermaxx4190,
Who did you talk to about the LVC (I assume you're talking about the Kokam 18V LVC) I also assume you're running your Lipo's in series... I am curious how you can connect a LVC on just the 2s if the packs are connected in series. If thats the case, I'd suggest buying a scorpian pack, since its already comes equiped with a LVC designed for cars. Just a thought.

I am interested in going Lipo as well and am interested in the best (safest) setup.

Keep us updated.

:cool:

[supermaxx4190]

i talked to eric and nate at kokam. its hard to explain how i am going to hook it up, but ill take a pic when i get it hooked up. he said the packs can dump in about 5-10 seconds, but im not sure thats accurate. ill keep ya updated

[Batfish]

The FMA Scorpion packs with the LVC built-in are the current ultimate in lipo safety. However, I don't know how you'd run them in series due to their connectors. They have a lead that you plug into your receiver and you plug your ESC into the Scorpion pack. With the way you have to plug them in to use the LVC, I don't think you can wire them in series. The packs are only available as 2s or 2s2p packs.
I'm getting the BalancePro packs, which to not have an LVC. I'm getting two of the 2s2p 7.4V 6400 packs to run them in series on my 1/8th buggy. I'll program my 12012 to handle the LVC for the 4s2p packs.

My personal preference is to always run an ESC that can be set for LVC. Failing that, a specific device should be wired to serve the same purpose. Failing that, I'd test the heck out of the packs for probably 5-10 real bashing and/or racing sessions, stopping at 4 minutes to test voltage the first time, then 5 minutes the second time, then 5.5 minutes the third, and so on right up until the tested voltage at the end of an X minute run is equal to 3v per cell. Once I got that X measurement, I'd regularly stop 1 minute short of it during every session. Think about it... if you knew that you'd destroy your $150 dual 7-cell GP3300 packs just by running them low, wouldn't you stop running them low? :)

One last option is a radio system with telemetry that reports battery voltage. I'll know how this works soon enough ;)

[starscream]

Yup, the Sensor has on board voltage meter along with everything else you can think of. Its $500 bucks though.

[supermaxx4190]

yup the sensor would be perfect for this!