New Guy with a New Truck
 

Hey guys as the title says i'm new here to your forums. I recently purchased my first electric brushless set up, with the flux.

http://memimage.cardomain.com/ride_i...0193_large.jpg

I'm not much of one to leave things stock so here's what ive done and what i plan to do.

1) notched and flip the battery boxes, so the deans fits thru better as well as easier to get to the batteries

2) red loctite the pinion

3) Tightened Slipper right down (no play needed from what i understand)

4) Rigged up Velcro for the boxes

5) Install HPI "bullet proof" diffs (in the mail :) )

6) Install TCS 5mm Chassis

7) Install HPI Big Bore Aluminum Shock

8) Install HPI HD DRIVE GEAR 18-23 TOOTH

9) install wheelie bar

10) ordered novak pinions (18 19 and 20t)

11) set it up with castle link

12) Replaced stock tires with badlands.

http://memimage.cardomain.com/ride_i...0211_large.jpg

http://memimage.cardomain.com/ride_i...0213_large.jpg

I Got Zippy 2s packs and a Turnigy 8150 charger from hobby king and so far im fairly happy with it all together. With this all set up it does standing backflips no prob and seems to have crazy power.

A few questions i have tho since im fresh to this electric business is this.
1) why is it that when i charge one of my packs one cell is only 4.05v and the other is at 4.2 (it will climb higher then that if i dont shut it down but i stop the charge at 4.2v. I tried taking the pack down buy putting it into "storage mode" then recharged it tonight and still got those numbers. its on balance charge too. The other pack charged up to 4.2V on each cell perfectly. stayed balanced the whole time. i just want to make sure nothing is going to go wrong to cause big troubles. thanks guys and i look forward to scouring your forums for knowledge.

the higher voltage cell in the pack will stop charging at 4.2v. if it gets over 4.23, disconnect it from the charger immediately, but if it stays at 4.21 or less, it's all good. 4.22 is even ok as the voltage will drop to 4.2 after charging. if it does go above 4.23, which i doubt it will, the charger is likely defective.

which flightmax packs are those? i have the 3s 25c 5000mah flightmax packs and they have been fine so far.

also, welcome to the forums. RC-M is different then other forums in the sense that there are a lot less people here and this forum doesn't have strict rules or tyrannic moderators.

i think the reason this forum isnt crowded cuz ppl dont realise that its a gold mine :lol:

ohh and why didnt you go with rrp pinions?

Never heard of them. are they a bit tougher? i just made an order at TCS and figured id throw them in so i had some options/spares.

The charger may be defective as well then, because the first time i let it go to 4.26 before shutting it down. i dont know if if would keep going or not. the charger is kinda a cheapy entry one ill just have to watch it closely as it charges that one pack to make sure i shut it down before 4.22

thanks for the welcome btw, this forum is indeed a gold mine. i was recommended to come here since there was so much knowledge on BL, and lipos.

Does the charger have a balancer built in? Should have ordered RC-Monster pinions!

Charger does have balancer built in
http://www.hobbycity.com/hobbycity/s...idProduct=7523

heres the packs i got
http://www.hobbycity.com/hobbycity/s...idProduct=9436

another question i have. ive seen lots of the flux guys using this
http://www.hobbycity.com/hobbycity/s...ad_(2_x_3S)6S_

Is there anything out there that i can use to charge my two 2s packs at once? cutting charge time in half would be pretty nice.

those chargers have a 3 month or 1 yr warranty. i have the $35 version and it has worked very well for me. the only downside of getting a warranty replacement is sending the defective one in. shipping to hong kong is a little pricey.

that charger is supposed to have the same "brains" as mine and mine is dead accurate. 4.20 is the usual cutoff per cell. occasionally it'll only go to 4.19, but that is good enough unless you have severe OCD.

edit: i have that 2x3s adaptor, but only because i run 2 3s packs in my BL converted savage. if you do end up ordering from hc again, you should pick up 2 of these
http://www.hobbycity.com/hobbycity/s..._20C_Lipo_Pack

those packs are only 20c, so if i were you, i would use the 18t pinion for 6s. some people say those packs are underrated and are actually 25c packs. for $30 each, you can't go wrong.

ya i dont want to be w/o it for the shipping time, as well as paying the price to ship it there would suck too. there should be no problem with just watching it closely is there? im never gonna charge the batteries unattended anyways right.

if your charger is charging one of the cells too high, i wouldn't use it. those packs are pretty nice and i would rather buy another charger if i couldn't wait for a warranty. i have the $35 hobbycity charger and i love it. for your 2s packs, you won't know a difference when charging. for 3s charging, it will not go all the way to 5 amps though. it charges at about 4.3 amps, which is still pretty darn fast. before i went lipo, i charged all my ni-xx batteries at only 1.8 amps.

I was just curious about something. If it was the charger, why would one battery charge fine, and then the other be sa far off. it almost leads me to believe there may be a weak cell in the pack. i know it shouldnt charge over 4.2 to a cell but is it possible it only was a cut off for 8.4V instead of the 4.2V per cell? It has never gone above 8.4v. These packs are rather cheap, so i was thinking that they may be the problem. although they run the truck very nicely.

Hmm. A weak cell in eother lipo wouldnt explain the charging imbalance, it would just mean that cell self-discharges quicker once removed from the charger (come back to the lipo after a few days and one cell will read 0.2v lower than the other or there abouts).

What is odd that it only does it with one battery and not the other- have a look at the balance taps on that lipo and check it isnt loose, and that the metal contacts arent dirty either. I would be inclined to say its a charger fault rather than the lipo- if you're charging it in balance-charge mode like you said, and its set up correctly (5amps charge rate and 2s lipo), then the charger should stop pushing current to the cell thats climbing too high, and in actual fact drain it down slightly until its back at 4.2v, then add extra current to the lower voltage cell until its upto 4.2v per cell (long winded sorry).

That issue aside, you've chosen a nice tidy setup and list of upgrades. My only question would be are the novak pinions hardend steel, or just aluminium? If its the latter, keep a close eye on them as they will wear down very quickly against the steel spur gear.

Our industrious lord and master Mike sells pretty much the best pinions available that will work on the savy, these or these (mod 0.8 is essentially the same as 32pitch, so they are interchangeable as such).

About charger. I have iMax B6. From what I have read from the Internet there is also many other clones of SkyRC iMax. And they tend to have from time to time wrong calibration. There is sequence with buttons and 6S LiPo charged correctly to do calibration. But it can be done only once. So maybe it is the case...

Well, you're right if you're assuming that only the overall voltage counts as cutoff, means 8.4 V for a 2s Lipo pack. Your problem is the fact that on your "bad" pack a cell seemed to have drifted a little too far out for your built in balancer to be able to balance it out when charging at full rate.

Here's my tip: Charge that pack with only 0.1 C. That means if your pack is rated at 5000 mAh, then go charge the faulty pack with only 0.5 A instead of the 5A you would normally use. That way it would take about 10 hours to fully load your pack but it leaves your balancer with plenty of time to balance your cells out. Rince and repeat and after 3-4 times charging it that way your cells should be good enough to be charged normaly again.

If your problem persists after 5 times loading your pack with 0.1 C, I'm afraid that a cell or, and that's far more often the case, the internal wiring of your pack is faulty.

One other thought I had- use a multi meter or voltage check to test the cell voltages, just in case its the charger lying about the actual voltages.

If its in balance charge mode, and set for the correct cell type and count, then a correctly functioning charger will never send a cell over 4.2v (give or take a few 0.01volts...).

Hey guys thanks for all the tips. ill have to try those pinions next. truth be told im hoping the stock one hangs on cause i like the way its geared as is, but stuff always breaks. Im gonna take your advice on charging it at .1C but will it be ok unattended? i dont know if i could sit there for 10 hours lol. 30 mins is one thing. by rinse do you mean run the pack in the truck? before i charge the pack at .1c should i maybe put the pack to storage mode? Once again i appreciate the input you guys do know your stuff. and if the lipo is done for ill just order some more. maybe 3 this time and hope for all good ones and side line the problem pack.

Voltage measurement in such devices typically has a precision of +/- 5 %.
For 4.2 V that means +/- 0.21 V. So seeing 4.4 V on a cell is perfectly possible.

If you read the instructions on some of the battery packs, you'll find out, that most manufacturers of quality cells have warnings regarding this issue, since Kathodes of Lipo cells tend to corrode faster when applying to high voltage.

It is true that, even an entry lvl modern electronic loader will cut off a cell that's going to high in voltage, but the described problem may lead to an increased difference in internal resistance of the cells, only making the problem of an unbalanced pack even worse.

All that theory means that you have to get your packs balanced, or the problem will get worse and the method described in my first post above is a nice and easy way get things balanced again.

"Im gonna take your advice on charging it at .1C but will it be ok unattended? i dont know if i could sit there for 10 hours lol. 30 mins is one thing. by rinse do you mean run the pack in the truck? before i charge the pack at .1c should i maybe put the pack to storage mode? Once again i appreciate the input you guys do know your stuff. and if the lipo is done for ill just order some more. maybe 3 this time and hope for all good ones and side line the problem pack."

Indeed run your pack in your truck after loading it, after all you want to see if it can handle the power output you need. The desribed method for loadbalancing your packs with 0.1C is safe, even when overcharging, at least when using new generation cells, which will not explode and/or take fire with this low charging current. But in the unlikly event of overcharging 1 or more cells for a long time, they will corrode and increase their inner resistance to the point that they will be unusuable. This will only occur if at least 1 cell was in that state before you tried to load the pack, so no loss there.

That sounds like your pack possibly has a bad cell. Everyone seems to be suggesting the charger is the problem, but if it can balance your other pack to 4.2v on both cells then it sounds like the charger is fine.

Keep and eye on the cells, especially the one that isn't holding a charge (check all the cells with a digital multimeter). If the one cell stays at 4.05v and won't charge any higher then you most likely have a bad cell. Not much you can do to fix a bad cell unfortunately.

I run the same 30C 2s hardcase Zippy lipos as you and they are great. The only issue with buying from HC is service and support. It doesn't make sense to send anything back to them for repair/replacement. By the time you pay for the shipping you're better off buying a new pack.

88gtanotchback, are those Maximizer wheels? Are they normal or 1/2 offset? What adapters did you use to fit them to the Flux?

no adapters needed. they are the 1/2 inch offset and yes they are maximizer's. great product!