Radio Controlled Car Discussion

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Geek
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# 2253626 7-Jun-2019 10:37

networkn:

Anyone know of a source of cheap good quality 2S and 3S Batteries in NZ? Ideally high capacity 5000mah+

Have your tried MrPositive , I was buying a watch battery there the other day and noticed they have quite an extensive RC range ....

networkn

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# 2253627 7-Jun-2019 10:39

Man, they have 6S batteries now. I can't imagine what an RC Car drives like with those.

I got my last batteries at Coast to Coast RC when I was in Australia. Having a look now, they seem like they are still a good choice. I see they have managed to get some 8000Mah 2S batteries into the same exact form factor as my 6500Mah ones!

I was looking last night at 6000Mah 3S batteries but they are MUCH taller meaning I would need to mod my car or get a battery expansion kit.

I still need to find another Slash 4x4 shell too.

Mistenfuru

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Master Geek
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# 2253628 7-Jun-2019 10:40

I'd love to get into Traxxas RC cars!....

Sadly all my money is currently going into my High Power Model Rocket Hobby.....

networkn

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# 2253642 7-Jun-2019 11:00

The nice thing about the Traxxas is the TSM (Stability Management). I think it wouldn't be as much fun without it, as these things are so powerful, it's hard to get a handle on them without it.

russelo

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Ultimate Geek
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# 2253951 7-Jun-2019 15:49

networkn:

Hmm discontinued. I'll look up tomorrow and see what replaced it, unless you know off the top of your head?

They have better ones now, check this out for dual port charging:

https://hobbyking.com/en_us/0620duo-600w-charger-300w-x2-version-2.html

or the 4 port charging:

https://hobbyking.com/en_us/turbo-charger-1200w-4-300w-synchronous-balance-charger-discharger-version-2.html

networkn

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# 2254792 9-Jun-2019 13:02

I was thinking of bidding for these:

https://www.trademe.co.nz/toys-models/radio-control-robots/parts-accessories/batteries/listing-2174213342.htm?rsqid=7ebec905e43a48cf9e959409c6f4b735-002

Problem is they are quite a bit bigger than my 2C 6500Mah models which means finding an adapter, also they are 2-3 years discharged and I am unsure of the issues with that, and I'll need to convert the connectors to traxxas compatible.

They are usually $200 each so good value, should I take the risk?

networkn

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# 2254814 9-Jun-2019 14:12

@russelo (or anyone else) 2 questions :

1) I pulled my old RC car out, and found a battery which has 6 x 4200 Mah 1.2v batteries added together in a "pack". I am unsure it's capacity so I can charge it properly using my Imax b6. It's NiMH by the looks. Just wondering what settings to charge it at?

2) Your 2 chargers above are probably a little spendy, wondering if, since I can charge each battery in 20 minutes with one of these, I get a single port charger?

richms

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# 2254823 9-Jun-2019 14:30

My b6 which I think is a fake is totally useless with nimh - basically it would just keep going at the set current till it felt like it had done enough. voltage going all over the place so it should have been able to detect some form of end of charge but no, just keep on going. Pack getting really hot. Wasnt possible to do a quick charge on it, had to set it to C/10 and just leave it for ages.

The lack of per cell charging for nicad/nimh really cant help, but at least they arent going to go explosive on overcharge so I think its just a case of we've never needed that before so why add it now?

Richard rich.ms

networkn

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# 2254825 9-Jun-2019 14:33

Ok, so a bit of a search resulted in a 7.2v 4200Mah Nimh battery so I charged it at 4amps for about an hour hopefully, that's ok.

Edit : Said it was full after just a few minutes. Worked ok in the car for about 30 seconds!

Charging again same settings, if anyone else has any bright ideas, let me know.

Pretty sure my B6 is genuine. Came second hand from a respected member of the local RC Club who went to a 4 port after the bug really bit him.

networkn

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# 2254829 9-Jun-2019 14:51

I think I am missing something fundamental. It charged for around 10 minutes. Said it was full, but the capacity (I think that's it, bottom right of the display) showed only 363.

When I charge my Lipo's, when it's finished, it showed pretty close to the MAH rating of the battery!

richms

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# 2254902 9-Jun-2019 16:59

Thats because it has no idea when its actually full and just cuts out whenever. If you do it again it will put some more into the battery and then stop.

I would just set it to c/10 and leave it overnight. Thats low enough to not cook the cells, assuming they are still in OK condition and will get it to full. I cant find anyone with anything nice to say about the B6's handling of non lithium packs.

Richard rich.ms

networkn

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# 2254948 9-Jun-2019 20:14

So, an interesting afternoon.

First two charges were 10 minutes approx with 350 rating, give or take. after running it flat in the car, the second two charges were 980 or thereabouts, and after the run flat, then the last one I pulled the power out after it got to 4500.

Runtime was similar in the last 2 charges

richms

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# 2255007 9-Jun-2019 22:59

The problem with NiMh is you dont know if that power is going into stored energy, or just making the pack hot. You can easily put many times the pack capacity into them and come back to a charged but really hot pack, or else have them terminate early because one cell is doing something weird. As the packs are never ballanced, or in most cases even capacity matched if you have something that cuts out at a fairly sensible voltage then it can be quite a way off balance.

Richard rich.ms

Yogi02

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# 2255066 10-Jun-2019 09:31

One person supports this post

A good friend of mine and his 8yo son had been putting up a lot of FB pics from an Outdoor racetrack in Palmy over a couple of weekends, decided to take my 9yo along (I always had an interest as a kid).

Bought him a 1:10 arrma truck, got some 6 cell NiMH's and he started in the kids class. Had a couple of breakages. Out of about 20 trucks there, 75% were Traxxas slash's. About a month ago I picked up a 2wd Slash on TM with a brushless motor, decent esc, servo and a swollen lipo and charger.

Ive picked up a couple of shorty 2S Lipos and Im having an absolute ball, My son has been using it in a detuned state as well.

We are moving indoor next weekend and about 16-20 people are entering a new stock class using 1:14 tamiya racing truck kits using the tt01e chassis and brushed motors, should be a hoot.

After watching a few meetings, I can see me moving into the 1:8 buggy class using 4s/6s lipos - They look like crazy fun outdoors.

Netwrkn - The Batteries I have been getting are a rectangular hard case "shorty" 2S 7.6v 4000mAh - The reason is, they easily last a race and I can wire them up as a 4S for use in a buggy

I am awaiting an ebay order from China - XT60 extra connectors (got all my charger, batteries, cars the same, silicone wire, lipo fireproof bag, voltage meter as well as some other things from same seller.

Quite enjoying making up all the cables too.

Think my 9yo has lost interest for now - Im sure its temporary and envisages that if he says no to everything that he will become a full time fortnite player, LMAO, in his dreams!

russelo

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Ultimate Geek
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# 2255115 10-Jun-2019 10:58

networkn:

I was thinking of bidding for these:

https://www.trademe.co.nz/toys-models/radio-control-robots/parts-accessories/batteries/listing-2174213342.htm?rsqid=7ebec905e43a48cf9e959409c6f4b735-002

Problem is they are quite a bit bigger than my 2C 6500Mah models which means finding an adapter, also they are 2-3 years discharged and I am unsure of the issues with that, and I'll need to convert the connectors to traxxas compatible.

They are usually $200 each so good value, should I take the risk?

I won't buy it. The cells are probably dead or will die soon.

From: https://rogershobbycenter.com/lipoguide

I feel the need to reiterate: the most common problem people have with LiPo batteries is a direct result of improper storage. When a LiPo battery sits for a long period of time (and not at proper storage voltage), it tends to discharge itself. If it drops below 3.0V per cell, the vast majority of LiPo chargers will not charge it. Sometimes, batteries with this problem can be rehabilitated, but just as often, they are a lost cause. So again: if you take a 'laissez-faire' approach to the storage of your LiPo batteries, it's entirely likely that you will be purchasing new batteries sooner than you think.

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