Lipo/ electronics help for Dummies

[fred2000]

Alright, I am in the process of returning my YZ10 to life and I would love to run Lipo's as I am just going to use the car to run around (not race). I have ancient electronics (Novak T5) and old old Twister stock motor. I am looking at the Lipo stuff and I am having a hard time finding out what I would need to make the move. I know I need a Lipo saddle pack of some kind - maybe this - http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXVCD8&P=FR.

Would I need a new ESC?
Can I run any motor? Would it be better just to go whole hog and go brushless?
Do I need a balancer or do most chargers have them biult in?

Lastly, I would really like to do it on the less expensive side of things as I don't have a lot of $$$ to sink into this right now, I just want to get it rolling and have a good long run before I need to recharge.

Thanks for help in advance and if there is a good primer somewhere on the web about running lipo's please point me to it.

Thanks, Fred

[wyldbill]

you can use older style esc's but you need a cutoff module so you dont run it down past 6v
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXPGM8&P=7
i have seen guys at my local oval track run them without a cutoff but they dont keep running them all the way down. they just race then recharge.

[fred2000]

Thanks. I am guessing most car cells are 2 cells? I know, I really know zero about this.

Then with one of these I could run the old novak and an old motor (the cheapest option). Do most new ESC's include the 6v cut off?

Is there a good inexpensive lipo charger out there?

Thanks, Fred

[Mr. ED]

Hey Fred,
if you're not going to race it, why not stay with ni-mh's?
They're still a lot cheaper and easier to put in the saddle-pack configuration you need for your YZ-10.

[fred2000]

You are right. It might be a little easier and a little cheapers. I figured since I think I need all new stuff that Lipo seems to be the way to go. I seem to have missed NiMH altogether as I was running Nicads when I hung things up for a while.

Are the new NiMH good? Seems like I have seen some 1200 mAh packs and 4200+ mAh packs - area the high mah ones good, they cost more so I would think so.

Fred

[Mr. ED]

The higher the amps, the longer your runtime and the higher the price tag.
Oh, and ofcourse you can use hotter motors for the same runtime but that's pushing towards the racers edge again.

If you're going to use an older Novak, don't go to crazy with the motor: the new batteries can handle it, but the ESC was not made for that kind of 'abuse' over longer time.

[Group B]

<snip>If you're going to use an older Novak, don't go to crazy with the motor: the new batteries can handle it, but the ESC was not made for that kind of 'abuse' over longer time.

Is a Novak 410 MXC suitable for this kind of abuse?

Do you know if it can be used with Lipos?

[Mr. ED]

I don't know the specific models, just some general concepts:
1. the older ESC's were made for runs of 5 minutes on a hot motor
Depending on the specs of the ESC, and the motor you use, you could still use Lipo's or high amp Ni-mh's, but don't do the typical basher thing: do NOT run the car till the battery dies. Stick to 5-8 minutes max. Leave the ESC to rest/cool down, and then run it again

2. you'll need an external cut-off for lipo's on any ESC that predates the lipo's.
Actually you don't if you're very careful, but it's the only fail-safe you got against over discharging

[dubfreak]

i run li-po in all of my rigs best move ever made contant power long run maintenance free just need a good charger with a balancer incorporated or extenal and a esc that have a cut off you'l be amaze from the power and ride time it gave you once your are well equip electric rc is not the same was one of the first here to use li-po every body was so jalous of my run time now they are all on li-po

frank

[slazzaro]

You can use Lipos with whatever esc and motor, keeping attention to two factors:
1) Mr.Ed is right: the operating temperature shall be controlled as a life parameter for the system.
Not only the ESC temp, but also the motor one, especially if you use conventional brushed motors and your application is high power (i.e. high current flows in the system)
2) I would never run a Lipo pack without a saver: remember that just one full discharge (or a "too deep" discharge below 6V - 3V per cell) is enough to permanently ruin that costly pack.
It is definitely better having a charger with internal balancer: even if good quality packs don't need to be balanced so often you will need to do it sooner or later.
I balance my Lipos twice or three times a year.. and I use them!
My final suggestion is: spend a little more and have Lipos instead of Nimh, as time passes more versions become available, and some "sport packs" are sold at competitive prices.
Nimh packs are heavy and need more maintenance than Lipos, even if less than Nicds.
Not to mention the increase in power...

[Bent]

Ok guys I am a tad lost here?! Ya'll are saying that yes you can use a lipo battery on a brushed system as long as you have a fail safe and proper charger?

Also I have a rc10t that I am wanting to go brushless with. Its a dirt oval but what would be the best, best priced, and so on for my truck? Also how do i tell what transmission is in it?

[Bongo Fury]

You MUST use a lipo charger, in lipo (CC/CV) mode. Or else everything goes up in flames. Cannot allow an individual cell to go above 4.2 volts (technically 4.25v if you like standing right on the edge of the cliff, but your meter better be accurate). A balancing charger is highly recommended.

The low voltage shutoff is not absolutely required, just very highly recommended. Risk discharging too far, the battery will not charge again. 3 volts per cell is typical recommended minimum, 2.7 being the real limit. As I understand it not a safety issue, but I'm not completely sure. If you don't use a LVC, it is vitally important that you either time your runs (typically no issue in timed racing) or stop as soon as you notice ANY drop off in punch/perfomance. Don't even drive the car back to you, go get it and get it unplugged. Don't leave it plugged in, as any small parasitic drain will cause problems. Lipos maintain perfomance/voltage quite well, until they drop of at the end quite quickly. Note for best lipo life it is recommended to not use more than 80% of the charge. Many set their LVC to 3.2-3.4v per to be safe. Also going past 80% will tend to drive the pack out of balance.

OK to charge the battery the night before, they hold charge quite well. But for long term storage a 50-80% charge state is recommended. 3.8v per cell is frequently suggested.

One other major safety issue, do not puncture or pinch the pack. Which is why ROAR rules require a "hard case" to protect the lipo. Internal shorts resulting in what we like to call a "thermal event".