I need basic info on lipo and brushless terms

[Dave_In_Florida]

I'm new to crawling, but used to do alot of 1/10th scale off-road and oval racing growing up. The problem is, lipo's and brushless motors were not around when I was big into R/C. As such, I just don't know alot of the terms used by vendors and posters here. Can someone point me to a good site that will break down what all of the numbers mean for lipo's and brushless motors?

TIA
Dave

[Szczerba]

Welcome to the crawling side of the hobby. Your on the right website and in the right section. Grab a cup of coffee and check out the "Sticky" threads in the the electronics section. Tons of information, you just have to read it all.

[Charlie-III]

Hmmmm...not a lot here in the stickies.... http://www.rccrawler.com/forum/newbi...1-15-11-a.html, and this.... Definitive ESC, MOTOR, and BATTERY threads - RCC's top tech threads!

In general:

LiPO:
mah = pack capacity (just like NiCD/NiMH)
The "S" in a part name = cell count, cells are nominally 3.2 volts (a 2S LiPO is similar to a 5 cell NiCD/NiMH)
The "C" in a part name = "rate the pack can supply power", the higher the better, sorta. It is used in conjunction with mah to determine total power. Small packs (small mah) NEED a high "C", large packs (high mah) can use a smaller "C".

You WILL need a LiPO capable charger, preferred is to get one with a balance plug so you can balance charge your packs. There are a few different balance plug types so be careful shopping.

Brushless:
"Turns/T" or "KV" = speed of the motor. If listed in "T", it's like brushed, smaller "T" = less torque, more speed. If listed in "KV" it's "RPM/volt applied", thus low "KV" means it will spin slower while giving better torque than a high "KV". Sorta opposite of brushed "T".
Sensored, unsensored = does the motor have a sensor in it, it lets the ESC know which way the motor should spin and gives speed control feedback to the ESC. This is really needed in a slow application like crawling. Non-sensored/unsensored will usually be rougher getting turning and "COG" (ratchet) when going slow, this makes low speed control harder. Non-sensored/unsensored are also a bit cheaper. You will also need an ESC that can deal with a sensor.

I believe www.HolmesHobbies.com has some more motor info (like an idea of how brushless KV ratings compare to brushed turns.

I'm hoping www.CheapBatteryPacks.com gets their FAQ back up, they are a great vendor, good product (NiCD, NiMH & LiPO) and decent prices.

Hope this helps out.

I still run my home made AE RC-12L & AE RC-10L pan cars on NiMH.....

[Dave_In_Florida]

Wow, thanks for that info. Now I can at least follow the forum posts and refer back to this as a cheat sheet

Thanks again

Dave

[Charlie-III]

Originally Posted by Dave_In_Florida

Wow, thanks for that info. Now I can at least follow the forum posts and refer back to this as a cheat sheet

Thanks again

Dave

You may also want to look on the forum main page, near the bottom, for a group/club near you. Then you can find people in this hobby that can help out some more as well as find local comps.

I'm sorta new to this end of RC as well, but this is a good forum to peruse for crawler specific info.

[Dave_In_Florida]

Looks like I may be jumping into lipo's sooner than I thought I took my MRC out in the back yard on our improvised crawling course and the run time on the stock battery sucks. I got the setup used, and I'm sure the battery has been cycled to death. I just can't replace and miss a great opportunity to upgrade.

Looks like I'm going through CBP for a 11.1v 1100mah 3s pack, their low voltage alarm, and wall charger. That should get me started safely.

[SMR 510RR]

I will add to what Charlie-III posted:

While not that common in crawling some Lipos have both parallel and series connections inside.
"S" is actually the number of cells in Series
"P" is the number of cells in Parallel

So a pack listed as a 2S2P actually has 4 cells, its basically like two 2s packs combined into one higher mah 2s (same voltage as 2s) pack.

This can be helpful to know if you are trying to fit a pack in a tight spot. Typically as pack mah increases the pack gets wider and longer but the height remains almost exactly the same. It may be beneficial to find a pack that is 2x the height but 1/2 the length (roughly of course). Of course this mostly applies to scalers with higher mah packs and full interiors.

You can also achieve the same effect by buying/making a parallel adapter for 2 packs, you could either stack them or use them like saddle packs.

[Charlie-III]

Originally Posted by Dave_In_Florida

Looks like I may be jumping into lipo's sooner than I thought I took my MRC out in the back yard on our improvised crawling course and the run time on the stock battery sucks. I got the setup used, and I'm sure the battery has been cycled to death. I just can't replace and miss a great opportunity to upgrade.

Looks like I'm going through CBP for a 11.1v 1100mah 3s pack, their low voltage alarm, and wall charger. That should get me started safely.

When you pick out a charger, maybe look for one that is DC & AC capable. This way you can charge at home (AC) or in the field (DC)! I use a 12volt ~7Ah gelcell to power up my charger at comps, it works well and costs ~$23.

[Charlie-III]

Originally Posted by SMR 510RR

I will add to what Charlie-III posted:

Thanks for the additional info SMR,