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Battery life calculator


Jackofall

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So from some of the posts people may know I am looking to convert my hyper st's both to electric for bashing/racing friends around a redneck style track we have built in a friends field.

I am looking at putting a 150A 2000kv turnigy esc and motor combo in from hobby king and ideally I would like to run it on one battery... preferably an nimh but I'll go to lipo if I must.

It needs to be semi fast but not racing fast (my current dominus 10tr is basically fast enough I just want 1/8 scale).

Is there a calculator or anyone with advice out there that can advise on what the battery life/pace would be like with different batteries? Electric just confuses me! Any education or direction would be brilliant.

Assume I'm an idiot [emoji3]

Regards

Whitey

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On a 4s 30C 6000mah I got max 8 minutes running in a 5kg truggy with 3.8" wheels weighing 240gr each. My C rate was too low.

On dry dirt I got 15 mins

On gravel I got 15 mins

On tarmac I could eek 20+

With race size 3.8" wheels weighing 175gr each I got an extra 2 to 10 mins terrain depending.

 

Calculator is impossible.

My advice would be not to go too cheap if serious about it at least a 4s 40C 6000mah or the biggest 4s brick that fits the box and maybe get 2 of them for a decent outing. (I've got 4x 6s for a 1hr run but mainly grass)

 

Don't go too cheap on charger either otherwise you'll say "forget it I'm off" with waiting. Example for a 6000mah 4s you want at best a charger that'll do 6A but also 110w  (14.8v x 6a + 10% = 110w). Wattage is where many people neglect and make a huge mistake. If you put one of those 4s on a 6A 50w you'd be waiting 2 hours for charging.

 

I came across this, Ideal for 2x 4s 6000mah+ bricks (7000mah flat out) :yes::thumbsup:

http://www.ebay.co.uk/itm/Trendy-GoolRC-GC120AC-240W-Balance-Charger-Discharger-for-RC-Battery-G9E3-/291933956726?hash=item43f89eaa76:g:RYsAAOSwcLxYHGQr

Edited by dazp1976
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46 minutes ago, evssv said:

there r too many factors to take in to account to predict how long a lipo will run for.....and u cant run a brushless esc/motor off a ni-mh......u will need lipos.....

You'd either keep cutting out all the time, get constant brown outs or stress the esc and blow it with nimh. Maybe all three.

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As people have said, there are too many factors, although, they don't make run times differ hugely, as I found out.

My old 8ight-Te was running a 150a ESC and 2000kv motor, I ran mine on 5,000 4s 35-70C Nano-Techs and got on average 20 minutes run time, if I really ran it hard, constantly on the power back and forward, it didn't really drop by much, maybe 16/17 minutes.

I never timed it from start to finish though, but 3 batteries used to get me an hour or so run time of general bashing and jumping.

Don't waste your money on converting it if you want to put a NiMH in it though :lol:

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Lipo it is. Cheers for the input guys. I just don't understand electrics enough!

I was worried if I put a the 150A 2000kv combo in with a 4s 5000mah lipo I'd get like... 5 minutes. My local store are ALL about racing and they can't get in their head I just want to have fun. They are all about the first two laps etc.

So a decent 4s 5000mah 30-70c should work

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The Dominus TR is a very, very slow rig. Going 1/8th with a big combo will be world's apart in terms of everything....

 

If you don't understand electrics, perhaps read up on lipos and lipo safety before purchase.

 

For note, I would not buy a Turnigy combo, but fit an esc from Quicrun instead with a cheap, black can from eBay.....may cost a little more, reliability shouldn't be a worry.

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Fair play fella, sure you'll be on top of it soon.

 

Essentially, 5000mah minimum with, imo, 35c minimum discharge. This gives a constant current of 175a (5 Amps X 35c). 

 

Provided your constant current is greater than the stated capacity of the Esc, in this case 150a, then all should be well. The motor draws the current, so if you whacked in a can outside of the ESCs stated size and kV, then geared it really badly, there could be a wee disaster....

 

Fortunately, the manual for the Esc will state what kV range is suited to your chosen cell count. Gear appropriately and enjoy.

 

NiMH to lipo is like the rig is being kicked up the backside, hard! Remember not to hold full throttle for longer than 10 seconds, lipos in cars don't appreciate it.....use bursts of power instead....

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I hear what everyone is saying and I appreciate the advice. But the track we have in three back garden the dominus are fast enough for. We are only looking for like 10% more speed. What we want from recycling our old hyper st's I'd more stability. Little bumps throw the dominus over. Not an issue we had with nitro hypers.

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You shouldn't run brushless on nihms simple as, at the least you will get very poor performance at worst it will catch fire.
 
Why not sell the sts and buy somethin else?

I do plan to run lipos. So that's a non issue.

Plus it's more fun and the quickest way to learn...

As for something else... I've looked around and the only 1/8 truggys that are worth getting are 400 odd quid and way overkill for what we need.

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I saw a video on YouTube of someone who converted their st and it basically wheelies on the power constantly. I didn't want it to be that punchy. I'm guessing that was a 6s? But was worried a 4s would die after 2 minutes or barely roll. I just don't understand how to work out what the outcome would be. I've basically succumbed to getting a 4s. Testing. If it doesn't work I will up it from there.

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4s will be fine if it wheelies too much turn down the punch control on the esc.

 

6s won't last longer than 4s it's mah capacity that goes by hence why people have told you to get 5000mah. Have a read of the lipo guide.

Edited by stretch
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4s will be fine if it wheelies too much turn down the punch control on the esc.
 
6s won't last longer than 4s it's mah capacity that goes by hence why people have told you to get 5000mah. Have a read of the lipo guide.

Thanks for that!

I'll be honest I had a read but my head hurt. So what would I benefit from if i put a 6s in it?

Just to clarify... I think I have it.

If I got a 4s 3000mah and a 4s 6000mah the 6000 would last twice as long and that's the only difference. Assuming the discharge rate and everything else is the same?

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8 hours ago, stretch said:

4s will be fine if it wheelies too much turn down the punch control on the esc.

 

6s won't last longer than 4s it's mah capacity that goes by hence why people have told you to get 5000mah. Have a read of the lipo guide.

Technically 6s does last a bit longer using a lower kv motor that will give the same max rpm as a 2000 on 4s.

Doesn't need to use as many amps, same size motor pulls max <90a opposed to 120a . I gained about 5 mins running but I have turned the punch right down too. On demand wheelies can get on your nerves.

 

Stick to highest mah highest poss C rate 4s you can fit.

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