batterie capacity question

I order a Neu 1515 2.5d for my MBX5T and i'am to order a 6s pack. I've think to the Flightpower EVO25, 5000mAh, 6s, but it's very heavy weight, 799g.
The only thing i'll do with my truck will be race at the track, and i'll run only 5-6 min at the time, and i'll recharge the pack after every run.
So my question is, did you take a 5000mAh, or a lighter 3700mAh or 4300mAh????

I know on the 3700mAh, the continuous current is less than on the 5000, but is that 92.5A constent on the 3700mAh will be enough for my truggy?

[lincpimp]

Originally Posted by david lamontagn

I order a Neu 1515 2.5d for my MBX5T and i'am to order a 6s pack. I've think to the Flightpower EVO25, 5000mAh, 6s, but it's very heavy weight, 799g.
The only thing i'll do with my truck will be race at the track, and i'll run only 5-6 min at the time, and i'll recharge the pack after every run.
So my question is, did you take a 5000mAh, or a lighter 3700mAh or 4300mAh????

I know on the 3700mAh, the continuous current is less than on the 5000, but is that 92.5A constent on the 3700mAh will be enough for my truggy?

I am sure that the 3700 25c pack will be fine. I run a 5s poly rc 3700 25c pack (same cells as the fp) in a revo with a 2000kv aveox and it does fine. I am sure that it will get you at least 10mins, I get 25-30 mins with my revo. I am bashing, not racing though.

[sleebus.jones]

I'm sure the 3700 will be fine. At 6S it's doubtful you'll be pulling over 50 - 60A continuous.

[lutach]

Will be more then fine for 6 minutes. I ran my MBX5T geared for 50mph+ and it lasted longer then 6 minutes on grass.

Originally Posted by lutach

Will be more then fine for 6 minutes. I ran my MBX5T geared for 50mph+ and it lasted longer then 6 minutes on grass.

What's your setup lutach?

[lutach]

Originally Posted by david lamontagn

What's your setup lutach?

My set up in that video was only 4S Poly RC 3700mAh lipos, M.Troniks 120A Truck ESC and a Feigal 9L motor. You can even try 6S 2200 to 2600 packs for only 6 minutes. Your vehicle is going to be very light. I run my MBX5T now on 6S 2200mAh (2 x 3S) packs and 6 minutes goes without any problems. I went as far as 20+ minutes in my Ofna MBX buggy.

[Finnster]

Here's what I do to judge runtime and buy batts, I've got it from quite a bit of data using my ET and monitored batt charging.

For a "trackable" setup on a truggy or MT setup, I use roughly 5 Joules of energy per minute. I don't drive WOT everywhere, but works pretty well for hard bashing as well. Using that figure, you can gauge any setup independent of cell count.

However, to make things fair between cell types (A123s, lipo, even NIMh) I use loaded voltage estimates

EX:
Voltage*capacity (Ah)=Energy (in J)
For a 4S 5000 lipo pack:

4 cells*3.5V/cell*5Ah= 70 joules
so that: 70J / 5 J/min=14 mins
----One caveat---- You will not pull the entire pack capacity out. Realistic runtime is more like 12-13 mins. Also, if you drive harder, also less. Its prolly safer to overestimate a bit and use 5.5 J/min or so. Some track runs on my Revo I was only pulling 4.5 J/min tho, but again driving somewhat conservative.

For an HV setup on A123s (assuming loaded voltage of 2.8 V/cell):

10cells*2.8v/cell*2.3Ah=64 J
64 J/ 5.5 J/min =12 min
Pretty damn close to what I get @ a track pace:

So.. to answer your question:
6*3.5V*5Ah = 105J
105/5.5=~19 mins May clear a 20min main if you don't jam it hard.

If you want to find a pack to run say 7-10min on 6S
min: 7mins*5.5 j/min=39 Joules.... 39J/ (6*3.5V/cell)= 1.85Ah
===> A 6S 2100 pack should cut it, a 2500 pack would give a nicer cushion if you have a hot setup or drive really hard. 3700 would be overkill runtime wise. Most likely you will need a 25-30C 2500 pack to give enough burst amperage tho. A 30C 2100 pack may cut it. YMMV tho.

[Arct1k]

David I savent que vous regardiez 6s mais ce sont assez bon marché pour 5s et seulement 485g - vous pourriez courir 2p pour 970g

David I know you were looking at 6s but these are pretty cheap for 5s and only 485g - you could run 2p for 970g
http://www.amainhobbies.com/product_...ducts_id/16870

[lutach]

How about 6S 4400mAh with 2 of this:

http://www.amainhobbies.com/product_...ducts_id/24726

Or just get one and you'll be good for 6 minutes.

Edit: I hope Mike doesn't get angry at me, but here are some other options. 2 of these http://www.readyheli.com/Kong_Power_.../kp-3225-3.htm would work good too and only 600 grams.

[Arct1k]

Mais c'est $260 pour 6s 4400mah vs $88 pour 5s 4000mah...

PS 6S 2200mah 30c at max C that;s only 66amps vs 80mah

[lutach]

Originally Posted by Arct1k

Mais c'est $260 pour 6s 4400mah vs $88 pour 5s 4000mah...

PS 6S 2200mah 30c at max C that;s only 66amps

Yes, it up there, but you will get 30C instead of 20C cells. He can only use one and thats $130.

[Arct1k]

You could always get 3 x 5s and chop down to a 6 and a 4...

[Finnster]

For his short runs I would try and get 30C ~2100 packs.

here or here
That's only 360g of batts, and can charge @ 2C. $130 for the batt isn't bad at all. Less than half the current weight.

or here for longer 10 min mains. 20C, but only $100 out the door. That's only 500g.

[Arct1k]

Very encouraged that you guys are thinking that 60/66amps is enough... Hopefully 80amps at 5s will be ok....

David. PVI si vous examinez mon fil de Truggy au sujet de la rue hyper 5s recommandé par Mike pour assurer des 1515 2.5D

[Finnster]

Originally Posted by Arct1k

Very encouraged that you guys are thinking that 60/66amps is enough... Hopefully 80amps at 5s will be ok....

David. PVI si vous examinez mon fil de Truggy au sujet de la rue hyper 5s recommandé par Mike pour assurer des 1515 2.5D

That's continuous tho. 60C burst. I imagine his peaks are only ~80A or so.

If he has an ET he can judge how close he can cut it. If I am doing a pure racer, I hate to carry more batt than I need. Its just ballast at that point to break parts and F up handling. FWIW, on my CRT.5, I was only running a 3S 20C/40C 2100 batt on a 12s can (2900kv.) A 30c/60C 2500 batt had more punch, but the smaller batt was fine and didn't get hot at all. Peak amps were ~80 I think.