Batteries Why do Cars need two batteries?

why is it that, most of the cars/trucks I look at require a twin battery set up?
As in why do I have to put two 1S batteries to create a 2S pack?
or two 2s to get a 4s?
Why can't it be like planes or helicopters where I just get a 4s pack and stick it in...
Too confusing and way too difficult!
 

Tony

Staff member
Back in the day, I only ran one 7.4 pack. it was 6 cells (not S, cells lmao). You could get two fo them in the size you want, but run them in parallel to get more mah out of the run time. I think they do it this way to keep the balance of the vehicle right in the center.
 
the battery I think sits slightly off centre.... but with the motor on the other side it would kinda balance out. But if you're going to put two batteries side by side I don't see the difference in two packs or one. Unless as you say they put them in parrallel to get the longer run time. I could run two 3s packs in parrallel and get long run time, and then down the track put them in series and get killer speed!! hehe
 

xokia

Active Member
You put two batteries because they usually hang them off the side and they want the truck to be evenlly weighted on both sides. Also by running 2 batteries you get twice the run time. The equavalent 1 battery would be larger and then all the weight would be stuck on one side. Take the 2 batteries you have now stack them on top of each other now try to figure out where you are going to put it. By splitting the batteries up you are able to get more battery into the truck and have more mounting options.
 
Thanks Xokia, I would understand that if the battery tray was on each side of the centre line of the truck, but in this case the tray is on the right hand side only.
I'll wait until I have the truck in my hands, it may make sense to me then.
I will get back to working out how i'm going to fit a lipo into my car instead and how i will set up the brushless system in the car.
 

xokia

Active Member
Thanks Xokia, I would understand that if the battery tray was on each side of the centre line of the truck, but in this case the tray is on the right hand side only.
I'll wait until I have the truck in my hands, it may make sense to me then.
I will get back to working out how i'm going to fit a lipo into my car instead and how i will set up the brushless system in the car.
I see yea that is strange my savage the batteries are on both side of the frame between the wheels.
 
That would make sense to me then, and I'd totally understand and be happy with having two batteries run that way.
i'm sure though that they have the battery close to centreline, but not on it, and have an adjustable tray to suit whichever battery you end up running. Pulling the trigger on the purchase in about 30mins, and should have it here this arvo, so I can work out what's going on then! :)
I did end up going with HPI in this instance, seemed a bit more bash worthy compared to the sc8.2, next one will probaby be sc80GT
 

Diederik

Member
I bought my one son a DHK Hobbies megatron running 2 3200MAH 2s batteries, really, really fast runs a claimed 75MPH but after 2 weeks gave it back and got my money back, looking around I gave the HPI Savage 4.6ss a good look but ended up buying a Kyosho Mad Force Nitro.25. My friend races the Savage and my Mad Force accelerates faster but his handling is better, but I love the sliding of the car and the backward flips it can do which the savage can not, I think for racing the Savage, for fun the Kyosho. Keep in mind there is only .2 difference in HP
 

xokia

Active Member
Try a savage flux at 6s nitro has nothing on it can't even come close. I run two 3S 5000 mAh packs. My savage had the .26 picco motor which was pretty quick. After swapping to brushless the speed and power is insane. I can do back flips at 40 mph with ease.
 
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Diederik

Member
True, Nitro will not catch it, I was always electric only. Since i bought this kyosho i changed that attitude of mine quickly, the sound and fun factor is awesome, electric is just fast and thats it, I do not race IOW I do not need the fastest like my Megatron was, but each to his own.
 

xokia

Active Member
True, Nitro will not catch it, I was always electric only. Since i bought this kyosho i changed that attitude of mine quickly, the sound and fun factor is awesome, electric is just fast and thats it, I do not race IOW I do not need the fastest like my Megatron was, but each to his own.
If you dont like fast just go in the ESC and change the throttle curve. Or what I did was bought a spektrum DX4S remote and change the throttle curve on the remote. I have one model set up for normal driving which is limited by 50% throttle and gives me about 30-40min run times and then another model set up to 100% throttle which gives insane speed and power. But yea the sound the nitro puts out is cool amd electric cant replicate although it angers neighbors. And I got tired of snapping one-way bearings. But they are both a blast for sure.
 
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My issue with nitro is that it costs about 20 bucks for a litre of nitro.... If i get a petrol one it will be two stroke... cheap as chips to run then!!
I'll look at a nice 1/5 scale two stroke later. I've heard some electrics make some nice noises.....
Living where I do nitro would upset too many people, and the electric is just as quick and has plenty of run time.
I am thinking I might have a go at racing, there is a club and track not far from my house
 

Diederik

Member
Is True, we pay less here, in US $ we pay $5 for 1 liter 0f 20% fuel, the problem I have with battery is that they run empty, with 2 young boys that is an problem, my younggest has a 1/10 Electric skull crusher running 4500mah 2s batteries, expensive and he has 2 of them. They take on averge about 45 min to recharge, 10 - 12 minutes to drain. my other son runs the whole day on 1,5 liters of fuel on a big bore engine. to buy enough batteries so that the electric can run as long as the Nitro is extremely expensive. BUT...........for racing...........electric, electric, electric, you just can not beat the power of a brushless motor. But you had better buy a good quality one as they break their dogbones, strip pinnion gears, go throug clutches etc, big power = lots of wear
 

xokia

Active Member
The run time is the reason I went to 6S. 6S is stupid power no one could really use it. But that extra voltage also contains longer run times. I drop the throttle down to 50% which is still faster then my .26 picco was and I get 30-40 min run times. My charger charges both my 5000 mAh batteries in 20 min charging them at 3C. So 2 sets of batteries I could run all day if I wanted to.

I agree it has an much higher initial expense. But in the long run the lipo will win the cost battle. That's assuming the batteries are decent.

The power issue I agree with you 100%. But I broke stuff when upgrading from the .21 stock motor to the .26 picco motor. I haven't really checked out to many brushless trucks currently on the market. So I just know my truck. The HPI savage brushless differentials and dog bones are some serious beef!!
 
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The dog bones and many of the suspension and steering parts are pretty damn beefy!!
I don't think it really changes that much between electric and nitro. I haven't managed to get through a batter set yet, but I'm expecting to get about 30-40mins of run time out of my twin 2s 5000 mah batteries.
Big strong batteries, and will see how they go... I also have a 4s battery that I'm going to come up with an adaptor lead so I can run just the one battery.
But yeah I am looking forward to playing around with it
 

xokia

Active Member
I don't think it really changes that much between electric and nitro. I haven't managed to get through a batter set yet, but I'm expecting to get about 30-40mins of run time out of my twin 2s 5000 mah batteries.
Big strong batteries, and will see how they go... I also have a 4s battery that I'm going to come up with an adaptor lead so I can run just the one battery.
But yeah I am looking forward to playing around with it
I can't comment on other trucks as I just have my savage. There was a HUGE difference in the differentials and dog bones between the nitro and brushless. I converted my Nitro savage to Brushless. The conversion kit replaced the differentials with significantly larger and stronger units. Same with the dog bones.

Let us know what kind of run time you get it sounds fun. Have any pictures?
 
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Diederik

Member
There will be a difference is Beefieness due to the higher power output. I have just up graded my youngest son Skull crusher, which is a 10th scale wheelie truck (running 4500 mah 2s bats) from the standard dogbones to Savage HPI one, has to machine the heads a little to make them fit. The reason for this was that he broke one and HK up to date cannot tell me which one to replace it with as they do not show it on their parts list. The HPI one is twice the thickness of the standard ones. The Skull Crusher is no serious racing truck by any means although very fast, the truck pure fun as it is setup purely for wheelies etc but isn't that what a 10 year old wants? And at $149 RTR it is dirt cheap. I know there is a lot of No Hk guys here but my son son has for the last 2 months run 2 4500 batteries through it per day and the only thing i have replaced were the pinion gears and the big spur gear(put Kyosho in) and the dogbones. He has rolled it countless times and the shell is still in good nick. We ride the Kyosho Mad Force and the Savage HPI's with out shells on the minedumps as they break to quick. I will post a quick video of the Skull Crusher which I took the day the pinion gear started bending it's teeth, hence the whinning sounds. We where out quad riding and we took it with.
 

Diederik

Member
Here are they having fun

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IMG_00000069.jpgAlexander still had megatron there for which I managed to get a refund from the local HS

IMG_00000069.jpg
 
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Diederik

Member
And this is Alexander playing on the minedumps, not takingit flatout yet as the engine was still new.

- - - Updated - - -

This is the Kyosho Mad force, as mentioned without the shell
 
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xokia

Active Member
Love the sound of nitro :) that brushless truck looks under powered. Maybe that's typical 4S power? I've never ran 4S so I don't know what it's like.

Are both those trucks just rear wheel drive? Looks like they are having a blast though.
 
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