Why use more batteries or cells in a Truck?

[Rabiedmushroom]

I've noticed that some folks use bigger / more celled batteries in their monster trucks sometimes. As a comparitive novice, I have no idea why this is done! Is if for more power, or longer battery run?

I am prompted to ask when I see fancy things like this on Ebay, where 2 separate packs are joined into one standard connector. How does that affect a Clod's performance then?

http://cgi.ebay.co.uk/7-2V-6000mAh-RC-CAR-...1QQcmdZViewItem

[mud4fun]

I can only imagine it would be useful for more punch in qucker 'race' trucks. Bigger heavier packs are useless in a crawler because they are generally mounted high up in the chassis and bigger packs would just increase the CoG too much causing the truck to topple more easily. The gains in power would also be negated by the motors having to work harder to carry the extra weight.

Personally I run a cheap silver can 550 sized motor with reduction gearboxes as it consumes very little current and allows me to fit a smaller lighter pack. I can get an hours runtime from a 2000 7.2v pack in my crawler.

I guess some people just assume bigger, more powerful packs equates to better performance whereas the reality is that a single torquey motor makes a lighter truck with a lower CoG than one with two less torquey motors and thus uses less power and gives better crawling performance and longer runtimes (on a shaft driven truck). To a degree it depends on what truck you have and how you intend to use it?

On a Clod you have no choice but to have two motors and don't have much scope for fitting reduction units so bigger packs may be the only way to get longer runtimes and more punch. I have run bigger/higher voltage packs before and they do give huge increases in torque.

[mymonsterbeetleisbroken]

Thats a special battery system designed for the standard clod buster chassis. One battery goes in the front of the plastic tub chassis, and the other goes in the back. then the normal battery holding compartment is not used.

its wired in series, so its giving the same 7.2 volts. The pack is designed to give superior run times, as clods eat standard packs for breakfast [] but i dont think it will make the truck faster, in fact the extra weight will probably slow it slightly, and as mud4fun said, it will roll easier with the extra weight.

those clod batteries have been around for many years. they made more sence years ago when "fast" chargers took ages to charge, and batteries only went up to 1200 mah. but nowdays it would make a lot more sence to have some 3000 mah stick packs charged and ready to go.

it wont give 14.4 volts, if it did, the motors would fry and that poor old tamiya connector would melt []

[TWINSET]

Yup, what he said []

 

Rabid - if you're new new, then the Mah on the battery gives you some idea as to runtime for 2 similar condition batteries;

for instance, 1200Mah will not run as long as a 2400Mah

By spreading the batteries out like that, it does look like 2 sets of batteries, but it's actually just one large capacity battery split into 2 easily placeable lumps.

Check out Neo's crawler in his showroom, he splits a normal 6 cell battery on his TLTs for more even weight distribution (and cos he's a bling tart [])

 

[DJTheo]

Yes, they use 4x6 cells (1500mAH) connected in parallel giving thus the same voltage (7.2V) but 4 times the capacity (6000mAH) and runtime. I personally don't find it a good idea, as they used little AA cells which have no high current capabilities and die fast when used with high currents, also using many cells increases the risk of one failing, reversing its voltage and memory effect due to tolerances. I would rather use 3 large capacity cells in the front and 3 in the back. For racing often paxks are connected in series, giving 14.4V, meaning double power, but even less then normal runtime and special ESC and motors needed.

Cheers

[Rabiedmushroom]

Great replies guys - and nicely put in 'laymans' terms so I understand. Thanks [H]

No I'm not new-new, but haven't done a lot of custom mods, only hop-ups bought off the shelf.

Extra run time is always handy. I'm currently trying out some 3000 Nimh batteries as a step up from my trusty 2100 Cds.

I'm perfectly happy my current set up, but its always nice to learn more so one can consider options for future projects or options. []