Need some input on batteries

[toughtrax1]

I have a general idea about batteries but I was wondering if someone could break down what you should look at when buying batteries for 2wd mod offroad buggy and for 1/10th scale on-road?

[HyperformRacing]

You want to look for the same things regardless of what type of racing it is. First off, you want to know what the discharge rate of the cells are and the cutoff. A 30amp discharge rate with a 0.9 cutoff is industry standard at the moment. Some matchers will play with these numbers to make cells appear better then they really are. Also look at average voltage, runtime and actual internal resistance. Good voltage numbers are between 1.170 and 1.179. Excellent average voltage numbers are 1.18+. Good runtime numbers are 400-419 seconds, excellent runtime numbers are 420+. Good internal resistance numbers are 2.4-2.5, excellent internal resistance numbers are 2.2-2.3. All this applies to the current crop of 3300 cells. Hope this helps...

Hyperform Racing

[metalry101]

He's right. However, he didn't mention what each of those translates into in the car.

Voltage is speed. Higher voltage means more rpms which means more top speed.

Resistance is drag. The less resistance you have the more responsive your car will feel to throttle inputs, meaning better acceleration out of the hole and out of the corners.

Run-time shouldn't be an issue in any properly set up race car unless you're doing endurance racing.

IMO the most important of these is resistance. Run time is all but a non-issue with modern cells. Voltage is important, but if you're losing races because you're not quite as fast down the back straight then your batteries aren't your problem. Punch is what gets you in front on the start, it's what keeps you in front coming out of a corner.

[highroller]

Knowing what the information on matching label means and what type of racing you do and whether the high runtime/voltage are really needed. If you race offroad on a loamy, loose condition the high runtime/voltage are generally no benefit. With stock racing runtime is never an issue even in oval, but voltage is. 1.159 is an acceptable voltage for stock offroad average 1.16 while stock oval 1.175+, 1.19 were the favorites when they were available.
Look at runtime, determine the average you need to compete 420+ may too expensive, also look at charge voltage used (usually 5 or 6amps), amp load used (20, 30, 35) and learn to equate the loads, runtout lood for 5000 runtout those using other runout can cause runtime to seem low, while voltage tends to be higher, voltage cutoff standard is .90 those using .88 or .80 again can cause the actual numbers to seem higher than those using a standard 5000 runtime and .90 volt cutoff. Internal resistance is listed either as 22 or 2.2 depending on setup the lower the internal resistance number the more punch cell is able to deliver.
The amps loads used in the matching process doesn't really matter much, once you begin using it, cells generally will perform good regardless. Matchers generally match for a specific type of RC racing those that use 20amp feel this is good for stock, while those using 30amp feels this is good for modified or it weeds out the weaker cells that get by at lower loads and now some are matching at 35amps those are more oval oriented and again the explanation is the higher rates weed out the weaker cells. There are also companies like Integy that use they own brand of matching equipment but their cells perform just as good as other brands their 1.24 cells are generally close to a 1.175 cell matched at 30amp on a CE matcher.
Some guys have purchased unmatched (unlabeled) cells for stock racing, even bulk loose cells and had good luck. Here you can just match by cell voltage but for mod oval you kinda want all the numbers tightly matched.

Word of caution, having the best cells with a medicore motor and other equipment won't always bring about the results you are looking for. Runtime is never an issue in stock racing, but in modified oval racing it can be even in a four minute heat with cells in the 438 runtime, 1.18 voltage guys have dumped hard if gearing or motor timing were a tad off.