From tyounger@csc.UVic.CA Thu Feb 18 03:15:56 1999 Date: Mon, 15 Feb 1999 12:40:20 -0800 From: Tom Newsgroups: rec.models.rc.land Subject: Re: Need Battery info ie.SCR1400? On Mon, 15 Feb 1999, Jorg wrote: > I've checked Deja and searched the web but I can't find any comparisons or > explanations for the variety of prices and designations for batterys. I don't > mean differences in run time but questions like; > I think I've answered a question similar to this before, but it was some time ago. > What is the difference between RC and SCR ? That's just the name type. Lots of your questions are similar, and will be answered just with a simple history lesson. > What is a 1500 vs. a 1400 pack and why are there so many different cell > types? > What are these generic stick packs made of, you know, the 3 for $35.00 > kind? > Is there any weight difference between 1400, 1500, 1700, and 2000? > I've heard that 1400's are punchier(?) than 2000. Is this true and why? > When I started racing oh so many years ago, the only batteries anyone used were Sanyo 1200 SC's. My understanding was that the SC stood for Sanyo Cell or something like that -- what it stands for is not important. These had yellow shrink-wrap with red printing. I'm still using some of them to power a laptop computer. . . Capacity was 1200 MAh. A few years later, Sanyo came out with their "Rapid" cells, designed to be fast charged and fast dis-charged. This was designated with an "R" appended to the name, designating rapid. These were 1200 SCR's, 1200 MAh capacity with lower internal resistance than the SC's, and hence better able to withstand the rigours of high current abuse. These had red shrink-wrap, with black writing. A few months after that, I remember Sanyo came out with another battery, the "Extra" battery. This was their high (or extra) capacity battery, called the Sanyo SCE, with 1700 MAh of capacity. These had a relatively high internal resistance, and many people reported fragility, although I never had any significant problems. These cells had yellow shrink-wrap, with black printing. A year or two later is when I remember the 1400 SCR's coming out. These were basicaly the same as the 1200 SCR's, with the exception of slightly more run-time, and slightly higher internal resistance. These too had red shrink-wrap with black writing. Then came the RC specific cells, designated with RC. First was the 1700 SCRC, a low-resistance durable variant of the 1700 SCE. These had black labels with white printing, and multi-colored graphics. A few years after these came out, I took a 2 or so year hiatus from R/C racing which saw the introduction of the RC 1700's and the RC 2000's. As I understand it, there were some brown labeled ones that sucked, and the current blue labeled ones are better. These are supposed to be lower-resistance variants of the SCRC, with the same and slightly increased capacity (same idea as comparing these with the past with 1700 SCRC = 1200 SC, RC1700 = 1200 SCR, and RC2000 = 1400 SCR). Note that nowhere did I mention KR1500s -- I've concentrated only on Sanyo batteries that were used in competetive R/C racing (the Panasonic P-170 is deserving of a place in this history, but it's Panasonic and not Sanyo). The 1200 SCR had, from my experience, the most pronounced "dump" of all these batteries. They could be matched very precisely, and would go from all to nothing in just seconds. The 1400 SCR's were not quite as pronounced as this, and the 1700 SCE's took aeons in comparison. Anyway, to answer your questions, the number (1500 vs. 1400) is a measure of cell capacity in MAh. The higher the number, the longer you can drive. However, there is a trade-off I'll mention in a moment to answer another question. The generic stick packs tend to be made up of cheap cells, usually 1500's. I don't believe 1400 SCR's are being manufactured anymore. I've never weighed them, but I'd imagine there could very well be a weight difference between the different cell types. Although their overall dimensions are constrained to a standard, their construction differs with different membranes and amounts of electrolyte. In short, they could weigh different amounts, but I don't know myself. And 1400's are indeed "punchier" than 2000's. This is the tradeoff I said I'd mention. As the battery capacity increases, the internal resistance of said battery increases as well. This means that the voltage the battery supplies under load will decrease as the resistance the battery has increases. Since 1400's have a lower internal resistance than 2000's, they will supply more current to the motor, and hence you'll accelerate quicker. But you can't drive for as long. This is why some people have different types of batteries for different types of races. Extra battery capacity at the end of a race is quite useless, so why not trade this for a battery which will have less residual capacity, but will cause you to accelerate quicker? Many racers do this. In fact, in the good ol' days with 1200 MAh packs, you would gear for run-time, not peak performance. You adjusted your gear ratio so that you could do exactly one lap more than the race length. Over-gearing the motor was not an issue like it is today, since there wasn't enough battery capacity to over-gear and still have any sort of run-time. > I plan to buy six cheap packs (play for my son) and four race packs (novice > dirt track racing for me). Should I buy the 1400SCR's or the 1500 AmpMax for > cheap packs? I dunno what them AmpMax things are, but stick with Sanyo cells. > > I will be running a stock motor in a buggy and believe all I need is 1700's > to make the race. Should I buy 1700 or 2000? Cheap 1700's as long as they are > RC1700's? As I mentioned, extra battery capacity at the end of a race is useless. If you can make run-time with 1700's, then by all means get them. They're both cheaper and faster than 2000's. > > How soon after use can I rechare the batteries? Do I need to let them sit > for a day or can I charge them once they are cool? > Heck -- I've only got one 4-cell 2000 pack that I use for racing. But do as I say, not as I do. You should at LEAST let them cool before charging, best is to use them no more than once a day. > If you can direct me to info like a comparison test, please do. > That'd be cool. . . ___ TTTTT OO M M The sixth sick shiek's sixth sheep's sick. |~~~| T O O MM MM @o o@ T O O M M M So if it is in or if it is on it is as it is, * T OO M M be it in or on. `-'