Match cells by what?

[Northy]

I know what your all going to say but hear me out please...

The normal way you would match cells is by run time, but in my opinion this is becoming less and less of an issue, I race off road and can not remember the last time I dumped.

If you were matching some of the new high capacity cells would you still match by run time (discharge capacity)? I am thinking that it might be better to match by charge capacity, as that way no cells get over or under charged during charging and damaged.

If the cells had diferent discharge capacities then all that would be needed would be to discharge after a race to a higher than usual voltage (eg 6 Volts), and then equalise. This way no cell is getting damaged on discharge either.

Does this make sense? Or does charge capacity tend to follow the same curve as discharge capacity and would therefore be sort of the same thing?

How about matching by voltage? Whats that all about then?

Comments welcome

[darren]

With the new hi-cap cells, I agree, matching for run time is a thing of the past. I also have yet to dump using even my 3300 practice packs, and I still haven't tried 4000+ cells, I probably won't either as I don't think the weight to power benefit is really there.
That being said, matching depends on the type of racing you are doing, if you are running stock motors, then you really need the voltage, heck, we need the best 1.2+ volts for everything! Until mains start going over 5 minutes, it is really just a moot point.

[pro4nut]

Is matching still needed?

Have been running unmatched cells since 3700's were available, now running intellects instead, I think how you treat them when charging, discharging is more critical.

[Northy]

Thats what I'm trying to get at, we have control over discharge and can discharge individual cells so as not to damage them.

BUT we caharge as a pack! So the weakest cell will always get over charged.

See what I mean now?

G

[pro4nut]

Yes.
I believe you can get a single cell charger ( looks like an overweight smart tray) which would give one solution. or 6 advantage chargers.

I was actually discussing whether matched cells were worth the price ( £50 - £80) with my local hobby store, i also asked why they did not stock unmatched cells.
Not stocking unmatched cells came down to the problem of how little money would be spent on them and that the distributors would then struggle to sell matched cells at all. Trying to get past this is tricky, one of the bigger problems in the uk market is the level of price control the distributors have.

[DirtRacer]

I suppose matching them yourselves in small numbers would be the way to go and just sell off what you dont need?

[Northy]

Why do you think I'm asking the question? ;D

[DirtRacer]

Well, i could just easily do that myself too since i got hold of a turbomatcher just the other day for nuts and unmatched cells in bulk are just as cheap too but as its time consuming and cuz packs are far cheaper to buy than matching them yourselves i aint gonna bother . I suppose its something i could consider if i aint got nothing better to do or when i get close to retirement age, in about 40yrs time? ;D

[YoKoMo-MX4]

One thing that has not been mentioned is that most cell matching companies 'treat' their cells (i.e. 'zapping') to get much better performance than a 'raw' cell can produce. My LHS bought a batch of raw GP3300 cells some time back and cycled them three times to get numbers. While some of the raw cells had good numbers most of them were not stellar.

The trouble with zapping for the 'hobbyist' is that a production level zapping setup is expensive and due to current world events, many of the components needed for building a zapper are difficult to find, thus driving the price up even more than normal.

As a hobbyist, I am happy with mid-high-level matched packs (not the most expensive, usually one tier down from 'the top') ... I find that the extra bit the 'top' packs give I can't use

Northy, maybe you need to get a battery sponsor? That way you wouldn't have to worry about it as much

'nuff said,
MX4