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#1
08-01-2011
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Batteries
Nimh batteries;
Mah v Brand. Which matters most? And if brand, which brands return best performance? Cheers guys 
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#2
08-01-2011
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I think Nimh are a bit thin on the ground these days with lipo being so easy to use.
What matters most is looking after each cell, discharging each cell to the same voltage after use - approx .9volt - then charging on a good charger, hopefully over time your cells will remain balanced. Problems arise as the batteries become out of balance, one cell reaching a fully charged state may trip the charger to off/finished, the other cells being undercharged and under power. If you can buy matched cells you will start off with a pack that should last, look here: http://demonpowerproducts.co.uk/index.php?cPath=46_47 We used to carry 6 or 8 packs of side by side for a meeting, only using each pack a max of twice a day, discharge & balance between meetings. Now we have 2 lipo packs that are easypeasy, loads of power and could easy run all day on one pack topping up between heats. Dedicated lipo charger required. I can see this sounds like an advert for lipo but you will find most use them for these reasons
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#3
09-01-2011
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Whilst there are lots of advantages of lipo, for now I'm sticking with Nimh.
Nimh are somewhat cheaper, and getting one to last for a 5 min race shouldn't be a problem. But more importantly, I'm just starting out. My B4 was designed to run with a nimh/nicad in it, and I don't want to switch to a much lighter lipo and then have to start messing about with lead balancing it, well not just yet.... Keepin it simple
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#4
09-01-2011
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Quote:
you'll need 4 packs of nimh, an equaliser, battery bars and female corally's (unless buying pre-built) and a charger. And they require constant maintenance to keep right. Or... 1 pack of lipo cells and a lipo charger with built in balancer. Are you sure nimh is cheaper? The B4 was designed to run with a brushed motor, but that doesn't mean you should 
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#5
09-01-2011
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Darn double post
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#6
09-01-2011
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Um, yeah I think so.
I already have 3 packs, and a charger. And yeah, I would be looking at prebuilt packs, so all I need is 1 battery pack, maybe 2 just in case. Oh, and I am running a brushed motor 
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#7
09-01-2011
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Quote:
__________________
who knows who cares 
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#8
09-01-2011
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The first nimhs I had were 3000mah - unbranded that came with car.
I actually found these to be on the whole quite good. For a 2nd battery went for a core 5000mah, performance just as good, however runtime was vastly improved (at this point in time was only bashing in field and alley) in fact run time was so good - managed to melt the tamiya connectors. Thats about the only exp I have on nimhs, unbranded performing just as well as branded, the only diff being the higher the mah, the longer the playtime (not too important if you racing and have a charger with you tho).I've actually taken a step even further back than nimhs and running nicads in one of my mini's
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#9
09-01-2011
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As well as the price arguments lipo also saves you a hell of a lot of time. You wont need to discharge them, You would get two races from a decent lipo pack and they will give a better constant voltage during a race unlike nihm which will slow down as the race goes on.
The time saved is worth the cost any day.
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My feedback http://www.oople.com/forums/showthread.php?t=19395
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#10
09-01-2011
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I have in the past sold a LOT of NiMH cells to a lot of people (many here on oople who I think will say that I gave them a quality, well matched product at a good price).
Then hard cased Lithium Polymer batteries came along and killed the market over night. The Lithium polymer cells available today are far easier to charge than NiMH, the chargers are less expensive, you don't need to discharge each individual cell after each meeting and they weigh less. Apart from the initial investment there is no need to run NiMH cells any more. If you do want to continue to use them and you are buying cells second hand then check there are no weak cells in the pack you are buying. Make sure you have a cell discharger (Novak or similar) and that you follow the BRCA charging advice. Cheers Neil
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#11
09-01-2011
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I think when talking about lipo vs nimh it's important to remember how many more cycles a lipo will still perform top notch compared to nimhs!
A good quality lipo will do 100+ (this is full discharges too, so probably about 2 races worth), Nimhs do much less and each run would be considered a full cycle (due to having to discharge and equalise after every run).
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#12
10-01-2011
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As you have asked for nimhs, then we still do them at www.dpmodelracing.com
we only do 4600mah, but the cells we use are lighter than the IB4600SHV but provide just as much punch and runtime if not more. Have a look 
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#13
10-01-2011
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IBs are good cells.
If you really want to use NiMh I got a Novak discharging tray for sale cheap, PM if interested. I would nevertheless recommend to go LiPo direct for the above mentioned reasons.
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#14
10-01-2011
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Quote:
LiPo is where you have to head really, and I still really dislike their power delivery (far too harsh for my tastes) but getting good NiMh is now near impossible as Neil says. Buy a decent quality charger now and it should serve you well for years (no need to spend more than about £60). If your not racing seriously then NiMh will still power your car well enough though.
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#15
15-01-2011
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So if I sink a lipo in, can I chop and change between nimh and lipo?
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#16
15-01-2011
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If you mean in terms of your esc, then yes, but this will depend on your esc and whether it has lipo (voltage) cut off on it. And whether of course the esc itself is compatable with lipo packs?
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#18
16-01-2011
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As far as I'm aware there is no good quality esc that won't take both lip and nimh, however if you're going to get 1 pack of lipo you won't need any nimh
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#19
16-01-2011
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I've just check and my esc is compatible with Nimh, so no problem there. No idea about a cut off, it's this one http://www.modelsport.co.uk/index.php?product_id=31552
Description says built in fail safe, but I presumed thats to do with going out of radio range?
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#20
16-01-2011
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The mtroniks esc that i've got allows you to switch between lipo and nimhs mode. Looking at your one am not sure if it has this? As far as i'm aware your right, that failsafe is more to do with radio range than batteries.
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