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Author Topic: NiMH Battery Discharge Rates  (Read 3324 times)

Nige52

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NiMH Battery Discharge Rates
« on: November 21, 2010, 02:19:06 pm »

All Lipo batteries have a max discharge rate on them, usually 10c up to 35c, so you know the higher the rating, the more amps can be drawn, correct? I found this out (Again) when blowing a 15c rated battery through using a too powerful motor, lesson learned.  %)

I need to buy 4 NiMH batteries for my new club 500 for next season so I thought to go with the biggest C rating I could find,....but I can't find any batteries with this on? Only the capacity, 2500, 3700 or 4600 etc. It's ok having a high capacity battery, but if it has a low discharge rate it's not much good for racing is it? So how can I tell the discharge rate (Or quality) of Nimh's?

Thanks
Nige
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nick_75au

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Re: NiMH Battery Discharge Rates
« Reply #1 on: November 23, 2010, 11:01:58 am »

Ni-MH are not prone to damage like Lipo with high discharge, they tend to self limit current because of their internal resistance, there are different C rating for NiMH though, most "racing" buggy packs are high discharge, but many high capacity C and D cell Ni-mh have low C discharge rates., those will have a greatly reduced life if asked to put out high current.

the safest way is to buy a buggy pack and strip it down to the 4 cells required, otherwise you will be looking for data sheets on the net.

Nicad had a prefix or suffix Ii don't recall which) that indicated discharge capability.

Nick
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BigA

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Re: NiMH Battery Discharge Rates
« Reply #2 on: December 02, 2010, 11:50:02 am »

I buy my packs from Iain at the Component Shop - he also sells on E-Bay (ID is itl-e) and his listings include the maximum discharge current as well as capacity.

My George Turner Bluebird model (seen here: www.gdmbc.co.uk/Club%20Models.htm) is powered by a custom 8.4V 2400mAh pack (from Iain) made from individual AA cells of low discharge capacity. At full throttle, I get a duration of 24min. The motor draws and estimated 5.5A with the set-up described. The pack has been used several times and appears to be lasting well. Only downside is that, having a low discharge capacity, it takes a wee bit longer to get up on the plane. Once it's there, though, it's great  O0
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grasshopper

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Re: NiMH Battery Discharge Rates
« Reply #3 on: December 02, 2010, 01:18:14 pm »

I use CPC on-line and their catalogue - see link below,  there are also tech sheets available if you hunt for them. There are a couple of suitable made up packs for your boat - but they also offer single cells  for you to make up your own packs.

CPC don't manufacture as such, they're distributors so sell other company products - some of these packs are made by overlander that advertise in the model mag's so might be another source..


http://cpc.farnell.com/jsp/search/browse.jsp?N=411+1003196+500001

Hope this helps.
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tony23

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Re: NiMH Battery Discharge Rates
« Reply #4 on: December 04, 2010, 07:54:41 pm »

Try giving Overlander a call they have been in the model battery business for a long while and use a good quality brand like Sanyo. http://www.overlander.co.uk/
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