Author Topic: NiHM question  (Read 2629 times)

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Offline h3roTopic starter

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NiHM question
« on: September 22, 2007, 11:26:57 AM »
Last time I decided to try to do something with my batteries it ended with kind of bad results, so now I am going to ask BEFORE I do it just to be sure.

Does NiMH batteries require a special charger?
What is the advantage of buying a battery pack over making one?

Planing on buying 8 2700mAh NiHM batteries from a local shop and make my own pack, if its not a really lousy  idea.

Thanks in advance

Offline snow

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Re: NiHM question
« Reply #1 on: September 22, 2007, 11:52:45 AM »
Charging NIMH: http://www.powerstream.com/NiMH.htm.

So if you want to charge them fast (like in 1 hour) you need delta peak charger (charger that detects voltage drop when batteries are full). If you dont need fast charging you can use DC power supply where you can set voltage and current.

Normally if you buy packs they are good. If you want super pack (very high current, ultra low resistance, etc.) you will probably have to make your own pack. Some RC shops can do that for you.

Or you would want to make your own pack if you will have some strange number of batteries in it or some custom shape. 6 - 8 batteries in pack are quite common for RC cars... so check some RC stores.

Offline h3roTopic starter

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Re: NiHM question
« Reply #2 on: September 22, 2007, 03:09:06 PM »
Thanks for your reply.

Im planning to buy something very close to this, just an other brand but same mAh and voltage.
http://www.sparkfun.com/commerce/product_info.php?products_id=335

I have a charger that supplies 500mAh at 3v/4.5v/6v/7.5v/9v/12v. From what I understand I can use that one if I set the voltage at 7.5 while charging my homemade 6V pack?

« Last Edit: September 23, 2007, 02:32:42 PM by h3ro »

Offline Admin

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Re: NiHM question
« Reply #3 on: September 24, 2007, 04:59:04 AM »
FYI, soldering wires to batteries is really hard. The batteries absorb the heat really fast, keeping the surface too cold for a good bond. If you take too long, the heat can damage the batteries.

You need a soldering iron where you can adjust the heat to really high . . .

Getting battery holders such as in the $50 robot tutorial would be easier . . .

Offline h3roTopic starter

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Re: NiHM question
« Reply #4 on: September 24, 2007, 06:15:03 AM »
Yeah, but I haven't found any places which sells 5 packs. And  I want to keep it as small as possible to fit my lite robot platform (I see the point of CADing now.)

But will the charger work?

Edit:
Had a nice trip?

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Re: NiHM question
« Reply #5 on: September 24, 2007, 06:48:01 AM »
Try here:
http://www.onlybatterypacks.com/

Also, try ebay.

Charging NiMH batteries are really easy and you can use just about any charger. At home I use a hacked wall adaptor, but at work I got a nice ~$60 automatic charger with good features.

Quote
Had a nice trip?
yup! I really needed the vacation. I really missed my old highschool buddies, too. And I totally forgot how good the food in Louisiana really is . . . I went to like 10 restaurants in 3 days, ordering waaaay more than I could eat at each :)  Cajun folk dun eat ta live, we live ta eat! hehe

 


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