Looking for VDC help

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Old 10-28-12, 11:46 AM
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Question Looking for VDC help

Hi.. I am a newbie... I'm working on a project using a silicone heating pad. It is rated 100 watts, 8.4 amps, 12 volt dc. It is just wire wound encased in a fiberglass reinforced silicone pad. I'm experimenting at running it off a 12 vdc battery used for power tools. It doesn't have as much capacity as I'd like. I've been looking at a larger capacity 18vdc battery. I am unsure what would happen. Is this possible to use a different voltage without negative results.
Any help would be much appreciated
 
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Old 10-28-12, 11:51 AM
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You need higher amp hour capacity not voltage. Two batteries in parallel is the simplest solution.
 
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Old 10-28-12, 12:18 PM
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Thanx for your reply ray... So if a battery has a 2.5 amp hour, it alone is no good for an 8.4 amp draw...
 
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Old 10-28-12, 12:32 PM
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Some tool battery packs have the current listed on the pack. The current isn't terribly high....3-6 amp max. Tool battery packs are probably not the best way to go. Lead acid is the most cost effective. You can use gel cells or even small car batteries. Tell us more about your project. I do a lot of engineering for custom projects and I should be able to give you more help.

On edit.... a lot of power tool battery packs are now lithium ion. A very high current battery but very unstable. Requires particular recharging methods.... so keep that in mind in your use of tool batteries.
 
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Old 10-28-12, 12:38 PM
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Hey PJ... I went looking on Amazon... and they appear to be 2.5 amp hours... I am leary as to how far to go as I'm in the process of patenting a product that runs off a 12 volt receptacle... I was looking to make it more portable.
 
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Old 10-28-12, 01:03 PM
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I went looking on Amazon... and they appear to be 2.5 amp hours
Four of those wired in parallel will give you 10 amps for one hour, or 8.4 amps for a little more than 1 hour and 10 minuted, in theory (before inefficiencies, and given that batteries usually don't fully discharge.

What kind of performance were you hoping to achieve?
 
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Old 10-28-12, 01:09 PM
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100 watts is a lot of power.... to power by battery. For example....if you needed 8.4 amps at 12 volts of power and used a 12v 8.4 ah battery pack you would get less than an hour of useable power. That same load could only be connected in a car to a cigarette lighter outlet for several hours without killing the car battery. Look at it this way......your car headlights draw approx 100 watts. So you can see how long your device would be able to be powered. Does this help any ? Patent involved .... I can understand that.
 
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Old 10-28-12, 01:22 PM
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Thanx all for the help... I didn't think it would be possible to use the available battery technology beyond what I have already done. But you never know if you don't ask.
 
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Old 10-28-12, 01:35 PM
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Keep us posted on your progress.
 
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Old 10-29-12, 02:46 PM
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Hey PJ... Now I'll show my real ignorance... OK... There isn't presently a battery available to meet my needs. Is it possible... that a rechargable battery could be created to put out the 8.4 amps and still be kept to a size of approximately 4-5" diameter and maybe 3" tall. It would only need to function for 30 minutes or so between charges. What do you think..? Thanx
 
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