Couple Battery Questions - RC Groups
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Jun 18, 2012, 12:40 AM
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Couple Battery Questions

Okay. so as you know li-po batteries are crazy ass expensive! so heres the deal i made my own out of li-ion cells out of a laptop battery. i bought a charger for then because a ni-mh ni-cad charger obviously wont charge li-po li-ion batteries. i got a imax b6 charger just to try. so the batteries i made worked excellent when i first made them they obviously die after awhile of use. i charged them put them in the rc car get ready to go and bam. it goes slow as if the battery was dead. im not sure whats going on here i had it set on the li-po 7.2v setting. could this be caused cuz i didnt use a cell balancer??!? ugh please help me.
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Jun 18, 2012, 01:18 AM
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It's because the batteries that you pulled from your laptop have far too high internal resistance to be useful in your application. As you draw current, voltage drop is far too great to properly power your car.

If you want your car to move, buy better batteries. I know that this is now what you wish to hear, but it's the truth...

Jun 18, 2012, 02:15 AM
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flydiver's Avatar
Yep, low performance batteries designed for low draw laptop.
Jun 18, 2012, 02:58 AM
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Laptop batteries (and those in many other consumer goods) are designed for low current applications over extended periods. It's not really about the quality of the battery -- it's just their design. They can't supply high current, which is what your motor wants.
Jun 18, 2012, 06:40 AM
RC plane addict ;-)
startazz's Avatar
Yeah i'd have to agree with the other advice your getting mate,but you can buy some good cheap batteries out there now if you want to look around for them,you might also want to go for a good C rating too to get more of a punch when you need it.

Here i'll leave a link so you can check them out and maybe look for what you might need.
Jun 18, 2012, 08:15 AM
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flypaper 2's Avatar
The LI-ion used in power tools are the ones you want. They are high discharge and work well in planes. Not as good as lipos but do the job. Also a little heavier than lipos for the same capacity. They will take more of a beating than lipos though.

Jun 18, 2012, 02:33 PM
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That and lipo is one of many types of li-ion cell. I highly doubt those laptop cells are the same voltage as a lipo. He was probably over charging them on the LiPo setting when the LiFe setting probably would have been more appropriate.
Jun 18, 2012, 02:35 PM
Registered User
And yeh lipos are pretty cheap now. Unless you bought surplus laptop batteries which were already past their prime I fail to see how you could spend LESS money then just buying a lipo.
Jun 22, 2012, 12:40 AM
That is right. low performance batteries designed for low draw laptop. . hope it will help you.

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