[Shop-talk] Cordless tool battery packs - the current state (LiPo Conversions)

[Jack Brooks]

Balance chargers are used in the Radio Controlled hobby.  I’ve converted many devices from NiCad or NiMH to LiPo using bare batteries that have balance plugs built right into them too.  The critical part is to include a low voltage beeper, which attaches to the balance plug on every LiPo used, as LiPo’s fail quickly if they are discharged fully.  I’ve assigned one of these to each converted device. They are a dollar or two from DX.com and other vendors.

The technology is there and easy to implement if you have the exposure and knowledge, but it’s not quite up to plug and play for the general public.

Jack

From: Shop-talk [mailto:shop-talk-bounces at autox.team.net] On Behalf Of John Innis
Sent: Friday, February 03, 2017 11:16 AM
To: Matt <mbarre at juno.com>
Cc: shop-talk <shop-talk at autox.team.net>
Subject: Re: [Shop-talk] Cordless tool battery packs - the current state

You can't really convert a ni-cad or nimh pack to Lithium easily  or cheaply.  This is because with micad or nimh, you can just change all the individual cells in the pack in series.  But to properly charge a lithium pack you need to balance each individual cell.  For an 18v tool there are 5 cells in a pack and the charger needs to monitor and adjust each cell to keep them all balanced.  So instead of 2 contacts between the battery and charger (+ and -) you now need 7.  One way around this is to put all the balance charger circuitry into the battery pack itself.  This makes the battery pack heavier and more expensive, taking away any advantage of using lithium batteries to begin with. When you buy a replacement pack that has (or is supposed to have) lithium batteries instead of nicad, you really don't know what is in that pack.  Does it really have lithium batteries?  Is there a built in balance charger?   Also lithium batteries (especially cheap ones) occasionally bust into flames.  Not having a balance charger increases this risk.

On Fri, Feb 3, 2017 at 10:31 AM, Matt <mbarre at juno.com<mailto:mbarre at juno.com>> wrote:
I have 2 questions for this august body, but for simplicity I will break them up:

Time to repower my fleet of Porter Cable 18V tools.
I have seen over the years the various options to rebuild the battery packs and it looks like there are services and do it yourself packs that are already assembled for the DIYer to put into their plastic housing.  THe rebuilder folks claim they use quality batteries and they produce better packs.
EBay seems to have plenty of "new" options as well, mostly from China.  I currently have nicad chargers but the availability of dual nicad or li-ion widens the options.
I don't use these every day, or even every week, but a couple of times a month I am working on something.

Any guidance from the group re nicad vs li-ion.
Off the shelf vs US rebuild or battery pack?

Thanks!
Matt in GA

_______________________________________________

Shop-talk at autox.team.net<mailto:Shop-talk at autox.team.net>
Donate: http://www.team.net/donate.html
Suggested annual donation  $12.96
Archive: http://www.team.net/archive
Forums: http://www.team.net/forums
Unsubscribe/Manage: http://autox.team.net/mailman/options/shop-talk/jdinnis@gmail.com




--
=================================
= Never offend people with style when you   =
= can offend with substance --- Sam Brown  =
=================================
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/shop-talk/attachments/20170210/a3a0f6bf/attachment.html>