Bit of a question gents:
Some really cheap option popped up
A123 ANR26650M1A LiFePO4 Rechargeable 3.2v Cells
Not 3.7v making it need be 9, not 8… to make up to be 28v
Could someone clarify if I am looking at the wrong cells or else?
Thanks!
A123 is a manufacturer of cells, not necessarily what size battery cell they are. That said, according to the rcgroups link they look like 26650 size cells (which makes sense since A123 developed the 26650 standard). There is both a nominal and a max voltage for any LiIon cells, which for 26650 should be 3.3 nominal and 3.6 max (28.8V, which is where the name comes from). Any reputable 26650 cell should work, but this is more or less a dead cell standard, so you may have a bit of a hard time. I’d try and keep the mAh close to the original 2300mAh to prevent possible charging issues. Either way, A123 has discontinued those cells, so searching for 26650 cells and matching specs as close as possible would be the way to go. If those cheap ones are legitimate, those should be 3.3V, not 3.2V and would be the correct cells. I’d get them if they check out. Best alternative I found with a quick search was this:
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The one you linked up is 3.7v 4200maH and Out of Stock
I cant find none in UK new, most are from US, that with Brexit, on the top Li-Ion transport restrictions hardly will post anyway.
Chinesium ones… I don’t believe, anything they say, as at the end of a day wrong voltage / capacity will render electronics non functional or worse.
Yes, them newer ones are all 3.2v rated with capacity rate of 2500maH- 6000maH - no use.
Q 1 (still) :
Back to the question why I’m not just buying any (IE from US or even China), is that if I replace cells with new ones- I aught to balance them out upon first charge? That I can not do…
Q 2 :
Anyone would be aware for 100% the actual final figures of 28v battery for charge input from charger and discharge rates please?
(As due to the size, I’m thinking replacing not just cells, but electronics insides with newer (whatever 28v make) battery)
Q 3 :
If to get one US specified charger, was it exactly half of a charge rate vs discharge rate of an battery?.. My thinking is to load battery shell with resistors and couple up two chargers in parallel to recreate corded saw out of it…
Thanks!
Do you have more in depth figures by any chance?
Or maybe having an voltage reductor 54v in to 28v would work, considering DeWalt is making one (be it rather expensive) adaptor these days?
We’re not dead yet! A former distributor/reseller has acquired rights to produce NEW 26650 cells:
As for my tinkering–I found that simply connecting the tool + & - terminals to an external battery didn’t work. Apparently the 2nd connector atop the Dewalt battery packs and connects to the battery balancing circuit inside the pack is needed for the tool to start. Might be as simple as a jumper but I lost interest in exploring this option and opted to open up my faulty pack instead. NOTE that the pack that isn’t working is a New-Old pack in a welded “clamshell” original package bought off eBay a few years ago but never needed until a month ago. This pack has a 2007 date code.
My New/Old pack had ONE dead cell inside with the result that the battery balancing circuit wouldn’t let it charge on the Dewalt charger. I have a 36V pack of 26650 cells on hand to cannibalize for good replacement cells as needed to keep my precious track saw running,
Today I cut out the dead cell & replaced it with an identical old-but-working cell from my spare pack. I’m good to go until the NEXT cell failure. I guess I can keep up this nonsense for a few more years. My only regret in buying this tool was that I didn’t buy the CORDED version.
A track saw doesn’t NEED to be cordless. You don’t typically use it out in the middle of a field, or on the roof.
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Now some educated opinions…
(Re Q3) It would be difficult to find a battery eliminator (what you’re calling a “reductor”) with enough current to run one of these saws. Even the best cordless circular saws slow down on a long 8-foot rip through a 3/4" sheet of plywood (18mm). The 26650 that A123 makes is capable of 50 amps. No “portable” 28V power supply can do that. You would need to somehow connect an external battery pack to the tool via a suitable length of large-gauge flexible wire. Two small lawnmower batteries in series should do the job–IF you figure out what needs to be “tricked” on the tool to run with an external connection.
(Re Q2) The 26650 battery has a nominal no-load voltage of 3.3V. It uses a charging voltage of 3.6V at a recommended current of 100% of rating (“C1” rate) of 2.5A. This means the charger has to feed energy into the 28V LiFePO4 battery pack without exceeding 28.8V or exceeding 2.5A. Once 28.8V is achieved the charger should reduce to a “float” current of 125mA. This is all from the A123 battery spec sheet. Not many chargers can do this properly and I suspect the very lightweight charger that came with my saw “cheats” by charging at a much lower current than ideal.
(Re Q1) Perfect “Balancing” is a goal of performance-oriented users of rechargeable batteries.
Think “competition” here–RC helicopters, planes, cars and the like. It doesn’t matter much to a drill or saw if the individual battery voltages vary by a couple tenths within the pack.
I’m not a battery expert. This is all useless info I’ve learned since I unfortunately bought a $400 tool system that the OEM quickly killed off & ended support for. This sucks.
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