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REPACK MAKITA 3.0aH WITH MORE CAPACITY
#11
(12-18-2019, 03:28 AM)Korishan Wrote: No problems using higher capacity. it's only when voltages change is when it becomes an issue.
Also make sure the discharge rate of the pack is the same or higher than the origonal battery. Working with high power density battery packs is a whole nother can of worms than a powerwall. I would know, I build ebike packs.
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#12
A Makita 3Ah will have 1500mAh cells, probably 15Q or equivalent Sonys.

As said by other members above, you must not use Samsungs of 2800mAh as they are low current cells and will fry. The power tool may actually start and work but at continuous use the cells will overheat to the point of fire. You need to use same type of high current cells. Replacing 15Qs with 30Qs will make you a 6Ah battery. Note that 25Qs are very easy to find so you may as well get these and make a 5Ah.
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#13
(04-10-2020, 10:49 PM)Crimp Daddy Wrote: Not that this is going to directly help you, but I did a tool battery conversion and figure I share in case it gives you any ideas...  I opted not to use a BMS, and used the manual monitoring / RC balance charger route to maintain the packs.

https://secondlifestorage.com/showthread.php?tid=4670
I did similar with my 12v ni cd battery for my drill.  definitely not a flash job like yours but i still get to use the small drill.  later i may look at putting in balance when i re do other ni cd batteries like you have done. tks for the help
Smile

(05-08-2020, 05:46 AM)Overmind Wrote: A Makita 3Ah will have 1500mAh cells, probably 15Q or equivalent Sonys.

As said by other members above, you must not use Samsungs of 2800mAh as they are low current cells and will fry. The power tool may actually start and work but at continuous use the cells will overheat to the point of fire. You need to use same type of high current cells. Replacing 15Qs with 30Qs will make you a 6Ah battery. Note that 25Qs are very easy to find so you may as well get these and make a 5Ah.
yes tks for info.  i am still learning.  getting vtc4 from dyson packs and some lgdahd2 so i will be using these without mixing.  just a pain getting the last 2 batteries out of the dyson holder.  think i will revert to forcing them out and putting tape around the torn wrapper Smile

(04-06-2020, 09:47 PM)loyd Wrote: You will need to get a new BMS / Pcb board. On the original ones there is a chip which destroys the board when there is under voltage / no voltage.
You can find them cheap on Aliexpress.

Andy
some of the battery packs show voltage before i pull the case apart.  other battery packs show zero voltage.  once i have pulled the battery apart i can take the bms off the pack.  if i connect the bms to a 5s pack with wires and put a meter across the bms and if i get the correct readings will the bms be ok to put on a 5s pack and put the battery back to work on my drill.  what does low voltage destroy on the bms?  is it something to do with the charging of the pack? Sad
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#14
(05-08-2020, 05:46 AM)Overmind Wrote: .


[quote="Overmind" pid='45381' dateline='1549614099']
Today's power tools are very complex.



Inside a Makita battery there are 8 (14.4V) or 10 (18V) 18650's, and the BMS.
Here is there the  design flaw: the BMS draws power only from the first pair of cells. If you leave it sitting for a while, the BMS  will deep discharge that first cell to zero, while the others remain charged.  Result: dead battery.
If you put it in the charger, the charger will mark the battery as bad (the data pins I was mentioning) and it's unusable forever.


I was trying to reply to your post on a different Makita battery thread you've posted on but it was more than 3 months old and I couldn't post on it. ? So I hope its OK to post it here.


Did anybody figure out yet how to reset or disable this on the original makita boards? Without replacing the boards with the not great ones that can be bought online.

I have a load of the batteries that won't charge and show 0V on the battery pins but if I measure the voltage on the cells they are perfectly fine and balanced with each other.

This is really "stupid" from Makita (I know it makes perfect business sense) because it forces people to dump these batteries and buy new ones or those who dare to open them up and replace the boards, but loose the balancing capability while charging.
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#15
(04-11-2020, 09:33 PM)CUDAcores89 Wrote:
(12-18-2019, 03:28 AM)Korishan Wrote: No problems using higher capacity. it's only when voltages change is when it becomes an issue.
Also make sure the discharge rate of the pack is the same or higher than the origonal battery. Working with high power density battery packs is a whole nother can of worms than a powerwall. I would know, I build ebike packs.
Hi Korishan, i am not into ebike or car packs but if someone is building a pack should they use the same brand batt same capacity and what would the discharge rate be needed for the battery to use in ebike pack, cheers Huh
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#16
@Saby I switched all my tools to Milwaukee and for these you can find cheap fake batteries with junk cells that can be refitted with good cells. The boards in them is what matters and the are compatible with all tools. There may be similar ones for Makitas, not sure really, but I know you can find lithium battery PCB chip boards for them like: BL1840, BL183,0 BL1815, LXT400.

As for the non-functional ones, on the battery connection nearest the spring-loaded white catch there is a small bridge of metal with a hole in the center. If this fuse is melted you can solder it back together by sanding the two pieces and putting a glob of solder on them or put a different fuse there.
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