Super-Fast-Charger for selfmade drill-battery?

L4M4 · 2018-10-05T19:34:27.000Z

Hi!

I had a 5Ah 4S LiPo Battery for my drill but one cell died - so I need a new one.
Now I want a 4Ah 3S LiPo - the 4S killed the switch-FET (only 0 or 100% possible now)

If you have the original Makitas for example, the batterys are charges within half an hour - are there chargers (for 230V) that can achieve this for LiPo-Packs, too?

I know that the battery suffers from that, but that’s OK.

Thanks!

DavidEF · 2018-10-05T20:32:03.000Z

How about a hobby charger? Gut out the old charging cradle, wire in some leads for a standard hobby charger, then plug it into the charger when needed. Bonus is that the hobby charger may be able to charge several different chemistries, so it would be useful for more than just that one tool pack.

L4M4 · 2018-10-05T20:45:18.000Z

Sorry, I forgot to mention that the battery will be charged with one of these - I have the SkyRC LiPro Balance Charger (Original), but I always had a big Power Supply next to it, so not good for to-go

I don’t even know, where the original charger is by now
I charged the battery via a XT60 Plug + Balance of course

DavidEF · 2018-10-05T20:49:17.000Z

So… I’m trying to figure out what part, exactly, you’re missing… the big power supply? (in portable form, I guess)

JasonWW · 2018-10-05T21:42:27.000Z

Keep in mind that the reason the tool pack chargers are so fast is because they stop charging at maybe 4v instead of 4.2v. They don’t do the constant voltage, just the constant amperage part of the charge. This speeds up charge times as well as increases the battery life and the number of charges it can do. Same thing Tesla does for the same reasons.

DavidEF · 2018-10-05T21:53:17.000Z

JasonWW:

Keep in mind that the reason the tool pack chargers are so fast is because they stop charging at maybe 4v instead of 4.2v. They don’t do the constant voltage, just the constant amperage part of the charge. This speeds up charge times as well as increases the battery life and the number of charges it can do. Same thing Tesla does for the same reasons.

That’s some good (interesting) information! Thanks!

Jerommel · 2018-10-05T22:28:06.000Z

I thought it was also because they use fairly low capacity cells.
You’re not gonna find VTC6 or 30Q in there.

DavidEF · 2018-10-05T22:35:30.000Z

Jerommel:

I thought it was also because they use fairly low capacity cells.
You’re not gonna find VTC6 or 30Q in there.

I thought VTC6 was a low capacity high drain cell - exactly what I’d expect to see in a good quality tool pack.

JasonWW · 2018-10-05T22:58:38.000Z

Jerommel:

I thought it was also because they use fairly low capacity cells.
You’re not gonna find VTC6 or 30Q in there.

Keep in mind that a 30Q only charged to 4v would have less capacity. It would turn it into a 2600mah? cell. Something like that.

I think some tool battery packs start off with 2400mah (older model to save money) and end up with 2000mah which is why you’ll see a 5S pack rated at 2Ah and 18v.

There should be 5 cells in the pack above, all in series. Instead of 21v (4.2 x 5) we see 18v printed on the outside. In reality the pack should measure closer to 19.5v or 20v. Some Dewalt packs will say 20v max. Some brands might say 19v.

So even if you spent the money and time to swap 30Q into a battery pack you’d probably end up with 2.6Ah instead of 2Ah and it may not be worth the time and money to swap.

Jerommel · 2018-10-05T23:58:39.000Z

Usually the voltages on packs are based on 3.6 Volts per cell.
3 x 3.6 = 10.8 and 5 x 3.6 = 18 etc…

It will probably depend on the price of the tool how high the capacity is.
For home use you usually don’t need high capacity.
For professional use it is nice to have a pack that can last a while.

I’ll have a look some time at to what voltage my 2 budget cordless tools charge.

kiriba-ru · 2018-10-06T06:40:45.000Z

1. Most cordless tool batteries are overrated. You can find 1300mah sony cells in 1.5Ah pack
2. Fast chargers can set current to 6 or 9 amps. This is 30 minutes of charge for 3amp rated pack, including CV mode. All chargers I’ve seen ended with 4.2v per cell.
3. Some hobby chargers have ac-dc power supply, you can use one of those if bigger size is not a problem

JasonWW · 2018-10-06T06:52:23.000Z

kiriba-ru:

Fast chargers can set current to 6 or 9 amps. This is 30 minutes of charge for 3amp rated pack, including CV mode. All chargers I’ve seen ended with 4.2v per cell.

Are you talking about a tool battery pack charger or a hobby charger?

That CV mode seems to add a lot of extra time, sometimes double the charge time to get that last bit of power into the batteries.

kiriba-ru · 2018-10-06T06:51:11.000Z

Tool battery pack

L4M4 · 2018-11-09T21:13:30.000Z

Hello again

I just orderes 6 Samsung 25S for the 2 Makita batteries (3S1P).

Can I just put a 12V Meanwell PSU set to 12.7V onto the batteries?
I will use a BMS with balancer on it
That should do the trick - or am I missing something?

if I am right, I can rework the original charger (gut it and put the 12V Supply in it plus Volt-Display) to be used for this, which would be very nice.

BlueSwordM · 2018-11-09T21:21:03.000Z

IMO, just charging the cells to 12V would be your best bet.

You’ll always be able to super charge the cells without concern for cycle life at 4V/cell.

And max charge would be 12,6V.

I would personally be on the safe for a full charge at 12,5V + the BMS you linked above.

L4M4 · 2018-11-09T21:28:47.000Z

If I only charge to 12V the balancer would never balance, so the batteries could go a bit unbalanced.
That’s what the Volt-Display should be for - so that I can see when the batteries hit 12V and are pretty much full, but with the opportunity to balance when left in the charger.

But that’s something I will decide when I have all the stuff - it is more important, that a simple 12V PSU + a balancer-board are pretty much a full blown charger.