Ridgid Tools goes Li-ion, lifetime warranty

[TylerDurden]

I don't know the law regarding warranty registration.

They do make a distinction between the 3yr. warranty and the Lifetime "Service Agreement".


As per the included documents:

The warranty requires proof of purchase and is NOT transferrable. The Service agreement requires registration and submission of the original UPC, and is also NOT transferrable.

[fechter]

OK, one thing keeps popping into my head when talking about building packs from power tool batteries. The BMS has FETs to open the circuit in the event of overcurrent or undervoltage, and possibly overvoltage.

If you put a bunch of these packs in series, and the BMS opens on the end pack, the FETs would see the entire pack voltage, which could be higher than their voltage rating. Actually if any of them go open, they could get full pack voltage. Careful setting of the current limiter on the controller should prevent the BMS from ever going open circuit.

But, if it has a lifetime warranty, who cares?

[TylerDurden]

OK, one thing keeps popping into my head when talking about building packs from power tool batteries. The BMS has FETs to open the circuit in the event of overcurrent or undervoltage, and possibly overvoltage.

If you put a bunch of these packs in series, and the BMS opens on the end pack, the FETs would see the entire pack voltage, which could be higher than their voltage rating. Actually if any of them go open, they could get full pack voltage. Careful setting of the current limiter on the controller should prevent the BMS from ever going open circuit.

But, if it has a lifetime warranty, who cares?

How about a bypass relay that switches the pack into the string when voltage is present at the battery, but switches the pack out if its voltage is cut by the bms?

Or is there a way to integrate the T terminal on the pack to switch the pack out. Doesn't the charger get some signal from the T terminal in the pack when charging, or is that just a thermal-breaker of some sort?

[fechter]

We need to rip one apart and see the BMS. I vaguely remember seeing a picuture of a DeWalt BMS. It would be nice to know what the component ratings are.

Wild guessing, I'd say the third pin sends a signal to kill the charger when the cells are fully charged.

If one of the BMS "circuit breakers" opens, and the voltage is too much, the FET will likely short, which would maintain the circuit. You might not even notice it if it happened.

I'm not sure if the big FET "circuit breakers" are used to limit charging. During charging, if one opens, the voltage across it will be minimal, so it should remain happy.

Seems like as long as the controller is fused or limited at a current level below where the BMS kicks out, you should not have any problems.

[TylerDurden]

Ya gotta break a few eggs, they say...


I'll see if I can get in there without cutting.

[xyster]

I recall somebody from the old V tapping into their Dewalt packs battery leads underneath the BMS, and in such a way the packs still interfaced with tools properly, and could quickly be returned to stock appearance for warranty service.

[TylerDurden]

The board looks a bit ratty, as there is still a lot of gunk that they used when they potted the BMS.

The ribbon cable on the left side carries leads to the cells (1 each) and a thermister for the back of the pack.

The heatsink tabs lead to the negative pole, the jacketed lead in the center is the +24V out via thermal breaker.

The red lead at the right goes to the T connector for the charger.

[fechter]

Thanks Tyler,

From the IR website,

IRF4104
VDSS = 40V
RDS(on) = 5.5mΩ
ID = 75A

So if you built a pack of these that was over 40v, it might self-destruct if the BMS ever opened the circuit.

What does the little push button on the board do?

[TylerDurden]

The little button is the battery-check... the pretty little LEDs light up to indicate the level of charge.


So.... use 'em at 24V..... or is there a way to safely put two together for 48V?

Edit: That is, a way to use them at 48V without internally modifying the units... It is a pain to open them without damage.

Thanx fer lookin!

[mcharles13]

someone mentions on the forum there magnesium based cathode like similar to milwaukee. I'm quite surprised no-one is yet selling them for ebikes yet. it seems lots of places making them in china.

I can build packs for e-bikes using these cells. I own Big E-RC, http://www.bigerc.com and can make almost any configuration necessary. I've been making packs with emoli's for a while now and just recently also started building a123 packs.

What configuration / cell count do you need them in?

,mike