So it begins...... Battery spot welder

[sternwake]

Your ebike is 48v nominal.
Ryobi 18v nominal x 3 in series is 52v nominal.

You'd have to use a bucker, and converters can have issues if input and output voltage are relatively close.

https://www.ebay.com/itm/405184245824?_s...BMlOzhx4dm

https://www.ebay.com/itm/376013590764?_t...SR3YYRQMPW

Not my favorite booster, but is capable enough.
coukd two ryobis in series into booater outputting 60v, or 3 in parallel.

Got to get another charge oort connector too of course. If it has three contacts and communicates with provided charger there can be issues working around that.

[rvpopeye]

The bike charger charges to ~52-53 v so 54 isn't too much of a stretch and just pop the batteries out to charge from the original tool chargers. Cheapest option.
.Plus I have tool chargers plugged into solar . Extra cheapness for free !

The DIY battery with quality cells is still on the list. Most fun option.

As is a plug in replacement from bike mfg. Most cost option.
The bike charger is a 300w load....

Your links are saved , your opinion is gold for best of most anything in that dept. thx.

Weldon the Magnificent will be your new secondary title in a few pack builds from now , no doubt.

COMWS

[sternwake]

Ryobi and all 5s power tool batteries are 18v nominal, and 21 volts when fully charged. Dewalt and other '20v' power tools are playing on human stupidity.

Most power tool chargers only charge to 20.6 or 7 volts though. cycle life is improved greatly by not charging to 4.2volts per cell. There is not much energy stored in 4.1 to 4.2 raNge, so I only harge to 4.2v when I am desiring absolute max range and max torque on the first two acceleration.

Also my specific DaLy dumb BMS will only passively balance P groups which go above 4.18v, so charging to 4.1 would prevent balancing u less the pack is severely out of balance. whjch is unlkely if the pack was initially assembled with quality cells of equal voltage.

There can also be cell balance issues , usually on older packs, where one battery will come.off the charger at 20.72, and another will be 20.32.

Hooking two.such batteries in parallel can potentially cause issues with the internal BMS, if one exists within the battery.

Not all power tool batteries have a BMS. The low voltage cut off is designed into the tool, and cell balancing, if any, is controlled by the charger. Dewalt and Makita do this, and both batteries outside their respective tools can be easily ruined by overdischarge.

The one ryobi i took apart seemed to have the BMS in the battery, but i can't look at a PCB and read it.

[sternwake]

Ryobi and all 5s power tool batteries are 18v nominal, and 21 volts when fully charged. Dewalt and other '20v' power tools are playing on human stupidity.

Most power tool chargers only charge to 20.6 or 7 volts though. cycle life is improved greatly by not charging to 4.2volts per cell. There is not much energy stored in 4.1 to 4.2 raNge, so I only harge to 4.2v when I am desiring absolute max range and max torque on the first two acceleration.

Also my specific DaLy dumb BMS will only passively balance P groups which go above 4.18v, so charging to 4.1 would prevent balancing u less the pack is severely out of balance. whjch is unlkely if the pack was initially assembled with quality cells of equal voltage.

There can also be cell balance issues , usually on older packs, where one battery will come.off the charger at 20.72, and another will be 20.32.

Hooking two.such batteries in parallel can potentially cause issues with the internal BMS, if one exists within the battery.

Not all power tool batteries have a BMS. The low voltage cut off is designed into the tool, and cell balancing, if any, is controlled by the charger. Dewalt and Makita do this, and both batteries outside their respective tools can be easily ruined by overdischarge.

The one ryobi i took apart seemed to have the BMS in the battery, but i can't look at a PCB and read it.

[sternwake]

Sorry about double post. I opened thread in a new tab and it did not show I had clicked reply, soni clicked it and then it showed I posted it 11 hours earlier.

Ive been reading some on endless sphere, which is e bike centric but includes all PEV's, and it seems like a lot of Ebike chargers are also avoiding charging to 4.2 volts per P group.

The same as with Lead Acid battery chargers, I recommend not only checking the voltage, but how many amps are flowing at that voltage..

Check the voltage at the plug when not connected to the battery. It likely will not be what is written on the charger, Its probably slightly higher voltage, and lesser max amps than it says.

One should also note at what threshold the red charging light turns green.

Most cells will be considered full charged when held at 4.2v, the amperage tapers to 0.2

I have 7s 29.4v power bricks actually output over 30v, and the red light turns green as soon as 0.32 amps tapers to 0.31. it does not stoo charging though, when the green light comes on. Amps will tPer towards zero, and if any one cell exceeds the BMS disconnects the charger, or at least it should.

Therd is no real reason to charge above 4.1 volts per cell, from a capa ity/range standpoint. One might onky get a 1/2 mile at minimum throttle extra, and the cells will lose capa ity far faster than if one stopped at 4.1 volts per cell.

Now BMS' like mine only start balancing at 4.18v, resistors bleed off only 0.020 amps of that particular cell/parallel group, which is very slow., while the other pgrouos catch up.

It can take hours to balance a pack, it might take days on a badly out of balance pack.

I'd prefer to charge low groups up to the higher groups, if one group is suspiciously low.

Smart BMS's can show a lot.of good.info on Pgroup voltage, but that bluetooth never shuts off and a small pack stored at low voltage is in danger of overdischarge, and even bigger packs have been killed by a smart BMS

Figure out what your charger is doing. Doing so can alert you to a potentially dangerous Battery or charger.

And with lithium, if you want to parallel batteries, they need to be super close in voltage, if not exactly the same. Even 0.25v difference can exceed the charge port fuse rating, and larger packs might even threTen the max charge rating of the BMS.

Not all charge ports are fused. I have blown many charge port fuses being stupid, like hooking up a 12v Nominal powerpole to a 36v nominal.battery. Pop goes the fuse.

Without a fuse the BMS would fry, perhaps with Mosfets closed, then charge port wiring would turn red hot in seconds, and the cells would be dumping everything they can into a direct short, and they could get so hot as to go into thermal runaway, and then turn into minature rocket engines, and burn down the house.

[rvpopeye]

THX . Lots of good info there SW !  
Looking forward to the next cormorant safari , 
 wish I was there to witness the terror.

And so after that timely warning at the end.


I've decided to not get too invested in lithium ion based power.
Going with a factory B/U one with mystery cells for now . Plug-n play 
Same with rig power as well..
Cheapest option isn't my usual style anyway.
Waiting for aluminum ion for possible DIYing and hopefully not too long.
But probably wait for second  or third upgrade cycle ...

17.5 mi. mostly @15mph today 3 bars out of five left on the power display 
12Ah

[BCGuy]

I prefer this version.

[sternwake]

I bought a 500 gram syringe of the copper.welding flux/Brazing Paste that DIY500amp sells for 20$.

20% less power is required to achieve solid welds with 0.2mm copper and 0.1mm NPS sandwich.

The welds also appeared to be larger, leaving bigger dots of copper on the cell.
The copper removed, looked like it was tinned in close proximity to the welds and the entire space between the welds.

I believe the flux paste not only reduces the power to.achieve stronger Fatter welds, but heats the cell less, The welds themselves being fatter will curther reduce resistance, and the tinning of the coooer likely also makes more contact between cell and copper strip.

I ran out of cells to sacrifice welding.

I tried to weld 0.2mm copper without nickle plated steel on top, but was a little to close to the edge of the cell and punctured it. I guess it is thinner there.

So underpowered welders will benefit.from this brazing paste, at least onnl copper. I didnt test it with pure nickel, yet, but i will likely never use nickel again.

I did order another BAK45d, so I can make a 3s1p 11.1v, nominal 12.6v max battery for fans and leds.

The store owner sent me two 45D's and a bunch of 0.2mm copper. He has a laser cutter and lots of scrOs left over from custom busbars.

I also ordered two Ampace JP30's, a high power tabless 18650 that can deliver 3000mah at 28 amps continuous and remain below 70c. Very impressive. My flashlights cant really utilize this available power, but they should get a bit brighter and stay cooler for longer at highest output levels.

When it is time to rebuild power tool batteries that use 18650's, this is currently the best cell to do so.
But the BAK30D and EVE 30PL are not far off and likely close competitors in performance, and possibly a better price.

Most all power tool batteries will utilize tabless cells in the not too distant future. Not all tools can utilize their extra power, but those that can compete or exceed corded tool power.

[rvpopeye]

It gets better and betterer ! Coming soon to a forum near you . A warp drive battery build !

[sternwake]

My 420 watt portable charger is functional.

   

Gets a little too hot for my liking at 300watts, even with a massive heatsink.

   

Its 7s2p prebuilt 104wh battery is not confidence inspiring.
I could in theory make a 7s2p 18650 with double that rating.

But capacity ratings are very misleading when cells are  discharged above 0.2c.

Right now I'd  choose EVE 35v's as they perform very well upto 10 amps, and are 2.95$ each.

They outperform the Panasonic/Sanyo 3500mah GA cell that is used in a lot of e bike packs, and  cost half as much.