Search found 6185 matches

by john61ct
Jul 24 2021 10:17am
Forum: EBike Technical
Topic: Noob Question re BMS
Replies: 60
Views: 952

Re: Noob Question re BMS

I assume these are LFP being measured in 2S units?

I doubt li-ion 1S could even reach 7V without exploding
by john61ct
Jul 24 2021 10:15am
Forum: EBike Technical
Topic: Noob Question re BMS
Replies: 60
Views: 952

Re: Noob Question re BMS

BMSs do not balance all the time, nor should they. No matter what device is doing the balancing or if done manually by you, it is an occasional maintenance procedure that is performed at a single spot in the voltage / SoC% curve. At all other points in the curve, the cells will be "out of balan...
by john61ct
Jul 23 2021 11:27am
Forum: EBike Technical
Topic: Noob Question re BMS
Replies: 60
Views: 952

Re: Noob Question re BMS

bobbill wrote:
Jul 20 2021 4:47am
I have some 30 cells. Cells vary in voltage from 6.1v to 6.9v
There are no lithium cells that go that high.

Maybe those are 2S packs of LFP?

by john61ct
Jul 23 2021 11:25am
Forum: EBike Technical
Topic: Noob Question re BMS
Replies: 60
Views: 952

Re: Noob Question re BMS

You can maybe guess that balancing has started, but it is bad for cells to sit at that high voltage for long so really, IMO it is critical to know when balancing is complete and for that you need an accurate per-cell level volt readout. If I used a BMS to do my balancing - and no, as I've stated mos...
by john61ct
Jul 23 2021 5:45am
Forum: Battery Technology
Topic: good balance charger recommendations please
Replies: 11
Views: 248

Re: good balance charger recommendations please

I designed the first of that kind together with Jason from Chargery around 15 years ago (maybe more). It has the advantage that very little parameters set is need in order to charge any kind of battery. We made it with the idea of just plug and play, not be like 5 min. setting up the charger before...
by john61ct
Jul 22 2021 10:41pm
Forum: EBike Technical
Topic: Noob Question re BMS
Replies: 60
Views: 952

Re: Noob Question re BMS

BMW also sells some individual components as evidenced by this BMS that is listed with quite a bit of detail. Not sure if it's the one in my pack or not. https://www.ebay.com/itm/52V-14S-45A-Li-ion-Battery-Protection-Board-BMS-PCB-Electric-Bike-Ebike-14S-BMS-/303799457857 Fine if you trust him and ...
by john61ct
Jul 22 2021 10:32pm
Forum: EBike Technical
Topic: Noob Question re BMS
Replies: 60
Views: 952

Re: Noob Question re BMS

John, cell cannot be off a tenth or three??? Tenth of a volt is not much to balance, seems. Cells should all be exactly the same before putting in series. a delta of 0.1V can take a very long time for a cheap BMS or balancer to eliminate given the usual pitifully low balance current rates. Thus the...
by john61ct
Jul 22 2021 12:10pm
Forum: Items for Sale - New
Topic: TIG torch for battery spot welding
Replies: 32
Views: 764

Re: TIG torch for battery spot welding

Wouldn't the term PURE copper, from a trustworthy supplier eliminate such a variant?
by john61ct
Jul 22 2021 12:01pm
Forum: Battery Technology
Topic: 18650 vs prismatic - which is safer?
Replies: 30
Views: 651

Re: 18650 vs prismatic - which is safer?

The knowledge of the operator and thus the care provided is just as important if not more than the chemistries involved. But yes, LFP and LTO are **much** more forgiving of ignorance and carelessness than the higher voltage li-ion chemistries at 3.6 - 3.7V nominal. Using appropriate hardware to **as...
by john61ct
Jul 22 2021 11:52am
Forum: Battery Technology
Topic: ULtra Compact 1800W charger + Eltek programming
Replies: 298
Views: 61469

Re: ULtra Compact 1800W charger + Eltek programming

WOW WOW WOW

Please strive to keep these available in stock for purchase

Charging enough to make that work sustainable for those involved
by john61ct
Jul 22 2021 11:27am
Forum: General Discussion
Topic: Electronic load for testing - any thoughts on ET5410?
Replies: 9
Views: 1517

Re: Electronic load for testing - any thoughts on ET5410?

excellent contribution.

If you feel further inspired, a write up on how you would rig an accurate CC load discharge test

as high current and low voltage as possible, ideally 1S

would be greatly appreciated
by john61ct
Jul 22 2021 3:20am
Forum: Battery Technology
Topic: How to charge bike battery to only 80% ?
Replies: 34
Views: 858

Re: How to charge bike battery to only 80% ?

Trying to get every scrap of Ah capacity utilization means pushing closer to the mfg spec min/max voltages at both ends greatly reducing longevity, possibly in a low C-rate context can mean getting 120 cycles rather than 1200 cycles before hitting EoL say 70% SoH. But getting that 1200 may be sacri...
by john61ct
Jul 22 2021 3:02am
Forum: Battery Technology
Topic: New EM3EV Shark battery has different charge port
Replies: 8
Views: 170

Re: New EM3EV Shark battery has different charge port

Making up simple adapter pigtails should be a required skill for anyone serious about the hobby.

Not rocket science, whole community to help you learn.
by john61ct
Jul 22 2021 2:59am
Forum: Battery Technology
Topic: 18650 fire!
Replies: 22
Views: 846

Re: 18650 fire!

Safest is buy the cells - top quality, recent date, brand new Grade A, from a trusted vendor and build your own pack, or have someone local do it You need to educate yourself, so you know exactly where the battery is in its lifespan and never leave such a risky chemistry battery charging unattended....
by john61ct
Jul 22 2021 2:53am
Forum: Battery Technology
Topic: Build your own Battery Kit to start a beginner?
Replies: 8
Views: 205

Re: Build your own Battery Kit to start a beginner?

No. Start with a couple weeks' reading past threads, googling to understand new jargon etc.

Lead battery is a much more straightforward and cheaper way to start.
by john61ct
Jul 21 2021 9:28am
Forum: Battery Technology
Topic: How to charge bike battery to only 80% ?
Replies: 34
Views: 858

Re: How to charge bike battery to only 80% ?

The question is, for **your** rig, hitting that LV mark under load if you stop, isolate it and rest for over an hour, what is the pack voltage after bouncing back? Too low for me prioritizing longevity, may be just fine for you. There is no "damage" to the pack until well below 2.8Vpc or s...
by john61ct
Jul 21 2021 8:54am
Forum: Battery Technology
Topic: good balance charger recommendations please
Replies: 11
Views: 248

Re: good balance charger recommendations please

Node chargers do not technically do any balancing at all. They charge each cell-group through the balance wires thus at a very low effective current rate via a separate 1S charger on each cell-group, independently regulated. If each is set to the same charge profile, then at termination the battery ...
by john61ct
Jul 21 2021 8:49am
Forum: Battery Technology
Topic: good balance charger recommendations please
Replies: 11
Views: 248

Re: good balance charger recommendations please

is this what they call active balancing? No "Active" balancing can mean A. circuitry maintains the same balance current rate even as delta decreases, approaching target spec (most slow down), or B. as energy is removed from high cell-groups, it is added to the low ones (most just bleed of...
by john61ct
Jul 21 2021 8:39am
Forum: Battery Technology
Topic: How to charge bike battery to only 80% ?
Replies: 34
Views: 858

Re: How to charge bike battery to only 80% ?

Yes percentage of voltage is virtually useless. Percentage of Ah/mAh is what should be targeted whether using theoretical maximum capacity or SoC% between the 0-100% definitions arbitrarily defined by the user according to their preferences, balancing range vs longevity. But actually calibrating tho...
by john61ct
Jul 20 2021 3:15pm
Forum: EBike Technical
Topic: Noob Question re BMS
Replies: 60
Views: 952

Re: Noob Question re BMS

Usually there is no one who both speaks English and also has a clue technically involved in the supply chain. The outfit selling the goods often understand nothing about what they are selling. Everything driven by cutting costs, swapping parts middle of a production run, no documentation at all avai...
by john61ct
Jul 20 2021 3:10pm
Forum: Battery Technology
Topic: How to charge bike battery to only 80% ?
Replies: 34
Views: 858

Re: How to charge bike battery to only 80% ?

Are you mixing up HVC and LVC?
by john61ct
Jul 20 2021 9:30am
Forum: Large EV General Discussion
Topic: Push / pull kart?
Replies: 11
Views: 252

Re: Push / pull kart?

bins can get very heavy when loaded
by john61ct
Jul 20 2021 9:22am
Forum: Items for Sale - New
Topic: QSMOTOR,0.5-12kW Electric Hub Motor & Mid Drive Motor Manufacture China
Replies: 1437
Views: 317496

Re: QSMOTOR,0.5-12kW Electric Hub Motor & Mid Drive Motor Manufacture China

The US market would explode if good value kits were standardized, say 3-4 options

that would allow handy owners to convert common pushbikes,

or could at least be done by local shops willing to take on the liability

which is the biggest roadblock to widespread adoption.
by john61ct
Jul 20 2021 9:11am
Forum: EBike Technical
Topic: Noob Question re BMS
Replies: 60
Views: 952

Re: Noob Question re BMS

You need to at least roughly balance the cells before putting them in parallel, say under 0.1V delta, at which point they will start to naturally equalize. Then those groups need to be equalized with each other, in effect one big group so they are each exactly the same voltage before assembling the ...