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by john61ct
Apr 15 2021 8:32pm
Forum: Items for Sale - New
Topic: QSMOTOR,0.5-12kW Electric Hub Motor & Mid Drive Motor Manufacture China
Replies: 1418
Views: 306818

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

LFP is much lower density.

A123 makes NMC pouches should deliver same level of energy and power in a lighter smaller form factor.

But much shorter lifespan and much more thermally risky.
by john61ct
Apr 15 2021 7:47pm
Forum: EBike Technical
Topic: Ampy: Open source python display/interface project for ASI controllers
Replies: 13
Views: 1358

Re: Ampy: Open source python display/interface project for ASI controllers

Works with LFP voltage values?

Still 21S max?

24s LFP for many is 87V, but for me more like 82V maximum
by john61ct
Apr 15 2021 9:01am
Forum: Battery Technology
Topic: Super fast charge
Replies: 18
Views: 455

Re: Super fast charge

Actually, one way to do this correctly would be to charge through the motor using a suitable controller. Adaptto and Nucular can do this: " Charge mode through the motor with the controller, plug any DC supply to the controller to charge your battery " Yes if you can figure it out, that's...
by john61ct
Apr 15 2021 9:00am
Forum: Battery Technology
Topic: Super fast charge
Replies: 18
Views: 455

Re: Super fast charge

I'd expect current limits are deliberately ignored with any charging method. I'm an advocate of safety, but due to the dynamics of equalization (and because it would be supervised) I actually don't see this as being that dangerous. Depends on resistance of the source side chemistry. From Lead to LI...
by john61ct
Apr 15 2021 7:39am
Forum: EBike Technical
Topic: Programming APT AE96600 controller (update: NOT recommended, unstable program)
Replies: 218
Views: 29887

Re: Programming APT AE96600 controller (update: NOT recommended , unstable program)


bingbwy wrote:Motor QS 5000w 12 inch
What model motor?

Wattage does not designate that. QS138, QS205?

by john61ct
Apr 14 2021 3:41pm
Forum: Battery Technology
Topic: kWeld - "Next level" DIY battery spot welder
Replies: 1328
Views: 203846

Re: kWeld - "Next level" DIY battery spot welder

Yes better to rig a current-limiting circuit that does not vary so much as voltage / SoC drops. Of course a PSU / charger powerful enough to "just barely almost" keep up with the welder's Ah/minute consumption would allow for a smaller battery, just using it as a short-term buffer, maintai...
by john61ct
Apr 14 2021 12:04am
Forum: Battery Technology
Topic: Super fast charge
Replies: 18
Views: 455

Re: Super fast charge

You of course **can** charge from a 100% Full pack to an "empty" one but then if they are the same Ah capacity, bith are now at 50%. You need to (MUST for safety) limit the current transfered when initially paralleling them. Both problems can be solved with a quality DC-DC **charger**, but...
by john61ct
Apr 11 2021 9:57pm
Forum: Battery Technology
Topic: Super fast charge
Replies: 18
Views: 455

Re: Super fast charge

Since you have two identical batteries, just set them up to swap easily? Better (safer simpler easier) to charge one pack at a time but if you really want to parallel them, do so at the cell/group level 1S so whatever you are using to keep the packs in balance can monitor at that level to prevent an...
by john61ct
Apr 11 2021 9:49pm
Forum: Battery Technology
Topic: Super fast charge
Replies: 18
Views: 455

Re: Super fast charge

Get a charger (or PSU, or DC-DC converter) that allows you to custom-adjust both maximum setpoints, CV and CC current.

If your source is cheap grid power, don't need to be too concerned about efficiency.

Auto-termination is IMO much more important, safety first.
by john61ct
Apr 11 2021 12:30pm
Forum: Battery Technology
Topic: Super fast charge
Replies: 18
Views: 455

Re: Super fast charge

LTO chemistry is an exception, 10min charge NP

But much lower energy density, for a low speed dump truck or big bus maybe
by john61ct
Apr 11 2021 12:28pm
Forum: Battery Technology
Topic: Super fast charge
Replies: 18
Views: 455

Re: Super fast charge

Current **limiting** is not a function of any BMS I know of. Most don't even have current protection, they just give a rating - usually too optimistic - and release the magic smoke if current is allowed to go too high. Charging very fast can greatly reduce pack lifespan, especially in cool weather. ...
by john61ct
Apr 11 2021 12:22pm
Forum: E-Vehicles General Discussion
Topic: Battery Three way switch - any issues with this design?
Replies: 8
Views: 392

Re: Battery Three way switch - any issues with this design?

at a given voltage, drawing at a lower C-rate results in higher Ah capacity regardless of resistance, heating losses etc A 0.1C rate will show higher capacity than a 0.3C rate. So, swapping out three 30Ah batteries sequentially gives less range than one 90Ah battery See Peukert's Law Unless maybe if...
by john61ct
Apr 11 2021 11:57am
Forum: Battery Technology
Topic: kWeld - "Next level" DIY battery spot welder
Replies: 1328
Views: 203846

Re: kWeld - "Next level" DIY battery spot welder

Apparently the welding circuitry does not limit current drawn, I've read about batteries delivering "too much" power? I was hoping (if that is the case) there might be guidelines for getting to "as much as possible without going over". Or maybe going to big lead units would be be...
by john61ct
Apr 11 2021 12:18am
Forum: Battery Technology
Topic: kWeld - "Next level" DIY battery spot welder
Replies: 1328
Views: 203846

Re: kWeld - "Next level" DIY battery spot welder

So what are the pack specs to get top output power?

Voltage range?

Actual peak vs continuous maximum amps drawn?

What are the specs that might get to be "too much"?

Would a pack tested capable of true 25C continuous be better or worse than one that can only handle 15C?
by john61ct
Apr 09 2021 6:04pm
Forum: E-Vehicles General Discussion
Topic: Battery Three way switch - any issues with this design?
Replies: 8
Views: 392

Re: Battery Three way switch - any issues with this design?

yes all DC circuits should have a Common Reference, tied in with Negative Returns
by john61ct
Apr 09 2021 12:33pm
Forum: Battery Technology
Topic: Isolation between cells needed?
Replies: 4
Views: 284

Re: Isolation between cells needed?

Aha I thought you meant electrical isolation, like diodes or circuit protection between groups

rather than physical protection, insulation
by john61ct
Apr 09 2021 12:15pm
Forum: E-Vehicles General Discussion
Topic: High Power power supply for testing EVs motors controllers without battery pack
Replies: 3
Views: 325

Re: High Power power supply for testing EVs motors controllers without battery pack

But why?

How many watts for how long are needed?

Even a low Ah pack will deliver much more power than you could with a reasonable PSU

and if warm, then fully recharge in 10min or so, without losing too much lifespan.

So two more normal PSU/chargers, two packs, swapped out. . .
by john61ct
Apr 09 2021 9:27am
Forum: Battery Technology
Topic: Isolation between cells needed?
Replies: 4
Views: 284

Re: Isolation between cells needed?

If by group you mean (as is standard) cells in parallel only, at the "lowest" level in the layout at 1S voltage, then those (cell) groups connected together to create one series string then No there is no current flow possible between those groups, they do not affect each other even if at ...
by john61ct
Apr 09 2021 9:15am
Forum: Battery Technology
Topic: Spot Welding Copper Strips to 18650 Battery Cells
Replies: 505
Views: 86049

Re: Spot Welding Copper Strips to 18650 Battery Cells

Think of each section (sub pack?) involving strips, whether soldered or welded as a rigid monolithic block, no flexing stresses allowed at all. Then the flexible wiring with zero solder involved, connecting between those blocks, their connection ends well supported so the crimped terminations are (o...
by john61ct
Apr 09 2021 9:07am
Forum: E-Vehicles General Discussion
Topic: Battery Three way switch - any issues with this design?
Replies: 8
Views: 392

Re: Battery Three way switch - any issues with this design?

You'll get longer range (higher actual Ah capacity) by paralleling for the whole ride.

Better current flow, less voltage sag and longer lifespan too.
by john61ct
Apr 08 2021 11:01pm
Forum: Battery Technology
Topic: Spot Welding Copper Strips to 18650 Battery Cells
Replies: 505
Views: 86049

Re: Spot Welding Copper Strips to 18650 Battery Cells

I am not talking about strip, at all. I am saying, where you are using the wire I spec'd to accommodate flexing, abstain from touching that wire with any solder. If you are connecting wire to strip, then do so via solid connectors with a wide contact surface area crimped to the wire, perhaps quality...
by john61ct
Apr 08 2021 7:33pm
Forum: Battery Technology
Topic: Spot Welding Copper Strips to 18650 Battery Cells
Replies: 505
Views: 86049

Re: Spot Welding Copper Strips to 18650 Battery Cells

No solder terminations, use crimp connections.

Again, no flexing until you get well into the insulated wire body.
by john61ct
Apr 07 2021 6:52pm
Forum: EScooters/EMotorcycles
Topic: Finding a battery - Alibaba?
Replies: 9
Views: 311

Re: Finding a battery - Alibaba?

LFP is only rarely used for EVs. Much longer lifespan, thus better value by far much safer, thermal runaway (boom, fire) less likely but also lower energy density, thus slower performance and/or lower range. Tesla using it in the China-produced models only. Otherwise the 3.6 - 3.7Vnominal chemistrie...
by john61ct
Apr 07 2021 6:44pm
Forum: Battery Technology
Topic: Spot Welding Copper Strips to 18650 Battery Cells
Replies: 505
Views: 86049

Re: Spot Welding Copper Strips to 18650 Battery Cells

Fine-stranded tinned wiring, ideally marine grade UL 1426 rated (BC-5W2 usually 105°C)

No movement at terminations obviously, just leave slack in the length portion.