Search found 6252 matches

by john61ct
Jun 19 2021 11:37am
Forum: EBike General Discussion
Topic: 36V Yose Power kit with a 48V battery
Replies: 2
Views: 63

Re: 36V Yose Power kit with a 48V battery

need a new charger

ideally an adjustable one like Satiator

their #4808 "24V-52V" output range 24-63V @8A (manual states 12-63V)
by john61ct
Jun 18 2021 2:27pm
Forum: Items for Sale - Used
Topic: FS: 72 Volt 30AH Ebike Battery
Replies: 5
Views: 174

Re: FS: 72 Volt 30AH Ebike Battery

Best to discharge it now, ~74V
by john61ct
Jun 18 2021 2:24pm
Forum: Items for Sale - Used
Topic: FS: 72 Volt 30AH Ebike Battery
Replies: 5
Views: 174

Re: FS: 72 Volt 30AH Ebike Battery

So nominal 2.9Ah x 12P should be ~34Ah

DM sent
by john61ct
Jun 18 2021 4:27am
Forum: Items for Sale - Used
Topic: FS: 72 Volt 30AH Ebike Battery
Replies: 5
Views: 174

Re: FS: 72 Volt 30AH Ebike Battery

So 20S ?

What is the total cell count?

What certainty level do you have that the cells are genuine?
by john61ct
Jun 17 2021 12:05pm
Forum: Battery Technology
Topic: 40T, neodymium magnets, plasti dip cycle test
Replies: 180
Views: 14600

Re: 40T, neodymium magnets, plasti dip cycle test

Once you get tons of shock and vibration in play

those copper edges would IMO risk scraping through the wrap and making contact with the cylinder wall "shoulders"

I know with A123 that is positive, but even on cells where it is negative that would create problems
by john61ct
Jun 16 2021 3:42pm
Forum: EBike Technical
Topic: Which advice to follow???
Replies: 6
Views: 156

Re: Which advice to follow???

Yes once assembled the pack is one monolithic unit wrt the power +/- leads. But for per-cell voltage monitoring, HVC LVC and balancing, you need to leave the cell/group-level connections accessible for meters, balancers, BMS, hobby chargers etc. Most packs the BMS gets "buried" but IMO sho...
by john61ct
Jun 16 2021 11:58am
Forum: EBike Technical
Topic: unknown connector
Replies: 2
Views: 308

Re: unknown connector

post on rcgroups
by john61ct
Jun 16 2021 11:57am
Forum: EBike Technical
Topic: Which advice to follow???
Replies: 6
Views: 156

Re: Which advice to follow???

Can go either way. Paralleled groups for equal capacity and matched resistance is most common and best for longevity.

But serial first may allow for higher power flow, IMO speculative.

Note those using sheet rather than strips or wires

are often doing both at once.
by john61ct
Jun 14 2021 11:45am
Forum: Battery Technology
Topic: Spot Welding Copper Strips to 18650 Battery Cells
Replies: 539
Views: 90213

Re: Spot Welding Copper Strips to 18650 Battery Cells

Hopefully using more than just two connection points.

The copper making the cell contact is much more reliable, the nickel just helping with the spotweld process.

Propulsion use cases inflict lots of shock/vibration, you don't want points of higher resistance causing hot spots current bottlenecks
by john61ct
Jun 11 2021 4:27pm
Forum: Battery Technology
Topic: Charging LTO at Max Speed?
Replies: 118
Views: 8344

Re: Charging LTO at Max Speed?

Yes to be clear, if the receptacle handles only 40A the breaker should be 40A

even if everything else could handle more.
by john61ct
Jun 11 2021 7:22am
Forum: Battery Technology
Topic: Charging LTO at Max Speed?
Replies: 118
Views: 8344

Re: Charging LTO at Max Speed?

Everything in a wiring path should be rated at least as high ampacity as the circuit breaker. With that latter rated higher than the greatest load that will be plugged into that circuit. Getting an electrician in to install the right wiring to the appropriate location is not an optional expense your...
by john61ct
Jun 11 2021 7:14am
Forum: Alternative Energy
Topic: 36v packs to power off grid trailer
Replies: 3
Views: 190

Re: 36v packs to power off grid trailer

The fact that random thermal runaway becomes exponentially more likely as they age

Boom bad!

Proactive replacement at 75-80% SoH would reduce the risk, but many don't even know how to do cap testing.

Timed CC loading is more precise than using a coulomb counter.
by john61ct
Jun 10 2021 8:10pm
Forum: Items for Sale - New
Topic: Prismatic lifePo4 cells 50ah Sale
Replies: 19
Views: 857

Re: Prismatic lifePo4 cells 50ah Sale

maybe not.

I think supply chain between Asia and NA may continue to be disrupted for years, maybe get worse, so many dosastrous possibilities

best to plan for that being the new normal
by john61ct
Jun 10 2021 8:05pm
Forum: Battery Technology
Topic: bms bluetooth connecting problem
Replies: 14
Views: 406

Re: bms bluetooth connecting problem

ahmedalasadi wrote:
john61ct wrote:
Jun 08 2021 11:56am
Different phone / Android version?

$20-30 on eBay
: :!: :!: :!: :?: :?: ..didn't understand U
Use a different phone.

If not a different iOS version

then Androids are super cheap secondhand on eBay
by john61ct
Jun 09 2021 7:13pm
Forum: EBike General Discussion
Topic: E-bike mid-drive motors hardly outperforms hub motors
Replies: 93
Views: 2899

Re: E-bike mid-drive motors hardly outperforms hub motors

I thought the bigger QS have liquid cooling?

moto not bike I know
by john61ct
Jun 09 2021 7:05pm
Forum: Motor Technology
Topic: Low Speed, High Torque Hub Motor?
Replies: 11
Views: 260

Re: Low Speed, High Torque Hub Motor?

Also check out Grin GMAC
by john61ct
Jun 09 2021 7:01pm
Forum: Motor Technology
Topic: Low Speed, High Torque Hub Motor?
Replies: 11
Views: 260

Re: Low Speed, High Torque Hub Motor?

It is not meant to climb hills all day, it's only required to keep a steady speed across a field, with potentially a little incline. And the operation is only a few minutes at a time, with long brakes in between. Well that is a completely different use case than your OP. Literally any DD hub will d...
by john61ct
Jun 09 2021 6:57pm
Forum: Battery Technology
Topic: Charging LTO at Max Speed?
Replies: 118
Views: 8344

Re: Charging LTO at Max Speed?

3 times the density is 1/3 the weight.

So, you meant a third to a quarter the density.

Or 3-4 times the weight (or volume).

by john61ct
Jun 09 2021 1:03am
Forum: Items for Sale - New
Topic: Prismatic lifePo4 cells 50ah Sale
Replies: 19
Views: 857

Re: Prismatic lifePo4 cells 50ah Sale

Only way these days to ensure a steady supply to build cred with customers is inventory yourself, keep (at least) six months' optimistic projection local, re-order top-ups every couple weeks as sales increase, ramp up the inventory very quickly. Capital intensive business, can't compete on price but...
by john61ct
Jun 09 2021 12:51am
Forum: Motor Technology
Topic: Low Speed, High Torque Hub Motor?
Replies: 11
Views: 260

Re: Low Speed, High Torque Hub Motor?

The problem without gearing is high amps at that low a voltage

you need controllers with heat sensors to stop before it melts

really big heavy ones will withstand the heat better

but look at gearing if you want to lighten the load.

Grin's simulator. . .
by john61ct
Jun 09 2021 12:47am
Forum: Battery Technology
Topic: Charging LTO at Max Speed?
Replies: 118
Views: 8344

Re: Charging LTO at Max Speed?

Back to chargers... Can someone explain why something like this would be a bad idea, other than just "it's chinese". Serious question i want input on this. https://wemaxpower.en.alibaba.com/product/1600158425594-819922260/Laboratory_research_8000W_50V_160A_64V_125A_80V_100A_100V_80A_125V_...
by john61ct
Jun 09 2021 12:29am
Forum: Battery Technology
Topic: Charging LTO at Max Speed?
Replies: 118
Views: 8344

Re: Charging LTO at Max Speed?

It is routine in mobile off-grid use cases for big alternators to charge deep cycling banks at well over 250A, even seen 15+ kW at 28V and mains chargers to get doubled up to deliver close to that as well. Yes you need solid know-how, purchase quality infrastructure, etc but it is not rocket science...
by john61ct
Jun 08 2021 11:56am
Forum: Battery Technology
Topic: bms bluetooth connecting problem
Replies: 14
Views: 406

Re: bms bluetooth connecting problem

Different phone / Android version?

$20-30 on eBay