Search found 6147 matches

by john61ct
May 16 2021 12:31pm
Forum: Battery Technology
Topic: Compression of pouch cells, info/data
Replies: 33
Views: 189

Re: Compression of pouch cells, info/data

Note that "prismatic" often means "in a hard case" as opposed to raw pouches. Traditionally from top LFP vendors, a hard dielectric plastic case, but cheaper recent products increasingly in lighter weight lower volume aluminum, which requires the pack builder to put rigid dielect...
by john61ct
May 16 2021 12:17pm
Forum: EBike General Discussion
Topic: Disaster today, almost set two fires with BBSHD and 52v batteries
Replies: 61
Views: 742

Re: Disaster today, almost set two fires with BBSHD and 52v batteries

You keep saying that connectors came from Luna.

Does it follow from that that the should have been reliable, correctly built and safe?
by john61ct
May 16 2021 11:49am
Forum: Alternative Energy
Topic: 36v packs to power off grid trailer
Replies: 1
Views: 55

Re: 36v packs to power off grid trailer

IMO the only lithium chemistry suitable for mobile House bank use is LFP.

The li-ion chemistries at 3.6 - 3.7Vnominal are way too prone to fires, "thermal runaway" for use anywhere near human habitation, much less within a small mobile living space.
by john61ct
May 16 2021 10:53am
Forum: Battery Technology
Topic: First DIY battery pack BMS
Replies: 2
Views: 79

Re: First DIY battery pack BMS

So long as the balance leads are accessible to be paralleled not just the power pair then just one BMS will work for all three configurations. Just ensure they are within say 10V before joining, charge and discharge together after that, no one way diodes needed, let the sub-packs self-balance togeth...
by john61ct
May 14 2021 7:45pm
Forum: Battery Technology
Topic: LiFePo4 15s Charger?
Replies: 33
Views: 523

Re: LiFePo4 15s Charger?

Dropping to a lower Float voltage is termination of the charge cycle. That is indeed what proper chargers do, some might do so prematurely if your goal is to truly get to Full. Better ones let you adjust the (CV) Absorb Hold Time Really all this focus on CV / Absorb cycle is a holdover from using le...
by john61ct
May 14 2021 7:40pm
Forum: Battery Technology
Topic: LiFePo4 15s Charger?
Replies: 33
Views: 523

Re: LiFePo4 15s Charger?

There are many ways to balance that work within a proper charge regimen conducive to cell longevity. If your BMS requires holding CV for more than a few minutes in order to "finish" balancing, then you're doing it wrong, either replace the BMS or stop using it for balancing. virturally no ...
by john61ct
May 14 2021 7:33am
Forum: Battery Technology
Topic: LiFePo4 15s Charger?
Replies: 33
Views: 523

Re: LiFePo4 15s Charger?

Would the extended life be from a shallower DoD? I was wondering how the HLG-xxxH-54A would behave with it's max Vo set to below 58v: would that run CC up to the Vo set point? Would that affect the life of the cells? The V setpoint is maximum it should allow. CC is just a label for the first part o...
by john61ct
May 14 2021 1:33am
Forum: Battery Technology
Topic: Anyone try this Tab Welder?
Replies: 2
Views: 87

Re: Anyone try this Tab Welder?

Yes if the circuitry works be worth reverse engineering too
by john61ct
May 14 2021 1:31am
Forum: Battery Technology
Topic: "Copper/nickel sandwich" buses for series connections
Replies: 61
Views: 4523

Re: "Copper/nickel sandwich" buses for series connections

Great stuff.

Best to also post this setup description with your results if successful to the main KWELD thread for reference there.

Using the kcap units in effect insulates the main unit from batteries that have too high/fast power output, is that correct?
by john61ct
May 14 2021 1:17am
Forum: Vendor Relations Corner
Topic: Trying to buy a PowerVelocity Controller
Replies: 18
Views: 462

Re: Trying to buy a PowerVelocity Controller


BobBob wrote:What a waste of time
But not a surprise right?

Maya Angelou: "When someone shows you who they are, believe them the first time."
by john61ct
May 14 2021 12:49am
Forum: Battery Technology
Topic: Compression of pouch cells, info/data
Replies: 33
Views: 189

Re: Spot Welding Copper Strips to 18650 Battery Cells

Yes compression case is required for LFP pouch or prismatic. The metal-cased ones need careful dielectric insulating between each cell as well as the floor and sides of the box with a material that does not compress, or it defeats the purpose. And a bit of puffing is inevitable for any bank used har...
by john61ct
May 13 2021 7:53am
Forum: Motor Technology
Topic: Hubmonster teardown
Replies: 173
Views: 9860

Re: Hubmonster teardown

The precise failure point will be different between the motor and controller.

In theory you could wreck lots of small motors with a robust enough controller designed for big ones
by john61ct
May 13 2021 7:47am
Forum: Battery Technology
Topic: LiFePo4 15s Charger?
Replies: 33
Views: 523

Re: LiFePo4 15s Charger?

High voltage cutoff, just a circuit that controls a relay / solenoid / contact switch when the specified voltage is reached. Most BMS types could be rigged to work, Arduino etc, some OTS adjustable units out there, "battery protect" "DIY UPS" circuits. Results in CC only charging...
by john61ct
May 13 2021 3:57am
Forum: Battery Technology
Topic: LiFePo4 15s Charger?
Replies: 33
Views: 523

Re: LiFePo4 15s Charger?

That is a a good unit, and yes that V range will cover both 15S & 16S ranges, decent flexibility. Note there is another step up in the HLG series for power, 600W iirc. But the HLG is a power supply, not a charger as such, no automated stop-charge best to look for an adjustable HVC to cut its AC ...
by john61ct
May 13 2021 1:15am
Forum: Battery Technology
Topic: "Copper/nickel sandwich" buses for series connections
Replies: 61
Views: 4523

Re: "Copper/nickel sandwich" buses for series connections

Cool!

key issue is, if the plating is thick enough to increase the copper's resistance enough

Please let us know!

Are you using Kweld with caps or lipo or? Optimizing the joules output might be critical
by john61ct
May 13 2021 12:47am
Forum: EScooters/EMotorcycles
Topic: More low end torque for up hill climbing power
Replies: 26
Views: 532

Re: More low end torque for up hill climbing power

Of course hub motors get hot when overloaded.

Hot enough to get destroyed if the controller has no overtemp protection.

Adding a CA v3 will also work well.

Doesn't even take a big hill, just increasing the load on a hot day can do it.
by john61ct
May 13 2021 12:43am
Forum: Battery Technology
Topic: Spot Welding Copper Strips to 18650 Battery Cells
Replies: 534
Views: 88468

Re: Spot Welding Copper Strips to 18650 Battery Cells

3> There is no 3 There are dozens of threads with discussion on all that. The third option is mechanical pressure, as with magnets, poron foam "springs" etc For this specific thread only one strategy is on topic. Start your own thread for general discussion comparing others if you aren't ...
by john61ct
May 13 2021 12:34am
Forum: Battery Technology
Topic: LiFePo4 15s Charger?
Replies: 33
Views: 523

Re: LiFePo4 15s Charger?

No, just easier to find cheap chargers.

Highly reco Satiator, very flexible for future proofing

model# 4808 labeled "24V-52V", I believe output range is 24-63V @8A (manual states 12-63V)
by john61ct
May 11 2021 1:07pm
Forum: Battery Technology
Topic: LiFePo4 15s Charger?
Replies: 33
Views: 523

Re: LiFePo4 15s Charger?

I would not go above 52V unless current at 0.5C or a bit higher, 54.0V max at say above 0.1C, CC-only is fine. Or for occasional cap testing to judge SoH%, 54.0V even if below 0.5C holding CV then, a high current rate doesn't matter, hold until amps trail to 0.2C. So adjustability is important. If g...
by john61ct
May 11 2021 7:53am
Forum: Large EV General Discussion
Topic: Dynamically reconfiguring pack voltage for RV
Replies: 8
Views: 225

Re: Dynamically reconfiguring pack voltage for RV

Skoolies have a high carrying capacity

not that they can't get dangerously overloaded, imbalanced.

Of course actual range is reduced with every extra kg carried
by john61ct
May 11 2021 2:10am
Forum: EBike General Discussion
Topic: speed relationship between wheel and bike
Replies: 12
Views: 308

Re: speed relationship between wheel and bike

the number of wheels should make no difference at all, if they are all the same size. Nor does electric motor(s) matter as a factor, vs leg power or petrol or. . . RPM vs bike speed is what I thought you wanted help with. One of those being known obviously (to me) is required bike speed being unknow...
by john61ct
May 10 2021 9:56pm
Forum: Battery Technology
Topic: Bought a new battery - the range just does not make sense ( Chamrider)
Replies: 15
Views: 311

Re: Bought a new battery - the range just does not make sense ( Chamrider)

still hard to think that it is really a 43.2ah battery when it is the same footprint of my 28ah battery. The only difference being 18650 v.s 21700 cells which should only lead to a 30 percent increase maximum in capacity . Yes, it's def not, you got ripped off for sure, at least on energy capacity....
by john61ct
May 10 2021 9:49pm
Forum: Large EV General Discussion
Topic: Dynamically reconfiguring pack voltage for RV
Replies: 8
Views: 225

Re: Dynamically reconfiguring pack voltage for RV

I estimate that with that pack it should be capable of a good 40-50 miles per charge. I'm guessing under ten. > I know they need to be at a different voltage, I'm just curious as to whether it's feasible to tap that voltage off of the same battery in segments instead. No, you must draw from all seg...
by john61ct
May 10 2021 1:04pm
Forum: Motor Technology
Topic: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?
Replies: 109
Views: 3362

Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

But in fact Justin has documented the higher performance enabled by just a little of his fluid, the idea is proven effective.

This thread is about getting a bit more is all, exploring other fluid types.