Search found 2231 matches

by flippy
Jun 01 2021 6:12am
Forum: Battery Technology
Topic: Tab cooling prismatics.
Replies: 27
Views: 529

Re: Tab cooling prismatics.

i am not saying tab cooling does not work. i am saying it works poorly compared to the alternatives. especailly if reliabillity is you goal i dont see how active tab cooling is going to be the superior solution to your problem. tab cooling is a nice idea, but far from usable in the DIY field. the bi...
by flippy
Jun 01 2021 5:35am
Forum: Battery Technology
Topic: Tab cooling prismatics.
Replies: 27
Views: 529

Re: Tab cooling prismatics.

the numer of welds being more prone to failliure is not a sound argument. while i fulyl agree that at face value it might appear so for the "untrained" observer. but from a engineering perspective its simply is false. its quite the opposite. spot welding tabs is actually a worse solution f...
by flippy
Jun 01 2021 2:52am
Forum: Battery Technology
Topic: Tab cooling prismatics.
Replies: 27
Views: 529

Re: Tab cooling prismatics.

you asked for advice to solve the cooling issue. i gave you 2 options that only need simple aircooling or much SIMPLER: no cooling at all. dont start complaining about spot welding being difficult (it isnt) when you are looking for some A-Team style contraption to cool unsuitable cells for your appl...
by flippy
May 31 2021 4:26pm
Forum: Battery Technology
Topic: Tab cooling prismatics.
Replies: 27
Views: 529

Re: Tab cooling prismatics.

useless. the tabs cannot wick heat away from the other side of the cells so you are still killing them. increase your number of cells, or get bigger ones and reduce the relative load so they dont heat up so much. best solution: switch to a better suited chemistry. you can fit a honeycomb shape into ...
by flippy
May 31 2021 4:09pm
Forum: Battery Technology
Topic: Building a large capacity battery for bicycle trailer
Replies: 94
Views: 1799

Re: Building a large capacity battery for bicycle trailer

are you lying on purpose to make prsmatic look better then they are? Nope. your math is completly broken. you are comparing crappy chinese used cells thst will NEVER reach their rating or lifespan with brand new cyclindricals wich are way too expensive. No, I wasn't comparing "crappy chinese u...
by flippy
May 31 2021 1:32am
Forum: Battery Technology
Topic: Building a large capacity battery for bicycle trailer
Replies: 94
Views: 1799

Re: Building a large capacity battery for bicycle trailer

I think that for this situation lifepo4 is the way to go. Using this as a example: https://www.aliexpress.com/item/33054219276.html 3.2v 100ah Lifepo4 prismatic = 1.98 kg per cell. 16s1p = 16 cells = 31.68kg versus: https://ru.nkon.nl/rechargeable/li-ion/21700-20700-size/samsung-inr21700-30t-3000ma...
by flippy
May 30 2021 1:55pm
Forum: Battery Technology
Topic: Measuring super capacitor ESR?
Replies: 5
Views: 118

Re: Measuring super capacitor ESR?

fill them up. leave them at their rated voltage for a day or so to get fully saturated and then disconnect them and just leave them. measure after 12 hours what the voltage is. it does not tell you the IR but it does give an indication of self discharge wich is the best sign of a failing capacitor i...
by flippy
May 30 2021 1:16pm
Forum: Battery Technology
Topic: Constant discharge rate needed
Replies: 3
Views: 129

Re: Constant discharge rate needed

that is not how this works. consumption depends on acutal usage. the faster you go the more you consume. that your controller CAN do 33A does not mean it actually IS doing that constantly. a 500bhp ferrari stuck in traffic is also not producing 500bhp. buy the biggest battery you can afford and you ...
by flippy
May 30 2021 9:05am
Forum: Battery Technology
Topic: Meanwell HLG-320H Series Combination Charging
Replies: 6
Views: 193

Re: Meanwell HLG-320H Series Combination Charging

I'm also interested in this concept to charge a 20S pack (82-84V) - any recommendations? I'm also hunting around for a decent fixed-voltage charger but having the slight bit of adjustment typically found in a PS would be nice. (thanks) if you dont need waterproofing i recommend using the HRP series...
by flippy
May 30 2021 8:27am
Forum: Battery Technology
Topic: Measuring super capacitor ESR?
Replies: 5
Views: 118

Re: Measuring super capacitor ESR?

why would you want to measure the IR of a supercap? its capacity is well outside the range of normal IR meters. the only hope you have is to fully charge the cap to its full rated voltage and have saturated it (so it does not draw ANY current anymore)
by flippy
May 30 2021 8:08am
Forum: Battery Technology
Topic: The case for using Supercapacitors with Lithium-Ion batteries in EV's
Replies: 19
Views: 439

Re: The case for using Supercapacitors with Lithium-Ion batteries in EV's

If it is still to be manufactured wouldn't it be easier to spend the money on a lower IR battery. Less system complexity plus probably more capacity. The only negative is weight but does that really matter when most EVs are already quite heavy. Already existing EVs with tired batteries or racing EV...
by flippy
May 30 2021 7:54am
Forum: Battery Technology
Topic: Splicing/ connecting charge wires to battery
Replies: 34
Views: 531

Re: Splicing/ connecting charge wires to battery

I have a similar one that with which I could test that theory, Flippy. I almost built a hanging dead weight prony dyno yesterday for fun to figure the tq on a 24v motor I am using to charge off the steam engine in out current boat project. put some amps on it. lets see how long those crappy chinese...
by flippy
May 30 2021 5:00am
Forum: Battery Technology
Topic: Splicing/ connecting charge wires to battery
Replies: 34
Views: 531

Re: Splicing/ connecting charge wires to battery

cables can take a lot of amps for a short while, until they heat up. but generally at that point the current has already dropped enough. its certainly not the way its supposed to be done but companies that make crappy products simply use the buffer that real life usage provides. there is also no way...
by flippy
May 30 2021 3:36am
Forum: Battery Technology
Topic: Meanwell HLG-320H Series Combination Charging
Replies: 6
Views: 193

Re: Meanwell HLG-320H Series Combination Charging

if 1 unit comes up faster in voltage the other unit will detect it and shut down. so beware it wont work every time you plug it in.
by flippy
May 30 2021 3:33am
Forum: Battery Technology
Topic: Splicing/ connecting charge wires to battery
Replies: 34
Views: 531

Re: Splicing/ connecting charge wires to battery

did you consider the specs are bullshit?
by flippy
May 29 2021 10:02pm
Forum: Battery Technology
Topic: Splicing/ connecting charge wires to battery
Replies: 34
Views: 531

Re: Splicing/ connecting charge wires to battery

compare an SB50 with a XT90 and tell me the first thing you notice.

bear in mind that the SB50 is rated 35 amps (aka: basically half!) LOWER then the XT90....
by flippy
May 29 2021 8:52pm
Forum: Battery Technology
Topic: The case for using Supercapacitors with Lithium-Ion batteries in EV's
Replies: 19
Views: 439

Re: The case for using Supercapacitors with Lithium-Ion batteries in EV's

the biggest airport in europe only uses teslas a taxis for many year now. they actually NEED that range to be able to fill their drivable hours. i understand you think you can find an application for supercaps but they simply dont exist. not in any commercial or financial sensible place at least. ou...
by flippy
May 29 2021 8:45pm
Forum: Battery Technology
Topic: Splicing/ connecting charge wires to battery
Replies: 34
Views: 531

Re: Splicing/ connecting charge wires to battery

ok, the warning on XT90s is noted, thanks fatty/ flippy. what do people use to run 80 amps plus - XT150s, or it there an alternative? you bolt connections with pressed on (so no solder!) ring lugs. if you have to takr them out often you use a single xt60 or whatever that only does the precharging r...
by flippy
May 29 2021 5:14pm
Forum: Battery Technology
Topic: The case for using Supercapacitors with Lithium-Ion batteries in EV's
Replies: 19
Views: 439

Re: The case for using Supercapacitors with Lithium-Ion batteries in EV's

Just in case you didn't read the reference to "Simulations", it's still worth while to looking into the concept. A battery is not a one size fits all! Battery and Supercapacitor Power Density.png The Supercapacitor wins in the short sprint race every time, it's not trying to be a marathon...
by flippy
May 29 2021 4:19pm
Forum: Battery Technology
Topic: Splicing/ connecting charge wires to battery
Replies: 34
Views: 531

Re: Splicing/ connecting charge wires to battery

I'm new to XT90s . I found out that you plug in halfway for the resistor to engage then fully plug in And they only last so long. they're not meant to be plugged in unplugged and replugged and unplug. When the resistor burns up you can tell. I have a battery like that but 20s6p Samsung 40t BT. Have...
by flippy
May 29 2021 4:36am
Forum: Battery Technology
Topic: Meanwell HLG-320H Series Combination Charging
Replies: 6
Views: 193

Re: Meanwell HLG-320H Series Combination Charging

dont mix different voltages. it kills them. running identical models in series is no problem and i have been using that "trick" for nearly a decade for hundreds of installs. without getting into the weeds of electronic enginerding you are "pushing" in more current into the higher...
by flippy
May 29 2021 3:20am
Forum: Battery Technology
Topic: Splicing/ connecting charge wires to battery
Replies: 34
Views: 531

Re: Splicing/ connecting charge wires to battery

ok, thanks Chalo, the warning is appreciated. What maximum amps would you recommend running through that setup? The main reason for a new battery was range, rather than top speed/ power - I can limit the amps through the CA use temperature sensors on the bms and CA, shove the sensor in the heart of...
by flippy
May 29 2021 3:07am
Forum: Battery Technology
Topic: The case for using Supercapacitors with Lithium-Ion batteries in EV's
Replies: 19
Views: 439

Re: The case for using Supercapacitors with Lithium-Ion batteries in EV's

you can grapth it all day, but in the end the end result is the same: supercaps are stupid in vehicles. in the end its better to just increase the battery size then removing battery size to make room for supercaps and absorb the hit on added wear from hard accelerations.
by flippy
May 29 2021 3:04am
Forum: Battery Technology
Topic: Recommendations for 72v batteries
Replies: 2
Views: 135

Re: Recommendations for 72v batteries

without knowing what your actually -want- from the battery that is impossible to answer. you basically ask "i need a laptop, wich one do i need to buy?" without giving actual useful data. is pre-built mandatory or are you going/willing to build something yourself? how FAR and how FAST are ...
by flippy
May 29 2021 2:55am
Forum: Battery Technology
Topic: Building a large capacity battery for bicycle trailer
Replies: 94
Views: 1799

Re: Building a large capacity battery for bicycle trailer

cycle life does not really matter here. the rest of the bike will fall apart before you kill a 18650 pack of that size. and its 10kg lighter and can be made in a more practical shape... Calendar life kills 18650s way sooner than some other more commercial/industrial formats. Agreed that charge-disc...