Search found 4743 matches

by Punx0r
Oct 22 2019 10:25am
Forum: Battery Technology
Topic: Testing the internal resistance of a li ion cell and making determinations
Replies: 26
Views: 412

Re: Testing the internal resistance of a li ion cell and making determinations

If we knew the specific heat capacity and DC IR of the above 18650 cell we could work out the total cell heating and compare it to that predicted by simple ohmic heating - approximately - on account of heat loss due to imperfect insulation, heating of box interior etc.
by Punx0r
Oct 22 2019 2:36am
Forum: Battery Technology
Topic: Testing the internal resistance of a li ion cell and making determinations
Replies: 26
Views: 412

Re: Testing the internal resistance of a li ion cell and making determinations

It makes sense as a cell that sags under load will slowly recover its terminal votlage when that load is removed, presumably due to recharging of capacitance and the diffusion of ions "catching up". However, rather than voltage sag, lost capacity due to discharge at higher rates can only be due to h...
by Punx0r
Oct 21 2019 7:58am
Forum: Battery Technology
Topic: Testing the internal resistance of a li ion cell and making determinations
Replies: 26
Views: 412

Re: Testing the internal resistance of a li ion cell and making determinations

Hmm. Interesting. The difference between DC and AC (@1kHz) impedence being due to cell capacitance is well established but this goes much further. Especially with the capactive capacity lasting as long as ~2 seconds and then a sudden, sharp drop in voltage - seems like such an obvious characteristic...
by Punx0r
Oct 21 2019 2:27am
Forum: Battery Technology
Topic: Testing the internal resistance of a li ion cell and making determinations
Replies: 26
Views: 412

Re: Testing the internal resistance of a li ion cell and making determinations

The 0.11V drop you noted is not internal resistance. Most of it is voltage sag from the chemical process of producing current. If we had nearly that much resistive loss in our packs, e-bikes would be a very different game. It's difficult to quantify cell resistance because it's inseparable from vol...
by Punx0r
Oct 18 2019 2:19am
Forum: E-Bike Technical
Topic: what type of connector is this?
Replies: 5
Views: 171

Re: what type of connector is this?

Note the addition of a waterproofing O-ring on the Bionx version. It's likely either a lightly customised version of an off-the-shelf connector or they really did design their own, based losely around the connector commonly used for solar panels, trailer wiring etc
by Punx0r
Oct 15 2019 3:06am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 5284
Views: 211839

Re: Wind and Solar vs Coal, Gasoline, Nuclear

So, are you saying there have been , and are, NO trends ? At various periods there have have been cooling trends, ( 1940 - 1975) and other periods warming trends (1980-2000), ? The whole AGW debate is based on a trend .! Maybe you missed the facts stated by those eminent , qualified scientists, ......
by Punx0r
Oct 14 2019 2:12am
Forum: Battery Technology
Topic: Big lead acid single cell capacities
Replies: 9
Views: 625

Re: Big lead acid single cell capacities

:thumb:

Nice to see something well made with a long useful service life
by Punx0r
Oct 13 2019 12:42pm
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 5284
Views: 211839

Re: Wind and Solar vs Coal, Gasoline, Nuclear

I think solar thermal made more sense in the earlier times when many of the projects were started - before the precipitous drop in the cost of PV and batteries
by Punx0r
Oct 13 2019 5:21am
Forum: E-Vehicles General Discussion
Topic: Can EVs survive without subsidies ?
Replies: 12
Views: 261

Re: Can EVs survive without subsidies ?

How much of a direct cash bailout did the big U.S. car companies get from the American government a few years ago to stop them going bust?
by Punx0r
Oct 10 2019 9:49am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 5284
Views: 211839

Re: Wind and Solar vs Coal, Gasoline, Nuclear

You seem to be confusing this casual public forum with some academic science institute with formal rules and traditions ? And since much of “science and academia” seems to have stuck its head up its own arse over AGW, i would not pay it much reverence anyway. It does not matter where the words or t...
by Punx0r
Oct 10 2019 7:52am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 5284
Views: 211839

Re: Wind and Solar vs Coal, Gasoline, Nuclear

Because in science and academia it is customary (and expected) to provide sources for any material you quote. You linked to a paper and provided a quote, implying it was quote from the paper, when it fact it wasn't. This is at least sloppy, if not intentional missleading. I note you still haven't gi...
by Punx0r
Oct 10 2019 2:52am
Forum: Motor Technology
Topic: is this post correct?
Replies: 5
Views: 170

Re: is this post correct?

For those who know nothing of how electric motors and vehicles are rated, the Wattage IS NOT the power output but the peak load power consumption. Industrial electric motors are rated by power output not input. Hobbyist/RC motors might be rated by input power because it's a bigger number and also o...
by Punx0r
Oct 10 2019 2:40am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 5284
Views: 211839

Re: Wind and Solar vs Coal, Gasoline, Nuclear

I read the whole paper ..and other review papers, ...and agree with the conclusion.. “The authors stress that the resulting errors are in the order of magnitude of the greenhouse gas forcing. Thus the solar irradiation and the aerosol forcing are falsified.” Can you understand the implications of t...
by Punx0r
Oct 09 2019 3:25am
Forum: E-Bike Technical
Topic: Help ID compounds on Strain Gauge in hub motor? - photo
Replies: 9
Views: 236

Re: Help ID compounds on Strain Gauge in hub motor? - photo

That would probably work. The normal reason for gooping RTV onto gauges is to provide strain relief for the lead wires and seal the gauge from moisture. The Bionix system seems to be doing that with the epoxy and the clear silicone, so what function the white stuff is fulfilling I'm not sure. Someon...
by Punx0r
Oct 09 2019 3:21am
Forum: Motor Technology
Topic: DIY Motor Dyno/load?
Replies: 17
Views: 397

Re: DIY Motor Dyno/load?

Exactly. Not a great idea... An automotive disc brake is pretty compact and simple and can dissipate a fair amount (few kW) continuously but may not be that linear due to CoF changing with temperature. Another alternative is driving a hydraulic pump through a restriction and an oil cooler. Non-linea...
by Punx0r
Oct 08 2019 3:03am
Forum: E-Bike Technical
Topic: Help ID compounds on Strain Gauge in hub motor? - photo
Replies: 9
Views: 236

Re: Help ID compounds on Strain Gauge in hub motor? - photo

neutral cure silicone RTV is often used for covering strain gauges but your stuff sounds like something a little different, like AW says.
by Punx0r
Oct 08 2019 2:49am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 5284
Views: 211839

Re: Wind and Solar vs Coal, Gasoline, Nuclear

Germany did not produce those 7GW per year of new wind and solar capacity all by itself for those few years that it was at that level. Germany will produce around 6.9million cars in 2019 with an embodied energy of around 20,000kWh each. That's 138 TWh. We have plenty of capacity to build clean gene...
by Punx0r
Oct 05 2019 4:56pm
Forum: General Discussion
Topic: Active energy transfer balancing
Replies: 14
Views: 877

Re: Active energy transfer balancing

Yep, typo, was suposed to say "no LVC". That's a bit of a shame as it does mean it's fully capable of killing your battery rather than protecting it. DIP switches to select LVC in 0.5V increments would be a good addition. It's great to finally see active balancing hitting the hobbyist end of the mar...
by Punx0r
Oct 05 2019 4:46am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 5284
Views: 211839

Re: Wind and Solar vs Coal, Gasoline, Nuclear

We'll see if Hinckley C goes ahead - it's hugely expensive and keeps threatening to bankrupt EDF, the giant French energy company, who are supposed to be building it.
by Punx0r
Oct 05 2019 4:35am
Forum: General Discussion
Topic: Active energy transfer balancing
Replies: 14
Views: 877

Re: Active energy transfer balancing

If they are chemistry agnostic does that mean there is now LVC?
by Punx0r
Oct 05 2019 4:31am
Forum: General Discussion
Topic: White putty used in battery packs?
Replies: 11
Views: 327

Re: White putty used in battery packs?

Beware that electronics grade silicone is not the same as bathroom silicone, which evolves acetic acid as it cures (acetoxy) which corrodes metal. Instead it is a more expensive form that evolves only alcohol as it cures (alkoxy). It's also usually low rather than high modulous, which makes it more ...
by Punx0r
Oct 04 2019 2:12am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 5284
Views: 211839

Re: Wind and Solar vs Coal, Gasoline, Nuclear

Hillhater wrote:
Oct 03 2019 8:36pm
You may want to Check up a little about modeling random chaotic systems ..!
Poor Hillhater. Like so many climate deniers confusing climate and weather.
by Punx0r
Sep 26 2019 2:36am
Forum: E-Vehicles General Discussion
Topic: Wind and Solar vs Coal, Gasoline, Nuclear
Replies: 5284
Views: 211839

Re: Wind and Solar vs Coal, Gasoline, Nuclear

She is an autistic child with learning difficulties who is speaking her mind, and is being crucified by small-minded conservatives who are terrified that her message will resonate. but ..she is a child with learning difficulties , so where did all that fluff in her mind come from ?.. someone put it...
by Punx0r
Sep 25 2019 2:42pm
Forum: E-Vehicles General Discussion
Topic: Taycan video with some useful information
Replies: 33
Views: 973

Re: Taycan video with some useful information

Not sure on the provenance of this figure, but 800V system is supposed to save 4kg https://www.caradvice.com.au/789624/porsche-taycan-battery/ I'm not sure if this factors in the 50kW 400-800v dc-dc converter required to allow the car to charge from a standard 400V charger or it's just the differenc...