Search found 547 matches

by serious_sam
Mar 02 2021 5:06am
Forum: Battery Technology
Topic: Why isn't "node charging" through the balance leads more common?
Replies: 11
Views: 233

Re: Why isn't "node charging" through the balance leads more common?

every second or third thread in this subforum is for a misbehaving (or incorrectly-spec'd) charger or failed BMS. Please stop exaggerating and perpetuating the BMS myth. There's no particular reason that BMSs should be any less reliable than any other electronic hardware. Think about it logically. ...
by serious_sam
Mar 01 2021 7:11pm
Forum: EBike General Discussion
Topic: Build pack onto and around frame tube, rather than inside?
Replies: 27
Views: 401

Re: Build pack onto and around frame tube, rather than inside?

How many cells would you get in a string, along the short length of the downtube? You'd be limited to something like 10S.
by serious_sam
Mar 01 2021 7:03pm
Forum: Battery Technology
Topic: Why isn't "node charging" through the balance leads more common?
Replies: 11
Views: 233

Re: Why isn't "node charging" through the balance leads more common?

I would say just from a reliability standpoint, a single bulk charger plus BMS is an order of magnitude more reliable than an individual charger per cell group (I.e. node charging). A charger is a relatively complex circuit with many points of failure, whereas a BMS usually has relatively few compon...
by serious_sam
Feb 27 2021 6:05pm
Forum: EBike General Discussion
Topic: Build pack onto and around frame tube, rather than inside?
Replies: 27
Views: 401

Re: Build pack onto and around frame tube, rather than inside?

fatty wrote:
Feb 27 2021 5:43pm
-No cell holders or pack structural members necessary -- strong and light.
If you don't have cell holders, what is the structure ? I.e. how are the cells held to the frame ? Would this method work for non-cylindrical tube frames ?
by serious_sam
Feb 27 2021 6:14am
Forum: Battery Technology
Topic: 'on board' 1.5kW charger. Which alibaba supplier?
Replies: 100
Views: 2019

Re: 'on board' 1.5kW charger. Which alibaba supplier?

The modern world now tolerates, if not celebrates, neuro-diversity. Whatever that means, it doesn't mean you shouldn't make an effort to learn how to communicate in a universally accepted manner. Particularly if your first/only language is "English", and we are communicating in English. F...
by serious_sam
Feb 27 2021 4:56am
Forum: Battery Technology
Topic: 'on board' 1.5kW charger. Which alibaba supplier?
Replies: 100
Views: 2019

Re: 'on board' 1.5kW charger. Which alibaba supplier?

Why can't you write like a normal person ?

Instead

of making everything

so spaced out.

unnecessarily.
by serious_sam
Feb 26 2021 3:55am
Forum: Battery Technology
Topic: 'on board' 1.5kW charger. Which alibaba supplier?
Replies: 100
Views: 2019

Re: 'on board' 1.5kW charger. Which alibaba supplier?

john61ct wrote:
Feb 25 2021 10:59pm
It is normal practice to just ignore those you have determined are a waste of energy.

No forum function is required, just stop reading their posts, or at least don't take the bait and respond.
That's what we do with you John.
by serious_sam
Feb 25 2021 6:52pm
Forum: EBike Technical
Topic: Battery Autopsy
Replies: 11
Views: 267

Re: Battery Autopsy

I think we're witnessing the creation of an ebike addict here :lol:
by serious_sam
Feb 25 2021 6:46am
Forum: Battery Technology
Topic: 'on board' 1.5kW charger. Which alibaba supplier?
Replies: 100
Views: 2019

Re: 'on board' 1.5kW charger. Which alibaba supplier?

This is sort of pedantic. Two equal cells in parallel will still both rest together to a lower voltage. That's quite different from constantly topping off a cell to 4.2V, even if there periods of no current flow. We're not talking about resting voltages. We're talking about no current flow. I used ...
by serious_sam
Feb 25 2021 5:47am
Forum: Battery Technology
Topic: 'on board' 1.5kW charger. Which alibaba supplier?
Replies: 100
Views: 2019

Re: 'on board' 1.5kW charger. Which alibaba supplier?

It is harmful to cycling longevity to keep applying voltage to the point that there is no current flowing. In the context of this discussion (charger cutoff @ XmA vs. leaving a charger connected at CV for Y hours, for example overnight), you're wrong. I'm sure you will agree that connecting 2 equal...
by serious_sam
Feb 24 2021 4:34am
Forum: Battery Technology
Topic: 40T, neodymium magnets, plasti dip cycle test
Replies: 121
Views: 6612

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

Copper can have treatments that stiffen it, so annealing a roll of copper ribbon can make it what's called "dead soft". Annealing is when you heat it up to a certain temperature, and then allow it to cool down very slowly. Good idea. I've noticed that the copper sheet I've bought online h...
by serious_sam
Feb 23 2021 5:00pm
Forum: Battery Technology
Topic: Charging two batteries off a single charger OK?
Replies: 10
Views: 216

Re: Charging two batteries off a single charger OK?

Just as a caveat, you should confirm that your BMS will still activate balancing mode with the slightly reduced charge voltage (due to voltage drop across diode). And that the power dissipation across the diode won't cause heat problems. You could use a Schottky diode to minimise those effects.
by serious_sam
Feb 23 2021 3:26pm
Forum: Battery Technology
Topic: Charging two batteries off a single charger OK?
Replies: 10
Views: 216

Re: Charging two batteries off a single charger OK?

DrkAngel wrote:
Feb 23 2021 12:48pm
Possibility is to place directional diodes to each charge connection.
You want to directionally isolate batteries from each other.
This is what I would do. Then it doesn't matter if you have a different SOC in each pack.
by serious_sam
Feb 22 2021 4:25am
Forum: Battery Technology
Topic: getting cells up to 140f
Replies: 7
Views: 295

Re: getting cells up to 140f

This VTC6 datasheet implies 140F (60C) is in usable temperature range. Page 6.
SONY_US18650VTC6 (1).pdf
(300.26 KiB) Downloaded 1 time
This 30Q datasheet has a thermal abuse test to 140C. So again, assume 60C is ok. Page 15.
30q.pdf
(5.07 MiB) Not downloaded yet
by serious_sam
Feb 21 2021 2:19am
Forum: EBike Technical
Topic: What makes the FOC controllers so small and powerful?
Replies: 2
Views: 179

Re: What makes the FOC controllers so small and powerful?

john61ct wrote:
Feb 21 2021 1:27am
higher voltages means fewer FETs smaller size.
Nothing to do with FOC.
by serious_sam
Feb 21 2021 2:11am
Forum: Battery Technology
Topic: how to choose BMS in a battery pack?
Replies: 17
Views: 498

Re: how to choose BMS in a battery pack?

but if i am going for 7S i will need to get one with at least 70A nominal for the most simple solution, and preferable one with at least 150A true nominal output. and build a pack with (2AH cells) of 20 cells in paralell to get output of under 1C per cell. so i wonder what is the best, to make a 7S...
by serious_sam
Feb 19 2021 10:38pm
Forum: Battery Technology
Topic: Trying to increase my batteries longevity but did i actually destroy it doing so?
Replies: 22
Views: 530

Re: Trying to increase my batteries longevity but did i actually destroy it doing so?

this is the voltage of the 13s: 1)3,75 V 2) 4,13 3)3,95 4 3,85 5)4,18 6)4,19 7)4,21 8)4,23 9)4,20 10)4,22 11)4,22 12),4,22 13)4,22 Couple of things: - 4.23V isn't that bad. It isn't great for the cells, but it isn't the end of the world either. Don't stress about it right now. - Your multimeter mig...
by serious_sam
Feb 19 2021 8:09pm
Forum: EBike Troubleshooting
Topic: Help with stray voltage
Replies: 17
Views: 256

Re: Help with stray voltage

If nothing is electrically connected to the frame, then there should be no current flow. Put the meter on mA setting and measure current flow between frame to batt negative, and frame and batt positive. Both should be 0mA.
by serious_sam
Feb 18 2021 4:15am
Forum: Battery Technology
Topic: Any advice about my pack design
Replies: 8
Views: 329

Re: Any advice about my pack design

atkforever wrote:
Feb 18 2021 3:19am
I am about to solder everything soon so if I'm doing crazy mistake please tell me :D
If you're going to solder, use copper, not nickel.
by serious_sam
Feb 16 2021 6:58pm
Forum: Battery Technology
Topic: Battery design advice required
Replies: 19
Views: 518

Re: Battery design advice required

cellmate wrote:
Feb 16 2021 2:59pm
My plan (and would love feedback here) is do this:
The nickel layout is fine but not ideal (diagonals are longer than direct, so will have slightly more resistance), you just need to make sure you use enough nickel for whatever current you plan running and it'll be fine.
by serious_sam
Feb 14 2021 4:36am
Forum: Battery Technology
Topic: Wire bonding for high powered packs?
Replies: 12
Views: 498

Re: Wire bonding for high powered packs?

st35326 wrote:
Feb 14 2021 2:11am
Here's the one I use. Around $75k and works very well.
https://www.youtube.com/watch?v=2l4rB4igFG4
That's very awesome. I like how you can connect to the cell rim and avoid making connections on the other side the pack.
by serious_sam
Feb 14 2021 1:00am
Forum: EBike General Discussion
Topic: gap between swing arm and disc brake -- suggestions?
Replies: 26
Views: 797

Re: gap between swing arm and disc brake -- suggestions?

Lots of misunderstanding in this thread. I don't know if proposing an increase in shear load on the screws is just included to sound technical, but if you're loading the mount screws in shear, you've already failed. "just included to sound technical"..."you've already failed". A...
by serious_sam
Feb 13 2021 11:07pm
Forum: Battery Technology
Topic: Smart BMS with xiaoxiang app let discharging easy but not charging.
Replies: 10
Views: 333

Re: Smart BMS with xiaoxiang app let discharging easy but not charging.

Its shame that faulty BMS can't be returned/refunded as I had to solder copper plates and seller want to accept even faulty BMS with 'modifications'. The heat required for adding copper plates could easily be enough to unseat some small component elsewhere. From my own experience of changing MOSFET...
by serious_sam
Feb 13 2021 10:01pm
Forum: Battery Technology
Topic: Wire bonding for high powered packs?
Replies: 12
Views: 498

Re: Wire bonding for high powered packs?

2. "At 10A each wire converts 0.24W into heat" - Meanwhile, each cell in my example, converts at least 3,4W into heat. In ideal conditions! For me, the extra loss is marginal, minimum acceptable. Everyone reading this can see that those 2 things are totally different. Losses are a seconda...
by serious_sam
Feb 11 2021 7:22pm
Forum: Battery Technology
Topic: Wire bonding for high powered packs?
Replies: 12
Views: 498

Re: Wire bonding for high powered packs?

Lot's of false information here! Fuse wire is usable in low P high(ish) current per cell application too! I have a 6S4P pack where the cell connections are 0.3mm dia. copper wires. I regularly discharge the pack with 40A (10A/cell) without any issue. The fuse wire resistance is ~5% of the cell's in...