Search found 2378 matches

by Sunder
Dec 12, 2017 5:58 pm
Forum: Battery Technology
Topic: smart BMS - balance charging at partial charges?
Replies: 4
Views: 40

Re: smart BMS - balance charging at partial charges?

You can also get a dumb balancer. It simply daisy chains all cells, detects the highest cell and lowest cell, and sends power between them. Rinse, repeat, until all cells are balanced. Unfortunately, it will do that regardless of the cell voltage, so if left completely unattended, can kill batteries...
by Sunder
Dec 12, 2017 5:52 pm
Forum: Battery Technology
Topic: Super capacitors to save battery life?
Replies: 41
Views: 664

Re: Super capacitors to save battery life?

This isn't fully relevant, but it is a bit relevant, and I think a bit amusing. My dad used a 11S (24v) LTO pack to charge a 12v battery, unregulated. 1. The 12V battery died, unsurprisingly. 2. The 24v battery "recharged" with some cells at 3.6v, and some cells at 1.8v, so heavy unbalanced (no BMS ...
by Sunder
Dec 11, 2017 5:06 pm
Forum: E-Bike General Discussion
Topic: Car replacement in London/Other Cold Weather
Replies: 4
Views: 108

Re: Car replacement in London/Other Cold Weather

Hmm. So one saying without a car it would be difficult, one saying only 30% of people have cars... I guess living there a few weeks can't hurt and saves an inappropriate bike just sitting there collecting dust in a very small house, if I was wrong. There is always the option of cabs just for a few w...
by Sunder
Dec 10, 2017 6:44 pm
Forum: E-Bike General Discussion
Topic: Car replacement in London/Other Cold Weather
Replies: 4
Views: 108

Car replacement in London/Other Cold Weather

Hey everyone. I have just accepted a secondment to London to build a new branch of my boss' business. It's happening Nov-Dec. 2018, with an ideal launch date of Jan 2019, so just under a year away. My wife wants to try to live without a car there, despite having two young children. She believes owni...
by Sunder
Dec 09, 2017 7:12 pm
Forum: Battery Technology
Topic: Super capacitors to save battery life?
Replies: 41
Views: 664

Re: Super capacitors to save battery life?

Would you mind asking HPC what cells they use? The goalposts seem to have moved on this one. we've gone from using LTO to reduce voltage sag on ageing batteries and soaking up regen, to using it for rapid charging. Its possible that if you always use you batteries in parallel, and get a bigger charg...
by Sunder
Dec 08, 2017 12:42 am
Forum: Battery Technology
Topic: Super capacitors to save battery life?
Replies: 41
Views: 664

Re: Super capacitors to save battery life?

You might have forgotten he also needed to lower the effective internal resistance of some aging cells.
by Sunder
Dec 07, 2017 11:06 pm
Forum: Battery Technology
Topic: Super capacitors to save battery life?
Replies: 41
Views: 664

Re: Super capacitors to save battery life?

If you're talking about Inwo's cells, they can handle 100A. Very safe for any charger you can think of, but not impossible to put that much out on regen braking when you are: 1. Carrying that 475lbs + you 2. Going high speed. Regen braking from 110km/h on my eScooter which weighs about the same, I n...
by Sunder
Dec 07, 2017 7:39 pm
Forum: Battery Technology
Topic: Super capacitors to save battery life?
Replies: 41
Views: 664

Re: Super capacitors to save battery life?

LTO are sometimes called supercapacitors, because some models (mostly high end) behave more like capacitors than batteries, the capacitance issue aside. I've seen some that can charge at 60C without damage. LiPo can discharge at that rate, but try to charge it at that rate and you're asking for a fi...
by Sunder
Dec 06, 2017 7:19 pm
Forum: Battery Technology
Topic: Super capacitors to save battery life?
Replies: 41
Views: 664

Re: Super capacitors to save battery life?

@sunder I am interested in your system? So I am wondering if you did the something I am thinking of doing because of it effecting your batteries? I was looking at replacing the batteries with super capacitors but after a few hours of research that became clear it was not a possibility. That's when ...
by Sunder
Dec 06, 2017 6:00 pm
Forum: Items for Sale - New
Topic: 48v 11ah nos $150
Replies: 5
Views: 280

Re: 48v 11ah nos $150

Wow. $118AUD (Less than $100USD) to ship the box of generic goods. $968USD if I declare them to be batteries.

Will look into it further, but to be honest, even at the generic shipping rate, it's only about 20% cheaper than buying new.
by Sunder
Dec 05, 2017 11:29 pm
Forum: Items for Sale - New
Topic: 48v 11ah nos $150
Replies: 5
Views: 280

Re: 48v 11ah nos $150

Can these be shipped to Australia?
by Sunder
Dec 05, 2017 9:47 pm
Forum: Battery Technology
Topic: So confused, please help (24s 99.6V battery charging/safety)
Replies: 20
Views: 307

Re: So confused, please help (24s 99.6V battery charging/safety)

The overcharge would be negligible. I wouldn't leave it there for weeks, but you shouldn't leave any lithium battery protected or not, on a charger for more than the time it takes to charge it. You'll get a lot of opinions on best way to manage a battery. A lot of the more experienced members believ...
by Sunder
Dec 05, 2017 9:42 pm
Forum: Battery Technology
Topic: Wire or Cable size? 100ahr 12.8V Lifepo4
Replies: 3
Views: 90

Re: Wire or Cable size? 100ahr 12.8V Lifepo4

7" of 4 AWG @ 600A = 51 watt loss 7" of 2 AWG @ 600A = 33 watt loss 7" of 4AWG @ 200A = 5.7 watt loss 7" of 2AWG @ 200A = 3.6 watt loss 7" of 4AWG @ 80A = <1w loss 7" of 2AWG @ 80A = <1w loss As long as your times are accurate, I'd say dustNbone is spot on. I would not like to see 51w of heat dumped...
by Sunder
Dec 05, 2017 6:25 pm
Forum: Battery Technology
Topic: Super capacitors to save battery life?
Replies: 41
Views: 664

Re: Super capacitors to save battery life?

Short answer: Maybe and sort of. I've done it, but using high rate LiPo rather than Super Capacitors. I have a 40Ah bank of LiFePo4, which is really old. Really sags badly, but still maintains over half its overall capacity. Rather than ditch it, I "stiffened" it up with some a small amount of high ...
by Sunder
Dec 04, 2017 9:56 pm
Forum: E-Bike General Discussion
Topic: new eZip motor
Replies: 4711
Views: 251576

Re: new eZip motor

Want to know what's inside those fake 18650s? https://lightsngear.com/wp-content/uploads/2014/06/bad-18650.jpg That's if you're lucky. If you're not, you might actually get a real one - That has already failed and has been sent to recycling. I know our waste processing plants pay China millions of d...
by Sunder
Nov 21, 2017 6:06 pm
Forum: E-Bike General Discussion
Topic: new eZip motor
Replies: 4711
Views: 251576

Re: new eZip motor

And yes it is just what I thought. Nobody even has a clue how to put a motor on a 29" Mongoose with disk front and rear which has an excellent pedal drive system with fully working gears. The cheapest hub motor kit I found is made by Leaf and way over $300. Belt drive set ups for 29" wheels do not ...
by Sunder
Nov 15, 2017 4:41 pm
Forum: Battery Technology
Topic: MultiStar 6S/5200 mAh on sale from US warehouse
Replies: 22
Views: 996

Re: MultiStar 6S/5200 mAh on sale from US warehouse

Sounds more like a user issue than a pouch vs cylinder issue. You can get good and bad cells for both formats and you can get tidy and untidy in both formats, and you can get power density vs energy density in both. It just so happens that Multistars are cheap, have a low power density and high ener...
by Sunder
Nov 08, 2017 9:29 pm
Forum: E-Bike General Discussion
Topic: new eZip motor
Replies: 4711
Views: 251576

Re: new eZip motor

Charge the old 5.0Ah as paired sets, single 10Ah! It's not just convenience either. Lower charge rates extend the life of the battery. A 5A charger on 5Ah battery is 1C, or a fairly quick charge. A 5A charger on 2 x 5Ah batteries = 0.5C. Still on the fast side, but much gentler on the battery, espe...
by Sunder
Nov 08, 2017 1:13 am
Forum: Battery Technology
Topic: Speculate what happened to my cells
Replies: 3
Views: 141

Re: Speculate what happened to my cells

Wonder if I can puncture one and see what gas comes out then ;) What's the gas from overdischarge?
by Sunder
Nov 08, 2017 1:03 am
Forum: Battery Technology
Topic: Speculate what happened to my cells
Replies: 3
Views: 141

Speculate what happened to my cells

Alright, so I have no idea what happened to my pack. It's a massive LiFePo4 8S23P battery, charged by a solar charger, and discharged by a 3000W inverter. I have several theories, one of which is a prime candidate, but I don't know how to test for it. They are: 1. The pack was over-charged. The BMS ...
by Sunder
Nov 07, 2017 9:15 pm
Forum: Battery Technology
Topic: Charge 52V Dolphin with this MPT-7210A?
Replies: 10
Views: 424

Re: Charge 52V Dolphin with this MPT-7210A?

Alright, I am an idiot. After what Heath said, I retested my system. The issue is a 15m cable using 1mm^2. That is rated to 11A depending on the conductor, but at 10A, the voltage drop over the whole length is 2.55v, The battery is only "seeing" a lower voltage, hence lower potential difference betw...
by Sunder
Nov 07, 2017 6:29 pm
Forum: Battery Technology
Topic: Is it OK to replace 40ah scooter batteries with 35ah?
Replies: 27
Views: 481

Re: Is it OK to replace 40ah scooter batteries with 35ah?

I think you might be thinking of the wrong type of scooter. Try one of these: http://ilsau.com.au/wp-content/uploads/2016/09/Viper-8-mph-Mobility-Scooters.jpg Same concept though :P I had considered a Leaf cell upgrade for my Vectrix - too hard and expensive to get Leaf cells in Australia. They're a...
by Sunder
Nov 01, 2017 10:03 pm
Forum: E-Bike General Discussion
Topic: ebike Battery sellers
Replies: 20
Views: 577

Re: ebike Battery sellers

Build your own using Multistar batteries. It's cheap, it forces you to learn how the battery works, so you can do future diagnosis and repair yourself, and you know you're getting quality cells. Even some reputable sellers have been caught out by unknowingly buying and on-selling poor quality packs,...
by Sunder
Oct 30, 2017 10:09 pm
Forum: Battery Technology
Topic: Can you tell me anything about this BMS?
Replies: 12
Views: 266

Re: Can you tell me anything about this BMS?

Oh right. The 4 could be going to the 4P of cells, and the 5th going to the outer terminals of the whole battery. Hard to tell from the photo, but it looks like you have 4 going to the bottom right terminal, and the 5th goes further under the circuit board. I am taking guesses based on your photos t...
by Sunder
Oct 29, 2017 10:25 pm
Forum: Battery Technology
Topic: Can you tell me anything about this BMS?
Replies: 12
Views: 266

Re: Can you tell me anything about this BMS?

Re: 5 wires = Battery negative, cell 1 positive, cell 2 positive, cell 3 positive, cell 4 positive = 5 wires needed. Re: Batteries in parallel. What you described can't happen. Two batteries in parallel will create a current until they are equal. Unregulated, this can be very fast and can cause issu...