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Discussion Starter · #1 ·
I'm looking around and can't seem to find the actual discharge ratings of the new Thundersky batteries. On their site they have 3C continuous and 20C pulsed, but what does pulsed mean? 1 second? 10 seconds? What about at 5C, 10C, and 15C. I know I've seen these specs somewhere, but can't seem to find them.
 

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I'm looking around and can't seem to find the actual discharge ratings of the new Thundersky batteries. On their site they have 3C continuous and 20C pulsed, but what does pulsed mean? 1 second? 10 seconds? What about at 5C, 10C, and 15C. I know I've seen these specs somewhere, but can't seem to find them.
Everything that I've read about TS and CALB say 3C/4C is the max continuous discharge, and the pulsed rating is in the millisecond range to account for controller ripple current.

I've also heard of people drawing 5C from both brands with no immediate damage, but it might not be good for overall cycle life.

This is the reason I'm going with headways, it takes a BIG pack of TS/CALB to get the higher currents.
 

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Discussion Starter · #3 ·
Thanks.

While I have no immediate plans of doing a conversion I would like to do one when I've got the spare funds. With the way the economy has been the last few years who knows when that will be. The real problem is I wouldn't want to do it halfway. I'd want to do a conversion with at least 300 peak hp and with at least a 100 mile range. so I'd need at least $20k. Probably more. I'm too used to having a car with some grunt to put the time and the effort into a conversion that can only get me from point A to point B and not be able to have some fun with it. For now I'm just perusing components, wishing I had to money to do it or that someone invents a high power low cost battery to make it possible for much less money than it presently takes.
 

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Thanks.

While I have no immediate plans of doing a conversion I would like to do one when I've got the spare funds. With the way the economy has been the last few years who knows when that will be. The real problem is I wouldn't want to do it halfway. I'd want to do a conversion with at least 300 peak hp and with at least a 100 mile range. so I'd need at least $20k. Probably more. I'm too used to having a car with some grunt to put the time and the effort into a conversion that can only get me from point A to point B and not be able to have some fun with it. For now I'm just perusing components, wishing I had to money to do it or that someone invents a high power low cost battery to make it possible for much less money than it presently takes.
I couldn't agree more, that's the basis of my conversion. Unfortunatially it takes high discharge batteries to get the continuous current otherwise I would be packing around hundreds of extra lbs of TS/CALB but I would have killer range (if they would fit), so for my conversion I'll be using the Warp 11HV, Soliton1 and a 90series 7, 8, or 9 parallel pack of 38120S 10AH headways. Which should get me around 300hp peak.

Initially I had the idea of doing a conversion to save money.... well it turns out I wanted to many of the nice features and more power so I couldn't do it on the cheap like many people do and are very happy with. So I ditched the idea for a year and came back with a different point of view, it's a project car to make something fun and powerful, instead of just a commuter. (although it will probably be my daily driver when it's done) for me the key was treating this like a toy or project instead of an investment that will pay itself off over the years, it's not going to and I'm ok with that.
 

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Hi Jeremyjs

I found this from David85 - 15 seconds

http://www.diyelectriccar.com/forums...&postcount=137


There was another post from China specifying that 10C was OK for 3 seconds with a 3 second rest then 10C again - did not say how long you could keep it up!

15C was 2 seconds with a 4 second rest

I calculate that if I put pedal to the floor on my machine it will take ~ 6-7 seconds to reach 3C - it will exceed that for 3-4 seconds then I will have to lift to prevent my motor overrevving at about 80 mph - I will be running out of voltage about then as well so I may not have to lift as it will self limit


A123's or headways seen to be available, Headway are about 1.5x the price of Thundersky

Also
http://www.diyelectriccar.com/forums/showpost.php?p=213346&postcount=43

Pulse/burst seems to be in the seconds - which makes sense to me if a cell can take 3C continuous then 10C won't overheat it for at least a couple of seconds

my back of the envelope calcs were worse case 10C/sec temp rise
 

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I calculate that if I put pedal to the floor on my machine it will take ~ 6-7 seconds to reach 3C - it will exceed that for 3-4 seconds then I will have
Just curious how you calculate it will take 6-7 seconds to reach 3C? What cells are you talking about? I'm just comparing it to the default settings of a soliton where the slew rate is 500 or 600A per second, meaning you could reach 1000A in 2 seconds or less. Or with more aggresive settings 1 second or less. If it takes that long to reach 3C you have some very "energy saving" settings. Perhaps you were refering to something else?

I would personally ask for some feedback from TS users on here about what they feel is a realistic limit on discharge rates. I've only tested TS 100ah cells at 2c discharge and couldn't imagine the voltage sag at 10-20C. These definatially aren't A123 or Kokams or even headway calibre from all the research I've done as well as the limited testing I've personally done (only 100ah TS, and 38120S 10AH headways)
 

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Just curious how you calculate it will take 6-7 seconds to reach 3C? What cells are you talking about? I'm just comparing it to the default settings of a soliton where the slew rate is 500 or 600A per second, meaning you could reach 1000A in 2 seconds or less. Or with more aggresive settings 1 second or less. If it takes that long to reach 3C you have some very "energy saving" settings. Perhaps you were refering to something else?
In all likely hood you will reach motor current limit before you reach battery current limit. At stall the motor voltage is really close to 0V. Ignoring losses say the motor voltage at some point is 10V at 1000A. This is 10,000W. If your battery is at say 200V then that would only be 50A from the battery. It will take some time for the motor to spin up to the point that 3C will be taken from the battery. That is what I see with my car only in my case it takes 2-4 sec to reach max battery current. I'm only running a 64V nominal pack and limit my current to 430A to the armature.
 

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Hi RWAudio

My rough calculations,
My car (part built) should weigh less than 600Kg
150 Volt x 60Ah TS pack (proposed!)

Motor should (I think) break traction at ~450 Amps
Open revolt controller (I have ordered the kit)

RPM -----Motor Current -----Motor Volts ----- Battery Current
zero ------500 amps ----- 10v ---------- 500 x 10 / 150 = 33 amps ----- 1/2C
1000 ------ 500 amps ----- 10v + 30v? ----- 500 x 40 /150 = 133 amps ----- 2.5C
2000 ------ 500 amps ----- 10v + 60v? ----- 500 x 70 / 150 = 233 amps ----- 4C
3000 ----- - 500 amps ----- 10v + 90v? ----- 500 x 90 / 150 = 300 amps ----- 5C
4000 ------ 500 amps ------ 10v + 120v? ----- 500 x 130 / 150 = 433 amps ----- 7C
5000 - Back EMF = battery 150v no current - also maximum safe rpm - 86 mph

I hope to get to 4000 rpm - (over 60 mph) in about 7 seconds

When I start I am on less than 3C - as the motor revs rise the battery current rises until I reach 3C - fairly soon afterwards I have to cut the throttle or I over rev the motor

When I get my controller together I want to measure
Motor current versus Torque
Motor back EMF versus rpm

I have used rough numbers for these from some work QER did on a Warp9

I had originally planned on a 200AH pack but a 60AH pack will save me 200Kg and a lot of money
 

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Hi RWAudio

My rough calculations,
My car (part built) should weigh less than 600Kg
150 Volt x 60Ah TS pack (proposed!)

Motor should (I think) break traction at ~450 Amps
Open revolt controller (I have ordered the kit)

RPM Motor Current Motor Volts Battery Current
zero - 500 amps 10v 500 x 10 / 150 = 33 amps 1/2C
1000 - 500 amps 10v + 30v? 500 x 40 /150 = 133 amps 2.5C
2000 - 500 amps 10v + 60v? 500 x 70 / 150 = 233 amps 4C
3000 - 500 amps 10v + 90v? 500 x 90 / 150 = 300 amps 5C
4000 - 500 amps 10v + 120v? 500 x 130 / 150 = 433 amps 7C
5000 - Back EMF = battery 150v no current - also maximum safe rpm - 86 mph

I hope to get to 4000 rpm - (over 60 mph) in about 7 seconds
Ok, those number look like what I was expecting, but doesn't that mean you'll reach 3c in ~3ish seconds?

Are you going direct drive? What overall gear ratio and tire size. Based on the weight, it should be pretty quick if you can maintain traction.
 

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Well it looks like you've done the math, but I would seek confirmation that pushing the cells past 3C more than "once in awhile" won't have negative short or long term effects.

It does sound like a cool project though, good luck!
 

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Hi RWAudio

I would like to think it will be 3 sec to 3C and then 3 sec to max revs! - but I was being a bit pessimistic

I would also like to hear about real life experience with TS
The numbers make sense to me - but the proof of the pudding is in the eating

The diff I had was a 4.1:1 but I have just been given an LSD - not sure of the ratio
Direct drive
I have a set of 14inch x 185/70 wheels and tires - off my old Subaru
but I may be given some 15 inch 205/60 instead
There are a lot of old Subaru parts around here!
 

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I looked hard at TS cells, and I read every review and build I could find that used TS. I eventually ruled them out for my build because I thought I would be pushing them too hard or require a massive 300ah pack. Perhaps I was wrong, I would just hate to see anyone damage their expensive lithium pack. I'm even a bit worried I'll be pushing my Headways too hard, and they are rated 10C-15C continuous depending on who you ask.

In your calculations don't forget to consider the voltage sag under heavy loads.
 

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Hi RW

What can your motor take?
I have an ex forklift unit rated at 10Kw at 48v (200 amps)
Looks just like a Warp11 and weighs 102Kg

If I triple the voltage I get 30Kw (200amps)

If I had a high voltage controller I would probably go 200V - 60AH at 3C = 36Kw

With that I think I am equally abusing my motor and my pack!

I haven't bought the batteries yet (last thing)

I am thinking of a 150v 60AH pack - maybe I should be thinking 100AH??
 

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Your probably right to keep the voltage to a resonable level.

When I was working out the details of my conversion I knew it was going to be expensive, even just a warp9, 1000A controller and some lithium to go along with it add up pretty darn fast (lithium being the very expensive part) So after a lot of number crunching I found that the difference in price between an 80kw setup (warp9/TS/160v warp drive) and a 270kw (warp11hv/headway/soliton1) setup was really only about 25% more money I decided it was the route to take. Basically I traded some range for power keeping the pack price about the same, but the warp11hv and Soliton1 will let me take better advantage of the headways. I did do some further cost cutting by designing my own charging method, which doesn't require a traditional BMS, and the charger integrates individual cell voltage monitoring, so Charger/BMS/Guages are all in a single system costing about $1000 instead of 4000-5000 for a decent charger, 90cell bms and some guages. (it's a hell of a lot more work though, instead of buying an off the shelf product). It basically came down to if I was going to go ahead with the project I was going to do it the best I could within my budget. Unfortunatially due to the cost of the upgraded parts it will take longer to buy them all, and oddly enough my fiance is 100% behind me and suggested the sale of our '07 Infiniti G35 Sedan to help fund it. :eek:
I just have to get the gas powered Porsche 944 on the road before that can happen, then it's full steam ahead on the Electric 944.

Sorry for the rather off topic detour there, my motor is the Warp11HV and should be good for 250-288V. So the pack is designed to start getting close to the voltage limits of the Soliton1 (328.5v charged).
 

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I did do some further cost cutting by designing my own charging method, which doesn't require a traditional BMS, and the charger integrates individual cell voltage monitoring, so Charger/BMS/Guages are all in a single system costing about $1000 instead of 4000-5000 for a decent charger, 90cell bms and some guages.
I'd like to hear about your basic design of your charger/BMS system. It sounds like the way it should be done.

Electric Porsche "944DC" or should it be "944HV" ??
What about E-944-HV or EP-944-HV.
 

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I'd like to hear about your basic design of your charger/BMS system. It sounds like the way it should be done.

What about E-944-HV or EP-944-HV.
I have a little info in this thread:
http://www.diyelectriccar.com/forums/showthread.php/different-kind-chargeri-51588.html

Basically it's 90 individual dc/dc converters, fed by a high quality 48v power supply. Each battery box will be a 15S pack, so 15 dc/dc converters, each cell is optocoupled to a multiplexer to measure it's voltage. I'm using a 16 port multiplexer so the 16th port is battery box temperature. These will be fed over shielded ethernet cable to a microcontroller that will monitor the cell voltages (and add them for total pack voltage, list high cell, low cell and average cell voltage, another board will measure battery current, and possibly track SOC)

Since each cell has a dc/dc converter it can't be overcharged, monitoring the voltage would show if a dc/dc converter failed. The power supplies auto adjust to 85-264v ac input, and the setup I'll be using is 3kw off of a 220v plug, or 1.5kw off of a 110v plug. With more or larger power supplies the system is capable of about 7.5kw (based on 90 cells). And is adjustable from 3.3 to 3.65v depending on the desired charge voltage.

I kinda like E-944HV
Thanks!
 
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