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My plan was to only discharge the pack half way, 17 miles. That's why I went with the ts solution. My max speed is about the same, a little over 40 on a straight away, but the acceleration seems faster. I will probably never need to put more than 20-25 miles on one cycle ever. Not for most of my trips.
I think I might need to charge the first and last cells in the pack with a ps. When I leave the charger on for a few hours and check on it, the first and last cells in the pack are at like 3.4, but when I turn the charger off and back on, it starts charging again and they are all balanced a little time later.
Is the internal resistance of brand new, never charged cells higher than cells that have already been charged to 3.7? This would seem to be the case. The cells I charged with a power supply easily go to 3.7 now.
matt, you've been a phenomenal help, pjd as well. Thanks again.
Bruce how many cells are you using to get over 40mph ??
Hi Bruce,
before i forget, you could try one of these when you eventually go lookign for a suitable AH meter:
http://www.eagletreesystems.com/MicroPower/micro.htm
has a different set of features to the cycle analyst (such as datalogging) and might be slightly cheaper.
Matt
Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km
ah, 17 mile commutes with the odd emergency 34mile has been fine in my experience.
im afraid i havent measured internal resistance on these cells before as such.
i have done a few readings from which internal resistance could be infered, however these were done under differing conditions (ie temp, SOC).
cells at high SOC do seem to be more ready to dish out amps though.
you're welcome Bruce, happy to help a fellow EV'er.
PJD - id be really interested in that write up as too how how change the stock emax end of charge voltage (not that it would help me, both mine are dead, but for curiostities sake)
also, how is your lithium emax going? im at 10'000km (6250miles) all lithium
Matt
Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km
Matt,
I never found a way to change the end of charge voltage. It varies from charger to charger between 59 and 60 volts It would be difficult to change the voltage without a schematic. The only adjustment is the current, not voltage, at which the charger ends it's CV stage.
If you have the blue e-max chargers the cause of a dead charger 80% of the time is just the NTC Thermistor inrush suppressor. The big input rectifier capacitors often go bad too.
I've got a bit over 1000 km on one and a few hundred km on the other. Both are doing fine, although one cell on each acted up and were replaced. With cooler temperatures of 8 to 12C on the morning commute, sagging voltages are noticeable - down to about 46.0 volts under a 90 to 95 amp load under a 50% discharged pack. It will be interesting to see what they will do at below freezing temperatures come November - I could be seeing the 2.5 volt per cell limit on even a freshly charged pack. Low temperature performance may be their one real down side.
16 TSlfp40aha cells in series.
The real downside of the project is this:
1. After all the money and labor I put in building two of perhaps just a couple dozen operable lithium-ion powered electric vehicles in all of North America; and
2. With decals clearly stating "LiFePO4 Electric" several places on the scooter,
All I got for my trouble is mocking and derision, and sometimes outright hostility from the ignorant people here in the suburban "South Hills". The people here either are too stupid to notice or simply don't care about such an eminently practical form of electric transportation. To them, I'm just someone on a "moped" which means I must be a "loser" (a uniquely USAn term). One needs a thick skin to go riding on the things most days.
The only respite comes when I'm inside the Pittsburgh city limits, where people seem to be a bit more more open minded and educated.
Bruce,
Do you experience the same attitudes in the (presumably more affluent) Chicago suburb where you live?
Matt,
I assume people are a bit more enlightened out there in Oz aren't they?
More affluent! LOL! Chicago has an enormous construction base. I'm totally surrounded by construction type, tough guy people. 5 to 1. I see more hummers around here than I see priuses.
As far as people laughing at me, and I hear them as I pass, but I know for a fact that I'll have the last laugh. Remember the emporer's new clothes? It took a child to point out the emporer is naked, eg. larger vehicles people pay more money for are indeed worthless. Bigger is NOT better!
When gas prices go back up, they will be asking you how they can get one, you can bank on it. I almost hope ghawar gets bombed, that will make the point crystal clear for everyone. Take a huge oil field off line so people have no choice but to be smart about how they get around. I've already accepted that is what it's going to take to get them out of their SUV's. $7 a gallon to get most people out of their trucks and into something reasonable, not until they have exhausted their paychecks paying for gas, that's the mentality.
Yeah, I'm pretty much alone here in this area. To be honest with you, it's kind of a shithole around here. The wilderness is mostly gone to the retail and town home sprawl where I live, you used to have a small town atmosphere years ago. It's become quite ugly. I'm not sure if the culture out in california is really any different, ditto for oregon as well. The one time I payed visit out west,(portland, orgegon) I noticed lots of large trucks and ugly sprawl out that way as well. Nowhere near as bad as here, but the "bigger is better" culture seems to have infected everything here in america. The landscape in portland was a 70 percent improvement though, I could smell the difference in air quality the minute I stepped outside the airport there.
As far as people behind me not liking the 40 mph max speed, tough. I'll stop riding my scooter when the skinny 120 lb blondes get out of their tahoes, yukons and hummers and into something more thoughtful, as well as stop gabbing on the phone while they drive them and tailgate people in corollas.
Some people have called the recent bank failures a market adjustment due to bad debt.
Big houses were the first thing to go... Next... Big cars. Just like people are complaining their chipboard mansion with the inflatable smurf in the front yard, is 3 times less than what they payed for it, so too will they complain when gas exceeds 6 dollars a gallon and they have to sell vehicles they payed 40k for, back to the dealer or to the scrap yard for 500 bucks. That's a real possibility by the way.
This will be the next step.
Bgood.
hi Guys,
based on both your descriptions of what you've encountered id have say people are a *little* more open minded out here. I've only had two instances where ive encountered hostility, the first was way back when i was only running 15cells and my top speed was 50-55kmh, and i held up traffic on this one lane road. the other was when a "blokey" guy in a commodore (a big american inspired vehicle manufactured by GM-Australia) decided i was this familiar loser or 16yr old kid on a moped. (over here you can get a licence to ride a moped at 16, but have to wait until 17 to get a car)
of course petrol out here is $6/gal. Im not sure if i could say the same for a few years ago, but of course a few years ago i was driving on petrol. not that $6/gal has stopped people commuting in 4wd (a misnomer actually, relatively few of these are actually more capable of going off-road than my beat up old honda). but it has forced people to be a little more open minded. alot of my friends are now looking at motorbikes for their daily commute (alas not electric, but moving in the right direction)
One thing you may notice when petrol gets that expensive, is that the interest in electric vehicles, especially the more expensive lithium based converstions, will skyrocket. that way big bulk buys, especially for batteries will bring the price down. When i went to lithium for my emax (19 40AH cells) it cost me around $4k AUD all up. now a days i can get the same thing for $1400 AUD. and this is just a year after the price of petrol really started to rise. we only had around 5 or 6 people who didnt mind spending $13-$14k each on batteries to bring he price to this level. of course that wuold require 50-60 scooters to go lithium, but thats where your local electric vehicle association makes it easier.
I actually haven't bothered with the stickers and such for my emax (aside from the big electric stickers it came from the dealership in). theres even gashes up one side from where i fell off at 60kmh (35mph). I gotta tell you, watching your bike overtake you is an odd experience.
alot of the speed limits around here are 60kmh (37mph) or 70kmh (43mph) zones, and my top speed is around 65kmh, 70 if the wind is blowing in the right direction or its a really warm day. all 70kmh zones are dual carriage way, and in 60kmh zones i speed like everyone else. there are occasions when ive really wanted to go to 96v and 200A so i could really show off what an electric can really do, but oh well.....lots of other projects to do first.
I have had a few positive experiences, especially among the older population. ive had many questions while stopped at a set of traffic lights. At work everyone has asked me at least once what the deal is with my scooter and the power cord. heck, at work, Aust Post were even kind enough to give me my own powerpoint in an under-cover area reserved for me :D.
PJD - how is your bike holding up with the greater peak amps?
how far have you gone since you cranked up the current limit?
have you run into any heat issues with the motor?
im very tempted to finally increase the current limit on my emax when i change the caps out (those original 63v caps have lasted wayyy longer than i thought they would).
Matt
Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km
Matt,
I raised the controller current limit to 95 amps back in late 2006, so I've had two seasons running at the higher current - about 14,000 km between the two scooters.
The whole long discussion is here:
http://visforvoltage.org/forum-topic/motorcycles-and-large-scooters/166-more-e-max-controller-mods-shunt-resistor-trick
I've had no heating problems, but summers aren't particularly hot in my area. It might hit 32C a couple times.
Bruce,
I guess I had figured almost anywhere is better off than Pittsburgh, where the Rust Belt and Appalachia cross.
The only part of Chicago I'm familiar with is downtown (and O'Hare Airport of course) My stereotype of suburban Chicago is plush, leafy commuter-line suburbs where well-paid suits in the FIRE industry ride to their loop skyscrapers every day on those double decker commuter trains.
Paul,
Are you having any wierd issues with the 6th cell going too high at the end of the charging cycle? If so, is this normal? During the end of charging, all the red lights will light up except for the 6th(the one that is tied to the jumper)then, when the pack reaches 59.5 volts it shuts off and the bi color led switches from red to green and then the 6th led lights up and the voltage goes back down on that cell. This concerns me a little because during the end of charging, the cell gets pretty close to 4.2 volts. That can't be right, this is driving me insane!
No, on both my BMS's all cells are held to about 3.70-3.72 at the start of shunting, then all cells settle between 3.66 and 3.69 once all leds are flickering at uniform brightness and the shunts are substantially on. The bi color LED transitions from red to yellow.
You BMS is malfunctioning - Channel 6 doesn't seem to be working on your board.
Generally the regulator LED should never go full green, because unless a cell goes open-circuit, because the shunt never goes 100% on, so the charger current regulator never fully shuts off.
Also, the charger should not normally ever shut off because at 3.69 volts (or so) per cell, the charger never quite reaches the CV stage voltage, so the low current limit setting doesn't work. (although this might warrant looking further into) Yours is probably shutting off because the high cell is pushing the charger to the 59.5 volt limit - so it is fully entering the CV stage and the current limit shutoff eventually activates.
On some chargers, if the current adjustment on the charger is set high (pot turned CCW) some e-max chargers will shut off prematurely - you have to turn the pot 9-10 turns clockwise.
Paul,
Can you post a picture of your board for me? I believe I'm using a slightly different revision than you, not sure.
The latest and final version of the PC board layout was v1.5. Image files of it are available in the "Even Newer 16-cell BMS" topic in the voltage forum. The final revisions from the prototype test version (v1.4d) were to correct for incorrect B-C-E order for the KSA931 PNP transistors, and the use of the LM78L12 regulator in place of a PNP transistor/zener diode setup for providing 12V power to the MOSFET driver.
I've never hooked up the brake controller and ground wires to the board. I've really never felt I needed to since I'm only discharging this pack half way at most. Could that be the reason the sixth light won't shunt? Another thing strange:
If I put pressure on the pack wire harness during the last stage of charging, the bi-color led lights up and then the 6th shunt will light up and bring the cell back down to 3.7 volts, then the charger shuts off. That tells me the shunt works, just don't quite understand what I did wrong here. I'll post a video of it tonite. I'll try hooking up the controller ground wire tonite as well.
The LVC connections have nothing to do with the charging voltage regulation part of the LVC. But an LVC is an important part of a BMS and should be connected. The 2.1 volt cutoff voltage on this BMS is a bit of a limitation since the recommended min voltage is 2.5 volts. But this minimum voltage goes down in lower temperatures.
I would strongly recommend putting an accurate, 0.1 volt resolution voltmeter on your scooter. Don't let the pack voltage go below 42 volts. They make self powered (2 wire connection) digital panel meters that are easy to install.
Do you know how to install the LVC connection? In a scooter, the "brake" wire is connected to the throttle's signal wire (usually green) and the controller ground is connected to the (usually black) ground wire to the throttle. A 1000 ohm resistor placed on the signal wire between the throttle and your connection to the signal wire.
The thing you are describing is a bad connection - the most obvious location being near where you are pressing. If you pressing where the board is flexing, the bad connection could be in the form of a bad solder joint or trace on the board.
The first thing I checked for was loose components on the board. That's what I would have assumed it was too, but I couldn't find any part where I didn't use enough solder. I used plenty.
During the end of charging when the lights started going on, I thought I might start wiggling individual parts on that particular circuit to see if I could get it to go on. Sure enough, when I pushed the 5 watt resistor over a little, the shunt went back on. I unsoldered it, put another one on, and used extra solder on it. Even after that I had to move it in a certain spot to get the shunt to stay on. Oh well, it's working for now. The next board I build I'll have put through the wave solder machine at work.
I rode it almost everyday this week in 45-55F temp. The voltages do sag a little from the cold, but not enough to kill any part of my trip. Besides the speedometer going flaky, so far I didn't encounter any problems with the bike or with people on the road. In fact, surprisingly, when I'm at a stop sign, people have been giving me the right of way and staying a respectable distance behind me during travel. I'm also driving most of my route in 35 mph speed zones so this isn't too much of a surprise. I've got about 200 miles so far on this pack.
I'll end up getting a cycle analyst and some led lights for this eventually. I'm also going to have it painted all black with a small bat sign.
Bruce,
When it comes to soldering it isn't quantity, it is quality!
Each solder joint should look like tiny, shiny Hershey's kiss. Many poeple - and practically everyone over 45 years old like me, needs to use a magnifier for soldering the smaller joints. You shouldn't see any roughness or porosity.
You might want to look over the traces with a magnifier for damage to a trace on the board.
There are plenty of sites on the internet with soldering tutorials on them. Briefly,
30 amp soldering iron.
Thin rosin core solder wire
Sharp tip, periodically check for tightness on the iron,
Pre-tin the tip so it is shiny with solder - if the solder won't stick, clean it with fine sandpaper
Keep the tinned tip shiny at all times by wiping the hot tip on a wet sponge every few joints
Use a bench magnifier or wearable magnifying lenses of some sort.
Work fast - especially the heat sensitive transistors IC, optocouplers - a quick dab usually does it.
The only exception where you might want to be bit generous on the solder is the charge-regulator FET, since this might have to handle up to 20A current if you use a big charger - but work fast to avoid heat damage to the FET.
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