BobCs emax scooter thread

Just had 1st little ride with lithium power. Yes; - transformation, the lumbering slug has become a perky and sprightly little thing. Now I have to get the batteries balanced and charged (didn't dare go far with batteries as supplied: I suspect they're pretty full but there's really no way of knowing without cycling them...). It fairly rockets up to its 30mph speed limiter now. (and I've not tried the "boost" button....)
It now has 18s sinopoly 40Ah LifePO4 & the bus voltage sits at near 59V. In time that will be taken up to 26s - this easily fits in the battery box with the 40Ah cells. The installation looks good actually. looks "proper" & right.
DSC01661.JPG
 
was with bob earlier today working on a lebowski board whilst he put this together.

Since then I've been working on my greensaver power shelves. Not quite the tesla power wall but probably more cost effective since I got these batteries out of the emax scooters that I'm converting.View attachment 1View attachment 2
Does look a proper job there bob. Thanks for the help today, much appreciated.

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Doing a "manual" top balance (batteries came mostly charged it seems). It's taking a wee while :) I'm using the single bench power supply that I own...
Then I can range check & use bulk charging short term 'till my charger controller is fully spammed up
Andy L - you'll need some current sensors (I got the 200A ones from RS) and 4 gate driver chips (RS do those too). Otherwise PCBs are ready for test.

OK 10pm, all cells at 3.4V & I checked out the power supply trim resistors on my Lebowski control board; 4.87V and 14.27V so a pair of 12k's will do it.
phew

time for a beer & watch the Olympics :)
 
Charged all the cells up to ~3.4V & rode around 27 miles. Still 57V in the battery (3.17V/cell) so riding to work and back would appear to be quite feasible.
Excellent! Cells all seem nicely balanced so can bulk charge for now :)
Charging with the 48V "meanwell" followed by boost converter (total £27 of ebays finest ...). Next charge will be solar ( + boost converter).
Bought some connectors for the bms and the usb/rs232 thing has arrived. I now need yards & yards of wire for the balancing connections & decide where to fit it.
Oh yeah, clamp plates (stainless steel) were picked up today from the laser cutters to properly mount the batteries - another £20. I'll post a picture when they're all installed + I'll need some lengths of M6 studding too

OK - I can't see any other threads concerning using a cheap switcher + a boost converter in combination. This works pretty good,
I'm never confident that a cheap ebay switcher will current limit reliably or accurately. So the boost converter gives me 1) as many volts as I want (this £13 one goes over 100V) and 2) a reliable adjustable current limit. The switcher delivers 48V at up to 5A so I set the boost converter to 61.5V and 3A. This tops up the batteries nicely to around the 90% charge and limits the power draw from the switcher to 185W (+ about 10 for inefficiency) which the switcher can supply comfortably. In the final system the charging will be switched off by the BMS at 3.5V on the "fullest" cell so the boost voltage setpoint will be turned up a little as it now becomes a "safety backstop limit" for the event of charger controller failure. The 185W max is just 15A when I run the system off the solar battery bank, and this is comfortably below the 20A input current max for the boost converter. The system looks safe and effective. 3A charge current is 13hrs (to 40Ah) but I suspect it won't generally require the full 40Ah of juice to top it up!
The other advantage to the system of course is that no modification at all is required to any of the component parts. Nothing is dismantled or adjusted away from nominal settings or has extra components kludged on to make the circuit operate in a manner not intended by the designer.
 
Good to hear about the rs232 connector arriving. I should drop off the current sensors and gates so that both yours controller and mine can be calibrated at the same time. Are you busy this evening I could drop them on my way home?

Totally agree with the boost & cheap switcher idea, not least as I have plenty of cheap switchers and can charge any battery up to 120v using the boost convertor, like a poor/cheap mans version of grintech's satiator. Its very tempting to go up to 18s sooner than later seeing your success. The thing holding me back is the pain do discharge all down to 2.8v to bottom balance and making a support to hold the extra two cells at the side of the other 16.

Got onto the solar panel chap Victor to see what the cells currently cost. £59 per panel discounts only at 25+ panels seems like his business is doing a lot better these days. Going to try get my idea working on a really small booster from 12v to 13.8v replacing the current control pot. In some respects it might be too far the other way i.e. the smaller boost convertor I have might have a upper current limit that will rarely drop the panel voltage under the requirement for the psu. There are some that can do 1200w up to 83v with a pot that is removable but then that is 9 more panels, £531 to cover the roof of the garage, not sure it worth it. As you have said probably easier to go with 12v ones.

Good news that you can commute on it though, its now actually serving its purpoise. would have scooted this morning, weather is perfect but have lots of parcels delivered at work too big for a scooter.
 
scooted electrically to work this morning. There should be enough charge to get me home again....
Bit cold actually (just wore a fleece)
Yes - drop round, I should be home 5ish

If not I will be pushing a red scooter, somewhere between Congleton and Knutsford....
 
shame you cant charge there, your batteries would cycle a lot shallower, probably last longer that way.
 
Journey home was more tense than I hoped - police closed a road because of an accident & the detour was an extra 12 miles!!!!! So it did 39 miles on a charge. I didn't have to get off and push, still 56V off load when I got home (going down to 53ish on load). But I was clenching a bit with a couple of miles to go....
 
Battery charging equipment to screw on the wall
DSC01662.JPG
Top right is a big 2 pole changeover switch which cost significantly more than the rest of the equipment put together.....!!
I have (allegedly) about 300Ah of SLA on the solar cells, which should be enough to tank up the emax. But the SLAs are all questionable.......
It might be a problem if the SLA voltage collapses - that can fry a boost converter, although this one has a 20A input fuse
Now I need to finish the "BMS"
 
Everything is in place now for the PV panels to charge to scooter. Did a 10 mile ride & hooked up the charger:- perfect (tanked up emax and no smoke)
I'm officially the greenest man I know...... :)
Other news, I got a couple of the big ixys mosfet 6packs (ref design notes above) so I need to crack on with inverter design. I'm close to getting the serial setup comms with my board going (just lack of wire holding me back...)
 
Ahem, I am pretty green. Probs just envy though. Could have brought wire today if I'd have known :(

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OK yeah point taken I was a bit rushed yesterday. will put everything in the car so that it comes with me every time. Still think the pic for the psu might be the wrong voltage range
 
Scooted to work again today, nice easy ride - Cheshire looking spectacular in the early morning mist :) Warm & quiet coming home in the afternoon, bike on charge via solar.
At home I have rs232 usb thingy talking to Mr Lebowski's board: all seem to be behaving mostly sensibly (I can only get 35V max on the board input so the PSU rails aren't properly up to snuff), parameters mostly write OK (pulse frequency sometimes makes up crazy numbers) and the storage option seems to do the business. Got test pwm out of the lower gate drives (no power stage so the uppers have no juice). That's it - I've got to start work on the power stage now!

Wednesday - charged overnight, SLAs still at 12.5V and emax full this morning, so came to work on it again! The system's all working & it looks as though I can commute every day (provided there's a bit of sunshine). Peak solar charging current into the SLAs is 27A and this is about double what the emax charger draws - so it has to be nice weather for me to commute daily. In winter I'll be down to once a week (or less) from solar - but the mains backup is always there of course :)
 
Loving the good weather - I've not used the car to commute for 2 weeks! - alternating the scooter & my pushbike.
Did a little spanner check & sorted a couple of things. I get 'clonks' from the rear swingarm, probably because I've removed 50kg of lead.... A colleague at work is bringing me a 'c' spanner tomorrow, with luck that will make that better.
 
Ditto the good weather. Used mine today too. I was told at the mot my damper in my shock is knackered and that the shock needs replacing. That shouldn't be true for yours since it in far better condition than mine. Basically its too quick to rebound which means you really feel it on any speed bumps. Itching to get a bit more speed now. Would be just that bit safer if I could keep up in the 40mph/50mph bits.
 
Let's get a couple of these made in 4oz copper & see what Mr Lebowski's controller can do....
Speaking of which - If we get up towards the 100A, would we benefit from V2.81 firmware? (if no benefit I'll not bother reflashing...)
powerstack.JPG
 
PCB above ordered from china - will get 5 in 2oz copper for £40. 4oz copper was available at a ridiculous price hike - so on these prototypes I'll simply beef up the traces where necessary.
Used my car for the first time in about a month yesterday.... Scooted again today :)
I got the boost converter (charger) to display Ah (thanks 'overclocker') so looking forward to seeing how many Ah my commute is using!
Andy (whereswally) convinced me to repair my broken brake light switch (bit of epoxy seemed to do it) - I'll fit that back on tonight
I also bought a stash of M6 studding to properly fix my batteries, I got the clamping plates lasered the other week. I just realised the studding needs to be galv or stainless... DOH what am I like.... (it's plain mild steel)
 
Now able to use the "amp hour" measurement on the boost converter: my 27.6 mile commute needs a 27.6Ah recharge - honestly!!!
That's average of 1680W at 30mph
For comparison the greenpower racing car uses about 450W at the same speed. I guess that's mostly testament to the lousy aero of a motor scooter....

Same commute 2 days later on a colder and windy day with the headlight on continuously - 30.6 Ah recharge
 
That's funny I noted almost parity on ah to miles for my 25 mile commute. I figured my batteries weigh a little more having 20ah extra in each cell but I am a touch lighter :lol: . All else seems equal (till we get the Lebowski) controller on there. :shock:
 
Hah - you're about a whole ordinary person lighter..........
But I have 2 extra cells (another 12% or so volts)
And I probably go a tad slower (stock control settings)
 
I do tend to full throttle as much as possible but only cause I've so far to go. any updates on the Lebowski boards?

did you manage to change the halls over and are the other ok?

Been talking to bas about using blue tooth to serial for the rs232 so we can update the settings from a phone. His
reply was I think "cant see why not, try it"
 
whereswally606 said:
I do tend to full throttle as much as possible but only cause I've so far to go. any updates on the Lebowski boards?
Click to expand...
PCBs have been shipped, will arrive some time in the next month.....
 
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