DIY Electric Car Forums banner

41 - 55 of 55 Posts

·
Registered
Joined
·
4,293 Posts
Check out Synkromotive controllers. I guarantee you will want to belt out more than 500 amps.

I really DONT want to be able to send more than 500 amps since I will most likely build with 144v of 100ah cells. I don't really want the ability to pull more than 5C because I don't want the temptation to suck the life out of the cells.

I am not intending to build a dragster, just a 'decent performer' minimizing cost and maximizing system life. 500amps at 144v to a ADC 9" in a 2000# car will be more than enough for a 50 year old vehicle.
 
G

·
Guest
Joined
·
0 Posts
My MG is not a dragster either but it can take a good whopping 500 amps for a moment or so to get the car up to speed in a reasonable time frame to keep with traffic. I keep an eye on my battery voltage closely and see frequently close to and more than 500 amps. I am not talking motor amps either. I am talking battery amps. Yes, you will want a controller that can belt out that and keep an eye on battery amps. My synkro will monitor both the motor and battery amp draw and log them. I do not hot rod my MG. It is not a race car, it is a sports car. Somehow folks mix the two up. Yours is a sports car and not a hot rod or race car. For that you'd want a soliton1 or Zilla 2k. I just think that the curtis is an anemic controller. Some folks don't seem to think so but my little 72 volt 550 amp controller I had with my first conversion did a whopping good job. For a 72 volt system and a steel bodied Ghia it push it to 65 mph no problem. Nothing more than that but it would handle high amperage well. Better than any curtis. If you go with the curtis make damn sure you have a whopping good heat sink and large cooling fan connected. I have a picture of my 72 volt controller with the heat sink and fan. I could no longer get it hot with the sink and fan attached.

I guarantee you will at some time or another wish you had the ability to give it more ooomph. With a synkro you can program any parameter in to limit amps too for both the motor and battery pack. You can limit throttle too. You can have RPM and thermal cut back if motor or cells get to hot. Over all a pretty nice setup. So far so good. Two years with a beta unit and a few months now with a production model.

Pete :)
 

·
Registered
Joined
·
4,293 Posts
Check out Synkromotive controllers. I guarantee you will want to belt out more than 500 amps.
ok, ok, I am leaning more toward making a really SPORTY Alpine as long as I am doing it... but still afraid of toasting motor or batteries. I'd like some way to reliably monitor motor and cell temps to prevent too heavy a foot for too long.

so, I am attempting to compare the 'higher end' 1000amp controllers to compare and contrast features for safety, durabillity, etc. Soliton, the new Netgain Warp controller, Raptor, Zilla if they ever come back.... all in the running. I will try to find the info on Syncromotive. I would you compare to Soliton for instance?

...and a related topic is whether anyone has done any testing to see just how long you can push a 9" at 1000amps, or TS/CALB cells at 10C before temperature becomes an issue?
 
G

·
Guest
Joined
·
0 Posts
The Synkro does not does not fall into the same category as the Soliton1 and Warp controller. I am only stating those two because they are the only NEW 1000 + amp controllers available. There should be plenty of folks with Soliton1 controllers to give you the information you need. As for the Warp, I only know of one so far that is currently running one and that is Corbin. The Synkro is an excellent controller and I have had my controller in the 600 amp zone for over a minute with no ill effects. I have never had it over heat. It is fully programmable. I can't compare them myself because I don't have a Warp or Soliton1 but I'd like to have all three to test and compare in a car. I think it would be an excellent show or program to do a comparison of all three in their natural habitat. Maybe I can sometime during the summer.

Pete :)
 
G

·
Guest
Joined
·
0 Posts
Of the two biggies I'd bet my paycheck that the Soliton1 is King all the way around. So far there is no refuting that.

I'd almost bet that they would kick the butt off the zilla too. In some areas the Soliton1 is in its own universe. It really is good.

Pete :)
 

·
Registered
Joined
·
4,293 Posts
The Soliton sure is an attractive package, but double the price is hard to swallow. I do like the stated features. It would probably run cool enough just with air for me since I would only push it at the occasional stoplight, not extended highway. I am facinated that the docs say it doesn't need a main contactor, that simplifies some things and saves a little expense!

I would LOVE to see some tests showing:
- how long a DC 9" motor can handle 1000amps until it approaches a reasonable temp limit from 'ambient'. i.e coming off a stoplight, would I have 10 seconds, 30 seconds, or a minute joyride before I'd have to back off?
- how long a TS-100ah cell can dish out 1000amps (10C) until internal temp is approaching rated limit... this would be meaningful if we had a good idea how the internal temp translated to what we could pick up at one of the terminals with a good temp sensor.
 

·
Registered
Joined
·
1,760 Posts
- how long a DC 9" motor can handle 1000amps until it approaches a reasonable temp limit from 'ambient'. i.e coming off a stoplight, would I have 10 seconds, 30 seconds, or a minute joyride before I'd have to back off?
There's no definite answer on that because it depends on RPM, ambient temperature, how well the brushes are seated etc, but I doubt you'll get a minute. Not with ONE WarP 9". :rolleyes:


- how long a TS-100ah cell can dish out 1000amps (10C) until internal temp is approaching rated limit...
Motor current is NOT equal to battery current EXCEPT when the controller is completely off (ie no throttle, no current) or when the controller is 100% on. To put it simple a controller converts power to power, but since motor voltage is proportional to RPM it means that when the motor is still the only power drawn from the pack is to overcome the losses in the controller, cables and motor.

This means:

Pmotor = Pbattery (I'm ignoring the losses here)

Umotor*Imotor=Ubattery*Ibattery

But since the motor voltage is very low at your red light but the pack voltage is what it is (a constant if you ignore the sag) the battery current must be very low even when motor current hit 1kA. So for example if your motor voltage is half the pack voltage and your motor current is 1kA your pack current will be half that, or 500A. If your motor voltage is 1/4 pack voltage, your battery current will be 250A and so on.

So even with a rather "crappy" pack you can still get 1kA out of the controller provided the motor voltage (and thus motor RPM) is low enough compared to the pack voltage.
 

·
Registered
Joined
·
4,293 Posts
But since the motor voltage is very low at your red light but the pack voltage is what it is (a constant if you ignore the sag) the battery current must be very low even when motor current hit 1kA.
this is the concept that continues to elude me... I can't follow how motor current can be higher than battery current. Is this the magic part of controllers? Basically 'pulsing' high amps chunks of current to motor?

If I AM following... it sort of means that for the first say 10 seconds of acceleration from a stop light it is most likely that if the motor amps were limited to 1000amps, the battery amps would not see 1000amps until the last few seconds.

Has anybody done any 'real life' testing with a 9" motor and cells wired with good thermocouples? starting 'cold' at summertime ambient of something like 80 deg F, and putting the hammer down for 30 seconds at 1000amps and plotting the temp rise?
 

·
Registered
Joined
·
1,760 Posts
this is the concept that continues to elude me... I can't follow how motor current can be higher than battery current. Is this the magic part of controllers? Basically 'pulsing' high amps chunks of current to motor?
Pretty much, yes. The controller turns on and off the current very fast and the induction in the motor and the capacitor on the battery side smooths things out so that if you have 100 Volt in and the pulse width is 50% the average voltage over the motor becomes 50 Volt despite that it's 100 Volt you switch.

On the battery side the current draw is, for example, 1kA, 0, 1kA, 0, 1kA and so on, but it gets smoothed out by the capacitor so you get an even (well, more even) current of 500 Amps.

If I AM following... it sort of means that for the first say 10 seconds of acceleration from a stop light it is most likely that if the motor amps were limited to 1000amps, the battery amps would not see 1000amps until the last few seconds.
Exactly!

And if you want to protect your battery you can set maximum battery current to, for example, 500 Ampere and if you have a pack voltage of 100 Volt (as above) it means that as long as the motor voltage isn't higher than 50 Volt you get 1000 Ampere (since 50*1000=100*500) but when motor voltage starts to rise above 50 Volt the controller will start decreasing the motor current to keep the battery current at 500 Amps maximum. So when motor Voltage reach pack voltage (100 Volt) the motor current is down to 500 Ampere.

Of course, then you have to add voltage sag, losses etc, but, well, na. Too complicated. The Soliton recalcs everything 100 times/second anyway so you don't have to worry. :D

(and yes, there's other controllers that behave the same, for example Zilla has similar parameters you can set and works in a similar way to protect both motor and pack, of course)
 

·
Registered
Joined
·
4,293 Posts
ok, I am liking the idea of a 'modern' controller more and more for high performance... I could set motor amps to 1000a and battery to 500a, have great accel off the line and be pretty sure I won't pull over 5C from 100a cells even when at full steam for *short periods* of accelleration.
 

·
Registered
Joined
·
3 Posts
Hi

I wondered if you could update us on the progress/status of your Sunbeam Alpine please ? Here we are mid 2020 and I am considering a similar project and would love to get the benefit of your experience please.

Best regards
Clive
 

·
Registered
Joined
·
4,293 Posts
Hi Clive, sure I'll give an update....

I've been messing with my eMiata for the last couple years as a build/test platform before taking on the Alpine because the Miata tranny, suspension, brakes were all good to go. My intention shifted to working all the bugs out on the Miata, and then transplanting EVERYTHING to the Alpine. I now have 25k electric miles on the eMiata, upgraded transmission, brakes, ended up with a Warp9, Zilla 1k, 156v x 130ah CALB super fun little car that I hesitate to take apart. ;) With this setup, the gear ratios are too low... and what I may do is is swap in the getrag rear diff with a final ratio of 2.73 to give me a more useful 1st gear, and a nice low rpm for highway speed.

Given my experience with the need to beef up the Miata driveline to handle the torque, my opinion is that you should definitely consider a complete remove/replace of Alpine driveline, brakes, and suspension as long as you are doing it. The Alpine is so narrow, this is going to take some creative design, a good welder, and likely a decent local machine shop.

You COULD go with the stock stuff if you would be satisfied with low performance, limit the power, and have the patience to restore original to best condition possible. IF I'm going to all the trouble to convert, I wanted to build an eTiger.

so..... back to the Alpine. It's sitting in my driveway, fending of mice and tires rotting out from under it as I don't have time or money to build it while I still have the eMiata. Can't seem to part with the eMiata, so contemplating selling the Alpine and all the bits I've gathered, but will likely not have time to build with. I have a new Warp 9, and a refurbished zilla, and some other stuff.... wanna buy it all?
 

·
Registered
Joined
·
3 Posts
Hi Dan

That's very helpful and what a coincidence as we have a Miata as a second car !! Unfortunately we live in the UK and thus the expense of getting all those parts over would be prohibitive! I do have a holiday home in Sanibel but my wife would kill me if I accumulated hobbies there too!

Perhaps I can pop over and say Hi once I am back in Florida:)

Best regards
Clive
 

·
Registered
Joined
·
4,293 Posts
The Miata is pretty much the modern Alpine.... cheap, fun, repairable...... the eMiata drives pretty much like the '66 Tiger I had torque-wise, but has far better suspension/steering/braking. I do love the look of the Alpine, but I am much more of a 'driver' than a 'restorer/collector', so converting the Alpine is making less sense as time goes by.

If you are ok with a low power, short range..... sticking with Alpine running gear, I would still recommend swapping out the tranny from a Miata, probably from '98 or newer. Part of the reason is that the motor/transmission adaptors for Miatas are available 'off the shelf' from CANev.com. Used/rebuilt Miata trannys are available cheap, and replacement parts like new clutch plate are easily available compared to retaining an old Alpine tranny.

If you intend to go on the smaller conservative side I would still recommend:
  • 8" brushed motor ( ADC, or Netgain )
  • modern high capacity controller like Zilla 1k or Soliton Jr. , which can be dialed down so you don't break things
  • for simplicity I much prefer the large format prismatic LiFePO4 cells rather than reworking junked high-voltage packs from OEM evs. for a moderate build, I'd go with 120v nominal (38 cells) x 130ah cells.... something high quality like CALB.
  • consider constructing battery boxes from 1/4 sheet polypropylene, it is not too expensive, easy to work with, non conductive, and you can get some ideas from the pix on my website envirokarma.org as I showed construction of battery boxes.
  • I have great luck with NO reservoir for brake booster in the Miata, using an in line sensor, SS relay. If you stick w Alpine brakes, there is no booster required anyway.
  • other major tips that I will share, but many disagree with is I am a believer in top balancing Lithium batteries, letting the typical charger do it's job as designed, and periodically checking cells to make sure none are getting too high at the end of charge. The most important thing is the initial top balance BEFORE you use the pack charger.... Use a revolectrix or some other little programmable charger to bring each cell up to a known 'full' state (3.65v for LiFePO4), and then do a couple charge cycles.... check as the pack approaches end of charge, and drain a little energy from any cell that is above 3.70 to enable the rest of the pack to catch up and finish closer to theoretical average vpc.
With CALB LiFePO4, max recommended voltage and of charge is 3.65. I do initial cell balance to that, and periodically (like every 1000 miles), go thru the whole pack and re-top-balance to that. Then, I have pack charger set to end charge at theoretical average cell voltage of 3.50-3.55.... this give room for cells to drift a bit and stay within safe range until next balance.

The alternative is to add either a 'dumb' BMS that ends charge as soon as the first cell hits 3.65, or a smarter BMS that includes active shunting, and balances on the fly as cells hit 3.65.... something like the Orion or similar seem to be well developed now, but weren't available when I built my cars, and add over $1k in cost.

If you do get to Santa Fe, NM, USA.... give a ring, and I'd be happy to do a garage tour and talk details!
 
41 - 55 of 55 Posts
Top