[SyCo]

Originally Posted by bliksem

I did not mean that the torque will damage the transmission , but rather the
vibrations and run out. Judging from the quality of the welds I will undo as much as possible.

ha ha... ok... I too was doubting of the welds, but aligment is supposed to be done with 0.001 tolerance.

"run out" I'm not sure what you mean ?! I speak french so my english is not perfect .

Then again I will try to run at low rpm in a higher gear to minimize vibrations. The car itself will not go at high speeds. If I see / sense too much vibrations, I will surely advice and consider going with a more direct drive.

[icec0o1]

You're right SyCo, low RPM on that motor will give you more torque. For example, you'll get 210NM torque at 1000 rpm, and only about ~90NM at 2000rpm. You would probably get more torque by just doing the 2:1 ratio to the flywheel which will have your motor running at 1000rpm, 210NM torque and give you 2000rpm at about 105NM torque - 2-5% losses.

So running the motor in low RPM is better, however I'd do it with the transmission by starting in 3rd and going to 5th instead of adding 5% additional losses with a 2:1 ratio and then using 1st to 4th gear.

1500rpm in 5th gear will probably get you about 50mph which would be perfect if you had the motor directly connected to the transmission since 15HP wouldn't get you going faster than that. Of coure, it's not worth changing now that the chain drive has been built unless it damages your transmission. And I rally can't guess if it would. I'd rather the welds break than the transmission though

[SyCo]

@icec0o1, ... okay, that is what one of my friend told me also. I will try working with torque since everything is already in place aka 1:2 chain drive. If I'd do it by myself it would have been direct to the transmission like you've suggested.

At least I've received the motor learning procedure from Curtis and I will be able to confirm my settings .

Next thing will be the batteries selection. I've been looking at Costco's biggest batteries which are "900 cranking amps" and are quite big in size but I don't find the AH rating ?! Does it have to do with the Style/Size written on the batteries like 78DT-120 or something else ? (still newbie here )

[major]

Originally Posted by SyCo

I've been looking at Costco's biggest batteries which are "900 cranking amps" and are quite big in size but I don't find the AH rating ?!

Look for the words Deep Cycle. Batteries advertising cold cranking amps are most likely cranking batteries. Good for 30 or so deep cycles. Real deep cycle Pb-acid batteries are good for 300 or more deep cycles. Look for golf cart batteries or similar.

Check out the Battery section of this forum.

Regards,

major

[SyCo]

Originally Posted by major

Look for the words Deep Cycle. Batteries advertising cold cranking amps are most likely cranking batteries. Good for 30 or so deep cycles. Real deep cycle Pb-acid batteries are good for 300 or more deep cycles. Look for golf cart batteries or similar.

Check out the Battery section of this forum.

Regards,

major

Ok I will, and I suppose those type of batteries will have AH ratings... Thank you!

[SyCo]

I did my first test drive yesterday, with full acceleration I read ~275A DC on the Fluke meter. At half throttle, I read 150A DC.

So 48x275=13,200W (~17hp) and 48x150=7,200W (~9hp). I think that is within the specs of my motor.

In second gear acceleration was surprising, even in third gear but top speed was not that fast ~15-20 mph. I did not try 4th because I did not have enough juice. Keep in mind tests were done in a small street and I may have reached a better top speed with more road available or in 4th/5th gear since I'm running low RPM on my motor.

I will have to get some decent batteries to do more tests.

[icec0o1]

That's sweet. Congrats on the good buy. Do you know what RPM your motor was running at at 20mph and 3rd?

[SyCo]

Originally Posted by icec0o1

That's sweet. Congrats on the good buy. Do you know what RPM your motor was running at at 20mph and 3rd?

Unfortunately not ... It was at night and I did not have enough light to look a the programmer (monitor) and the meter.

I will, of course, do some tests during the day and keep notes of everything I can

[SyCo]

Here is an estimate I'm trying to do of my Ah requirements using some wiki information.

Since I'm using a 48V high amps AC system, I've guessed 400Wh/mile efficiency (anyone one with more accurate value for my efficiency is welcome to chime in ).

I want to be able to travel 20 miles.

So total energy required at 100% throttle (275A) is 275x20=5500 or 5.5Kwh.

Since my voltage is 48V this means my Ah rating will be the total energy divided by the voltage. In this case 5500W / 48V = 114.5Ah

I plan on going 80% DOD. So 114.5Ah x 1.25 = 143Ah

Now add Peukert effect. 143Ah x 1.8 = 257Ah

This is the worst case scenario for my energy consumption. I hope, after more tests, to get lower amps draw. In the meantime, I think that to reach my required distance, I would need something like 8 Trojan T-1275 rated at 150Ah. Two series of 4 batteries (total 48V) wired in parallel (total 300Ah).

Bank1: 12V-12V-12V-12V (48V, 150Ah)
Bank2: 12V-12V-12V-12V (48V, 150Ah)

Bank1 + Bank2= (48V, 300Ah)

Is this a realistic estimate ?

Note: I have not included my top speed since I'm using 100% throttle and I'm assuming I will need most of that to reach at least 30 mph.

EDIT: Btw I've got some price for local batteries...
Trojan T-105 6V, 225Ah @ 154$
Trojan T-1275 12V, 150Ah @ 224$
DEKA 8AGC2 6V @ 241$
DEKA 8GGC2 6V, 185AH @ 273$
T-105 reconditionned (1 year warranty) @ 61$
8AGC2 reconditionned (1 year warranty) @ 70$
Are those good prices ? What about recon batteries ?

[Buckster]

I think the chain will stretch pretty fast, you really need a slightly longer chain with a tensioner to preserve its life.