Will I see a big difference in 36 volt, 12ah versus 18 ah?

[MikeFairbanks]

The industrial trike I'm rebuilding (mostly re-configuring) will be pretty much the same as before, but with new batteries will be stronger and back to what I'm used to in terms of power. It gets me easily from home to work (four miles), including some pretty good hills. Two years on the battery is dead (SLA) and I'll be replacing it again with SLA (since the trike is technically the property of work and money is an issue).

I was going to just go back to what we had originally, which was 36 volt, 12ah SLAs.

But I'm thinking that I might want to extend range by using 18ah batteries instead. Everything else would be the same: 36 volt, 20 amp controller, 9c motor. The only difference at all would be going from 12ah to 18ah.

So my questions are:

1. Can my controller handle that increase of power?

2. Will I feel any difference in performance other than extended range?

I realize I won't increase speed (and don't want to), but will I increase torque or hill-climbing ability? I wonder this because I'll have my 80-pound kid with me occasionally. The trike can handle all that weight (batteries, me, kid) without a problem. It has a total capacity of 500 pounds. The batteries will weigh about 40, my kid 80, and I'm 180, for a total of 300 (well within the limits).

3. What is the most powerful combination (staying at 36 volts....24 is too slow around town and 48 is too fast) my controller and motor can handle?

I'd love to be able to get a ton of range out of it. My electric golf cart (Club Car, four-seater) uses lead acid in a 48-volt combo (I have no idea the AH in those batteries) and can go about 20 miles on a full charge while hauling all four of us up and down hills throughout town. It never gives up on any hill.


Thanks, as always, to anyone who helps. ES is the best. There's nothing else like it in the world.

 

[liveforphysics]

So my questions are:

1. Can my controller handle that increase of power?

Your controller doesn't know or care what capacity the battery connected to it happens to be, 1mAh, 1Ah, or 1MAh, the controller only knows something is giving it an input voltage.

2. Will I feel any difference in performance other than extended range?

I realize I won't increase speed (and don't want to), but will I increase torque or hill-climbing ability? I wonder this because I'll have my 80-pound kid with me occasionally. The trike can handle all that weight (batteries, me, kid) without a problem. It has a total capacity of 500 pounds. The batteries will weigh about 40, my kid 80, and I'm 180, for a total of 300 (well within the limits).

Assuming the 18Ah cells have lower Ri (internal resistance), they will sag a little less (if they are 18Ah energy cells and the 12Ah cells were power cells, the bigger cells might have higher resistance and sag more, but it's likely they will sag less). This has the effect of giving you maybe 0.5-1v more going to the controller when under load (just taking a wild guess). That gets you a tiny bit more performance that may be noticeable.


3. What is the most powerful combination (staying at 36 volts....24 is too slow around town and 48 is too fast) my controller and motor can handle?

I'd love to be able to get a ton of range out of it. My electric golf cart (Club Car, four-seater) uses lead acid in a 48-volt combo (I have no idea the AH in those batteries) and can go about 20 miles on a full charge while hauling all four of us up and down hills throughout town. It never gives up on any hill.

In relation to the battery, the only effect the controller can know is the input voltage. It doesn't know if being powered from a DC power supply running out of a wall outlet and the capacity is effectively unlimited, of if it's running of a 1Ah Nano-Tech lipo cell, or 400Ah thunder-sag cells or whatever. It just knows something is providing an input voltage that it can switch to the motor with the correct duty cycle to maintain some tiny voltage across it's shunt that correlates to it's current setting not to exceed.


Thanks, as always, to anyone who helps. ES is the best. There's nothing else like it in the world.

Going from 12Ah to 18Ah and keeping with 18s lead should give you roughly identical performance, but for a bit longer range. The increase in range should be noticeable, the increase in performance may or may not occur or be detectable depending on the 18Ah cell's internal resistance (voltage sag power influences) having a greater or lesser effect than the added mass of the 18Ah batts.

 

[MikeFairbanks]

Cool. Thanks for the response.

 

[wesnewell]

To answer your questions;
1) There is no increase in power, so it's not even a valid question.
2) No. Why would you? There is no increase in power. Only capacity.
3) Staying at 36V, same controller, same motor, there are no other power combinations. You have to change something if you want more power. Cheapest thing to do would be to mod the controller shunt so it will put out more amps. Other than that, buy another 36V controller with an amp output higher than 20A.

 

[MikeFairbanks]

Another excellent response. Thanks. I didn't want more power or speed, just more range.

But I worked out a good deal on a 36 volt SLA prewired and ready to go.

Thanks for the responses guys.

 

[wesnewell]

There's no such thing as a good deal on sla batteries. I wouldn't use them even if they were free. Well, I did for a week, then replaced them with rc lipo. 42lbs of 36v lead vs. 8lbs of 44.4V 20c rc lipo that will last 2-3 times longer for $170, and have more power and range, just isn't a comparison imo.

 

[dogman dan]

Yeah, we been trying to get him to lithium up for years now. The trike is ideal for carrying lead though, so what can you do?

Any reason you couldn't put your black bikes lead on the trike and go for 5 ah of lipo on your lean mean single speed? Or is that lead about toast as well.

I can't see it costing you any more than the new lead, and I will send you a completely FREE 50w charger for the lipo. So go order two 6s 5 ah packs or three 4s packs from Hobby King dude. On the longer range trike rides, you'd of course take both batteries on the trike.

You'll fall in love with the ss all over again, with a 4 pound lipo pack instead of 30 pound of lead.