36v 30ah vs 48v 20ah for range

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bowlofsalad   1 MW

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36v 30ah vs 48v 20ah for range

Post by bowlofsalad » Feb 04 2013 1:57pm

Hello,

Thanks for looking into this silly question. I am trying to figure out what sort of setup would yield the greatest range. Assuming both setups are traveling at 15MPH (or the same speed achievable either way), on the same bike, settings, path, et cetera, which would yield a greater range? The 30ah setup would weight a bit more, and have more amp hours, so I would assume the 30ah battery would simply be capable of going farther no matter the voltage assuming they are both traveling at the same speed.

A second but related question, would the voltage of the setup effect regenerative braking efficiency or strength? I would guess that the 48v would gain more from regenerative braking than 36v, but the extra 10ah would still exceed the difference in regen braking between the two.

I've tried looking around for questions such as these but I wasn't able to find anything, sorry if this has been asked before.

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Re: 36v 30ah vs 48v 20ah for range

Post by Chalo » Feb 04 2013 3:16pm

More amp hours equals more range at a given level of power and efficiency. If you're talking about using the same motor in either case, then the lower voltage will put the motor in a more efficient speed range at the same (low) speed. The closer you get to 80% of the motor's free speed, the more efficient it will be, generally speaking.

In the real world, folks don't go the same speed when they increase voltage on a given system. They go faster, and therefore they use more Wh/mi.

Regenerative braking rarely recovers enough energy to matter. Plus you have to take care not to apply regen to a fully charged battery.
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Toorbough ULL-Zeveigh   10 MW

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Re: 36v 30ah vs 48v 20ah for range

Post by Toorbough ULL-Zeveigh » Feb 04 2013 3:42pm

Chalo wrote:More amp hours equals more range at a given level of power and efficiency.
no, it's the one with more watt-hours.
in this case the proposed 36V battery has 120 more of them.
generally if the 48V battery would be anything over 22.5 amp-hours it would have the greater range (AEBE).
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Re: 36v 30ah vs 48v 20ah for range

Post by bowlofsalad » Feb 04 2013 5:12pm

Interesting.

I don't know what aebe means, but the watt hours is great, thanks.

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Re: 36v 30ah vs 48v 20ah for range

Post by Drunkskunk » Feb 04 2013 5:30pm

36 volts X 30 amp hours = 1080 watt hours.
48 volts X 20 amp hours = 960 watt hours.

So the 36 volt battery is 10% larger, and will get you 10% further in terms of watts.

Now, what Chalo said is true in terms of running at the best speed, but that has to balance against things like higher voltages causing less loss to heating at the same wattage.
I have a bike built to run at multi voltages, from 36 to 100 volts. I have seen a slight increase in efficancy when I run at high voltages on my specific setup, but absolute power corrupts, and having more voltage on the same current limited controller will have more power, corrupting me into being a speed demon. :twisted: So in practice, I can reliably get my best efficancy running at 36 volts.

As for the regen, its near pointless. people who have done it long term see 5% gains in range over all. That doesn't mean that "today" you will have 5% more range, because "today" you might have only needed to brake 5 times, and never realy got to use your regen. So its more of a bonus, not something you can count on. Regen braking is still a usefull item to have for it's added braking affect.

So the short answer, the bigger battery gives the longest range.
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Re: 36v 30ah vs 48v 20ah for range

Post by bowlofsalad » Feb 05 2013 12:21am

Drunkskunk wrote:36 volts X 30 amp hours = 1080 watt hours.
48 volts X 20 amp hours = 960 watt hours.

So the 36 volt battery is 10% larger, and will get you 10% further in terms of watts.

Now, what Chalo said is true in terms of running at the best speed, but that has to balance against things like higher voltages causing less loss to heating at the same wattage.
I have a bike built to run at multi voltages, from 36 to 100 volts. I have seen a slight increase in efficancy when I run at high voltages on my specific setup, but absolute power corrupts, and having more voltage on the same current limited controller will have more power, corrupting me into being a speed demon. :twisted: So in practice, I can reliably get my best efficancy running at 36 volts.

As for the regen, its near pointless. people who have done it long term see 5% gains in range over all. That doesn't mean that "today" you will have 5% more range, because "today" you might have only needed to brake 5 times, and never realy got to use your regen. So its more of a bonus, not something you can count on. Regen braking is still a usefull item to have for it's added braking affect.

So the short answer, the bigger battery gives the longest range.
Excellent, well said. It is a preponderance I've had myself, if I could go faster, I likely would. As with you, negating range.

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Re: 36v 30ah vs 48v 20ah for range

Post by Chalo » Feb 05 2013 2:08am

Toorbough ULL-Zeveigh wrote:
Chalo wrote:More amp hours equals more range at a given level of power and efficiency.
no, it's the one with more watt-hours.
That isn't what I said, but it's what I meant.
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Re: 36v 30ah vs 48v 20ah for range

Post by dogman dan » Feb 05 2013 6:39am

Yep, but your statement was basicly correct, because the 30 ah one was in this case, the larger of the two batteries. Good that it got explained why, as often happens here.

Suppose you had a pair that were actually identical in watthours, then it would be possible to ride either one the exact same distance. For sure they'd go the same distance on flat ground if you have no stops at all.

But in my experience, you'd get just slightly less out of the 48v one if you had to ride up hills or do lots of starts and stops. The 48v one would allow you to pull more watts leaving stop signs, and chances are you would ride in such a way that you would use more power on starts or steep hills. My experience is, the real world difference between a 36v 20 ah and a 48v 15 ah is about a mile less from the 48v. The difference is much bigger if you ride one voltage faster than the other. But if you ride the same 15 mph speed on each one, there won't be much difference, if any.

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Re: 36v 30ah vs 48v 20ah for range

Post by mythprod » Feb 11 2013 11:52pm

When I was first shopping for my components I ran some figures in my head on how much range I could squeeze out if I took it easy and went a certain speed during certain conditions. Yeah, that all went out the window when I rode it for the first time. Now the faster the better. I can't lie. :twisted:

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Re: 36v 30ah vs 48v 20ah for range

Post by bowlofsalad » Feb 12 2013 2:15am

mythprod wrote:When I was first shopping for my components I ran some figures in my head on how much range I could squeeze out if I took it easy and went a certain speed during certain conditions. Yeah, that all went out the window when I rode it for the first time. Now the faster the better. I can't lie. :twisted:
Which is part of why I fear going above 36v, I'll probably end up going way too fast.

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Re: 36v 30ah vs 48v 20ah for range

Post by dogman dan » Feb 13 2013 6:33am

Very true. I have had the same dilemma. I needed more watts to get up hills, but it's truly hard to ride a 30 mph bike 20 mph for long. Every time you look down at the speedo, you are going 30 again. One solution would be a three speed switch, so you can select slow or medium.

For me, one way to solve it was to find and use very slow windings. So now I have a bike with 3000w of potential power but still cannot get past 25 mph. So I have power to get up hills when I need it, and no temptation to ride it 40 mph since it can't do it.

This works for me, but for others it would suck since they need more speed at some point in the ride. In my locale, I can just avoid a 45 mph street easily.

One of my most efficient versions of a commuter bike ran a 2810 9 continent motor on 48v. Able to reach just about 19 mph, it was just too slow to use much wh/mi. But still climbed a hill very nice, wasting less watts into heat than a faster 2807 motor did.

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Re: 36v 30ah vs 48v 20ah for range

Post by John in CR » Feb 17 2013 7:51pm

Get the 36V. It will give you a lot more range from both more energy inside and because you will ride slower. Then later you can get another 36V battery to put in series and go straight to 72V with a new controller and open up a whole new world of fun transport where you don't ride around at WOT all the time and choose the speed that best suits you. By then you will have saved so much $ over other forms of transportation that you can splurge on the battery and that couple of extra pennies a day in electricity. Then allow your priority to shift from cost to convenience, comfort, safety, and fun. :mrgreen:

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Re: 36v 30ah vs 48v 20ah for range

Post by bowlofsalad » Feb 18 2013 7:49am

John in CR wrote:Get the 36V. It will give you a lot more range from both more energy inside and because you will ride slower. Then later you can get another 36V battery to put in series and go straight to 72V with a new controller and open up a whole new world of fun transport where you don't ride around at WOT all the time and choose the speed that best suits you. By then you will have saved so much $ over other forms of transportation that you can splurge on the battery and that couple of extra pennies a day in electricity. Then allow your priority to shift from cost to convenience, comfort, safety, and fun. :mrgreen:
72v would be way way too fast for me. I am a little uncomfortable with the thought of approaching 30mph without 3 wheels.

I think I am going to aim for 48v in a strange way. I may get two 8s packs and wire them in series while in use using something http://www.progressiverc.com/series-ec5-adapter.html like this. 48v would give me any maximum speed and torque I'd likely ever need, but the real goal behind the two 8s packs is balance charger use.

I can't seem to find much in the world of RC chargers that go beyond 12-14s. So it's 8s-12s pack limitations. I am a bit too scared of some kind of battery over charge event to use a bulk charger. The more I think about it, the less likely it seems to occur, but I'd rather play it safe. I've heard good things about the powerlab 8 but I am sure there are other options.

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Re: 36v 30ah vs 48v 20ah for range

Post by Chalo » Feb 18 2013 12:12pm

bowlofsalad wrote:72v would be way way too fast for me. I am a little uncomfortable with the thought of approaching 30mph without 3 wheels.
You haven't ridden a trike, have you? Trikes are way scarier and more hazardous at speed than bikes.
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Re: 36v 30ah vs 48v 20ah for range

Post by bowlofsalad » Feb 18 2013 12:24pm

Chalo wrote:
bowlofsalad wrote:72v would be way way too fast for me. I am a little uncomfortable with the thought of approaching 30mph without 3 wheels.
You haven't ridden a trike, have you? Trikes are way scarier and more hazardous at speed than bikes.
Only briefly. Perhaps we are thinking of different trikes. There are several different configurations of trikes. I don't know of how much more scarier they are. But, I would say they are more safe than a upright bicycle. I was being a little vague when I mentioned 3 wheels. When I think of 3 wheels, I think of a recumbent tadpole style trike. In my mind, it is likely the most safe way to ride a cycle. The words of the late Sheldon Brown come to mind. (source: http://sheldonbrown.com/helmets.html)
"These days, I ride a recumbent tricycle, which is so stable and so low to the ground that I don't believe a helmet is necessary."

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Re: 36v 30ah vs 48v 20ah for range

Post by John in CR » Feb 18 2013 12:34pm

bowlofsalad wrote:When I think of 3 wheels, I think of a recumbent tadpole style trike. In my mind, it is likely the most safe way to ride a cycle.
Not with cars around. Your most important safety equipment, vision, is way too blocked on what is a poor handling by comparison 3 wheel gokart.

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Re: 36v 30ah vs 48v 20ah for range

Post by Chalo » Feb 18 2013 10:41pm

bowlofsalad wrote:When I think of 3 wheels, I think of a recumbent tadpole style trike. In my mind, it is likely the most safe way to ride a cycle.
OK, then try to run over your own legs and break them while riding an upright two wheeler. That's a known side effect of 'bent tadpoles. "Leg suck", it's called. I bet it does.
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Re: 36v 30ah vs 48v 20ah for range

Post by SamTexas » Feb 18 2013 10:50pm

bowlofsalad wrote:When I think of 3 wheels, I think of a recumbent tadpole style trike. In my mind, it is likely the most safe way to ride a cycle. The words of the late Sheldon Brown come to mind. (source: http://sheldonbrown.com/helmets.html)
"These days, I ride a recumbent tricycle, which is so stable and so low to the ground that I don't believe a helmet is necessary."
Keep in mind that Sheldon used his own power. That means he was averaging probably 15mph.

I have never ridden a recumbent tricycle, but unless it has full independent suspension on all three wheels, I doubt it can approach the stability of a regular bicycle at speed above 20mph while cornering.

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Re: 36v 30ah vs 48v 20ah for range

Post by Chalo » Feb 18 2013 11:07pm

SamTexas wrote:I have never ridden a recumbent tricycle, but unless it has full independent suspension on all three wheels, I doubt it can approach the stability of a regular bicycle at speed above 20mph while cornering.
If it does have full suspension but no anti-sway bar, it will roll to the outside in a hard corner. That's not really a stability-enhancing feature.

Three-wheelers load their wheels sideways, which is hard on them.
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Re: 36v 30ah vs 48v 20ah for range

Post by bowlofsalad » Feb 18 2013 11:20pm

Chalo wrote:
SamTexas wrote:I have never ridden a recumbent tricycle, but unless it has full independent suspension on all three wheels, I doubt it can approach the stability of a regular bicycle at speed above 20mph while cornering.
If it does have full suspension but no anti-sway bar, it will roll to the outside in a hard corner. That's not really a stability-enhancing feature.

Three-wheelers load their wheels sideways, which is hard on them.
Like any tool, it must be respected. People fall even from very grippy two wheelers, I feel that many of those circumstances, usually involving slipping, can be avoided with a trike. Honestly, I've never heard of someone rolling a recumbent trike.

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Re: 36v 30ah vs 48v 20ah for range

Post by Chalo » Feb 18 2013 11:28pm

bowlofsalad wrote:Like any tool, it must be respected. People fall even from very grippy two wheelers, I feel that many of those circumstances, usually involving slipping, can be avoided with a trike. Honestly, I've never heard of someone rolling a recumbent trike.
Took me about ten seconds to find an example on video:



EDIT:
In another minute, I found another:

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Re: 36v 30ah vs 48v 20ah for range

Post by w3l0n10782 » Mar 29 2016 7:02am

Here's my take on the distance and 20Ah and the 30Ah.
Conditions.
48V 1000w 20Ah and a 30Ah.
Columbus to newark using back roads that maxed at both points of 57 miles one way.
Hills to declines, 210lbs.
1st Battery- Efest 18650 1500 mAh 30 burst 15Amps, max with 1.5 continuious with a draw from system was at 1.9A per pack.
Starting voltage 58.10v
2nd battery-A123 Systems 26650 2500 mAh of 150 Burst and 50Amps and a 2.5A continuos. Draw 1.9A per pack.
Starting voltage 56v
Criterias.
1) Speed
2) Distance
3) Performance/Time
Efest
At 20Ah on controled speed was at 28 miles, 30Ah 51 miles.
at full throttle it was 17 and 33 miles
systems
at 20 Ah on controled speed was 56 and 83 miles
at full throttle 48 miles and 62.
The systems cells supplied power at 2.5A untill the BmS shutoff, the 18650's showed signs of over heating and then
drops in power when excelerating and inclines. The systems supplied even power throughout the entire trip witout
any fluxuations in power or amperage discharge. The power also increased after every stop not like the 18650's did.
There were 12 runs total and each test done twice for performance and distance. We found that the systems did not
drop in power or was substantial compared to the 18650 and its ability to remain cool at 70 degreese during the tests, unlike the Efests
that we had to stop several times on the full throttle for the cells to cool. The Evest series showed a loss in voltage
after the full throttle of .6 volts and would only charge to 3.7v max and any aditional voltage, it was lost over 2 hours
back to 3.7v. The systems cells showed no damage under full load at 27A draw. Each test the packs were placed in a concealed
lexicon flexi box. The controler was a 20A 48v tipical controler. Hands down, the systems beat the 18650's and never
underperformed after each test.
As for the trike, on any speed above 5mph. It is always the inside wheel that looses weight and eventualy at higher speeds
the wheel lifts from the ground and you become a 2 wheel bike once again untill you roll over. You can alway's visit Cleopatra
along with Bernie Sanders, Hillary and the Govenor of Ohio in denial. Sry, its all about that beast we cannot defeat. Gravity.

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Re: 36v 30ah vs 48v 20ah for range

Post by icerider » Mar 29 2016 7:50am

bowlofsalad wrote:
Like any tool, it must be respected. People fall even from very grippy two wheelers, I feel that many of those circumstances, usually involving slipping, can be avoided with a trike. Honestly, I've never heard of someone rolling a recumbent trike.
OK, so its off topic, but I can't pass this one up.

I ride a Terratrike Cruiser with Bionx PL350. Because I scavenged the Bionx from a 26 inch bike, my electric assist is limited to 17 miles an hour so faster than 20 is a downhill thing for me. Bike is fabulous up to 28 mph or so. Above that, my weight (260) and the relative flexibility of the chromalloy frame make the bike a little twitchy -- rideable but twitchy.

And yes, if I crank in a full turn to make a u-turn on a narrow two lane road at any speed higher than 9-10 mph, it'll go right over, been there, done that, got the road rash to show for it. And, at my weight, I'm on three wheels or no wheels, there is no pause at two wheels on the way to zero, once that inner wheel comes off the ground, it is going all the way.

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