What kind of performance can I expect

[smorse1]

Ok...the SLA's are out and LiPo is in the budget for springtime. I have been running 48v 9ah SLA's for my 5 mile ride to work I have ridden about 40 times as it has been reasonably nice this winter.
They are heavy at about 26 pounds, and I have to charge them at work. They make it almost the full 5 miles with light pedaling, cutting out 3-4 blocks from work or home.
I don't want to charge at work.
I don't mind disassembling the pack to charge, or the length of time it would take to charge on a smaller standard hobby charger.
I am pretty set on the Hobby King 5000mah 6s packs x 4.

My question is, will 4 of these packs make it the 10 mile round trip, and can I leave them semi-discharged for the time I am at work?

I would be riding to work 3-4 days a week, and from the looks of it, this might be an inexpensive alternative to ping batteries or something like that even if they only last 2 seasons.

 

[smorse1]

Also, at some point as the budget permits, I am planning on upgrading the controller to the lyen and adding a cycle analyst-is the cycle analyst needed immediately if the LVC on the controller can protect the batteries adequately?

 

[Ykick]

Your SLA performance sounds about right. If you leave controller/motor alone 12S2P 5Ah 6S RC Lipo will amount to about 10Ah for an easy 10 miles without deep discharging. Unlike SLA they don't care about immediate charge following use. You'll also get much more spirited performance over the discharge curve with RC Lipo. Majority of 12S discharge will take place between 46-48Vdc.

My daily commute is 8miles r/t and after 2 years the 12S2P pack is beginning to show some loss of capacity but still doing the job. You may have some trouble if your work parking situation isn't protected from cold. Freezing and below these cells sag quite a bit.

 

[ohzee]

I ride my bike to work and it's almost 10miles each way.. 4.5ah is what I usually pull out of my batteries.
I run different voltages either 18s or 24s.. since I go faster on the 24 I use a bit more power.

As long as you don't discharge the batteries past 8ah each way I would think you are fine. Depending on how
you want to use your lipo the least discharge leads to longer lithium life.

Personally if you have the funds I would add 5 or 10 ah more just so if you want to do a decent run sometime
you are not limited by the range you would have with sucha small pack.

Still glad your making the switch keep us updated.

P.S. Yea i know I should use WH rather then AH. I just don't watch that value as much.

 

[Drunkskunk]

Lipo are an answer, but 4 bricks of that may not be enough. your 48 volt, 10AH battery has about 300 usable watt hours of power (60% max of the rated power, typical for SLA). A 12s2P pack made from 4 bricks of 6s 5Ah cells will have about 360 watt hours of usable power (using 80%, as using 100% kills them quickly in repeated use). If you are able to burn through that 300 watts in the 5 miles to work, then the Lipo won't be enough, but I suspect you have other problems as you're burning 60 watt hours a mile.


Normaly the battery you listed would get you the distance you need, but your numbers show at least double normal consumption, that might be due to hills, weight, or riding style, Or there might be a problem with the motor or controller. Sort that out before you chose a new battery.

 

[French]

Assuming 3.7v nominal, 12s2p would be 444wh. Over 10 miles, that's 44.4wh/mi. That's about what my bike will consume going 30mph constant on flat ground (~265lb gross weight). I would think your pack could handle it without a problem, especially if you limit top speed to 25mph or so. I'm not sure what kind of wind your motor has, so I don't know if your hub can even go that fast @ 44v. Either way, I wouldn't sweat it.

EDIT: Just now saw skunk's response. I'm not as familiar with Lipo and the DOD limitations, I will admit, so I guess take my response with a grain of salt.

 

[smorse1]

... but I suspect you have other problems as you're burning 60 watt hours a mile.


Normaly the battery you listed would get you the distance you need, but your numbers show at least double normal consumption, that might be due to hills, weight, or riding style, Or there might be a problem with the motor or controller. Sort that out before you chose a new battery.

Well, when the SLA were brand new, I could go about 8-9 miles, but over time, the distance has essentially been cut in half. I think the projected usage in my case is a function of the battery's true capacity, not the actual usage per mile. While I would like to know this, is the only real way to install a cycle analyst?
That being said, bike+rider is a heafty 300lb and there is one fairly steep hill on my route, mostly up on the way to work and down on the way home.

 

[wesnewell]

Well, when the SLA were brand new, I could go about 8-9 miles, but over time, the distance has essentially been cut in half. I think the projected usage in my case is a function of the battery's true capacity, not the actual usage per mile. While I would like to know this, is the only real way to install a cycle analyst?
That being said, bike+rider is a heafty 300lb and there is one fairly steep hill on my route, mostly up on the way to work and down on the way home.

SLA batteries sulfate over time and lose capacity. You can desulfate them and get most of that capacity back if they aren't too far gone, but dumping them for lithium is a much better solution. And cold affects SLA a lot. 10ah 12s lipo should get you about a 20mile range at 20mph and about 11miles wot. The CA is the Rolls of watt meters. There are many options a whole lot cheaper. The Hobbyking HK-010 will give you everything you need too for under $20. So will the Turnigy, WattsUP, and others. I like the HK-010 because it has a built in balancer for up to 6s lipo that comes in handy for checking and balancing packs. But it's not back lit like some of the others. But to be honest, you really don't *need* any of them. Using 12s lipo, the lvc of your controller is 42v and will shutoff your battery usage before you can over discharge a 12s pack.

 

[dogman dan]

Drunksunk is right. 4 bricks is cutting it fine. Clearly the budget is an issue, so buy 4 bricks now, and ride slow enough to not whack em too hard.

Assuming your top speed will now be 25-30 mph, you'd be getting into lower discharges if you ride WOT.

But you should have easily 15 mile range in that pack if you rode 18-20 mph to 100% dod.

I think if you just keep it down to 20 mph, then you will be able to go 10 miles with the pack ending up at about 3.7v instead of full dod of 3.5v. (Actually 100% is even lower, but nobody advises less than 3.5v)

Later in the summer, pop for two more 6s packs. With 44v 15 ah, you'd easily make it both ways, and could take the long way home no problems. You'd have about 15 mile range with a discharge to 3.7v. Even WOT.