1000w motor, 10Ah LiFePO4 battery.. a problem?

[joeworrall]

Got my 48v 1000w hub motor, the controller is 35A, the battery is a 10Ah LiFePO4, is this going to kill my battery life?

If so, is there a way of limiting the current to the controller that isnt too expensive and wont hurt my top speed too much?

(more battery specs):

Voltage: 48 Volts
Capacity:10Amp Hours
Max Continuous Discharging Current: 20Amps
Charging Current: <10 Amps
Charging Voltage: 60 Volts
Rated Discharging Current: 10 Amps
Max Discharging Current (Peak): 30 Amps 10s

[Gregory]

Your options include..

1) Running with the existing 1C battery and it will result in a much shorter lifespan. You already figured that out.

2) Using the throttle gently will do it, but it requires lots of will power, pedalling, slow take offs and a watt meter (from $25+). Not really a feasible long term solution.

3) It's probably possible to open up the controller (or reprogram it?) and remove one of the shunts lowering the current the controller can draw. It will result in less power and weaker acceleration but approx same top speed. (Or get a smaller controller). $Free - $90.

4) Wire in a Cycle Analyst and use current limiting - different controllers will wire up differently $150

5) Or get a different or paralleled second battery. $400+?



I'd start with a cheap watt meter or Cycle Analyst and see what power I was using, and maybe #3.

[TMaster]

That 10AH china lifepo4 won't last long at all, You need a 20AH 2C at least. Or SLA going the cheap route, or A123's for about $150 more. Lipo's if you educate yourself for safety reasons also.

I bought the same kit from YXM for $300. I fugured spending around $800 total with the batteries and everything. The controller was pulling 22-25 amps continuous throttling, with spikes up to 31 amps. That was running 59.4V instead of the 51.2, or 48V. So im guessing your pulling around 22 amps full throttle, with spikes of 27-28amps. After big smiles I wanted more power so I'm running 66V and modded the controller, and peaks of 40 amps now. The A123 packs I made myself costed me around $400. I have around $1200 in the bike now and thats not including the bike. The A123s rock and the voltage drop under load is very minimal. Gives awesome power through-out the whole capacity.

[joeworrall]

How long would you expect it to last?

If i remove one of the shunts will i be able to solder it back on later? what are they made of?

I really cant afford anything more than 10Ah, even this was pushing it.. i was originally planning SLA's but my dad lent me some money.

and t-master, what was your top speed? range?

[HTB_Terry]

Joe, I agree with Greg...your pack is not perfectly matched to the controller so you have to monitor it carefully. First do step 2, get the cheap Turnigy meter. Then see how much current it really draws, maybe they were over stating the 35A. If it's over 20A, then do step 3: modify the shunts in the controller until it will limit to around 20A. The shunts look like large bare silver wires about one inch long raised from the circuit board. To lower the current you need less metal. So if there are more than one shunt, you can cut one leg of it (you can solder back). If there is a lot of solder one one of them, try taking all the solder off first. Adding solder or more wires, increases the current. I know nothing about your pack, but if it's really 10AH, then it should handle 20A with little or no decrease in cycle lifetime. Worst case you buy a cheap controller from Keywin. Then when you get some bucks, you can spring for another one of the 10AH packs and parallel them.

[dogman]

Did you buy it already? It will kill your battery quickly. It could do it in a few rides, in fact, but could last longer. With cheaper lifepo4, the rule of thumb is 1 ah per amp the controller has, so you are about 20 ah short. You have some sla's ( or do you)?, you could , using diodes to protect the lifepo4, paralell connect them with the lifepo4. Then the sla's would protect the lifepo4 till they run down. You would have to watch the voltage of the sla's closely to prevent them from getting overdischarged since they have less capacity.

A 20 amp controller would really help, till you have big bucks for a good set of lifepo4, with 5c discharge rate, such as headways. The lifepo4 might have a chance with a 20 amp controller and a light hand on the throttle.

[joeworrall]

Not got the battery yet, its in the mail. I didnt buy the SLA's. Was watching some guy on youtube, he has exactly the same setup and he got over 1000 miles not taking it so lightly on the throttle but i thought id better check to be safe. I might cut remove one of the shunts then get a cycle analyst then re-solder the shunt

[TMaster]

I would send the 10AH battery back or sell it when it arrvies, not even hook it up, unless you want to shell out for a second one and parrallel them together for double the amp capability like Terry mentioned. I'm not sure if you will be comfortable babying the bike all the time or modifying the controller so it pulls less amps. I have the Turnigy watt meter analyzer on my bike so I know exactly what the controller and motor can do.

On 6.9AH worth of a123s I can get about 9-10 miles gunning the throttle all the time, with some coasting before I brake, or down hills. I was babying it one day and calculated I could get 14-15 miles out of her if I took it easy and stayed around 20mph cruising. You would need 10-12AH of SLA to get these same ranges. My pack only weighs 10 lb's compared to a SLA's which would weigh 35-40 lb's to get this range.

I'm guessing the 51.2V pack you have will do 30-31mph if you parralleled a second with it. Theres a lot envloved here though. The weight of the bike, you, the type of battery with the voltage under loads etc...
At 59.4V nominal The top speed was 35mph. I have since modified the controller heavily and she'll do about 5mph more. But really the top speed is not really a concern, when you get past 30mph the wind resistance really sucks. Its a lot more fun and enjoyable for me anyway to have the low end power and acceleration. Thats why you see a lot og guys on here using 24" or even 20" wheels on the rear of a 26" bike.

Before I got into this I spent weeks on the forum here searching for information. Doing research constantly. lol..... I still do actually!

[dogman]

One thing you might want to do is confirm that the controller really is 35 amp. One vendor I know of sold a 22 amp controller as a 50 amp, and called the kit 700 watts. So 36v x 50 amps is 1800 watts, so yeah riiiiight. The kit is about 750 watts with a 22 amp controller. A car ampmeter can be used to crudely check what the amps really are. 48v won't bother it. Or mabye another here on ES has the same kit, and could tell your what amps his actually draws.

But as I said on the other thread, don't go riding full throttle much till you get a bigger battery.

[Lyen]

You may not have to worry too much about it since the average current draw on most controller is less than 25amps with the exception of going up hill and start up acceleration. If you are still worry, you may desolder a shunt in the controller and put it back later. You may also want to do yourself a favor by getting a 20-25amps controller and keep your existing one as spare just in case when you are hungry for more power, which is the case for most of us here.

BTW, take pictures of your controller internal + external so we can provide more details & solutions for you.

[Mark_A_W]

Is there something spectacularly crap about these batteries?

I run 1300w from my 10Ah Headways (30 amps peak, 10A average), and they've been doing it for nearly 2 years.


10Ah is a "normal" sized battery. 20Ah is big, and is just a PITA - where do you mount the damn thing? 10Ah fits in your triangle.

[TMaster]

Yeah Headway 10Ah cells are 5C, which is 50 amps continuous rated. His battery is 10Ah but its only 2C which is 20amps.

[Mark_A_W]

I still think they'll go a year or two.

[dogman]

You will not get a year or two out of a 2c 10 ah battery if you regularly pull 35 amps on hills and discharge it 100%.

But it's not impossible. Cruising at 30kph on flat ground, 15 amps should be all it draws. So you could pedal till you hit 15 kph, and then use the throttle and never get much above 20 amps. But you better live where it's dead flat.

On the other thread, you mention getting a wattmeter. See what the controller really draws, and if it's over 20 amps on starts, get a 20 amp controller or snip shunts till it is 20 amp. You can't afford to ruin the battery. 48v with a 20 amp controller will give you plenty of top speed, just slower off the line, slower up hillls.

[joeworrall]

Hey guys, its been a couple of days and i can now correct that my controller is actually 20amps. Sorry for all the confusion looks like my batteries should survive after all. Unlikely i will be pulling the full 20amps all the time as it looks like my motor is only 1000w peak (48v*20a=960w)

If i were to try using this setup on a 15 mile uphill of varying gradient (5%-20%), pedaling my hardest until all sweat breaks loose, what sort of current do you estimate i might be pulling? I can pedal for this length of time at about 280 watts constant on my own input.

Do you think my battery has enough juice combined with my pedal power to keep at a steady 6-10mph throughout?

Is it worth considering a regen controller or are they too much hassle?

[AussieJester]

Is there something spectacularly crap about these batteries?

I'm guessing there these :: cough:: superb duct tape packs, about as bad as it gets as
far as Lifep04 goes IMHO... I don't understand why people buy them when the alternatives are so much
better and not alot dearer...Headways are superb batteries went very close to getting them myself.

20Ah is big, and is just a PITA - where do you mount the damn thing? 10Ah fits in your triangle.

SO do 20ah worth of Lithium Polymer Mark ...just need to "ignore" the pesky exploding/fire
business associated with them is all

Best of luck with your pack joeworrall, with the 20amp controller and alot of pedalling i think you will be
good to go

KiM

[biohazardman]

Hey guys, its been a couple of days and i can now correct that my controller is actually 20amps. Sorry for all the confusion looks like my batteries should survive after all. Unlikely i will be pulling the full 20amps all the time as it looks like my motor is only 1000w peak (48v*20a=960w)

If i were to try using this setup on a 15 mile uphill of varying gradient (5%-20%), pedaling my hardest until all sweat breaks loose, what sort of current do you estimate i might be pulling? I can pedal for this length of time at about 280 watts constant on my own input.

Do you think my battery has enough juice combined with my pedal power to keep at a steady 6-10mph throughout?

Is it worth considering a regen controller or are they too much hassle?

Current draw depends on speed, weight, rolling resistance, temperature, your motor, controller and batteries, as well as the terrain so hard to say what you will pull but your controller will limit you to near it's rated capacity. At 6-10-mph, you will probly heat things up pretty fast. There is a good chance that you will cook your motor and or controller before the end of the 15-mile hill. Likely, you know that by now. The less expensive Lifepo4 packs do not deliver much juice usually in the 1.5C range. They also have a low charge rate so regen can damage them and or your controller unless you have a sufficient sized pack, which 10ah is not, to accept the amperage returned.

[dogman]

I ride a 15 mile route home everyday. I climb about 1000 feet of vertical hill along the way. I average a 15 amp draw the whole trip, and use 15 amp hours of 36v, or about 11 ah of 48v. On the hill that is about 1.5 miles of 5%, I draw the amp limit of my 20 amp controller, which is 22 amps.

So you'll make it about 10 miles up a continuous hill of 5% in my estimation before the pack runs out, at a speed of about 15-17 mph. You'll be drawing 22 amps the whole way, and the battery won't like it. Slowing down to about 6-8 mph and pedaling more really helps, and will keep the amp draw more like 10 amps, but still use just about the same amount to get to the top of the hill. The physics of lifting a weight up a hill cannot be avoided. It will take a minimum watthours to lift the weight, plus and additional drag from speed. But miserly doleing out of the battery up a big hill will perhaps get you to about 12 miles up the hill. Slowing down so the motor uses the power more slowly will also help with overheating the motor. If you run up a 5 mile hill full blast you will really heat up the motor.

Belive me, I ride in the rocky mountains, so hills I have lots of experience with. It's why when I go out touring this year, I'll have a 36v 20 ah and a 48v 15 ah battery on board. Sorry but 10 ah is for little trips around town.

[ian.mich]

darn should have done lipos, if u build everything yourself (harness and balance board) then it will only cost you about $350 for a 44V15AH and 300w charger