Battery Consumption

Been doing some range testing on my new build. Its a daily commuter for me and have been stretching the distance bit by bit to get an idea of the overall range.

Tonight I hit a new low and little concerned how fast it dropped. Bottom half of the battery smaller than the top? :?

Total of 21.7 miles. 976 feet elevation climb (combined on all routes) I help mostly on getting up to speed, and the heavy hill climbing. And to be honest I keep it at full ish throttle the rest of the time. On med power for the average stuff, only using full power for down hill, or long straight stretch's. Speed topped out at 39.7mph and averaged 12.7

All that considered it did pretty well. Except for the last 3 miles home after work. Speed was much lower, small hills I was doing 90% of the work, and battery went from 75%-25%. Only have the cheap led-810 display at the moment.

Is this what I should expect?
Am I 'abusing' the battery/motor for running it that hard?

MTB
EBIKELING 48V 1500W 700c Direct Drive Rear hub motor
Greenergia 48V/36V Li-ion 17.5Ah Battery

Apologize if i am posting, or formatting this incorrectly.

My newbie build thread :lol:
https://endless-sphere.com/forums/viewtopic.php?f=1&t=99287&p=1460726&hilit=29er#p1460726

I have the same ebikeling kit, but with the sw900 lcd display. When the battery pack voltage starts to get low, the controller will start limiting amps, which gets to be very noticeable the further you go. Also in my opinion the basic voltage based battery gauges aren't a linear gauge of battery capacity at all. It seems like once they start dropping, you're already below 50% capacity, but I've only tested my two kits so far.

I'd also like to add that using a smart battery management system (which would be difficult with your pre-built battery) really gives you a lot of good information about what your bike is doing.

thundercamel said:

I have the same ebikeling kit, but with the sw900 lcd display. When the battery pack voltage starts to get low, the controller will start limiting amps, which gets to be very noticeable the further you go. Also in my opinion the basic voltage based battery gauges aren't a linear gauge of battery capacity at all. It seems like once they start dropping, you're already below 50% capacity, but I've only tested my two kits so far.

I'd also like to add that using a smart battery management system (which would be difficult with your pre-built battery) really gives you a lot of good information about what your bike is doing.

Click to expand...

Am concidering getting another battery, possibly going for a 20ah plus.

When the display shows a drop in power when using the throttle, is that the drop in amps?

That is called "voltage sag" because the system as a whole is asking a lot of power from the battery, so the battery voltage sags when you got wide open throttle. Some lithium systems (LiPo vs LiFePO4) have it more so then others, also depends on the "Discharge" rating of each 18650, or what the builder labels the whole pack as. For example there are 18650's with 4.50A rating discharge, and say 2Ah capacity. Lets say you put 10 series string and put 4 of those in parallel, then you got 18A total discharge and 8Ah capacity. If your controller asks say 30A from your pack, the battery will try its best to supply whatever it can, but in that case the batteries are working too hard, and nothing good will come of it. The voltage sag would be too much. On the flip side, if you were to go with 20A 2.5Ah (25R's) on same battery pattern, 10S4P then your capacity is 10Ah, and your discharge is 80A, and your controller is only asking for 30A, virtually no sag until the very end of the capacity curve. One pack will last a long time, the other pack will last you a handful of rides.

markz said:

battery will try its best to supply whatever it can, but in that case the batteries are working too hard, and nothing good will come of it. The voltage sag would be too much.

Click to expand...

Considering how quickly it 'saged' looks like I'm in danger of damaging the battery? Forgive my noobness, but is it damaging just as it begins to sag, or even at full charge?

The info for the batter dose not specify beyond this.

Item Specifics:
Battery material: lithium
Nominal voltage: 36/48v
Rated capacity: 10.4Ah/12Ah//17.5Ah/20Ah
Charge current: 2A
Charging mode: CC/AC
AC input: 110-240v,50/60HZ
Max charge voltage: 36V-42V,48V-54.6V
Cycle life: About 2000 cycles
Charging time: 7.5 hours

https://www.amazon.com/gp/aw/d/B07KWZGMVS?psc=1&ref=ppx_pop_mob_b_asin_image

If that chinese battery has it's BMS programmed and functioning correctly, you shouldn't really be able to damage it. Can you go over again the series of events that you are saying was problematic? It isn't very clear. 21.7 mile range and 39.7mph peak speeds sounds ok to me.

PlanetDad said:

Tonight I hit a new low and little concerned how fast it dropped. Bottom half of the battery smaller than the top? :?

Click to expand...

Yes. If you were running a cell phone or a laptop computer, then both "halves" would be about the same. Under high loads like an ebike, the voltage sag will trigger the BMS before you might expect based on the amp-hours consumed. If you reduce the current limit on the controller, less sag and you can get more out of the pack.

Running until it cuts off or gets really close to the cutoff voltage is about the only way to really know what your range will be. As the pack ages the range will drop. Cold weather will also cause a significant drop.

Hi PlanetDad,
Can you confirm which battery you have? Type, voltage and capacity in Amp Hours?

Looking at the voltage is not a good way to estimate how full your battery is. Check some voltage curves – they are pretty flat. It is ok for a general idea. (Full, partial, empty.)

Let's find your potential range in a different way.
- Fully charge your battery
- Go for a typical ride
- Time how long your charger takes to fully charge.
- If you have a 3 amp charger, and it took 2.5 hours, it puts back 3x2.5 amp hours into your pack, or 7.5 amp hours. Aim to use 80% of your capacity at most. If you have a 15 amp hour pack, your battery is about 50% full.
- This will give you a rough idea. Timing might be thrown off while the charger "tops off" the battery, balances, etc.

Let's also look at how you are doing. Your range was 21.7 miles, and we assume the battery ran out around mile 19. If your battery is 17.5ah, and is 48v, that is 840 Watt Hours. Your consumption was 44 Wh/mile. I use about 1/3 of that, and average 18mph, but consumption varies. I guess it is normal for a high power system?

If you want to lower your consumption, you could:
- Obviously pedal more
- Be careful with the throttle. Add "just enough." At some point, in most conditions, adding throttle won't accelerate the bike. That's when you know you are wasting power and just heating up the motor.
- Limit power to the system. Can your controller limit the power output?
- Check the bike over for adjusted hubs, brakes, inflated tires, etc.

Hope this helps!

The BMS did slip my mind, I have never used a BMS..... yet.

The BMS "should" cut the power off, but there are so many BMS' out there, from cheap generic's to expensive and reliable bms'. But the "should" part is the key, just because its a BMS doesnt mean anything if its a cheap generic bms.

Dogman Dan has had a nightmare experience with generic battery packs.

Thank you ColinB

ColinB said:

Can you confirm which battery you have? Type, voltage and capacity in Amp Hours?

Click to expand...

1500w
48V
17.5AH
Samsung 3500mAh
2A charger

Max Constant Discharge Current: 30A -- I dont know what to do with that info yet

With the 810 led display I've only got the option for low med high power. Forget the volts on that ATM. But have been sticking with low in 25MPH zones, dose well enough. and MED for the stretch getting out of town.

thundercamel said:

If that chinese battery has it's BMS programmed and functioning correctly, you shouldn't really be able to damage it. Can you go over again the series of events that you are saying was problematic? It isn't very clear. 21.7 mile range and 39.7mph peak speeds sounds ok to me.

Click to expand...

Concerned I have done damage to the battery. Trying to take too much from it at a time. And your right, considering the speeds its not terrible. But hoped for more... Seriously considering getting tools together to build my own pack.

PlanetDad said:

Max Constant Disharge Current: 30A -- I dont know what to do with that info yet

Click to expand...

It appears that your controller will run up to 35A. I don't know what happens - the battery can discharge at higher rates briefly without harm, but if the 44 Wh/mile estimate above is accurate, I'm guessing you're up there more than just briefly, and I doubt the battery has sophisticated enough circuitry to prevent that from doing whatever damage it does. Until you can get a display that shows power draw, in Amperes or Watts, I think you should just lighten up on the throttle; when you have that information, you can specifically keep it under 30A. Or, in principle, that may be configurable in the controller - can in mine, anyway. Next battery you buy, look for higher sustained draw. Also, pay more attention to other people here who know a lot more about this stuff than me.

New 48V S830 Display is on the way. Will be gentle with it in the mean time.

Also, considering I have been riding this bike daily for over 2 weeks. 8-12 mile typical, some with the kiddo and trailer (45 lbs extra ish) Dont think I have done serious damage yet. But will be taking any advice you guys have on another pack.

Thanks!

PlanetDad said:

Concerned I have done damage to the battery. Trying to take too much from it at a time. And your right, considering the speeds its not terrible. But hoped for more... Seriously considering getting tools together to build my own pack.

Click to expand...

If I was in your situation, I would open the battery myself and check over all of the connections between cell groups, to make sure none show signs of heat damage. I've seen some pictures of prefabricated batteries not having beefy enough series current pathways through the cell groups. At the same time you could confirm that the cells are genuinely Samsung 35E. If so, the cells themselves are most likely still fine.

Also before building your own pack, you could try replacing the included BMS with a smart one such as this. You'd have to be confident in your abilities though, and there likely wouldn't be convenient room to mount the larger BMS.

thundercamel said:

You'd have to be confident in your abilities though, and there likely wouldn't be convenient room to mount the larger BMS.

Click to expand...

Not confident enough to put all my eggs in that basket yet, opening the battery is a possibility, will look into that.

Amazon minions are spying on me, got a email suggesting this battery. What do you think? Could/Would I need to purchase the BMS aswell?

https://smile.amazon.com/gp/product/B07GNDXDXR?ref=em_1p_1_ti&ref_=pe_945280_408226810&th=1&psc=1

22 miles on 840wh

if thats what actually have

seems about right to me

obviously last portion lower voltage


if capacity further degrades

perhaps attempt balancing

leave on charger several days

disconnect and reconnect several times

post final resting pack voltage


amazon 28ah pack comes with bms

life chemistry

who knows

no personal experience

PlanetDad said:

Amazon minions are spying on me, got a email suggesting this battery. What do you think? Could/Would I need to purchase the BMS aswell?

https://smile.amazon.com/gp/product/B07GNDXDXR?ref=em_1p_1_ti&ref_=pe_945280_408226810&th=1&psc=1

Click to expand...

Interesting. You're going to get a lot of push back on that from the regulars here, there's a lot of hating on LiFePO4, but I have a battery a lot like that (but "12" Ah), and I'm pretty happy with it. Along with the 50A discharge, you get better charge tolerance - you can let the charger go to 100% without shortening battery life, which is apparently not so true with the more common LiCo ("lithium ion") chemistry, you likely get more charge cycles out of it, less likely to self-ignite, and it doesn't need any cobalt, an environmentally unfriendly metal mined in African countries owned by China.

I can't say I can find the advertised 12Ah in my battery, it's more like 8-9, but it's the same 8-9 I started with. My other LiCo battery doesn't deliver its advertised storage either. I'm running it as it came out of the box.

Re: Max Constant Discharge Current: 30A -- I dont know what to do with that info yet.

This means the vendor has rated the battery for 30 amps continuous use. For your 48v battery, that's 1440 watts.
- If your battery is ok with 30 amps discharge, you might be ok. It's close to your 1500w motor and 35 amp controller.
- It does mean that you are using your equipment at their rated limits, so may not be great for longevity. Aim for 80%.
- If the vendor has been "optimistic" with their rating, performance won't be so great.

How can you tell if your battery is "happy?"
- It doesn't get overly hot when used
- Voltage doesn't sag under load (a lot)
- Delivers close to the same capacity at high power levels as it does at lower power levels.

If it was me, I'd find a way to limit the system power to 24 amps, or 1150 watts. I use a Cycle Analyst. Then you are operating lower than the limits of your battery, controller and motor. So they should last longer and be more reliable. With a Cycle Analyst, you also get voltage readings, consumption, etc. Downside? Well, it won't be as fun at lower power. And batteries will degrade just with age, no matter what you do. Some treat them as disposable, others (such as myself) try to make them last as long as possible. Compromises.

Colin

PlanetDad said:

Amazon minions are spying on me, got a email suggesting this battery. What do you think? Could/Would I need to purchase the BMS aswell?

https://smile.amazon.com/gp/product/B07GNDXDXR?ref=em_1p_1_ti&ref_=pe_945280_408226810&th=1&psc=1

Click to expand...

Did you look at the title and pictures? It shows right there that it comes with a BMS and charger, though again it's not a smart BMS. LiFe is supposed to be more stable and last thousands of cycles. Not many people use LiFe, I think because it's heavier and less common.

If I were to buy a pre-built battery, I would get one built by em3ev.com They build nice 14s batteries with a smart BMS built in.

The 44 wh/mile that ColinB calculated isn't very good. At least not if your average speed was 12.7 mph.

Even running my setup mostly at the top two power settings (650-950 watt draw) for a moderately fast commute and dealing with around 600 feet of net elevation gain, I still only consume a small bit more than 25 wh/mile while keeping the bike between 20 and 28 mph most of the way. I do pedal quite a bit, so that helps. But it shouldn't help tons. Also, I'm probably drawing 2-3 wh/mile on average to run my lights and losing probably 5% through my voltage converter.

Before I'd buy a new battery, I'd get some kind of watt meter and would measure my actual power use while I ride. That will tell you if your battery is actually delivering close to its advertised capacity and if you can see the display while riding, will tell you when you are drawing the most power.

Hey guys,

Trying out the display, right away could tell a difference in the response, speed and the level of power was more gradual. only changed parameters that I understood. But speed is off. I start of at 51-54V, while running full drop to 40-44 ish volts. Haven't tried a long ride yet.


Noob questions ahead

While using throttle; the battery percentage changes, as low as 20% toward end of ride. But 100% when still. Assuming this is sag?

What setting is best to use for limiting power? Been just using PAS settings (Although its not connected)

Cant find any info on what these setting should be.

P07: Magnet Steel Number for Speed Test Range: 1-100
P13: Power Magnet Steel Number:

Thanks guys,

PlanetDad said:

While using throttle; the battery percentage changes, as low as 20% toward end of ride. But 100% when still. Why?

Click to expand...

This is voltage sag. The voltage measured on a cell decreases the greater the current load applied. When the load is removed the voltage will recover. Difference cells have different sag characteristics. High quality, high drain cell can deliver a lot more current before their voltage sags significantly.

The controller you have will be 35A peak if its the Ebikeling 1500W
Your battery is supposedly made of Samsung 35E if its the 17.5Ah Greenergia like on Amazon. It will be a 5P pack. 35A of the controller divided by the 5 cells in parallel means the cells should see 7A each at peak. 35E cells are rated for 8A so if they are genuine they should be fine.

35E discharge curves are here http://budgetlightforum.com/node/45325

You can see that those cells sag quite a bit under 7A of load. The discharge graph shows that when a 7A load is applied, the voltage drops to 3.9V down from 4.2V straight away pretty much. That means your 13S pack should sag 13x0.3V or 3.9V between standing still and full throttle. If yours is sagging 10V then there is defiantly something not right. Either the controller is pulling more amps than what the rating says or the battery has some issue, maybe fake cells/bad cells or poor connections.

PlanetDad said:

But speed is off.

This would be a combination of P06, wheel diameter (set in inches). And P07, which you note below. Which is the number of magnetic pulses of your speed sensor. If you have a typical spoke mounted magnet and sensor, this would be set at 1.



What setting is best to use for limiting power? Been just using PAS settings (Although its not connected)

I wouldn't think the PAS settings even function with out a PAS sensor. (not being in PAS mode) But your experience would know. Perhaps changing the P10 power setting to 1 (throttle only) would help.
P14 would be used to limit current, but the manual I used to look at only has max current of 20 amps... see below. (A lot can change in 5 years... book date)



P07: Magnet Steel Number for Speed Test Range: 1-100

See above...


P13: Power Magnet Steel Number:

Thinking this is the number of magnets in your PAS ring.

Click to expand...

Used for reference...

LCD S830 Manual Control Panel
User Manual
The Latest Version 2014

https://www.google.com/url?sa=t&rct...0-pdf.22814/&usg=AOvVaw3sY94y4D781unaT8LqQK26


Regards,
T.C.

lionman said:

35E discharge curves are here http://budgetlightforum.com/node/45325

... If yours is sagging 10V then there is defiantly something not right. Either the controller is pulling more amps than what the rating says or the battery has some issue, maybe fake cells/bad cells or poor connections.

Click to expand...

Great info on the curve, looks right.

Now with the speed set correctly, P07 is at 46, for the direct drive motor according to ebikeling. Watching the voltages figure I'm using 1 - 1.4 Volts per mile. Keeping at 30-35 mph most my commute of 6 miles round trip, peddling little more than take offs, after 20 mph would have to work harder than the motor :lol: ( changing gears is on the list ). With P10 set to 1, throttle only. "PAS" settings (Guessing speed in throttle mode) Set to 9 intervals and using 7 max. Saw a break down of voltages per PAS level at one point in my search but cant find it now.

Conclusion: I'm a noob, But I have learned allot from you guys and I appreciate it. Thank you.

But if I open the battery, and its not 35E cells. Could I return it.. would opening it to find out void a return?

Any Battery suggestions, or should I make another noobie thread? :lol:

THANKS!

You coudn't return it legally in the mail. Lithium batteries have to be packed and shipped by someone with a certification.
And there are fake batteries out there with the official looking markings, so just by looking inside it would be hard to tell. Testing the discharge performance with a tester is about the only way to be sure.

fechter said:

You coudn't return it legally in the mail. Lithium batteries have to be packed and shipped by someone with a certification.
And there are fake batteries out there with the official looking markings, so just by looking inside it would be hard to tell. Testing the discharge performance with a tester is about the only way to be sure.

Click to expand...

Depends on the size of the battery I think. Cells under 20Wh and Packs under 300Wh can be sent without the Hazmat requirements.

As to voiding warranty, is there anyway they can actually tell that you opened it?