battery upgrade: ping 3.0? options?

[mrzed]

Hi all,

I've been running 10 months now with a 9C front kit from eBikes.ca. Overall very pleased, but my 8Ah niCad pack is no longer giving me nearly 8Ah. I had a blown controller replaced under warrantee, so perhaps it did something to the pack on it's way to the grave, or perhaps I just was not waiting long enough for the battery to cool down before charging. In any case, I'm looking at a near future replacement, and might as well do an upgrade at the same time.

I typically only use 6Ah on my round trip, but would happily use a little more. I would also be happy to have the option of longer trips. I'm leaning to prismatic LiFePo4, because this is not a hobby for me, it is transportation, so I'd like a combo of plug and play, low total lifecycle cost, and reasonable upfront cost and weight.

Other lithium seems to have lower total charge/discharge cycles, and I'm not as concerned about minimal weight, so the power density is a minor advantage.

I am running a 20A controller, 36v. This is the one other part of the setup I'm likely to change, as the ebike is primarily a hauler, pulling kid in trailer, and I would like more grunt up the hills, so I will possibly be looking to move to 35A. I considered going 48V to get more torque, but I don't want the top speed. 35Km/hr with pedaling is fine.

I'm currently looking at a 36v, 15-20Ah pack. I figure this will give me super low C-rate for now, and enough headroom to move to 35A and really improve my climbing. I'd also be doing very shallow discharge cycles, and could keep it in the sweet spot for max lifespan. I'd be fine with lower Ah (10-12) if I could get higher C, at the same or lower prices.

Questions:

- Seems Ping is the default recommendation. Is there any other reliable cost-effective alternative? I want to save $ while still getting good product.
- I read something here recently about a new version of the ping battery (3.0) about to be released with improved ?? Is this imminent? Improvements?
- I know lithium has far less sag under load. What does a LiFePo4 pack at 36V/15Ah typically sag to under 20A draw?
- What is the calendar life of LiFePo4? I'd like this to last 3 years or better - is this reasonable?

 

[dogman dan]

I'm not sure exacty what my ping sags to under load, but it doesn't noticeably slow down the bike till you are getting close to 90% discharged. Mines a ping v1 36v 20 ah. I don't have the ca, so I don't have all the numbers.

I ran about 2000 miles on my pack with a brushed hub, and 35 amp controller, no problems with it so I think you have the headroom for 35 amp controllers with a 20 ah ping, and using the 9c motor. A big motor like a 530x would be another story, it would pull higher amps a lot more. Even with a bigger controller, the 9c is going to pull only about 15 amps most of the time.

48v would really pep up the motor for hauling a trailer, so a 48v 15 ah would be good for you. Mabye you wouldn't even need the new controller. 30 amps discharge from a ping should be ok, and 35 would likely be only for short bursts.

Seems like the v3 pingbattery is due by now, but mabye higher c rate cells are still a fantasy. V2 had better cells than my v1, and I believe v2.5 improved the bms.

Calendar life is still a bit of a mystery. Mines 1.5 years old. Most discussions I've read debate whether it will last 5 years or 10. If I reach my goal of 10,000 miles it will happen in 3- 4 years. After 10,000 miles I plan to retire the pack as a museum piece if it stll functions.

 

[mrzed]

I did think about going 48v for help with the trailer, but I figure that only gives me 33% more wattage - would assume a similar torque increase. On top of the minor increase in wattage, up steep hills, I'm going slower, and the motor at 48v would be further out of its efficiency band when pulling 20Km/Hr or less up the steeps. I'm not too concerned on mild hills, as I already pedal harder to keep speeds in the 25Km/hr + range there. I've noticed a huge drop in efficiency when the speed drops under 20.

Upping to 35A almost doubles the available wattage. And It also keeps me in a more efficient cruising speed, both on the flats and up the milder hills.

I started thinking about 48v so I could keep the controller, but now I'm thinking that keeping the C rate lower is a factor. So I was leaning more to 36v now as I can get 20Ah for the same price. The higher nominal voltage and lower sag should give me a noticeable improvement at 36v. The NiCad pack drops to 32v pulling hard uphills even when fully charged.

Another factor is 36v keeps me legal, and I'd like to see eBikes take off, for me, part of that is not too many overvolters spoiling the party (no offense intended).

 

[dogman dan]

All true, what you said. 36v, and a legal bike is nothing to scoff at. The better efficiency of the motor would matter a lot if much of the ride is on hills.

My commuter is 36v, and most of my motors go 20 or 25 mph at 36v. But I'd love to have 48v, at least for the mile and a half I ride daily that is steep. No point in going faster than the bike is geared for though. In my state ebikes don't exist, just mopeds, legal to 25 mph. So 48v on my E-BikeKit motor would be legal for me. I'd go about 25 mph.

I could be wrong, but 48v might allow faster speeds up the hill, actually making up some for that loss of efficiency on the hills. A lot depends on the slope and length of hills when you start talking performance. What works great at 5% may suck at 8%. I haven't tested my Ebikekit motor at 48v yet.

I'd like to get a 48v 15 ah ping so I'd have mega range for touring along with my 36v 20 ah. I'd use 48v for hills, and 36v on the flats. When touring with my aotema motor I used 48v nicads on the hills, and got better performance out of the motor, with less overheating. I was usually climbing 5-10% at 5 mph, using half throttle or less, but not hauling a traliler. I found the best efficiency was had by climbing slow, pedaling briskly, and using only the minimum throttle needed. The aotema needed the 48v on hills since it's wound faster than the Ebikekit.

 

[GrayKard]

After 10,000 miles I plan to retire the pack as a museum piece if it stll functions.

The Dogman Museum of Decrepit E-Bike Parts

I hope you will have an online version. :wink:

Sorry, back on topic, I have no personal experience with ebike batteries as I'm still working on my first build. But I'm gonna throw my 2 cents in anyway.

I think the Ping sounds like a great option but if you want to go with less amp hours I would suggest you look at the 48V 10ah Headway pack from EV components. It's got a sustained 6C rate and a cutoff of 10C so more than enough and looks like a decent price.

Edit: I just read Ypedal's thread http://endless-sphere.com/forums/viewtopic.php?f=4&t=14015 on the Headway pack and he indicates that they are 5C and are best used at 3C. Knew it sounded too good to be true...

 

[BLUESTREAK]

GO Ahead and use 48 volts is really wakes up the 9C e-bikekit, i love it. If you need to up yhe amps on the controller contact (DNMUN) ON THIS FORUM.

 

[dogman dan]

48v with a cycleanalyst to limit speed is the ticket for a legal ebike, that still scampers up a hill. The CA can limit amps, or limit speed. So you could have a 20 mph top speed limit, and still have the volts and amps to get up the hill, just climing at a max speed of 20 mph. I belive it takes the direct plug in CA to do that though. Gets pricey too, but you could start with the battery and get the high amp controller and CA later. Just have to limit speed with your brain, a hard thing to do for me.

The headway cells are nice, but like me, Ypedal is conservative with the c rate. After all, if you discharge at 6c, you are not going to get 1000 cycles. At half that, you have a dang good chance of it. I consider my ping V1 a 1c battery, and the V2.5 a 2c battery. So I try to discharge my V1 at .8 c, and a V2 I'd aim for 1.5c. So the headways, at 3c are still a lot better.

The bms headway sent Ypedal didn't have the capacity to put out the spec amperage on that pack. It seems to work fine with another bms. Maybe Ypedal just got a stinker, and the others are ok? We just don't know yet on that. I can't wholeheartedly recomend the headway 48v pack till I hear from others that are happy with em. If I had the money I'd buy one though, and deal with it if I had to replace the bms. We know for sure the cells are great.