48v 30ah Ping 2.5 pack in electric moped??

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badnewswade
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48v 30ah Ping 2.5 pack in electric moped??

Postby badnewswade » Thu Jan 21, 2010 12:51 am

Have a look at this:

http://www.pingbattery.com/servlet/the- ... PO4/Detail

What do people think would happen if I installed them in this:

http://www.evalbum.com/2486

:?: :?: :?:

When I had a 20ah SLA it got 15 miles per charge (if I was lucky, often with hard driving more like 12 miles). These weighed around 24 kilos. This new Ping weighs 15 kilos and has half as much juice again.

I'm currently using 48ah worth of SLAs, which got me around 30 miles when they were new, but now more like 20-25 miles and getting quite sluggish and old.

Oh, and its' dry weight (ie without batteries) is probably somewhere around the, what, 70-80-kilo mark? Whatever it is they weigh, anyway.
34 Watt Hours per mile, or > 700 MPG. What, me, smug?

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Jeremy
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Postby Jeremy » Thu Jan 21, 2010 7:32 am

I've been running an original Ping pack, a smaller 36V, 10Ah, for about 18 months now, and am very happy with it. As far as I can tell, it has the same capacity now as it had when it was new. It probably has around 500 cycles on it now.

Everything I've heard from the many people on the Endless Sphere forum that are using these packs has been good, with the odd exception of one or two who have abused or physically damaged their packs.

The Ping BMS has a discharge current limit, as well as cell voltage protection, so the maximum current available, even in a short burst, is hard limited. If you try to pull more current than the BMS will allow then the pack cuts off to protect the cells. As long as your controller can't pull more than the cut-off current from the battery then you should be OK with this pack.

You'll find that this 30Ah pack will have the same usable capacity as a lead acid battery pack of maybe 30% greater capacity. If your 20Ah SLA pack achieved 15 miles, then I'd expect that you'd get at least 25 miles with the Ping pack, maybe more.

You will need to make some sort of protective housing for the battery, as these packs are just shrink film wrapped pouch cells. There are several ways to do this, but one of the simplest I've seen was to make a "box" from 6 bits of thin Formica or other rigid plastic sheet, with the joints simply taped up with duct tape. Some thin foam, like the stuff used for cheap laminate flooring underlay, wrapped around the pack before you slide it into the box will protect it from shock. You need to make sure there's adequate cooling air around the BMS though, as it gets a bit warm during the cell balancing phase at the end of the charge period.

If it were me, then I'd not hesitate to buy from Ping. If you have a problem with the space available in the battery compartment, then Ping will make you a custom sized pack, within the limits of the cell dimensions, if you ask.

Jeremy

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badnewswade
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Postby badnewswade » Thu Jan 21, 2010 1:22 pm

Thanks for that. Isn't the big scoot going to drain a lot more power than a bicycle though? By my calculations SLAs allow you to take ten times the amperage and Liths are 3 times as much - is that right?

I don't think 25 miles is enough to justify the expense at the moment. I need 30 miles to match my current setup, but for that sort of investment I'm more interested in extending the range to 40 miles and above.

A 50 or 60 amp-hour pack sounds more what I'd be interested in, probably cost a lot more though. What direction are prices going in? Is there any chance that Ping would make up a larger pack, and how much would it cost - I'm imagining around £1,000 for a 50ah pack which is, again, too much at the moment really.
34 Watt Hours per mile, or > 700 MPG. What, me, smug?

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Postby GregsGarage » Thu Jan 21, 2010 6:49 pm

badnewswade wrote:A 50 or 60 amp-hour pack sounds more what I'd be interested in...


For that size you may want to consider the various prismatic and larger cylindrical cells available. When I talked to Ping about larger capacity packs, he wasn't keen as he builds them from 5ah pouch cells and he thought that would be to many in parallel. It was well over a year ago, maybe close to two years, so that may not reflect his current views on larger packs. You can find prismatics in 50 and 60 ah sizes which means you don't need to connect any in parallel.
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191

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Jeremy
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Postby Jeremy » Thu Jan 21, 2010 7:00 pm

You may well be right about the cost/benefit of going down this route, at least in terms of the initial purchase price. In whole life cost terms, then I think that the LiFePO4 pack may well look pretty good though. I think you can pretty much bank on getting at least 1000 cycles from a Ping pack, probably closer to 2000. You'd probably struggle to get more than about 300 cycles from an SLA pack.

The 30Ah Ping pack is good for around 60A continuous, or 100A peak. 60A continuous equates to 30 minutes running time, which at 30mph would equate to a range of just 15 miles. Based on this, I think that it's safe to assume that your scooter uses less than 60A continuously, in fact it's probably going to be closer to around 30A. This pack will comfortably work at these sort of power levels, with a high usable capacity.

If we assume that 30A is the average current drawn by your scooter, then you'll get about 95% usable capacity from the LiFePO4 pack and around 70% usable capacity from a new SLA pack (much less as the pack ages, as you've found out). This means that your 48Ah SLA pack is really giving you around 34Ah when new and the 30Ah LiFePO4 pack would give you around 28Ah for at least half it's life.

In other words, the range on a 30Ah LiFePO4 pack (ignoring the reduced power requirement from the lower battery weight) would be about 80% of that from a new 48Ah SLA pack. However, whilst the SLA pack would be on it's last legs after 300 cycles, with much reduced range, the LiFePO4 pack would still give a range very close to that when it was new.

Even after 1000 cycles, you'd probably find that the LiFePO4 pack would still be giving you around 70% of the range of a new 48Ah SLA pack, yet you'd have purchased at least three, most probably four, sets of SLAs by this time.

Ping can almost certainly make you a bigger capacity pack, although the maximum current tends to be limited by the BMS systems he has available. This wouldn't be a problem for you, as the BMS on the 30Ah pack looks like it would cope well with the loads that your scooter would impose. Although the price would be higher for a higher capacity pack, the shipping cost might not increase by as much, so it could prove to be better value.

A 40Ah LiFePO4 pack, for example, would exceed the performance of a new 48Ah SLA pack and would give around 12% improvement in range. If you were getting around 30 miles from a new 48Ah SLA pack, then you could expect to get at least 33 to 34 miles range for at least 400 to 500 charge/discharge cycles (probably at least a year's regular use). With the reduced weight of the LiFePO4 pack, plus the reduced voltage sag, you may well find that the range is a bit better than this, maybe as high as 40 miles from 40Ah.

If, as I suspect, you're not getting close to 300 charge/discharge cycles from a set of SLAs, then you may well find that the investment in LiFePO4 makes more sense. On the other hand, if you can get hold of cheap SLAs, then it may not!

Jeremy

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ChrisB
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Re: 48v 30ah Ping 2.5 pack in electric moped??

Postby ChrisB » Tue Jan 26, 2010 4:20 pm

Check my "taking the plunge" thread viewtopic.php?f=3&t=2149

Bought from ping and so far I really cant fault them, loads of power, loads of the time, even in cold weather they seem good.
Only one very very slight concern is one cell appears to take a little longer to balance according to the LED's on the BMS but I suspect its nothing to really worry about, the early adopters dont have the LED BMS so wouldnt even know if one cells taking longer.

ChrisB
I reject reality and substitute my own !!!!!!

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badnewswade
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Re: 48v 30ah Ping 2.5 pack in electric moped??

Postby badnewswade » Tue Jan 26, 2010 6:12 pm

I had a look, but it's more about bycicles than mopeds. How much extra mileage did you get?
34 Watt Hours per mile, or > 700 MPG. What, me, smug?

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ChrisB
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Re: 48v 30ah Ping 2.5 pack in electric moped??

Postby ChrisB » Thu Jan 28, 2010 8:55 pm

Well my lowely 7-10mile range went to 20+ :shock: todate I have yet to find the absolute range as I get bored riding it :lol: :lol: :lol: :lol:

Thats going from 24v @ 12ah sealed lead acids to 24v @ 15ah LiFePO4's

ChrisB
I reject reality and substitute my own !!!!!!


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