Absolute cheapest 48V battery - Tiny distances

M

mattwilkinson

1 mW
Joined
Sep 19, 2015
Messages
11
Location
Victoria, Australia
Hi,

For work we are building a 1000W run around e-bike, it'll be ridden about 7km maximuum before being charged again....
We have settled for 48v 1000W and want to build this as absolutely cheap as possible

What's the smallest/cheapest battery we can get to run this sufficiently?


Can someone tell me why 4 of these won't work?
http://www.ebay.com.au/itm/Brand-New-12V-7-2Ah-SLA-Battery-12-Volt-7ah-Sealed-Lead-Acid-Rechargeable-AGM-/140984294937?hash=item20d3519e19
Cheers
 
See need advice in sig line.
4 of those will work, but they are big and heavy and won't last as long as a lithium pack which will cost about the same and will only weigh ~3.5 lbs compared to 22 lbs for the sla batteries. And the lithium pack will be about the size as one of those sla batteries. A 20C 5000mah 12s pack (two 6s in series) from HK in AU will cost about the same as 4 of those sla batteries.
http://www.hobbyking.com/hobbyking/store/__239__85__Batteries_Accessories-20C_Discharge.html
 
A 10ah 1C battery pack won't provide enough amperage for a 20A or higher controller. And that more than 3 times the cost. And he shipping from the US to AU will be very expensive. Even if it did provide enough power, it's more than twice the amount he needs for 7km.
 
The 26f batteries in that pack are rated for a 2C max discharge (5.2A). That's 20.8A max for the pack, so as long as your controller is rated for 20A or less it's fine. Sure, you can pull more from them at the expense of huge voltage sag and a shortened cycle life. And even at 20A you'll see considerable sag and a loss of cycle life.
http://lygte-info.dk/review/batteries2012/Samsung ICR18650-26F 2600mAh (Pink) UK.html
 
http://www.ebay.com.au/itm/26-Electric-Bicycle-E-Bike-Conversion-Kit-Brushless-Motor-48V-1000W-Rear-Wheel-/121200544687?hash=item1c381d8baf

^^ This is the kit here

What would 2 of these in parallel be like?
http://www.hobbyking.com/hobbyking/store/__8582__ZIPPY_Flightmax_5000mAh_6S1P_20C.html
 
lead batteries was cool ca. 1895 ;)

you need the lipos i -series- for 44.4 volt nominal.

maybe 8000 mah would be a more "safe" option, leaves a bit more buffer.
http://www.hobbyking.com/hobbyking/store/__56842__Multistar_High_Capacity_4S_8000mAh_Multi_Rotor_Lipo_Pack.html
 
They would give you a range of ~9 km at a top speed of ~44 kph and should last a lot longer than an sla pack. ~19 km at 30 kph.
 
You might want consider LiFePO4 for the chemistry. They are the safest lithium battery. LiCO is more volatile but may be required depending on the needs. From your modest amount of info I'd say LiFePO4. A 36v kit may be the answer and would require a smaller battery. At what rate of speed is required? What kind of terrain?
 
Couple things about the RC Lipo packs (bricks) OP linked. Personal experience with Zippy brand hasn’t been as positive as Turnigy 20-25C bricks. Not scientific but if I had to venture a guess all things being equal (capacity, age, use) I suspect many more 3-4yr old Turnigy bricks still in some form of service than comparable age Zippy.

Another is that OP mentioned parallel which wouldn’t be the way to look at this. 2qty Turnigy 20C 6S1P bricks would be series wired together to create 12S1p pack for nominal 48V system. (supplied main leads/bullet can accomplish this while parallel wiring requires custom connectors/wire harness.)

Yes, there’s more upfront cost for RC Lipo charging, testing, monitoring gear but that’s one time purchase. And considering the vast amount of battery cells RC Chargers handle it’s more than paid for itself in my household for all sorts of battery management tasks. How many things in our daily life use batteries these days? Get with this century's tech, right?

As far as safety? That’s a tough one. I can assure you many UAV (drone) photographers regularly handle and transport larger quantities of RC Lipo than this so it “can” be safely used in various environments.

The question becomes are you ready to accept the RESPONSIBILITY of handling storage batteries with so much energy density and potential flammability? That’s for you, your maker and insurance agent to determine.

But for OP needs 12S1P 5Ah 20C pack would be plenty and weigh around 5lbs plus fit in your hand. And you begin learning stuff that will serve you well for years to come.

Go slowly, carefully, ask for help...
 
Yep, I missed he said parallel. Definitely want 2 6s packs in series.
 
Sorry, I know nothing eletrically haha.
Me and my buddy work at a bike shop and have a bike we ride to get lunch on and thought it would be cool if we put a motor conversion on it.

So 2 of these you think?
http://hobbyking.com/hobbyking/store/__9176__Turnigy_5000mAh_6S_20C_Lipo_Pack.html


How far do you think those would go? I think we would be pretty heavy with the throttle but we would never go more than 10km... If we decided to add a third battery, it would bump it up to like 60V wouldn't it?
 
mattwilkinson said:
How far do you think those would go? I think we would be pretty heavy with the throttle but we would never go more than 10km... If we decided to add a third battery, it would bump it up to like 60V wouldn't it?
Click to expand...

Depends on your riding style. I used to have 4 of those, and it got me just shy of 40km with some mild pedaling going low 30s. If I went full stick (about 40km/h), no pedal, I'd use about 80% of the pack in 20km.

Range wasn't the reason why I was conservative though. I stealthed up my bike and wanted to look pretty ordinary, so I went ordinary bike speeds. Even contributed substantially up steep hills, which is what I think made most the difference in economy.

If you added a third battery, it would go over 60v, and would likely blow your controller. If you added a fourth, you could instead run 2 in series, 2 in parallel, and have a 48v battery that ran for twice as long.

One thing you may need to watch out for with the battery you chose, is voltage sag. You've got a low capacity battery, with a low discharge rating. (Note that the "20C" they claim is what it CAN do, not what is good for it over the long term). Even when I had the 4 batteries, effectively doubling the C rating, I got higher sag then I would have liked. The heavier on the throttle you are, and the less willing you are to pedal, the bigger an issue this will be for you. Temperature will also be an issue. My bike was noticeably faster in summer than in winter for this reason.

If you're that tight on a budget, two of those would do. In your position though, I'd be getting at least 4 if I was intending to be throttle heavy.
 
If you really mean " Absolute cheapest".. then forget buying lipo.
Just go and scrounge up some of those used wet cell acid car batteries from a battery recycler and sort out 4 of the better ones.
They wont give you the best performance, and they wont be very light weight, nor will they last many months...
.... but they will be the CHEAPEST.
but i suspect you have some other requirements also, like less size or weight, less hassle sorting out old batteries etc ?
So, better not to ask for something that you dont actually mean..!
Be more specific. :roll:
..Next cheapest..and more practical, would be to pick up a heap of old laptop packs ( free from recyclers !) and sort out the good cells to build a 14s 10p pack of 18650s.
a lot of work, but effective, and cheap,
 
Please follow the "Need Advice" link in my sig line and provide the info requested if you want accurate advice.
 
The old rule of thumb for 1000W 36/48V kits = about 1 mile per Ah worst case range. Often a little better than that but for some margin of reserve I’d count on about 5 miles or roughly 8km from 12S1P 5Ah assembled pack.

Past several years I've used Turnigy 5Ah 20C 4S hardcase bricks. 3qty of those provides same 12S voltage range. Plus they’re somewhat more protected by the hardcase plastic housing.

I add another for 16S but gotta use a slightly modified controller for reliable operation at that system voltage. (Adding a 3rd 6S brick as OP mentioned would be much higher voltage than unmodified controller can handle - 66-75V.)

Here’s a pic of my 16S1P roughly 5lb battery pack using those bricks - (59-67V). 16Sbattery.JPG

I like them but some folks hate them. I also see many people now going for “Multistar” RC Lipo in larger capacity bricks. Dunno anything about those though…

I started using only an RC Charger but now use a BMS. I'm sticking with these hardcase bricks until I can figure out how to buy reasonably priced spot-welded high C rate can cell packs.
 
Your distance is actually ideal for a 9 ah lead battery pack. But hauling ass on lead batteries will just wear them out in a month or two. At that distance, if you ride closer to 20 mph than to 30 mph, a 48v 9 ah lead pack could last you a year or even two. The real downside is riding around with the 25-30 pound chunk of lead tied to your bike. I really hate to advise lead for anything but trikes.

Though not likely the absolute cheapest, you might look into buying a lithium powered 48v yard tool.

Get a weed whacker, blower, or something like that. Essentially, you get the battery and charger cheaper by buying a cheap ass tool.

Usually 48v 2 ah now days, ideal for a very short ride at lower power than 1000w.

But if you plan on a short, but fast ride, you will need a larger lithium battery. So the next step could be a 4 ah lawnmower battery, or 5 ah hobby king lipo.
 
mattwilkinson said:
Hi,

For work we are building a 1000W run around e-bike, it'll be ridden about 7km maximuum before being charged again....
We have settled for 48v 1000W and want to build this as absolutely cheap as possible

What's the smallest/cheapest battery we can get to run this sufficiently?


Can someone tell me why 4 of these won't work?
http://www.ebay.com.au/itm/Brand-New-12V-7-2Ah-SLA-Battery-12-Volt-7ah-Sealed-Lead-Acid-Rechargeable-AGM-/140984294937?hash=item20d3519e19
Cheers
Click to expand...

For what you have described, just go to BMSBattery.com and get the small 36v pack for just over $100 + shipping.
 
Or,,, the 48v one since he might have a 48v low voltage cut off on that kit.

A lot depends on whether he plans to ride fast as possible or not. If he's pulling 30 amps at 10 stops along his way, it could eat a small cheap lithium battery.
 
chas58 said:
mattwilkinson said:
...We have settled for 48v 1000W and want to build this as absolutely cheap as possible...
Click to expand...

For what you have described, just go to BMSBattery.com and get the small 36v pack for just over $100 + shipping.
Click to expand...

Don't wish to piss in your Cheerios this morning but you would recommend that battery pack for a 48V/1000W kit?

OMT - try putting that battery pack in your cart and calculate shipping...
 
"Absolute cheapest" is making your own by recycling. Many different sources are possible with various chemistry, from laptop to tool packs. You need to acquire some knowledge and a few tools, but then you can make your own battery for next to nothing.
 
mattwilkinson said:
So 2 of these you think?
http://hobbyking.com/hobbyking/store/__9176__Turnigy_5000mAh_6S_20C_Lipo_Pack.html


How far do you think those would go? I think we would be pretty heavy with the throttle but we would never go more than 10km... If we decided to add a third battery, it would bump it up to like 60V wouldn't it?
Click to expand...
2 of those in series will work fine. The range will be the same as the others, ~9 km at ~44 kph or 19 km at 30 kph. But don't buy from the international warehouse unless there isn't a warehouse in your country. 3 in series would be 66.6V nominal and over 75V charged, which would blow the stock controller. If you want more range just get more AH by either adding 1 more in parallel or buy larger capacity ones to begin with. They sell 6s packs in a variety of sizes from ~1ah up to 20ah. They have 8, 10, and 20 ah packs too.
And you still need to fill in your location. Do it.
 
What about this lead acid battery?
http://www.ebay.com.au/itm/48V-48Volt-15AH-Sealed-Lead-Acid-DEEP-CYCLE-BATTERY-Pack-DIY-Cable-eBike-Scooter-/350939859947?hash=item51b5a54beb

Or 4 of these?
http://www.ebay.com.au/itm/Blue-DC-12V-6800mAh-Super-Rechargeable-Protable-Li-ion-Battery-Plug-Adapter-/191498694972?hash=item2c9636313c


How would that compare to 2x 6S 20A hobby king 5000mah ones?
 
The lead pack weighs 13kg and will provide about the same range as a ~2kg 8ah pack, but won't last near as long.
That other 12v thing is rated for 2A. It'll blow up the minute you try and pul 20-30A from it.
BTW, the HK lipo is not 20A, it's 20C, 30C burst, meaning a 5000mah (5ah) is rated for 100A continuous and 150A burst. ah rating times C rating = Amp rating.
 
You must log in or register to reply here.

Similar threads

20Lush
Have a baseline, where next?
Replies
7
Views
916
john61ct
J
B
Anyone successfully spoke up a fatbike wheel?
2
Replies
31
Views
6,730
cycleops612
C
4LivesPerGallon
How Battery Chargers Kill Older Lead Acid Battery Packs
Replies
6
Views
1,602
neptronix
neptronix
E
Trek 4000 + 48v 1500w GM kit
Replies
0
Views
980
edzknows
E
stingray17
Dahon Mu SL + ebikes eZee kit + ping 48V 10Ah
Replies
8
Views
5,608
stingray17
stingray17
Back
Top