Headway 36v 20ah battery pack

Gern

1 µW
Joined
Dec 7, 2012
Messages
4
Location
Los Angeles, CA
Hello Riders!
I have a Surly Big Dummy and a Stoke Monkey in Los Angeles, for commuting, errands and fun rides.
All activity I have been doing already, just slowly!
I am totally a noob in the electric bike world, this is my first.
I have very limited knowledge and have not been studying long; I had no idea there where so many factor involved!
I have decided to purchase a pack already built and was wanting to run this potential purchase past all of you to see if it sounds correct, or if I'm missing something. I'm open to all info.
Headway 36v 20ah battery pack, The cells in that pack are the 38120SE cells (10Ah) that will be wired in parallel to make a 20Ah battery pack.
The 36V20Ah battery specs are:
36V nominal voltage
39.6V actual resting voltage
20Ah of capacity
720Wh of energy
50A continuous, 100A peak capability (1.8kW continuous 3.6kW peak)
Regen capable
18lbs +/- approximate weight
Anderson PowerPole connectors
In the shape of: 2X12X1 = 19" x 6" x 4".
The 36V20Ah comes with an 18A charger.
A bit of info from the dealer:
" miles per gallon and equating them to watt hours per mile, on average the total weigh of rider and bike is divided by 10, this is typically the average watt hours per mil (Wh/mi) that one gets by using just the battery power itself on flat straightaways without any pedal assist. On average, most eBike systems typically use between 20~35Wh/mi. For estimating purposes, if using the Wh/mi on the high end of the scale of 35Wh, take the Wh of the battery, 720Wh (voltage multiplied by the ampere hours), and divide by the Wh/mi number and this will provide you with an approximate of range in miles. 720Wh / 35Wh/mi = approximately 20 miles of range"

I thank you all for the input you give.
Cheers
 
18A charger? why can't you name the manufacturer? is it a secret? what BMS will they use? do you know if it will fit your bike if it is so big and do you know how much it weighs? 460gm/10Ah cell.
 
The 18A charger is what he said comes with the 36v 20ah. What are your thoughts about that?
It is a Headway battery pack, assembled by Headway-Headquarters in Washington State, USA.
Not a secret, really.
I will ask what BMS comes with it. Thanks.
It will fit on my SBD cargo bike , yes.
18lbs +/- approximate weight, still leaving me plenty more cargo capacity!
 
it has the headway BMS. that is the best, and jimmy D does a good job building them. but that is a powerful charger, the BMS can handle it though. it can handle 100A discharges too.
 
There are some benefits to having two 10 amp-hour packs:
  • Redundancy
    Lighter weight for short rides
    Easier to carry pack between charger and battery
    Charge one while using the other (solar charging more feasable)
For long rides carry both; it's not hard to stop and switch after 10 miles or so. But for permanent mount on the bicycle, or If you really need 50 amps, parallel cells might be better.

I have no experience with paralleling at the pack level on my Yuba Mundo but that might give you the best of both worlds.
 
dnmun said:
it has the headway BMS. that is the best, and jimmy D does a good job building them. but that is a powerful charger, the BMS can handle it though. it can handle 100A discharges too.

What are your thoughts exactly about the charger? Does the 18A charger have a detrimental effect on the batteries in the long run?
I don't need to charge faster than 6 hours. I don't know the stats, and I'd rather treat the pack kindly!
 
dak664 said:
There are some benefits to having two 10 amp-hour packs:
  • Redundancy
    Lighter weight for short rides
    Easier to carry pack between charger and battery
    Charge one while using the other (solar charging more feasable)
For long rides carry both; it's not hard to stop and switch after 10 miles or so. But for permanent mount on the bicycle, or If you really need 50 amps, parallel cells might be better.

I have no experience with paralleling at the pack level on my Yuba Mundo but that might give you the best of both worlds.
Thank you, these are all good points. I can also guess that if the packs are smaller, they may stay solid and in working condition longer than a large pack getting jostled around, over a7 over.
 
nope, it is better to have one pack than two. the whole idea of carrying a separate battery and installing it after you discharge the first is totally wrong. a single pack will last longer and produce more power.

the 18A charger is just a very large charger. most chargers are about 5A and would take 4 hours to charge from total discharge. with a large charger like that it will charge in one hour.
 
One thing to note about that little quote about Wh/mile: it would only apply at some specific speed. If you are going a lot slower or a lot faster than whatever speed he's talking about (not listed in the quote), you could have a hugely different Wh/mile usage.

Also, if you are riding in constantly stopping/starting city traffic, your Wh/mile usage could be a lot higher than if you are just riding long distances without stopping.

It also makes a huge difference if you are pedalling or not, and how much.

Then there is your controller: if it's a high-current controller, and the motor setup is capable of demanding it, the high power levels pulled from a pack during startup from a stop could also seriously increase the power usage, makign your Wh/mile a lot higher than his estimate. Conversely, a very low-current controller could make that usage lower (but of course takes longer to accelerate to speed).

Then there is your motor: with a Stokemonkey setup that goes thru your gears, if you are properly shifting you'll get way better efficiency even in that stop/start traffic than you would with a DD hub configuration under the same traffic conditions.


For example: My 300lb-with-rider-but-no-cargo CrazyBike2 with a DD hubmotor gets roughly 30Wh/mile, which is about what his estimate shows, but that's only when I am riding a short 5-mile-round-trip work commute with lots (a dozen each way) of complete stops and starts (though all on nearly flat terrain), and using full throttle to accelerate to my cruising speed of 20MPH as fast as I can, with around 3.5KW of peak power, and no pedalling at all.

But if I ride on a long haul, say 20 miles round trip on a road with few stops, but otherwise doing all the same things, I might be able to get that down to 22Wh/mile--quite a lot less.

If I then also use just enough throttle to get going and slowly increase it to reach my cruising speed of 20MPH, isntead of hammering the throttle all the way until I get to speed, I can bring that down to 20Wh/mile or less.

If I were to also use a much less powerful controller, or change the current limiting on it to way less than it is now (around 80A+ peaks), it'd take another couple Wh/mile off, most likely.

If I could also pedal enough to really help (most days I couldn't), I bet I could bring it down to half of what I use on my work commute, around 15Wh/mile.

If I were to run the motor thru the gearing and optimized the gears for best motor efficiency on each one vs a particular speed, I could probably cut another couple of Wh/mile off of that.


So it could be dramatically less power usage depending on quite a few factors.


OTOH, it would also increase the Wh/mile quite a bit by riding just 5MPH faster (25MPH cruising) for enough of the same route. I can't test that empirically here due to the speed limit law for ebikes, but I would guess it'd add at least 25% to the usage, possibly a lot more depending on how much distance I'd be at that faster speed for.


Oh, another factor can be your tires, and the air pressure in them. Big fat tires with low pressure could increase power usage significantly, vs skinny tires at high pressure. But the former are probalby more comfortable than the latter on bumpy roads. :)
 
also to note if you have a 20 amp battery you also need a 20 amp controller, i discovered this to my expense when i tried paralleling a second battery to my bike and it fried my controller almost instantly, so as a rule i would buy 2 smaller batteries and swap when 1 is dead or make absolutely sure your controller can handle a 20 amp battery
 
oldskoolhead said:
also to note if you have a 20 amp battery you also need a 20 amp controller, i discovered this to my expense when i tried paralleling a second battery to my bike and it fried my controller almost instantly, so as a rule i would buy 2 smaller batteries and swap when 1 is dead or make absolutely sure your controller can handle a 20 amp battery

The amps the battery is capable of putting out don't have anything to do with whether the controller can handle that. A battery doesn't output any current except what is "pulled" from it by a load (like your controller).

A "20A" battery would be one that can only output 20A before the BMS shuts off the output. I suspect you really mean a "20Ah" (Amp-hour) battery, which simply means that the battery could output a total capacity of 20Ah, which has nothing to do with how many A (amps) it can actually supply, despite the similar terminology.

A "20A" controller would be one that should pull a maximum of 20A continuous from whatever battery is hooked to it, at the maximum loading of the motor attached to the controller (like when climbing a hill or starting from a stop). (it may pull more than 20A during very short peaks).



If your controller fried, I suspect that you might've accidentally hooked the second battery up in series with the first, which would have put twice the voltage across the controller than it had before (and probably too high for it's electronics). But this is OT for this thread, and should have it's own thread if you wish to resolve the reason it fried, and perhaps repair it. I can move your post to it's own thread for this purpose if you like.
 
Yeah, Oldschool did something wrong, but running a 20 amp controller on a 20 amp hour battery wasn't the mistake. My bet is on he fed it 72v too. Or a nicked wire at the hub shorted it. Those are the two typical causes for controllers going poof.

36v 20 ah sounds like a good minimum size for a big cargo bike. It won't be hard to carry on a big dummy. You'll either have about 30 miles range riding slow, or have enough range to ride faster up hills or when lugging lots of cargo, and still get close to 20 miles. wh/mi can vary a LOT with speed. My longtail can get 60 wh/mi if I blast around on it at 30 mph using1000- 2000w. Mine has a big powerfull motor and controller. Or I can ride it using 500w max, and get great wh/mi.

The 18 amp charger might not harm your battery any, still charging at less than 1c. But it will be bigger and more expensive than a 5 amp charger. A 5 amp will charge you in 4 hours, so that might be plenty quick enough. You will never want to carry around an 18 amp charger too charge on the road, too big and heavy.

I'd go with a 5 amp charger myself, unless you were considering a really big battery.
 
I don't know what happened, but neither my wiki entry nor my post made it in, and I don't seem to ahve a local copy. Maybe I fell asleep and only dreamed I wrote them. Anyway, here's a start on the wiki entry:
http://www.endless-sphere.com/w/index.php/Terminology_and_Explanations_of_Common_Misconceptions
but I don't remember all of what I put in there, so maybe someone else can go in and complete it?

(I'd started with a bunch of links to various posts from Dogman, Miles, Jeremy Harris, Bigmoose, etc., who have all explained such things repeatedly in pretty easily understandable ways-but I don't have copies of any of the URLs, thread names, etc., which also is all very strange, since I use a big continuous clipboard for it *and* I paste stuff in a notepad file, etc.)
 
How much does this battery and charger cost? Or did I miss that somewhere in the other posts. I only ask because I recently purchased a 36V 20A pack from bmsbattery.com for a total of about $390.00 and this included shipping. It comes with a 4A charger which puts the recharge time at about 5 hours if the pack is completely discharged. On a side note don't completely discharge your pack. It only weighs about 10 lbs. I've had mine for a couple of months with no problems. I don't know if you've ever seen one of e-bikekit.com's battery bags but it fits in there with room to spare. It took a little over 2 weeks to arrive and it's shipped by DHL. It's the 36V 20A shrink tube pack with bms. It provides plenty of power for my huge ass at 6' 3" 350 lbs. Of course it's hooked up to a 250W motor. I've ridden around for 15+ miles and it hasn't dropped below half on my throttle meter. I pedal constantly but I'm only supplying about 25% of the power and I tend to full throttle on slight downhills without pedaling. The top speed of my bike currently is about 25 mph.
 
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