Resurrecting an Ultra Motor A2B Metro with 20S power

[edamame]

Altonk,

I am using those batteries, four of them and they work well. I did have them cleanly mounted in the rear battery case but they made the bike tail heavy so I moved two of them inside the down tube with a special aluminum and Velcro fixture that protects them. I mounted the other two on top of the down tube with a acre of Velcro which moves all of my battery weight forward. This greatly enhances the bike's handling and balance. The front suspension works a lot better and I'm not continuously bottoming out the rear wheel against the rear battery case. I don't keep the rear battery case on the bike so I have a lot more rear travel. My rear shock actually works pretty well now. In general, the bike is just a bunch nicer though it just doesn't look as good with the batteries sitting on top of the down tube. I recommend that you not use the rear case to mount batteries, however convenient it may be.

Like a dork I didn't take pictures of the "trolley" I made to put the two foot long Zippys inside the down tube. I am gonna shoot a short YouTube video on my A2B for my crazyenergyprojects video series. I'll post the link here when I get it uploaded. Also, I do need to flip the bike upside down to pull the trolley to inspect for vibration wear so I will take pics then.

Jim

I have done a motor and controller upgrade on my a2b and was wondering if these are the batteries that you used in the rear battery case?
ZIPPY Compact 5800mAh 10S 25C Long Lipo Pack

I am going to be ordering a set soon.

 

[edamame]

Ultramotor A2B Metro RC Lipo frame batteries

Here I show how I successfully installed two Zippy 10S 5800mah long lipos inside my A2B Metro frame. I bought three foot long aluminum bar stock two inches wide and an eighth of an inch thick from Home Depot along with a $25 big industrial pack of 2" wide Velcro. I put a bend in the end of the aluminum bar to keep the batteries from slipping downward and then velcro'd the heck out of the aluminum bar and batteries to keep them in place and protected from chafing. I finished with two 6mm stop screws to keep the "trolley" in place once inserted into the down tube. I also had to extend the power and balance wires from the battery pack highest up inside the down tube.

[youtube]l09qAkCI08E[/youtube]

 

[altonk]

Great Idea, I'll think I'll give that a try. Right now I'm using the original batteries in the frame tube and the aux pack wired in series for 72 volts. As soon as they wear out or I get impatient I'm going to replace them with the zippy packs. I have to current limit to around 30 amps now to keep the bms from tripping.

here is the thread on my upgrade.

http://endless-sphere.com/forums/viewtopic.php?f=6&t=48063


thx for the info.

 

[altonk]

Actually if i can get two in the tube and four in the second rear pack that will give me 33 amp hours

 

[altonk]

I replaced the pos rear shock with a 6.5 inch rock shox air shock and that made the rear suspension really work well. It made the unloaded ride high a bit taller and I had to extend the stand but when loaded with me sitting on it the ride height is about the same.

 

[edamame]

The stock batteries are child's play compared to rc lipos. I sold mine off a couple of month's ago. I also tried a 6.5" rear shock but didn't like the jacked up rear end. I'm a little short at 5'7" so I went back to a 6" shock.

Good luck!
Jim

Great Idea, I'll think I'll give that a try. Right now I'm using the original batteries in the frame tube and the aux pack wired in series for 72 volts. As soon as they wear out or I get impatient I'm going to replace them with the zippy packs. I have to current limit to around 30 amps now to keep the bms from tripping.

here is the thread on my upgrade.

http://endless-sphere.com/forums/viewtopic.php?f=6&t=48063


thx for the info.

 

[john in dc]

The stock batteries are child's play compared to rc lipos.

@edamame -

Can you share with us what type of performance you're getting out of your A2B Metro @ 72 volts?

Would love to see a video !

Thanks...

- John

 

[edamame]

I don't have any specific performance numbers but it does go 37-38 mph. I can do a 14 mile round trip downtown running above 30mph on average. Is there any specific performance you want me to measure?

I don't have a helmet cam. I do plan on shooting an overall video just showing the bike but not while I'm riding it. Maybe I could do a flyby with the camera on the tripod to give a sense of how fast it accelerates.

-Jim

 

[altonk]

I'm getting 33 mph on a flat surface @ 31 amps with the stock primary and secondary in series with my crytsalyte motor and a 72v 40a controller. Looking forward to switching to lipo poly batteries.

 

[john in dc]

Is there any specific performance you want me to measure?

If you're running a cycle analyst, can you provide some of the statistics from it ie watt-hours/mile?

I'm also curious to know how steady/safe the bike feels at full speed. I would rarely need to go above 30mph but the occasional blast up to or near 40mph would be inevitable so knowing how it handles would help cement my decision to buy one.

Thanks for all of the awesome posts. Great stuff !

- John

 

[edamame]

The bike is two-hander at any speed. It works fine at full speed but you need bigger/better brakes than stock.

Taking weight off of the rear end enhanced all aspects of handling. The back end still gets a little choppy going fast around bumpy corners. There's just so much weight in the back wheel and swingarm. I have a good shock for a 30 pound mtn bike but it cannot fully cope with the 100 pound beast and bad pavement.

If the pavement is smooth it handles like a dream.

With my usage, I am consuming about 32 wh/mile. This is from the wattmeter on my solar battery bank and includes lipo charging losses. My route is very slightly hilly, maybe 40 foot rise/fall in 1/2 mile.

 

[altonk]

Same here. I use 30-32 wh/mi based on the cycle analyst. I put a rock shox air shock on mine and now the rear doesn't hop as much. The steep rake angle makes it handle quick. Many have complained but I like it. It is a lot like my trials bike. You definitely have to pay attention. The up side is you can turn quick at speed and really tight going slow.
I am going to stuff four of the 5800 maHr batteries in the secondary pack and two in the tube, Thanks to the info I got here. I am also thinking about going to a 100 amp controller from the 40 amp i have now, not so much for speed, 30 mph is fine for top speed, but more for acceleration. It should be able to spin wheels and pop the front wheel up with 100 amp bursts. With the HS3548 motor I shouldn't have any thermal problems and I'm going to put a thermistor on the winding as the CA V3 supports thermal limiting.

 

[edamame]

Altonk,

I can offer to lend (and send) you my rear battery case. You could stuff 17 pounds of rocks in it to give you an idea on how the bike will handle with four batteries in it. You might find you don't like it bottoming out. I know you have a longer 6.5" shock back there but it would be a cheap test for you. Send me a PM if you are interested. You could buy it from me if you decided the weight was not hurting your suspension too much. It is already modified to be used with those stick packs and I only have $25 in it. -Jim

...I am going to stuff four of the 5800 maHr batteries in the secondary pack and two in the tube, Thanks to the info I got here...

 

[john in dc]

Ultramotor A2B Metro RC Lipo frame batteries

Do those batteries fill up the entirety of the frame tube or is there still some room to add other assorted electronics if necessary?

An an unrelated note, I've searched the web looking to see if the stock in-built controller is capable of being modified - - ie capable of handling higher voltage levels or even being reprogrammed to modify the soft start feature - - but didn't come up with anything.

Do you know if anyone has tried to modify the stock controller?

Rgds...

- John

 

[edamame]

Once the bateries are slid up into the down tube there is no room for anything significant. It would be good enough for smuggling baggies of stuff if you were into that. Of course, riding a 38 mph quasi scooter on city streets without registration might make you a target for the local constabulary.

 

[fechter]

Do you know if anyone has tried to modify the stock controller?

Since it's potted in epoxy, there isn't much you can do with it.
I'd be curious to know how much voltage it can take. I bet it would be OK with 48V.

 

[edamame]

It has been shown by Ypedal that 48V on the stock in-motor controller does indeed work.

 

[edamame]

So I uploaded some more pictures for your viewing pleasure.

These are the batteries I am using. I spent $520ish on the four and got lucky that they are well matched and stay in balance. That's my size 8 foot there for scale:

Here are a few shots of the batteries mounted inside the rear case. I wrapped each battery in a padded FedEx envelope before I slid them into the case. I think the 17 pounds that this loaded rear case weighs kills the handling of the bike:

I moved the batteries midship a couple of months ago. Here is a shot of the 2 batteries on top of the down tube. The other ones are inside the down tube:

These are the two 6mm screws keeping my battery "trolley" inside the downtube:

An overall shot taken today:

On an unrelated note, if your A2B Metro centerstand is constantly getting loose like mine did here is a fix. I drilled out the 10mm bolt hole and drilled and tapped for a fine thread 1/2"-20 Allen screw with a backup locknut. I used copious amounts of blue locktite on everything and it has held fine for 8 months:

 

[fechter]

Nice. Where did you get the rear battery case?

 

[edamame]

Wake at ebikestore sold it to me: http://ebikestore.com/

Nice. Where did you get the rear battery case?

 

[edamame]

I think I might start a project to build a sheet metal battery box that hangs under the down tube and secured with rivnuts. It would hold the two batteries that are now on top of the tube on my bike. I would move the controller to the space where the rear battery case slides in. That way I could lower my CG even further and protect the batteries from the weather. It would also allow me to waterproof the electrics. As my bike is configured now, I only ride when the weather is completely dry.

I build sheet metal skid plates for VW's and Audis so a battery box shouldn't be too hard. Would anyone here be interested?

Jim

 

[altonk]

I can offer to lend (and send) you my rear battery case. You could stuff 17 pounds of rocks in it to give you an idea on how the bike will handle with four batteries in it. You might find you don't like it bottoming out. I know you have a longer 6.5" shock back there but it would be a cheap test for you. Send me a PM if you are interested. You could buy it from me if you decided the weight was not hurting your suspension too much. It is already modified to be used with those stick packs and I only have $25 in it. -Jim

Jim I already have a rear pack with the stock batteries in it. But if you want to sell your old one I will take it. That way i can build the lipo pack and not be down while doing it. PM or email me the details alton.keel@gmail.com

thx,
Alton

 

[joepah]

wow Edamame, that is one radical Metro! I just want to replace my stock battery pack... Haven't seen anyone build their own pack from 18650 cells... have to have the right equipment for spot weldind the tabs to the cells..

How fast is your beast?

 

[edamame]

37mph GPS verified

 

[John Bozi]

nice work.

How do you charge those 10s batteries? Is there a 10s balance charger out there?

I'd love to go to 20s2p. Currently on 21s2p and the amount of wiring everytime I charge in parallel is a pain...