Extend ebike battery (500w rear hub motor).

[Locko90]

Hey guys, I've got a dillinger off road kit on my bike battery is 48volt 13ah.

I was looking at getting a rear rack pannier with 2 bags and have 2 48v 20ah batterys on bike, to give me a total of 53ah battery capacity.

How would I go about wiring in the 2 battery's safely?

I've attached pictures of the batterys I'm wanting to put on the bike and the kit I'm using.

Any help would be great TIA

 

[Al in CT]

If I were you, I would just carry the second battery and swap it out when the first one is done. That way you know when to turn around and go back! That is one heck of a battery. How do your rim brakes do fighting this battery? I am asking because I have a nice "comfort bike" that I would like to convert as well. thanks

 

[Locko90]

Yeah mate thought of doing that but don't want to be carrying a second battery in a bag for long rides. I'm only getting about 30km distance on a full charge with the battery I have now. So getting a second battery would give me about 60km distance all up.
I'm more aiming to get at least 100km distance on a full charge.

The rim breaks do the job man haha

 

[harryS]

From experience, I can tell you that those inexpensive panniers rip apart and spill our spare batteries into the street.

I parallel some of my batteries with XT60 connectors and 14G silicone wire. I've noted that most ebike parts (controllers, battery cradles, etc) only use 14G. Should be OK for 500W motors.

 

[rich c]

From experience, I can tell you that those inexpensive panniers rip apart and spill our spare batteries into the street.

I parallel some of my batteries with XT60 connectors and 14G silicone wire. I've noted that most ebike parts (controllers, battery cradles, etc) only use 14G. Should be OK for 500W motors.

Every eBay bag of any kind I've purchased has sewing issues in the seams. You also shouldn't buy just any rack either. Carrying those two big battery packs will exceed the weight limit on many racks.

 

[Locko90]

Thanks for the info guys, something to keep in mind when getting the pannier.

So I'm thinking I'm going to have to open up the battery dock and add an extra positive and negative wire from the inbuilt controller to one of the new 48 volt batterys.

Then I would just solder the positive and negative of both 20ah batterys together then it should be all good?

Adding this much extra battery capacity won't break my built in controller?

 

[harryS]

The AH capacity doesn't affect the controller. It draws as much as its design will permit, depending on the voltage, If you increased the voltage, it would eventually break the controller.

One practice you must follow is to connect these packs together only when they are at the same voltage. Probably a quarter volt is safe. If one pack happened to be discharged while other were fully charged, huge currents would flow and bad things would surely happen.

Another thing that can happen when you're riding with two or more packs in parallel. One becomes disconnected at some point. Resist the temptation to re-connect if you don't know the relative voltages.

For that reason, and because you will be using such large AH packs, doing what Al suggests, running one pack at a time, and switching when one goes flat is a safer approach.

 

[Locko90]

The AH capacity doesn't affect the controller. It draws as much as its design will permit, depending on the voltage, If you increased the voltage, it would eventually break the controller.

One practice you must follow is to connect these packs together only when they are at the same voltage. Probably a quarter volt is safe. If one pack happened to be discharged while other were fully charged, huge currents would flow and bad things would surely happen.

Another thing that can happen when you're riding with two or more packs in parallel. One becomes disconnected at some point. Resist the temptation to re-connect if you don't know the relative voltages.

For that reason, and because you will be using such large AH packs, doing what Al suggests, running one pack at a time, and switching when one goes flat is a safer approach.

just curious mate, would it be better to wire the 2 20ah battery's in parallel then connect via charge port on the Dillinger 14ah battery? not sure if this would damage the battery charge port.
also not sure what bms is in the 20ah battery off ebay.

or would it bet better to open the battery dock and solder a connection from the 2 20ah batteries straight to the controller.


if anyone has made a booster battery for there kit would be good to hear from anyone that has done this before.

 

[Locko90]

I watched this video on youtube showing the process to building a booster battery for an escooter, ill add the video link.
In the video he builds a battery with a 2 way bms and plugs the booster battery straight in to the original battery charge port. effectively doubling the battery capacity.

only thing im unsure about is if I do this with 2 20ah batterys directly into my original battery charge port will it damage the charge port/controller/bms?
like I stated before the 2 20 ah batterys are 48v, the same voltage as original battery.

also im unsure of the cell type difference between the 3 battery's, will this matter if the battery's are of the same voltage?


video link.

 

[harryS]

I don't follow use of the charge port, other than it allows you to charge both packs off the booster packs charge port. When the motor is running, I believe the booster can only charge the main pack. Maybe I 'll set some batteries up like that and see where the current goes.

I would connect all three in parallel.

 

[Locko90]

I took apart the controler/dock

Looks like it's max current is 20ah.

Would I be able to run higher capacity then 20 ah battery with this controler?

Like say add a 10 ah battery to make a total of 24ah.

Or could I upgrade the controler and still use the same wiring harness?

 

[Dave711]

My solution was to buy a Laudation 20 AH, 48 volt battery on eBay and run my hot wires through a 3 position rocker switch before the controller. One position on the switch provides power from my Rad Mini battery, one position provides power from the Laudation battery. In the neutral position, both batteries are off. I soldered quick disconnects to the Laudation battery so I could remove it from the mini easily. I had an old tank bag from my DR650 which the battery nestles into easily. I used to get about 30-35 miles useful range out of the mini's stock battery; now my range is more than double that. Tired of constantly strapping and unstrapping my Laudation battery from the bike, I recently bought a basket that the battery fits into nicely.

 

[Dave711]

Thanks for the info guys, something to keep in mind when getting the pannier.

So I'm thinking I'm going to have to open up the battery dock and add an extra positive and negative wire from the inbuilt controller to one of the new 48 volt batterys.

Then I would just solder the positive and negative of both 20ah batterys together then it should be all good?

Adding this much extra battery capacity won't break my built in controller?

I think you're getting some bad advice on voltages. When batteries are wired in parallel, their voltages are identical; only the capacity changes. Low voltage means your motor won't turn or won't turn for long: think of your car. When your car battery is low, it can't turn the motor or can turn it for a brief time. Output at the battery - still 12V, no amps.
I like switching between batteries manually because if one battery gets depleted, you'll know and you might decide to turn around at that point. If all wired together and online at the same time, you might not know how much charge you have left.

just curious mate, would it be better to wire the 2 20ah battery's in parallel then connect via charge port on the Dillinger 14ah battery? not sure if this would damage the battery charge port.
also not sure what bms is in the 20ah battery off ebay.

or would it bet better to open the battery dock and solder a connection from the 2 20ah batteries straight to the controller.


if anyone has made a booster battery for there kit would be good to hear from anyone that has done this before.

 

[Allroads]

I went the simple route without wiring an extra cell. If I can't have a clean install and hide an extra battery. I decided to install a wire basket on the rear and swap out the batteries at will. Living in big cities I don't feel I want to bring attention to my setup with loose wires hanging off the frame. I purchased my extra 48v 14ah cell on Alibaba in March for $375 delivered.

 

[harryS]

I took one of my spare packs and connected it to the charge port of another battery and went riding. This bike has a 22A controller. On throttle, the motor gets 22A from the main battery, and the aux pack contributes 5A which must go toward charging. On coasting, the main pack shuts off, and the aux pack supplies 5A for another few seconds and then quickly trails off.

It works as advertised, but the main pack still shoulders all of the work. I think it's better from pack longetivity having them in parallel where both packs would supply 11A each, instead of one does 22A.