Regenerative braking with 2 batteries

[tsunamas]

Hello everyone,

Few weeks ago I bought this beautiful cargo bike from a local food delivery boy to start a project.
Details here (https://www.sunmono.com.au/product/e-mono-20-electric-cargo-bike-se-20b001-my19/)
I loved that it has double hailong battery (48v 15Ah X 2) and for the price seemed really convenient.

From here I would like to paint the frame and install a GMAC motor kit from Grin Tech. The problem is that but I'm not sure how should I proceed with the installation of the kit having a double battery, I'm not even sure how are the batteries connected between them. Could you guys tell me what should I be checking on to make sure i can add this kit to this batteries without doing any harm? I'm specially concerned about the regen energy going back to them, could this be dangerous?

Thanks beforehand. Also, this is my first post so If i'm breaking some rule please let me know.

Thanks,
Jorge

 

[markz]

Triple measure your rear dropout width so you buy the right hub motor. Yours look like a fat bike width.
Good news is there is lots of flat space on the rear axle bolts.

My advice for you is to not have such a shiny, eye catching paint job. Best is to have a black (frame) on black (motor) on black (rims) on black (spokes) on black everything. Get some black duct tape and cover that white writing on the batteries.

What voltage and Ah are those batteries?

 

[99t4]

I'm not even sure how are the batteries connected between them.

You'll have to study the wiring between the batteries. Provide some clear photos if you're not sure what you're looking at.

Guessing they are wired parallel, since they advertise 48V 31Ah. If they are in fact wired parallel, the controller sees them as one large 48V 31Ah battery, regen no more problematical than usual. Just make sure to not apply regen when the battery is full, or near full.

I like the color scheme. How much does it weigh?

 

[E-HP]

Hello everyone,

Few weeks ago I bought this beautiful cargo bike from a local food delivery boy to start a project.
IMG_4939.jpg Details here (https://www.sunmono.com.au/product/e-mono-20-electric-cargo-bike-se-20b001-my19/)
I loved that it has double hailong battery (48v 15Ah X 2) and for the price seemed really convenient.

From here I would like to paint the frame and install a GMAC motor kit from Grin Tech. The problem is that but I'm not sure how should I proceed with the installation of the kit having a double battery, I'm not even sure how are the batteries connected between them. Could you guys tell me what should I be checking on to make sure i can add this kit to this batteries without doing any harm? I'm specially concerned about the regen energy going back to them, could this be dangerous?

Thanks beforehand. Also, this is my first post so If i'm breaking some rule please let me know.

Thanks,
Jorge

Does the bike currently work? If so, unless there's a switch to switch from one battery to the other, then they are likely connected in parallel, so both batteries are always being used. If there's a switch, then it's set up to use one battery at a time. In either case, regen shouldn't be a concern, if you're sticking with 48V.
You should figure this out first (the configuration), since it may impact how to safely charge the batteries, which is a bigger concern than regen.

EDIT: Another configuration might be that one battery is just mounted but not connected, so you manually switch batteries. But, zooming in on the pics from the link, it looks like the front battery has one cable running to the rear battery mount. It looks like that's where the controller is located too, since on another picture, you can see the cable going to the motor, coming out from the same location. Seems like the batteries are attached in parallel, unless there's a cutover switch somewhere in that area.

 

[LewTwo]

I like the color scheme. How much does it weigh?

21kg (46 pounds) per the web site which is darn light for that much battery

Yep, I like the bright, beautiful yellow frame as well.

 

[markz]

If they are in parallel then the batteries need extra circuitry to isolate each battery, or they are manually changed, unplug one, plug in the other which is exactly what I do for a 36V 40A controller and 52V 14.5Ah battery and a 36V 20Ah battery. Louis Rossmann
showed the circuitry used for two batteries on youtube. Diodes. Bridge Rectifier I thinks the term.
https://www.youtube.com/user/rossmanngroup/videos

 

[tsunamas]

Both batteries are Samsung 48v 15.5Ah.

I'm not even sure how are the batteries connected between them.

You'll have to study the wiring between the batteries. Provide some clear photos if you're not sure what you're looking at.

Today I removed almost everything from the frame to start with the painting and opened the battery cases to check how are they connected. It is actually paralel

 

[mat h physics]

Not affiliated: https://eunorau-ebike.com/collections/ebike-maintance/products/eunorau-second-battery-connector

 

[tsunamas]

Not affiliated: https://eunorau-ebike.com/collections/ebike-maintance/products/eunorau-second-battery-connector

Hi,
What difference would that device make?

 

[E-HP]

Not affiliated: https://eunorau-ebike.com/collections/ebike-maintance/products/eunorau-second-battery-connector

Hi,
What difference would that device make?

There's no information on the device, but the wires look awfully tiny for any real battery current, although it's hard to judge scale without any dimensions.

This unit looks similar, but obviously has some smarts built into it. If manually paralleling two batteries, it's important for them to be very close in voltage before connecting them, so one doesn't fry the other. This device allows both batteries to be connected, even at different voltages/states of charge, and the unit is smart enough to use the one with the higher voltage, until it drops enough to parallel the second battery. Less error prone for a newbie or if you're worried about a lapse in attention that could lead to a fire.

https://wattwagons.com/products/dual-battery-converter

 

[tsunamas]

Not affiliated: https://eunorau-ebike.com/collections/ebike-maintance/products/eunorau-second-battery-connector

Hi,
What difference would that device make?

There's no information on the device, but the wires look awfully tiny for any real battery current, although it's hard to judge scale without any dimensions.

This unit looks similar, but obviously has some smarts built into it. If manually paralleling two batteries, it's important for them to be very close in voltage before connecting them, so one doesn't fry the other. This device allows both batteries to be connected, even at different voltages/states of charge, and the unit is smart enough to use the one with the higher voltage, until it drops enough to parallel the second battery. Less error prone for a newbie or if you're worried about a lapse in attention that could lead to a fire.

https://wattwagons.com/products/dual-battery-converter

That one looks great, and bring me to my other question; how would that work with the energy coming to the batteries from the regenerative breaking?

 

[E-HP]

That one looks great, and bring me to my other question; how would that work with the energy coming to the batteries from the regenerative breaking?

Probably solves one problem and creates another. Too costly a gamble to find out, so you better ask the vendor if you're going to spend that much on it. Or, you can just have a disciplined charging routine, which you should have regardless.

 

[tsunamas]

Probably solves one problem and creates another. Too costly a gamble to find out, so you better ask the vendor if you're going to spend that much on it. Or, you can just have a disciplined charging routine, which you should have regardless.

Yes, i think this stuff is putting off the idea of the regenerative breaking.

I’ll message the vendor to see if maybe there is an easy way.

 

[E-HP]

Probably solves one problem and creates another. Too costly a gamble to find out, so you better ask the vendor if you're going to spend that much on it. Or, you can just have a disciplined charging routine, which you should have regardless.

Yes, i think this stuff is putting off the idea of the regenerative breaking.

I’ll message the vendor to see if maybe there is an easy way.

I think if the two battery packs have 2-wire BMSs, then they can be connected in parallel AND charged through their discharge ports. That would mean that once you get them to the same voltage and parallel the two packs, you can keep them that way and charge both at once through the paralleled connections. If you are handy, and you currently have 3-wire BMSs (likely), you could replace them with 2-wire ones. Should be fine with regen too.

https://endless-sphere.com/forums/viewtopic.php?t=66250#p1154278

I haven't tried it, but the experts can explain more or if I'm wrong about it.

 

[Corrida victim]

Have you found out if these hailong batteries are shipped with a common port (2 wires) or seperate port (3 wires) BMS?

I'm looking to buy some of these second hand as a range extender. But only if they have a common port BMS. Otherwise it's too impractical

 

[NathanD]

Not affiliated: https://eunorau-ebike.com/collections/ebike-maintance/products/eunorau-second-battery-connector

Hi,
What difference would that device make?

There's no information on the device, but the wires look awfully tiny for any real battery current, although it's hard to judge scale without any dimensions.

This unit looks similar, but obviously has some smarts built into it. If manually paralleling two batteries, it's important for them to be very close in voltage before connecting them, so one doesn't fry the other. This device allows both batteries to be connected, even at different voltages/states of charge, and the unit is smart enough to use the one with the higher voltage, until it drops enough to parallel the second battery. Less error prone for a newbie or if you're worried about a lapse in attention that could lead to a fire.

https://wattwagons.com/products/dual-battery-converter

Hello - my first post here. I've just bought the same Mono Cargo bike as the OP (https://www.sunmono.com.au/product/e-mono-20-electric-cargo-bike-se-20b001-my19/), but the electrics seem compromised by me testing a more powerful front light on tiny wires , and while I have managed to unlock the LCD M5 display the manufacturer isn't being forthcoming with the protocol data I need to make sure all that is OK before I commit to an overhaul. The batteries seem to be in great condition, and the frame and motor seems rock solid with very low mileage.
I think that I'll probably need to go down the route on a new controller/display and wiring that will work with the dual batteries. I'm fine without regen breaking, and will be disciplined with battery charging. Can someone please point me in the right direction for a "fool proof" straightforward solution that will be virtually plug and play with my current dual batteries and motor?
Kind regards!

 

[Phasedout]

I don't think these devices are smart. They simply have diodes on each battery, so no reverse current flow is allowed. No Regen with these.
You have 2 identical batteries, paralleled from the manufacturer. I would think they have some idea how to do it.

 

[NathanD]

Well, it turns out that I cooked the 5V circuit on the controller (housed in the Hailong battery mount) by connecting the Hermanns light. I've ordered a Baserunner, CA and assorted bibs and bobs from Grin to make it run again. The batteries were simply wired together in parallel inside the controller.
I'll run it as a single battery model, and if I need the extra range, will carry and swap over the batteries when needed. It'll be nice to have regen braking. I'll use a switched DC DC convertor from the CA power out jack to run the headlight.