DIY: Range extender for Levo (and Kenevo)

[villho]

Range extenders seem to be a hot topic nowadays and there are already some commercially available options (Levo Range Extender, Levorex, Trailwatts) to select from. However, IMO they are quite expensive. I did not want to pay ~500 EUR for a battery that I need only on those long, full-day rides a few times a summer. Hence, I decided to make one of my own. The technology is basically the same as with the commercial options, but I was able to even tune it with a bluetooth-equipped BMS.

I already wrote a longer how-to in a Finnish cycling discussion forum, but maybe it's good to share the basics here as well, because I bet there are some Doc Emmett Browns in this forum as well interested on the topic. Of course (and for a person, who believes that everyone is responsible of their own mistakes, this sounds stupid) I will not take any responsibility if you burn your bike, blow up your house or lose your eyesight when a cell explodes on your face or any such thing.

LONG STORY SHORT:

Stuff needed:

• Case to put the battery in (I used a plastic tool pipe that I needed to form with a heat gun)
• Cells. I recommend to use only quality ones. I used 3350 Ah rated Sanyo 18650 cells ordered from Nkon.
• BMS. I used bluetooth-enabled "smart" BMS, ordered from GreenBikeKit
• "Ideal diodes". You need to have a way to avoid current flowing from one battery to another. There are few options for this, but ideal diodes are the best. I ordered that directly from the manufacturer re-voltage.eu
• All kinds of small stuff (nickel strips, battery holders, wire, shrink wrap, solder, glue, connectors....)

Tools needed:

• Quality soldering iron
• Hot air gun
• Drill
• Other basic tools

Steps:

1. Work with the battery case. My plastic tool pipe did not fit L size Levo at first, so I used the heat gun to soften the plastic and then re-formed it to fit in. Reforming made it quite bumpy and lumpy, so I mixed some 2-component plastic/polymer padding, spread it and sanded down. Thats the reason, why you see in some photos that the pipe has white/grey-ish cast.
2. Assemble the cells. Youtube is full of instructions for this. I made 10S2P, which means roughly 250 Wh. I did not have a spot welding machine, so I ended up soldering the cells together. Having a powerful soldering iron minimizes the time that you need to heat up the cell. Heat = not good. I did try make a spot-welder from car battery, solenoid and some copper nails, but after seeing the colour of lithium flame after puncturing one of the cells (luckily I ordered 21, i.e. one extra), I decided that heat or not, but I will solder them together
3. Connect the BMS. BMSes differ a bit from each other, so I will not give instructions to this either - the basic principle is to have BMS connected to the both ends of the battery (full voltage) and then also to all the +'es in between the battery. This way BMS can monitor the charge, discharge and cell balance.
4. Bluetooth and other battery connections. I plugged in the bluetooth and the app started to work right away. I was really surprised, asit was so easy. Then, I probably could have had just one set of leads for both charge and discharge, but ended having one for charging (inside the case, which is easy to open) and one outside the case for discharge, i.e. to attach to the bike. The BMS also had two temperature sensors: I put one between the cells and glued the other on top of the BMS heatsink. For charge and discharge connectors I used Amass XT60 that can easily handle the needed currents.
5. Connections to the bike. Ok, this is important: you don't want the current to flow between the batteries but only from battery/-ies to the motor. In order to do that, I used "ideal diodes" and needed two of them. I'm not an electrical engineer, but I drew a simple diagram for this (check below). I made the connections so that it's not that easy to return the bike to the factory form (I have the diodes on top of the motor, no need to remove the crank to get to them), but you can do this also so that you put the diodes under the motor (like commercial options have) and then have an extra battery -> motor cable. This way you can quite easily take away this tune. In any case, I'm not worried on voiding the warranty on my bike - if the bike has worked already a year, why would it break down anymore at this point
6. All done. I made a test ride and no smoke or flames and based on the iOS app also the extra battery got involved even though the batteries had different voltages to start with, so all good.
7. Finalization and paint-up. Hey, one needs to have a name for this type of thing. I named this to "Olkiluoto 4". Olkiluoto 3 is a nuclear power plant here in Finland, which has gotten delayed for like a decade due to all kinds of problems during the building phase. It is to be started next year, but I already have Olkiluoto 4 up and running over here

Cost:

• Case ("free" as I had it laying in the carage)
• Cells (~90 EUR)
• BMS (35 EUR)
• Ideal diodes (63 EUR for two)
• Small things (15-20 EUR)
• iOS app (1 EUR)

--> ~210 EUR I also bought 2 Amps @ 42 V charger (25 EUR).

Links:

• Levo Range Extender
• Levorex
• Trailwatts
• Nkon
• Ideal Diodes
• GreenBikeKit
• Xiaoxiang BMS (iOS app)

Photos:

Tool pipe is taking its shape. It has already seen the heat gun as it fits the Levo frame. I needed to turn the CC coil show up-side down.

Cells are already soldered and BMS being soldered. Zip tie is keeping the BMS in place during this.

Wiring up the bike. Ideal diodes are under the shrink wraps. They fit well on top of the engine. I used 4 mm2 wires which probably were an overkill. I also secured the + wires with additional webbing in the places where it might get some friction and wore out the insulation.

A simple diagram for wiring up the diodes. "Lisäakku" = the extra battery. "Levon oma akku" = Levo's own battery. "Pyörän moottori" = the motor.

All secured inside shrink wrap, bluetooth on and battery being charged.

Ready for the test ride!

A view to the app. Olkiluoto 4 is powering my Levo.

All done and finalized - ready for the long rides!

 

[Maastricht]

Congratulations with the result and big thanks for the detailed post!

Very impressive for a non electrical engineer!

 

[villho]

Thanks I didn't say I'm not an engineer - I'm just not an electrical engineer

There's nothing in this project that Google and a few carefully selected search phrases wouldn't reveal.

 

[Maastricht]

May I ask you a few more questions? I also asked the same in the Trail Watt thread...

On Aliexpress or other websites I can find these ones:
US $199.0 |Mini Kettle battery 36V 5.2ah 5.8Ah 6.4ah 7ah ebike Lithium Battery 36V 250W 350W Electric bicycle Battery -in Electric Bicycle Battery from Sports & Entertainment on Aliexpress.com | Alibaba Group

or this one:
US $210.4 20% OFF|36V 6.4Ah 6.8Ah 7.8Ah E Bike lithium Battery Newest small mini water bottle Battery with USB for 250W 500W motor-in Electric Bicycle Battery from Sports & Entertainment on Aliexpress.com | Alibaba Group

It would be almost the same investment as yours but much more easy to do for a non (electrical) engineer. They offer these with the following cells:
36V 5.2AH with Samsung 2600mah cell
36V 5.8AH with Samsung 2900mah cell
36V 6.4AH with Panasonic 3200mah cell
36V 7AH with Sanyo 3500mah cell

I am thinking of maybe buying such a booster and just fabricate own wiring.

What is your opinion? Do you think a diode is already part of these boosters?

 

[villho]

I'm 99,978 % sure that they do not include diodes - in the end, why would they, as the need of diode(s) really depends on the use case.

Actually, I probably would have built my custom-battery into one of those bottles, but didn't find any place where someone would be selling just empty bottles (and I was too lazy to ask about that option). TBH, they are much better form and fit, but I have to admit that I do also like the way how my own personal nuclear power plant looks like.

So, if you end up ordering one of those bottles, you need to prepare yourself to install those diodes and set up the wiring as in my diagram. That is not difficult, but you do need to make the step on cutting the standard battery-motor cable.

 

[Maastricht]

I'm 99,978 % sure that they do not include diodes - in the end, why would they, as the need of diode(s) really depends on the use case.

Actually, I probably would have built my custom-battery into one of those bottles, but didn't find any place where someone would be selling just empty bottles (and I was too lazy to ask about that option). TBH, they are much better form and fit, but I have to admit that I do also like the way how my own personal nuclear power plant looks like.

So, if you end up ordering one of those bottles, you need to prepare yourself to install those diodes and set up the wiring as in my diagram. That is not difficult, but you do need to make the step on cutting the standard battery-motor cable.

Thanks for your reply! I will think about it. I will anyway never cut the original cable. I would buy a spare one if I start experimenting.

I recognize your bottle, they use it to store manuals like on the mini wheelloaders below:

 

[villho]

Yeah, that's it. The bottle even said on the cap "User manual inside". Over here, guys have been using those to store tire tools etc. on their BMW GSes etc. such bikes. I had a similar idea, but never implemented it, before I sold the Beemer. Now I just have KTM EXC and Levo, but all the rides I did last summer were with Levo.

 

[Mcharza]

Well done. I especially like the name Olkiluoto 4, you was faster than Olkiluoto 3 (inside finnish joke)

 

[R120]

Top bodging!

 

[Xeretic]

Range extenders seem to be a hot topic nowadays and there are already some commercially available options (Levo Range Extender, Levorex, Trailwatts) to select from. However, IMO they are quite expensive. I did not want to pay ~500 EUR for a battery that I need only on those long, full-day rides a few times a summer. Hence, I decided to make one of my own. The technology is basically the same as with the commercial options, but I was able to even tune it with a bluetooth-equipped BMS.

I already wrote a longer how-to in a Finnish cycling discussion forum, but maybe it's good to share the basics here as well, because I bet there are some Doc Emmett Browns in this forum as well interested on the topic. Of course (and for a person, who believes that everyone is responsible of their own mistakes, this sounds stupid) I will not take any responsibility if you burn your bike, blow up your house or lose your eyesight when a cell explodes on your face or any such thing.

LONG STORY SHORT:

Stuff needed:

• Case to put the battery in (I used a plastic tool pipe that I needed to form with a heat gun)
• Cells. I recommend to use only quality ones. I used 3350 Ah rated Sanyo 18650 cells ordered from Nkon.
• BMS. I used bluetooth-enabled "smart" BMS, ordered from GreenBikeKit
• "Ideal diodes". You need to have a way to avoid current flowing from one battery to another. There are few options for this, but ideal diodes are the best. I ordered that directly from the manufacturer re-voltage.eu
• All kinds of small stuff (nickel strips, battery holders, wire, shrink wrap, solder, glue, connectors....)

Tools needed:

• Quality soldering iron
• Hot air gun
• Drill
• Other basic tools

Steps:

1. Work with the battery case. My plastic tool pipe did not fit L size Levo at first, so I used the heat gun to soften the plastic and then re-formed it to fit in. Reforming made it quite bumpy and lumpy, so I mixed some 2-component plastic/polymer padding, spread it and sanded down. Thats the reason, why you see in some photos that the pipe has white/grey-ish cast.
2. Assemble the cells. Youtube is full of instructions for this. I made 10S2P, which means roughly 250 Wh. I did not have a spot welding machine, so I ended up soldering the cells together. Having a powerful soldering iron minimizes the time that you need to heat up the cell. Heat = not good. I did try make a spot-welder from car battery, solenoid and some copper nails, but after seeing the colour of lithium flame after puncturing one of the cells (luckily I ordered 21, i.e. one extra), I decided that heat or not, but I will solder them together
3. Connect the BMS. BMSes differ a bit from each other, so I will not give instructions to this either - the basic principle is to have BMS connected to the both ends of the battery (full voltage) and then also to all the +'es in between the battery. This way BMS can monitor the charge, discharge and cell balance.
4. Bluetooth and other battery connections. I plugged in the bluetooth and the app started to work right away. I was really surprised, asit was so easy. Then, I probably could have had just one set of leads for both charge and discharge, but ended having one for charging (inside the case, which is easy to open) and one outside the case for discharge, i.e. to attach to the bike. The BMS also had two temperature sensors: I put one between the cells and glued the other on top of the BMS heatsink. For charge and discharge connectors I used Amass XT60 that can easily handle the needed currents.
5. Connections to the bike. Ok, this is important: you don't want the current to flow between the batteries but only from battery/-ies to the motor. In order to do that, I used "ideal diodes" and needed two of them. I'm not an electrical engineer, but I drew a simple diagram for this (check below). I made the connections so that it's not that easy to return the bike to the factory form (I have the diodes on top of the motor, no need to remove the crank to get to them), but you can do this also so that you put the diodes under the motor (like commercial options have) and then have an extra battery -> motor cable. This way you can quite easily take away this tune. In any case, I'm not worried on voiding the warranty on my bike - if the bike has worked already a year, why would it break down anymore at this point
6. All done. I made a test ride and no smoke or flames and based on the iOS app also the extra battery got involved even though the batteries had different voltages to start with, so all good.
7. Finalization and paint-up. Hey, one needs to have a name for this type of thing. I named this to "Olkiluoto 4". Olkiluoto 3 is a nuclear power plant here in Finland, which has gotten delayed for like a decade due to all kinds of problems during the building phase. It is to be started next year, but I already have Olkiluoto 4 up and running over here

Cost:

• Case ("free" as I had it laying in the carage)
• Cells (~90 EUR)
• BMS (35 EUR)
• Ideal diodes (63 EUR for two)
• Small things (15-20 EUR)
• iOS app (1 EUR)

--> ~210 EUR I also bought 2 Amps @ 42 V charger (25 EUR).

Links:

• Levo Range Extender
• Levorex
• Trailwatts
• Nkon
• Ideal Diodes
• GreenBikeKit
• Xiaoxiang BMS (iOS app)

Photos:

Tool pipe is taking its shape. It has already seen the heat gun as it fits the Levo frame. I needed to turn the CC coil show up-side down.

Cells are already soldered and BMS being soldered. Zip tie is keeping the BMS in place during this.

Wiring up the bike. Ideal diodes are under the shrink wraps. They fit well on top of the engine. I used 4 mm2 wires which probably were an overkill. I also secured the + wires with additional webbing in the places where it might get some friction and wore out the insulation.

A simple diagram for wiring up the diodes. "Lisäakku" = the extra battery. "Levon oma akku" = Levo's own battery. "Pyörän moottori" = the motor.

All secured inside shrink wrap, bluetooth on and battery being charged.

Ready for the test ride!

A view to the app. Olkiluoto 4 is powering my Levo.

All done and finalized - ready for the long rides!

Does installation of this booster include cutting the original wiring?

 

[khorn]

Does installation of this booster include cutting the original wiring?

All booster kits need a modified wire loom, DYI mean either cutting your stock loom or buy a spare to modify.

Karsten

 

[Xeretic]

All booster kits need a modified wire loom, DYI mean either cutting your stock loom or buy a spare to modify.

Karsten

Is this the correct item for cutting in the booster?
Specialized Levo Custom Wiring Harness with Rosenberger Plug - S166800008, S176800002

 

[xcentric]

I'm 99,978 % sure that they do not include diodes - in the end, why would they, as the need of diode(s) really depends on the use case.

Presumably you could add the diodes between the output of one of these pre-made bottle batteries and the motor (i.e. inline with the wiring loom?)

EDIT: seems this is essentially what you did with your battery pack anyway! So it should be easy to do.

However, the only problem I see remaining is that there are two battery management systems now, and each doesn't know about the other, and so there's a slight chance that they are unbalanced between the packs. Does that matter?

 

[xcentric]

.....and does anyone know where to order a spare wiring loom from - asking my lbs seems like a daft idea.....

 

[villho]

For example from Bike24. You get the part no. from that page as well. The cost is relatively high 70 EUR + postage and that’s why I decided not to have a spare one. I can always order it, if needed.

EDIT: Xeretic already had this in his message. I missed the earlier messages as I was reading the thread by phone.

 

[villho]

Presumably you could add the diodes between the output of one of these pre-made bottle batteries and the motor (i.e. inline with the wiring loom?)

EDIT: seems this is essentially what you did with your battery pack anyway! So it should be easy to do.

However, the only problem I see remaining is that there are two battery management systems now, and each doesn't know about the other, and so there's a slight chance that they are unbalanced between the packs. Does that matter?

Sorry, I was reading the thread by phone so missed the earlier messages.

Yes, if you buy a ready-made battery bottle, you can do exactly that: put a diode inline with the wiring that leaves the bottle (or depending on the wiring, even inside the bottle). The ground can be common between all the batteries, diodes and the motor (see my diagram and black connection). Please do remember that one diode is not enough, but you need to have one for each battery - also for the original battery. If you don't do that and your range extender has a higher voltage, your Levo battery goes to charging mode - and no, you don't want that to happen during a ride

Ideal diode manufacturer says that with currents up to 15 amps, a diode does not require any additional cooling etc. so we should be good with Levo (250 W @ 36 volts = ~7 amps, and while it peaks more, I wouldn't worry a bit).

The core thing with the ideal diodes is that you can have batteries with different capacities in use at the same time. For example: Levo's own battery at (let's say) 50 % capacity and the additional battery at (let's say) 95 % capacity. In practice the both batteries give current, but in this scenario the most of the current comes first from the additional battery which has higher voltage (capacity). This happens until the voltages level out between the batteries and then the voltages go down "hand in hand". Then it depends on the BMS' settings that how low it lets the battery go, i.e. what is the voltage, when BMS considers that 0 % capacity remains. When that happens, it in practice shuts down the battery. Now, if there is an electrical engineer, who notices that I said something wrong above, please correct me.

One needs to remember that if Levo's battery is empty, it doesn't help if you have the additional battery full, i.e. you need to have at least some capacity in the original battery and it needs to be on.

***

And BMSes take care of only the battery that they are attached to. They don't "see" each other in any way and don't mess each other. See the photo where I'm making soldering for the BMS - a BMS has lots of small wires that are attached to the battery structure for monitoring the voltages of individual cells (or cell pairs, cell triplets...). This below is not my diagram, but gives a good idea how BMS is attached to the battery. (It needs to be noted that in this diagram the charging is happening through the same port than the load is taken from. In my battery, I have separate ports and leads for charging and load. There are also other ways to connect a BMS but that depends on the BMS one has.)

 

[xcentric]

what is the physical size of your bottle?

 

[villho]

This is probably the easiest way to tell:

The cap part is basically empty and while it's quite tight fit for the cell structure on the other end, I would say that leaving out the black plastic cell spacers (can be seen in the soldering photo) and building the cell structure again and directly in to this shape, I should be able to squeeze in quite easily also one additional set of 10 cells making the full Wh up to 378. Maybe I'll do it later, maybe not.

 

[ccrdave]

that with currents up to 15 amps, a diode does not require any additional cooling etc. so we should be good with Levo (250 W @ 36 volts = ~7 amps, and while it peaks more, I wouldn't worry a bit).

@villho levo battery puts out 20amps at peak, is that a problem for the diodes without cooling?

 

[villho]

As long as you don't wrap the diodes in big chunk on heat shrink that insulates it totally, I wouldn't worry a bit. This is what the manufacturer says:

The maximum continuous current depends on the permissible temperature rise, the level of heatsinking and the air circulation around the module.

• Up to 15 A, no heatsink or special precautions are necessary.
• Up to 20 A, some means of carrying a small amount of heat away is recommended, eg., a small heatsink, forced airflow, connection to a busbar or stacked with another ID not carrying the same current.
• At 25 A a means of carrying heat away is needed.
• 30 A and over is possible with careful heatsinking. Above 25 A, however, it is worth considering paralleling modules. For instance, 2 modules in parallel will carry 30 A with no heatsink, whereas a single module will require a heatsink.

The key word there is "continuous".

One needs to note that the moments, when a range extender is in use, then in practice you are having two diodes in parallel. Which means that if the motor draws 20 amps, those amps will be split between two diodes (the exact amounts depend on the ratio how the current is drawn from the batteries).

Only if you have a customized wiring (incl. diodes) and you are using only Levo's own battery, then all the current goes through one diode. Still, having peaks at 20 amps and the continuous current somewhere 2-7 amps (depending on the assistance level) I would just smile and ride

 

[villho]

We are having a transition period from winter over here in Finland and I haven't ridden the bike properly since I got the DIY range extender done, but finally took a proper test ride yesterday. Actually to test the diodes and their heat management. Bike was de-restricted by BLevo, so I ended up riding 6 km with quite a good effort: turbo mode, average speed 29 km/h and average assistance of 97 %, so kind of "full steam" all the way. Once I got back, I opened the plastic frame piece quickly and measured the surface temperature of the diodes and it was basically the same as ambient. This was with running the both batteries in parallel. Maybe I try the same with just the original battery, but I would be really surprised if heat would cause any problems.

Is anyone else already building or planning to build their own extender?

 

[xcentric]

Currently debating whether to buy a spare and bigger battery from Specialized at a very good price, or do a DIY one using a Chinese bottle battery and the instructions above, plus a new loom, and saving a few hundred quid. But as I've not had time to get the current battery discharged yet, it's all a bit moot!!

 

[Andy A]

Currently debating whether to buy a spare and bigger battery from Specialized at a very good price, or do a DIY one using a Chinese bottle battery and the instructions above, plus a new loom, and saving a few hundred quid. But as I've not had time to get the current battery discharged yet, it's all a bit moot!!

I would get the proper Speciaized 700wh battery I know these range extenders are popping up everywhere but to me they just look like a DIY job and I know that's what they are but to me they just don't look right, with a strap here and some tape here and a wire going in here etc a bit naff, get the proper thing

 

[villho]

If I'd have a chance of OEM 700 Wh battery (which I don't with my 2018 model bike) or to save few hundred £ and build a range extender, for sure I'd also take the OEM battery. I'd probably then sell the 500 Wh battery and be then close to break-even.

One needs to remember that while OEM batteries work on their own, the range extenders always require an OEM battery and it having also some capacity. Then (unless you cut and modify the charger cables) you need to have two separate chargers as well.

However, I wouldn't (and I won't) hesitate using a range extender either. The installation is neat and tidy, it's done well with quality parts (I know, because I've done it ) and if needed, I can always take it out, and for sure it raises interest, when people see my personal nuclear power plant. I know that building such a thing is not for everyone (hey, some people take their bikes to a shop for even the smallest of maintenance thing), but to be honest, I like sitting in garage and tinkering with this stuff. It's the same thing with my cars and motorcycles - I like to know how their innings work.

 

[Maastricht]

@villho, for the future I am considering a Chinese bottle battery and then adding own wiring. I am only questioning myself if the diodes which you explained to us are really necessary.

I have been watching pictures of other range extender builders especially when I look at the pictures of their wiring booms I can't discover any diodes. So I can imagine that they maybe place one diode in the range extender itself but where did the leave the 2nd diode then which is required for the original Levo battery?

If the diodes wouldn't be required then that would be a huge benefit as the disadvantage is them being out in the open on top of the motor in a moisture environment. Do you have any idea why others don't seem to use them?

 

[villho]

I am only questioning myself if the diodes which you explained to us are really necessary.

I have been watching pictures of other range extender builders especially when I look at the pictures of their wiring booms I can't discover any diodes.

One way or another they avoid current between the batteries. I’m not going to ask from them directly, but to my understanding Italian Levorex and Belgian Levo range extender use ideal diodes and British Trailwatts some custom solution (which in the end might be exactly the same principle as ideal diode, but I’m not sure). Levorex web page itself says that they use ideal diodes and even show a diagram (added with some optional relays) what the setup is (basically the same that I have). And the photos that I’ve seen from those custom harnesses, look exactly like that they’d have the diode(s) under some shrink wrap. The diodes are not big, just some 2x4 cm or so, i.e surprisingly small. One fits easily to the bottle and the other to the harness.

Let’s put it this way, if you don’t use any solution to avoid current between the batteries and your OEM battery is at e.g. 37 volts and you attach a full range extender at 42 volts to it, the OEM battery goes to charge mode and the assistance drops off.

 

[Maastricht]

One way or another they avoid current between the batteries. I’m not going to ask from them directly, but to my understanding Italian Levorex and Belgian Levo range extender use ideal diodes and British Trailwatts some custom solution (which in the end might be exactly the same principle as ideal diode, but I’m not sure). Levorex web page itself says that they use ideal diodes and even show a diagram (added with some optional relays) what the setup is (basically the same that I have). And the photos that I’ve seen from those custom harnesses, look exactly like that they’d have the diode(s) under some shrink wrap. The diodes are not big, just some 2x4 cm or so, i.e surprisingly small. One fits easily to the bottle and the other to the harness.

Let’s put it this way, if you don’t use any solution to avoid current between the batteries and your OEM battery is at e.g. 37 volts and you attach a full range extender at 42 volts to it, the OEM battery goes to charge mode and the assistance drops off.

Thanks for your advise! I maybe explained myself not clearly enough too. I am not doubting if you need the diodes I was only wondering if they might already be part of the Levo battery and/or these kind of Chinese bottle batteries. If then adding diodes to the wiring, you would end up with two diodes behind each other.

I didn't find the Levorex page yet. I used google translator to understand the Italian page. Thanks for the info!

 

[nyx]

Hello villho,

really nice job and helpfull.
I am thinking about building a light and compact extender range that would fit inside the frame of my levo 2018 in front of the battery.
Thank's to you I know what kind of Li-ion cells, a simpler BMS than yours, 2 Ideal diodes and make my full integrated wirering.
The only problem I have, is that being fully intergrated, that battery will need to be put in place before the main battery. And as I wouldn't have to add a switch outside for power it up after powerring on my main battery, I am wondering what will happen if my range extender apply some voltage on the motor before the main battery is connected/ powered on.

I think you can have the same issue, for example even if you power on your extender after the main battery, after a doing a too long break, the Levo's main battery will auto power off, and then the extender will continue to power on the motor.
did you work on this point ? is there any risks to burn something ? or we don't really care, ok the motor will get some voltage, but without the main battery connected he won't do any thing ?

Thank you !

Thibaud

 

[villho]

Like you said, in that scenario the motor doesn't do anything because the main battery is off. I assume there's some communication required between the motor and the battery and if that doesn't happen, the voltage from the extender is not enough to do anything.

I've had many times the main battery off, but extender connected and "ON". It hasn't caused any problems.

 

[nyx]

Hi Villho,

Thank's for this really fast reply. I assume too that there's no problem to apply some voltage to the motor even if the main battery is off. If it wouldn't a good thing, it would mean that the "commercials" range extender like Levo Range Extender, Levorex or Trailwatts had add a relay that shutdown or power on the extender when the main battery is on/off. But it seems complicated to me and not so reliable. Indeed when you power off the main battery, the time the relay cut the extender, the motor stays a while powered by the extender (even if a very short time).

Anyway, I'll assume that there's no problem with that. So I'll build a Li-ION 10 cells battery that will fit in the frame in front of the main battery. This battery will be managed by this small and light BMS.
Just after the BMS I'll install a Ideal diode you linked, and then, wires will go to the motor throw the frame (there's a cable guide available for this, probably one for an extra light ?).
Near the motor, I'll install the second Ideal Diode for the main battery, and then connect all that to the wiring loom.

So with that install, 100% on the stuff will be integrated. No outside cable or anything. Seems pretty clean. And I keep the possibility to remove the battery (once the main battery removed) for charging/controling/cleaning it.

According to my calculations and tests, I should be able to install between 120 and 150Wh. It's not a lot, but about 30% more on my 460Wh main battery and probably less than 700 or 800gr which stays light and really compact / integrated.

I'll keep you updated about this project if some are interesed.