DIY: Range extender for Levo (and Kenevo)

[joliver]

Some update on my extender project ...
Finished and tested.
works fine.

View attachment 28691

View attachment 28692
the battery pack and the BMS are moulded in black epoxy which needed some more sanding afterwards


View attachment 28693
the battery holder and cable coming out of 1 of the bottle holder wholes.


View attachment 28694
Extender installed and ready to roll … 504 + 432 = 936 Wh


View attachment 28695

I was impressed by their work, especially the integration using epoxy.
I would like to ask you if you could give any more details about this process, how you have done it to leave the connectors, etc.
And if you could tell me the exact components, I would appreciate it, I don't have too much knowledge and I prefer to play it safe.
Finally, if you could tell us how you are working today.
Excuse me, my English is a bit rusty.

 

[joliver]

I have some conclusions, which I would appreciate if they were refuted.
- If one battery has more charge / capacity than the other, as long as this is the case, only one of them is consumed (until both have the same charge and then work as a team) so the system of both must support a possible work at 20A or be careful not to ask for the maximum power until they have been equalized.

 

[RCDallas]

If you are talking two battery packs in parallel then not exactly. If they are isolated thru diodes then that is true until the voltage of the higher voltage battery reaches the voltage of the lower voltage battery it will provide all the current to the motor. As the voltages start to equalize the the lower voltage battery will gradually supply increasing levels of current until both are at the same voltage. At that point capacity and internal resistance will determine how much current each battery provides.

If the two batteries are in parallel and not isolated then it is basically the same except that current will flow from the higher voltage battery to the lower voltage battery as well as to the motor until the voltage equalizes between the two. Connecting batteries with different charge levels/voltages is not a good practice and could result in very high currents that could damage both sets of batteries. The best practice in this scenario would be to connect after fully charging where both batteries at or very near to the exact same voltage. Charging both batteries at the same time with the same charger would be the ideal situation.

 

[joliver]

If you are talking two battery packs in parallel then not exactly. If they are isolated thru diodes then that is true until the voltage of the higher voltage battery reaches the voltage of the lower voltage battery it will provide all the current to the motor. As the voltages start to equalize the the lower voltage battery will gradually supply increasing levels of current until both are at the same voltage. At that point capacity and internal resistance will determine how much current each battery provides.

If the two batteries are in parallel and not isolated then it is basically the same except that current will flow from the higher voltage battery to the lower voltage battery as well as to the motor until the voltage equalizes between the two. Connecting batteries with different charge levels/voltages is not a good practice and could result in very high currents that could damage both sets of batteries. The best practice in this scenario would be to connect after fully charging where both batteries at or very near to the exact same voltage. Charging both batteries at the same time with the same charger would be the ideal situation.

First of all, thank you very much for answering.
Yes, I take the use of diodes for granted, I must look at why "ideal" are recommended as there are many "normal" 30A diodes that are really cheap and easy to find.

 

[joliver]

My previous question comes from the fact that batteries of different characteristics and input are used, at 100% they will not have the same voltage, right?
I mean, even though they are all 36v, I see that 252w and 378w bottles are used, 432w packages ... they are always of less capacity than the original battery, but could a higher capacity be used? I mean, put an additional 700w battery, to put a figure.
I see that some batteries have a nominal discharge capacity of about 15a, if it were of greater capacity than the original and it was connected, of course with diodes, it would use the secondary one at the entrance, and therefore it is necessary to make sure that the nominal discharge capacity is 20a, right?
I would have to take into account some other parameter when choosing the battery ... apart from the fact that the data they put in aliexpress is of relative credibility .

 

[joliver]

I was thinking ... for me, the ideal is to be able to first discharge the auxiliary and then the main battery. And that, I think that with a simple relay I could do it, if it has power from the auxiliary battery, it lets the current pass through it, if it doesn't have power (from the auxiliary battery) by default, it lets the current from the main battery pass. it could work?

Even perhaps a simple toggle switch that holds the 20a, is much simpler and usable ... taking into account to operate it without pressing the pedals, of course.

And I explain the reason, it turns out that I usually arrive right with the 460w main battery (each time we go up more meters through more broken places), and for that reason I had thought that I could put a 250w auxiliary battery. But this works for me 90% of the time, 3 or 4 times a year, the whole group goes on routes throughout the weekend, and on those occasions I take a second 460w battery that I have.

Therefore, I think the ideal in my case would be to have 2 auxiliary 250w batteries. One to use regularly and another to wear on those occasions ...

But if I use the system proposed here, I would have to be aware that the battery equipment was about to run out, to put the new auxiliary and then only pull it due to the higher voltage of it ... which could also work ... and from there came my first question that I should size the entire project (diodes) to reach the 20a, counting that at some point, I would have to put a second full battery, when the main and the first auxiliary were almost empty. .. and beware, if they were completely emptied, the second auxiliary would be of no use to me.

 

[RCDallas]

My previous question comes from the fact that batteries of different characteristics and input are used, at 100% they will not have the same voltage, right?

The various Lithium-Ion cells we use in most ebikes these days are of similar chemistries that are 4.2 vdc when fully charged. Each cell can have different capacities and internal resistances but generally have similar discharge curves where the voltage of a cell decreases as capacity decreases.

I mean, even though they are all 36v, I see that 252w and 378w bottles are used, 432w packages ... they are always of less capacity than the original battery, but could a higher capacity be used? I mean, put an additional 700w battery, to put a figure.

Each of those batteries you listed may use different brands and capacity of cells and could even have different form factor (18650 vs 21700) to create the capacity required, but all have 10 groups of parallel cells in series to make a 36v nominal battery pack. The current capacity is based on the cell used and number of cells used in each group. And yes, you could use any capacity battery you want as long as it has 10 series cell groups for 36v nominal.

I see that some batteries have a nominal discharge capacity of about 15a, if it were of greater capacity than the original and it was connected, of course with diodes, it would use the secondary one at the entrance, and therefore it is necessary to make sure that the nominal discharge capacity is 20a, right?

If the battery was to be used when your main battery was depleted then yes, you would want a battery that was capable of providing the full current required by the motor without detrimental effect to the battery life.

If, however, the battery is to be used to increase the capacity of the main battery and would be added to the bike at the same voltage level as the main battery then the current capacity is really of no concern as it will just add to the current capability of the main battery which is already able to supply the required current. Both the main and auxillary battery would then share current output based on each battery's capacity/internal resistance, and would discharge at the same rate/percentage based on voltage.

Important caveat.... How the battery is connected to the system and how the ebike's system handles that connection will determine what current capacity auxillary battery you would want. If the systems software prevents the main battery from powering the motor when an auxiliary power source is connected then you should get a battery capable of supplying full current.

 

[tomwoodward109]

Is it possible to make a kit for a specialized 2019 model with a gen2 motor?

 

[Grannyjones]

I have a 700 watt hour battery and rarely feel the need for more range. I can leave it in turbo mode and do 3 hours worth of riding.

However I have tried a few 500 watt hour batteries and find the range on those to be very insufficient. If it wasn't for the progression to 700 wH batteries I think I would never have got into E Biking in the first place.

 

[xbit83]

I have a DIY extender with ideal diodes and the same diagram connection of the first post. But I have a "problem" because the external battery (extender) discharges when the battery is connected to the motor (also without the bike in OFF or also without the main battery connected).

I have measures that the motor (in off mode) has 0.1A discharge without any use....

Is it normal?

 

[artzicat1]

hi so have been running the range extender for about two month now with two diodes so currently blevo show's original battery is 460wh and the extender is 250wh the numbers are ok i do around 50km+ trail riding on trail mode 35/65 depended on condition of trail wet stickie result in less mileage just have a Q is possible to make so the extender drains first .
another thing asked trailwatts if he is using diodes in his range extenders the answer was no .how does he make it work ?

Afternoon Activity - Artzi S's 52.3 km mountain bike ride

Artzi S rode 52.3 km on Feb 5, 2021.

www.strava.com

 

[fuikatasio]

I have a DIY extender with ideal diodes and the same diagram connection of the first post. But I have a "problem" because the external battery (extender) discharges when the battery is connected to the motor (also without the bike in OFF or also without the main battery connected).

I have measures that the motor (in off mode) has 0.1A discharge without any use....

Is it normal?

Yes, ideal diodes draw watts when the extender is connected to the ebike and the ebike is off. Tip, when the ebike is off, disconnect the extender. In this way the consumption of the ideal diodes will be minimal

 

[xbit83]

Yes, ideal diodes draw watts when the extender is connected to the ebike and the ebike is off. Tip, when the ebike is off, disconnect the extender. In this way the consumption of the ideal diodes will be minimal

But I think the same draw happens without the ideal diodes connected. Before ideal diodes, I connect directly extender battery to the motor with one XT60 adaptor and the main eBike battery disconnected (only + and - were cut, the other cables of the BMS and TCU are allways connected to the motor). And in that old connection (Now I have ideal diodes to run both batteries in parallel) it also draws watts and external battery (400Wh) discharges in 4 or 5 days (100Wh in 24h without using it).

In my installation, I have no option to disconnect the extender without oppening the side plastic guard of the eBike and disconnect the XT60 of the external battery. I have tryed it with only one connector in the black wire (-) of the external battery, but when I plugged it it gives a big spark. Is this bad to the battery or eBike motor? Can I install a switch or relay to avoid this voltage peaks?

 

[joliver]

But I think the same draw happens without the ideal diodes connected. Before ideal diodes, I connect directly extender battery to the motor with one XT60 adaptor and the main eBike battery disconnected (only + and - were cut, the other cables of the BMS and TCU are allways connected to the motor). And in that old connection (Now I have ideal diodes to run both batteries in parallel) it also draws watts and external battery (400Wh) discharges in 4 or 5 days (100Wh in 24h without using it).

In my installation, I have no option to disconnect the extender without oppening the side plastic guard of the eBike and disconnect the XT60 of the external battery. I have tryed it with only one connector in the black wire (-) of the external battery, but when I plugged it it gives a big spark. Is this bad to the battery or eBike motor? Can I install a switch or relay to avoid this voltage peaks?

You could indicate the specific model (at least one image) of the ideal diode, to try to find its datasheet and find out what it says about it, so much consumption does not make sense.

It is possible that the motor continues to receive power and keep everything "ready" to go pedaling ... although with the main battery off, it should not.

 

[xbit83]

You could indicate the specific model (at least one image) of the ideal diode, to try to find its datasheet and find out what it says about it, so much consumption does not make sense.

These are the ideal diodes that I install in my DIY Turbo Kenevo extender:

Page Not Found - Aliexpress.com

Heare you have all the information of my extender: (Also with the 3D design of the battery box)

Specialized Turbo Kenevo DIY Battery Extender by xudaondo

Proyecto Extender DIY que he ido evolucionando a raiz de una compra desastrosa que hice por Wallapop a un chico de Alicante en la que me vendieron una batería 10SP4 dentro de una funda de bolsa de herramientas modificada, que ni tenía los 20Ah indicados(Solo daba 3Ah y tenía una fila de 10...

www.thingiverse.com

But the problem, is not the ideal diodes, because if I remove them and connect the extender directly to the motor (Without the principal battery connected) the consumption still the same. 0.1A and in one week the battery of the extender is 0% or 10%

It is possible that the motor continues to receive power and keep everything "ready" to go pedaling ... although with the main battery off, it should not.

I think this is the problem

 

[joliver]

These are the ideal diodes that I install in my DIY Turbo Kenevo extender:

Page Not Found - Aliexpress.com

Heare you have all the information of my extender: (Also with the 3D design of the battery box)

Specialized Turbo Kenevo DIY Battery Extender by xudaondo

Proyecto Extender DIY que he ido evolucionando a raiz de una compra desastrosa que hice por Wallapop a un chico de Alicante en la que me vendieron una batería 10SP4 dentro de una funda de bolsa de herramientas modificada, que ni tenía los 20Ah indicados(Solo daba 3Ah y tenía una fila de 10...

www.thingiverse.com

But the problem, is not the ideal diodes, because if I remove them and connect the extender directly to the motor (Without the principal battery connected) the consumption still the same. 0.1A and in one week the battery of the extender is 0% or 10%


I think this is the problem

Given the difficulty of finding a watertight switch of at least 20A, I have chosen to put 2 switches of 10A to work in parallel.

1.74￡ |Interruptor de botón de Metal impermeable de gran corriente de 16MM 1NO|Conmutadores| - AliExpress

¡Compra fácil, vive mejor! Aliexpress.com

es.aliexpress.com

It hasn't reached me yet and I haven't tried it, but it should work.
My battery will be connected in parallel with the original one, so I do not expect consumption of more than 10A at most, apart from the fact that I do not usually use Turbo mode.



On the other hand ... if you connect the main battery first, the motor will already have its power and you will not receive the spark
, or at least it will be half intensity.


Greetings.

And the same in spanish:
Ante la dificultad de encontrar un interruptor estanco de al menos 20A, yo he optado por poner 2 interruptores de 10A para que trabajen en paralelo.

Mi batería estará conectada en paralelo con la original por lo que no espero consumos superiores a 10A como máximo aparte que no suelo usar el modo Turbo.

Aun no me ha llegado y no lo he probado, pero debe funcionar.

Por otro lado... si primero conectas la batería principal, el motor ya tendrá su alimentación y no recibirás el chispazo, creo, o al menos será de la mitad de intensidad.

Saludos.

 

[HarveyMiller]

Amazing, completely!
The only thing I'm not quite sure of is if it's worth it (strictly from a financial angle) to spend all the time, effort and money to do this, only to save a couple of hundred dollars or less.

 

[joliver]

Amazing, completely!
The only thing I'm not quite sure of is if it's worth it (strictly from a financial angle) to spend all the time, effort and money to do this, only to save a couple of hundred dollars or less.

Well it depends on whether you do it as a hobby in free time dedicated to the hobby, that time does not cost you anything. In my case the saving is 50% with an additional 540wh.
From a strictly financial point of view, and applying the same parameters, going MTB is not worth it either.

 

[joliver]

Making the introductions ...

460wh + 540wh = 1000wh

Battery with 30 x 21700 cells of 5000mah 10s3p equal to 15ah that at 36v make a total of 540wh.

 

[Troutwrestler]

Looks neat.

 

[joliver]

Working in progress...
What has given me the most work has been to desolder the diode anchors, at least it has been 2 hours ...

With dog hair

 

[joliver]

And finished... tomorrow test day

Reinforced floor with a old hdd cover plate

protecting a little

And finished

 

[joliver]

And it has worked perfectly, the main battery has been almost at room temperature the whole time. I have done a route of 64kms and 1400 meters of unevenness, all the time on Trail (40%) and Turbo (80%) and I still have 240wh left over.
Route through technical areas, many stones, trails, etc.

Very happy with the result.

Bag 1.7 liters
13.0€ 42% de DESCUENTO|ROCKBROS Bolsa de sillín de bicicleta de montaña, resistente al agua, alforja grande, bolsa de tija de sillín trasero rápido, accesorios de ciclismo|Maletas y cestas de bicicleta| - AliExpress

Battery pack
90.59€ 38% de DESCUENTO|LiitoKala Batería de alta potencia para bicicleta eléctrica, 36V, 15Ah, 21700, 5000mah, 10S3P, 500W, 42V, 15000mAh, BMS|Paquetes de baterías| - AliExpress


Important, the Liitokala cells are coming out quite good, they have good discharge capacity ... and always in the official store "Liitokala Official Store" that there are many imitators.

Charger 36v 3A
3.9€ 25% de DESCUENTO|LiitoKala cargador de batería de litio Serie 3 6 serie 7 Serie 10 Serie 12V 24V 36V 48V 18650 V 12,6 V DC 29,4*5,5mm|12.6v charger|charger for12.6v 3a - AliExpress

Cables
0.23€ |1M/5M resistente al calor cable 30 28 26 24 22 20 18 16 15 14 13 12AWG Ultra cable de silicona blando de alta temperatura, Flexible línea de cobre|Alambres y cables| - AliExpress

I have taken them from 12AWG, but better than not missing ... in theory with 14AWG it would work well ... these are very flexible and fire resistant silicone.

Ideal Diodes (x2)
7.29€ 18% de DESCUENTO|Controlador de diodo de alta tensión, Placa de protección antireflujo de carga de batería Solar, 50A, 12V, 24V, 36V, CC, 9V 45V|Controladores solares| - AliExpress

And then heat shrink covers, various connectors ... etc ... I don't know ... but less than € 200 all (I have spent a lot more because I bought switches, relays, fuses ... more connectors, a voltmeter, a 36v to usb converter, etc ... but let's go, like this, a little less than € 200 all.

 

[Timbo]

Very nice! I am tempted to have a go, thanks for the detailed post.

 

[xbit83]

And it has worked perfectly, the main battery has been almost at room temperature the whole time. I have done a route of 64kms and 1400 meters of unevenness, all the time on Trail (40%) and Turbo (80%) and I still have 240wh left over.
Route through technical areas, many stones, trails, etc.

Very happy with the result.

Bag 1.7 liters
13.0€ 42% de DESCUENTO|ROCKBROS Bolsa de sillín de bicicleta de montaña, resistente al agua, alforja grande, bolsa de tija de sillín trasero rápido, accesorios de ciclismo|Maletas y cestas de bicicleta| - AliExpress

Battery pack
90.59€ 38% de DESCUENTO|LiitoKala Batería de alta potencia para bicicleta eléctrica, 36V, 15Ah, 21700, 5000mah, 10S3P, 500W, 42V, 15000mAh, BMS|Paquetes de baterías| - AliExpress


Important, the Liitokala cells are coming out quite good, they have good discharge capacity ... and always in the official store "Liitokala Official Store" that there are many imitators.

Charger 36v 3A
3.9€ 25% de DESCUENTO|LiitoKala cargador de batería de litio Serie 3 6 serie 7 Serie 10 Serie 12V 24V 36V 48V 18650 V 12,6 V DC 29,4*5,5mm|12.6v charger|charger for12.6v 3a - AliExpress

Cables
0.23€ |1M/5M resistente al calor cable 30 28 26 24 22 20 18 16 15 14 13 12AWG Ultra cable de silicona blando de alta temperatura, Flexible línea de cobre|Alambres y cables| - AliExpress

I have taken them from 12AWG, but better than not missing ... in theory with 14AWG it would work well ... these are very flexible and fire resistant silicone.

Ideal Diodes (x2)
7.29€ 18% de DESCUENTO|Controlador de diodo de alta tensión, Placa de protección antireflujo de carga de batería Solar, 50A, 12V, 24V, 36V, CC, 9V 45V|Controladores solares| - AliExpress

And then heat shrink covers, various connectors ... etc ... I don't know ... but less than € 200 all (I have spent a lot more because I bought switches, relays, fuses ... more connectors, a voltmeter, a 36v to usb converter, etc ... but let's go, like this, a little less than € 200 all.

I would only change the bag. I tested one of this and when it rains, there was a lot of humidity inside of the bag near the battery. Finally, I designed and printed a 3D case, that you can find on thinigiverse.

Maybe you can edit the Sketchup file to adapt it to 21700 cells.

Regards,

 

[joliver]

I would only change the bag. I tested one of this and when it rains, there was a lot of humidity inside of the bag near the battery. Finally, I designed and printed a 3D case, that you can find on thinigiverse.

Maybe you can edit the Sketchup file to adapt it to 21700 cells.

Regards,

Thank you very much for the suggestion, but normally if it rains ... I don't go out, it doesn't rain so much in Barcelona that I can't go out.

There are also several alternatives, both helmet covers and shower caps that would largely solve the problem.

 

[joliver]

Very nice! I am tempted to have a go, thanks for the detailed post.

Many thanks, the internet is for sharing information ;-)

What gave me the most trouble was to desolder the anchors of the ideal diodes, I didn't have much experience in this, but in this thread there are other similar ideal diodes that do not have any anchor and it is much simplified.

 

[xbit83]

Thank you very much for the suggestion, but normally if it rains ... I don't go out, it doesn't rain so much in Barcelona that I can't go out.

There are also several alternatives, both helmet covers and shower caps that would largely solve the problem.

I am from Bilbao, and here, always rains a little and sometimes a lot!!! ;-D

Finally, I decided to design a water resistant extender case.

 

[chagolucho]

Hi everyone, I am finishing my external battery for a 2018 kenevo, and the BMS has different ports for charging and load. Can I use only one diode (for the original battery) as the BMS should not allow for current to flow to the external battery?

 

[joliver]

Hi everyone, I am finishing my external battery for a 2018 kenevo, and the BMS has different ports for charging and load. Can I use only one diode (for the original battery) as the BMS should not allow for current to flow to the external battery?

Well, it depends on whether the charging port of the BMS is alternative or exclusive ...

But I have never tried it, and since it can depend on the BMS used, I preferred to put two diodes and not depend on it.