DIY Turbo Levo range extender battery


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1:42 PM
Aug 21, 2020
Curious if anyone has built their own add-on range extender battery for a Turbo levo? Was thinking of building one myself it would be 36v @ ?A, with a BMS, additional blocking diode on the range extender battery, and the Turbo Levo battery to keep the two from back feeding into one another, then parallel the two batteries with the motor. Looking at the aftermarket battery setups there's a module attached on the wiring harness I'm thinking its a BMS, and possible diodes for protection?
I am not fully understanding why you would consider diodes in the mix. Diodes are usually used where the two batteries have different functions requiring isolation and you wish to charge them with one charger at the same time. Diodes may also be used when the battery chemistries are quite different. Unless you have something special going on the range extender battery has exactly the same function as the main battery. You either parallel them all the time or use each as a stand alone. You loose power through diodes and complicate power distribution.

All you really need to do is make sure the DIY battery is made from the same cells as the main battery and the same amperage BMS. Make sure they are the same voltage when you connect them and your main charger will also charge the backup battery. You essentially end up with one battery, not two.

If you are concerned about additional protection put a breaker or fuse in the parallel connection.

On my bike, my main battery is a 14s4p and my range extender is a 14s2p. Both are made from Panasonic 3,500 milliamp hour GA cells. Main battery is 720 Ah and the range extender is 360 Ah for a total of 1,080 Ah as a single battery. Both batteries are charged at the same time through the main battery connection and both discharge together as one. The larger battery has the advantage of lower voltage sag.

When I transport my bike I disconnect both batteries from the bike. If I am charging just before transporting the bike, I will disconnect the charger and wait ten minutes or so for the batteries to equalize before I disconnect them. If I don't the batteries can be slightly different voltages at the time or reconnection. Not enough to matter but I do it anyway. For a while, I would check the voltage on both batteries before connecting them again. I have kind of gotten lazy about that because of never seeing much difference. One of these times I might just get a pop but that is a clue to start looking at things.

There are a lot of ways to accomplish what you want to do. Some more complicated, some more and less efficient and just as many opinions to go with it. Visit Justin's site, Endless Sphere for more in-depth discussions and knowledge base.
Sounds like we have the same battery setup I was hoping to get above the 1000 watt level with a range extender. Still need to open up the motor cover, remove the battery to see what's inside i.e. battery types, and wiring configuration. Thanks for the heads up on Justins site never heard of his site before I'll peruse through the forums, and see what's there. The diodes were exactly that protection, and depending on the final battery voltage not sure .6 voltage drop would be a big deal that remains to be seen.
You can get above the 1000 watt hours with an add on triangle battery or, if you have access to power, go with a fast charger like 10 amp or better. For me that's 10 amps at 58.8 volts. I can put a hell of a lot of power into my battery over lunch. The ability to fast charge is dependent on the type of cell used in the battery pack.

Are you trying to tour/bikepack with this bike or just run higher power on longer trails? For me its about long range, not high power.
Why are theres the considered solution rather than, say, getting another 700wh battry and backpacking it in or strapping to the bike? Thats 1400 wh with one swapiut on the trail without any hacking needed.

This is not the viable option, why?
$1000 and done, you are riding on trails the next day. In my experience, when looking at jenky side solutions, the $100 battery DOES looks attractive....

Then it costs for the separate charger. Then the interconnects. Then the factory wiring has to be modified. Mounts have to be made. Maybe homemade PCB is needed for diode integration. Terminals, connectors, project box to keep mud and scrapes out, AC plugs.

Each is a couple bucks plus shipping. But it adds up over time.

I find that these projects can save maybe 30% of the bought solution, at the cost of being clunky, jenky, and have an efficiency loss.

By my estimate, the homemade solution would cost about $700 to make, result in the 1000wh solution rather than 1400wh, have a lower wh per pound ratio, and be more fussy in terms of keeping the system charged.

The advantages are: $300 buys alot of other bike parts. And that $700 is stretched over time rather than writing a $1000 check all at once which can be a hard swallow.


Is it worth it?

Again in my experience, no. I have more than a half dozen aborted projects in my garage where I was in for a penny, in for a pound, and it started life as a sinking ship but no choice other than to see it through because of the investment. I learned on the last projects that it's OK to abandon it and cut losses.

Don;t get me wrong. These kinds of projects are excellent when EVERY detail can be visualized and planned for in advance. That way, the problems that were not anticipated are cheap and easy to deal with, and the final solution remains polished.

But I don't think the savings here will be worth the effort, do you?
The battery is proprietary, meaning you have to hack the battery to figure out what signals the Levo battery sends back and forth in order to use one of your own home made battery packs, or any number of battery pack suppliers to the DIY market. That is just one of the draw backs to buying proprietary ebikes. Otherwise you need to just buy a Levo battery at whatever cost they decide to charge, yet another drawback of buying a proprietary ebike.

Reputable battery builders for the DIY market will charge around $0.85usd/wh plus Class 9 Dangerous Good shipping cost. Buy from the nonreputable builders/dropshippers then who knows what or how they built the battery. Aliexpress, Alibaba, Ebay all have good builders and who knows what builders. Its a matter of how big of a gambler are you, do you rent or own your place and do you have insurance.

If it was a DIY ebike with a kit, you just slap on whatever battery you want, with whatever connector you want, XT90 or XT60, XLR, bullet connectors whatever. I don't know what Luna does with their built ebikes for sale, if theres a little wink wink and heres how you unlock it.