Is It Wise To Power My 48 Volt Mid Drive System With A 52 Volt Battery, Master Yoda?

Use a powerful battery, you should. - Yoda

See how Yoda influenced Einstein’s look.

One of the more common questions I get asked is whether people should buy a 48v or 52v battery to drive their ebike mid drive kit. How much power you use on your builds is a choice everyone has to make for themselves, and many people seem happy with lower voltage while others want as high voltage as they can get away with, so they can eek out a slightly higher top speed. The BBS02 and BBSHD drive unit controllers can take a range of voltages from a low of 39v to a high of 60v, but there is no question that these units perform much better at the higher end of that range. A 52v battery fresh off the charger at 59v is a peppy wheelie machine, while on a 48v battery when the voltage drops below about 44v starts to feel pretty anemic. What are the long-term consequences of reliability from driving these units with a 52v battery versus the industry standard 48v battery?

These Chinese packs on ebay are sold as 48v packs, but I assure you they're not

Sold as 48v packs on ebay, they’re really 52v packs.  Be aware that these chargers really suck and mine actually blew up.

First, you should figure out what battery you have, as you might think you have a 48v battery that is really a 52v battery. When your battery pack is fresh off the charger just hook it up to a volt meter. If it reads around 54v then it is a true 48v battery, if it reads 58v or 59v then you have a 52v battery. LifePo4 batteries often come in a 16S (a string of 16 cells in series) configuration which equals about 52v volts nominal, although these batteries for whatever reason are often sold on the Chinese ebike market as 48v batteries. If you are running LifePo4 a ‘real’ 48v pack will only be a 15S configuration. 18650 cells that are 52v run in a 14S pack configuration although some Chinese vendors (like Paul) call these 50v packs for whatever reason, further adding to the confusion. ‘Real’ 48v 18650 packs are sold in a 13S configuration with a BMS that will be around 54.4v fresh off the charger. If you are running HK lipos they are about the same voltage as the 18650 cells, although there are people who run their BBS02 systems off a 12S system (44v nominal) , I really do not recommend it.

The Lekkie ring will help make the best chainline you can get with this setup.

The BBS02 had to be designed to take the power of a 52v battery or it would not have survived on the ebike market

Why would you want to use a more powerful battery pack than what the controller was designed for? That’s really the million-dollar question, and it is my belief that these mid drives were actually designed from the ground up to work with 52v packs. In China, it is not uncommon to buy a 48v labeled pack that is really a 52v pack, so the folks at Bafang had to design for that contingency. Since they had no idea what battery people were going to use with their drives, they made it work with the most powerful one that people would buy that they would expect to work with their drive unit. Now that Bafang has upgraded the controller mosfets, the weak point on both the BBS02 and the BBSHD is the nylon primary reduction gear . When the BBSHD was hooked up to a 65 Amp Lyen controller the nylon gear was the first thing to melt. Luckily the nylon gear is only about $20 to replace and it takes about an hour for a BBS veteran to swap out.

Do you really feel a difference when riding with a 52v battery instead of a 48v battery? I have spent hundreds of hours riding the BBS02 & the BBSHD with both 52v and 48v batteries from a variety of vendors. Honestly, right off the charger both the 48v and the 52v batteries feel about the same even though the 52v battery is about 4v more. I have not noticed any difference in the top RPM range of the unit, although it might be slightly higher with a 52v pack. The real differences come when your ride is about 1/2 over. With a 48v battery, once your battery is about half depleted you can feel the power drop off slightly. As the battery gets down to about 1/4 of its charge left, the difference becomes even more noticeable with both throttle lag and a noticeable lack of power. With a 52v battery this never really happens as the voltage never sags into the ‘ho-hum’ zone. With a 52v battery the BBSxx drive units run quite powerfully right up until the battery BMS cuts out.

The NCRb shark pack which crams 52v and a whopping 13.5Ah into a tiny low profile pack that looks very sleek and aerodynamic and weighs in at 7lbs and 11oz with a free custom skin included for $435 located here

The first ebike pack that impressed me enough to write a review on. The NCRb 13.5Ah shark pack

What about the long-term reliability of the drive unit based on battery usage? Unfortudently I am not the best one to consult on this because I have swapped batteries around on drive units pretty haphazardly and it’s hard for me to remember what battery I had on which drive unit at the time of failure. I know that on the BBS02 both nylon gear failures I suffered were with 52v packs hooked up at nearly a full charge. I also know that the one controller failure I had was with a 52v battery at nearly a full charge. In general, I have had enough problems with the BBS02 that I still hesitate to recommend it to people for singletrack riding. Those statements alone might be enough to keep you away from using a 52v pack with a BBS02, but also be aware that I’ve beat on my BBS02’s without remorse for over 500 hours with a 52v battery on brutal singletrack. That being said the BBSHD is an animal of another color.

The BBSHD seems to run just fine all day long at 30 Amps and with a 52v pack. This motor system was so overbuilt that I honestly have a hard time believing that you are going to have any problems with this unit using a 52v battery over a 48v battery. The controller has 12 mosfets instead of 9 with the 750W BBS02 and there are large cooling fins on both the motor and the controller. I’ve hooked up a temperature probe on my BBSHD and the thing barely gets hot even when climbing extended hills at full throttle. Try that on a BBS02 and you will most likely have a serious problem.

The BBSHD is totally overbuilt for 30 Amps of power

The BBSHD is totally overbuilt for 30 Amps of power, you will likely not have any issues with a 52v battery.

Overall the voltage of the battery you’re using is not as important as having the right sized chainring for the application. If you are trail riding, you will not want to use the large 46T steel chainring with the BBSHD or the 48T chainring with the BBS02. I find that the 42T Luna eclipse or the 42T Lekkie Bling Ring work pretty well for both trail riding and commuting. If you have a cargo bike or a tandem then a 30T Luna Mighty Mini is a decent choice, but I think it produces a little too much torque for the trails. On the BBS02 for trail riding, you will want a 38T or smaller chainring, I highly recommend the 30T Luna Mighty Mini for the BBS02. This is by far my favorite BBS02 chainring and it will help save your plastic gear and your controller when you are  running with a 52v battery. The average size of chainring on my BBS02 builds is 34T and I have had great luck with both the 34T and the 36T Raceface rings with an adapter.

Be aware when you buy your BBS02\BBSHD that there are a LOT of ebike kit resellers out there who will NOT warranty your drive unit with anyone else’s battery (regardless of the voltage). You should be aware of this before you plan to buy the drive unit and the battery from different sources. I recommend that you buy your drive unit and your battery from the same dealer so you are guaranteed that it will work and that you will have connectors that will match. When in doubt about whether your ebike controller will take a 52v battery without hitting the high voltage cutoff, you should contact your controller dealer before you purchase a 52v battery and ensure the controller will not cut out at 60 volts.

If you are running a hub motor and want to decide between a 48v and 52v battery I’d say just go with the 52v battery. Most quality controllers will be able to take the extra power and it should give you a few more mph of top speed. In general, if you want more torque you add amps, if you want a higher top speed then you add volts. When you add amps you have to make sure that your phase wires are thick enough and that the controllers have enough solder on the boards to carry the loads. When you add volts you really only have to worry about frying your mosfets in the controller. There are some newer 60v and 72v 18650 packs that are hitting the market, but as of right now I believe that the 52v packs offer the best reliability for the price and are also the safest choice.

I’ve used a lot of batteries over the years but the only two that have impressed me enough to write about are the 52v 14Ah NCRb shark pack (750W BBS02 only) and the 48v 21Ah 30q pack. I’m convinced that the next big thing is going to be the NCR18650GA cells and I’m hoping to get my paws on a 52v GA shark pack in the not to distant future for a review. When in doubt, the 25R cells are always a really safe bet, they are also getting pretty cheap in bulk (about $4.40 each).

Ride On.

Use a more powerful battery, you should. – Yoda

 

23 thoughts on “Is It Wise To Power My 48 Volt Mid Drive System With A 52 Volt Battery, Master Yoda?

  1. My Boston Power packs seems to give 61v/62v straight off charge. And it flys.

    I would definitely recommend a 52v pack, and a 30T chain ring, that’s the way to go 🙂

    Like

  2. Thank you for another excellent article!
    On the same topic, considering you can reach 20mph
    a) running the motor at full throttle on gear X
    b) running the motor at 50% in on gear Y
    Which approach would be better for the motor (a) or (b)? Would that be best for the battery, too?
    Thanks again,
    Robert

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      • btw, I’m actually converting my one to single speed. I find that with the 30T chainring and 17 teeth at the back the bike will do 21/22 mph, and still have shedloads of torque.
        And then I’ll have no derailer hassles / noise.

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      • I had 2 different bikes as single speeds last year, they were great when geared right and still did 20 mph. I find that the 3 speed IGH is the best solution for winter riding as they only add a pound or two and don’t freeze up like a derailler does.

        Karl

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    • Robert your question depends on a lot of different things. Since I assume you’re talking about mid drives let me talk a little about gearing. On my long distance commuter I have a 52T front ring which puts a LOT of strain on the motor and components. It does allow me to pedal along at 35mph which you can’t really do with a 42T ring. On my trail bikes I opt for a much smaller ring because I want the motor to last. When under severe load (climbing 20+ degree grades) you need for the motor to be spinning FAST. If it can’t turn fast enough then all the lost power turns in to waste heat destroying the motor in the process. On super steep extended hill climbs I do not use full throttle because doing so would roast the motor, instead I set the motor up to spin fast and give it only about 70% of the normal throttle.

      As for the batteries get a watt meter on your bike and look at the watts, that’s all the battery cares about. If you are pulling more watts then you generate more heat in the battery. If you have a high quality cell like the 25R, 30Q or GA cells you can beat on them pretty hard. If you’re using a low current cell like the 26F or the NCRb then you’re going to have problems with heat. A hot battery is one that will not work for as many years as a cool battery.

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      • My setup is: Boris + BBSHD + Luna 52V/11Ah/pf + Luna 30T ring + SRAM PG1030 11-36T Casette + SRAM X7. Oh, and I weight 230lb (yeah, I know, too much beer).
        I read every single article on this website and I have to thank you again – the bike is a beast. Gets 11mph on 36T and can climb hiking trails at 8mph. And using the 15T (which is the lowest gear I tried) goes at 27mph.
        The problem is – as soon as I get past the 15T the pedals are useless, so now that I’m riding a motorcycle instead of a bicycle what should I do to have the motor and battery last as long as possible (“long” as in “trying not to kill them”)?
        I have the watt-meter so I’ll plug it in and see which combination will draw the least amount of power.
        Best regards,
        Robert

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  3. I have a 48v battery with a standard cheap 2 amp charger and 52v Luna Battery with a blue Luna charger…Can I charge the 48v with the 52v charger or will bad things happen?
    Thanks

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  4. I have a 48v 14ah E-Rad battery with the standard 48v 2 amp charger and I have a Luna 52v 13.5ah battery with a 52v Blue Lunagizer charger…Dumb question… can I use the 52v charger on the 48v battery? If a 48v battery is often a 52v then I should be okay (if the volt meter reads 58v or 59v), right?
    Thanks,
    Phillip

    Like

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