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eBike Charging Stations / Onboard battery chargers.

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    eBike Charging Stations / Onboard battery chargers.

    This post is a bit long, so TLDR summary:

    -- eBikes could use a universal charging dock or rack.
    -- With different voltages and capacities the only near-term universal charging input would be AC to an onboard charger
    -- An onboard charger needs to be as rugged and waterproof as the battery and other electronics on the bike.
    -- Integrating the charger and BMS with the battery would make for the safest, most efficient setup for a solution to be left unattended in bike racks indoors and outdoors.

    Long version:

    I've watched a few videos about ebike "sharing" ( I guess that's cooler than "renting") companies. Of course, each company has a standard bike so the charging solution can also standard. One such company has a charging dock where the front wheel is stuck inside that both holds the bike up and connects it to a charger. These got me wondering about a similar setup in my garage. I'll have to look closely at the docks next time I'm in San Francisco as I haven't been able to find details online as to how they connect electrically to the bike.

    This got me wondering about a future possibility of charging stations for eBikes. Cars have a few standards where they can connect to charging stations in parking lots. Some can connect with an adapter. One option is less of a charger than a compatible AC connection with an onboard charger that can connect to a generic power source, like at an RV park.

    It would probably take years for a single charging standard to evolve that would work with ebike systems from 36-72VDC, differing battery chemistries and of course different connectors. The near-term solution now would seem to be a standard AC outlet in close proximity to a bike rack with an onboard charger that is specific to the battery on the bike. It couldn't be a simple dock like one that works when all the bikes that use it are identical, but it would allow for a bike to be secured and charged. Maybe a dock-like setup that would also secure the electrical connection inside a protected enclosure while the bike is there.

    An open standard bike rack with integral AC connection for charging seems to fit this requirement. The AC connection could also be controlled by some sort of mechanism for charging a fee to cover the cost of the rack and the electricity. While I know the amount of power is generally little, I recognize that the cost of installation and maintenance of these racks are not zero. It could allow for businesses to subsidize the rack by giving a code to allow for docking and charging.

    If made as a nice, tidy and compact method of holding the bike while providing a charging point this same setup could be used in a home garage, apartment or business. This would also eliminate long extension cords running to the bike or the bike needing a long charging cord. I haven't pondered how this rack would look yet, or how it could secure the power connection. Would be great if something could work both flat on the floor as well on the wall with the bike up on it's back wheel to save space.

    The next thought then is the onboard charger. Following the Tesla Supercharger model, I could see a fast charger being handy for getting a good charge during a brief stop. Then again, if you're parked at work for the day or overnight in your garage, charging slower is better for battery life. While my first thought of a built-in, onboard battery charger was a simple one, I now think there needs to be several requirements:

    -- Variable output ( rate and charge level )
    -- Waterproof
    -- Easily hard-wired to the battery and left connected while riding. (a relay powered by the incoming AC could connect/disconnect the battery output )
    -- Smart enough to leave connected when the bike is unattended. (more on this below )
    -- Made to be secured to a bike.
    -- Communications with the AC source
    --Toss in a SIM slot and cellular radio for the ability fo remotely monitor the state of charge or be warned about overheating or other adverse conditions.

    The Cycle Satiator from Grin meets some of these requirements, waterproof and variable output, but it's still really something designed to sit on a bench or the ground next to the bike. The smart part though might need to be improved.

    Battery charging, especially with a large powerful pack, can be risky. There's a reason some people charge their batteries while they're in ammo boxes or wood stoves. If the intent of an onboard ebike charger is to be outside unattended or in a garage then it would be best to be as safe as possible. Monitoring for overheating or other dangerous conditions should be integral to a charging setup designed to be unattended. I would think that this would be a function of the battery management system more than the charger. But should it? With only a DC connection between the battery charger and the BMS, there's only so much that can be done. The BMS can shut things down, but is that the best? Now I'm thinking that the BMS and the charger should be a unit. A battery with an AC input and the ability to change the rate or level of charge would seem to be in order. Both the battery and the charger need to be kept waterproof and cool. No chance of a mismatch between the battery and the charger. Thermal monitoring of the battery from the inside can slow or stop the charging process. This is again nothing new for a Tesla where the charging process is intimately linked to the battery management system.

    This would raise the price of a battery pack somewhat, but unless you have multiple bikes sharing a single charger then there's already a one-to-one battery to charger ratio. The battery would be mostly self-contained, able to be charged as long as an AC outlet if available.

    As for the options: For home or casual use, a standard AC power cord could be used. But going forward, a commercial or public charging dock might want to know or require that the device connected is a smart charger with the various safety features. A cord with minimal communications between the charger and the dock might be required for the AC outlet to turn on. The onboard charger would still handle all the charging functions only informing the dock that it's capable of doing so.
    The communications also be a good thing to have. Besides being useful for monitoring battery details from the battery to the user, the user could monitor the charge level or if something has gone wrong. If your battery was very low and you were assuming it would be topped off at the end of the day, it would be nice to know if charging was interrupted 10 minutes in, rather than 8 hours later.

    That's it for now. Going to sit back and let people throw rocks at this and tell me what I got wrong.

    For the forseeable future, the only universal anything you can expect to see is a generic power plug. Plus, I would not put so much faith in a BMS. They fail. I have a Satiator. In fact I travel with it on the bike. It sits in a molle water bottle pouch with the cord looped out and stuffed into the little caboose pouch. $11.95 and its a perfect fit.

    I also travel with a 1-to-2 outlet cord. If I am asking someone to use their power plug I stand a better chance of hearing 'yes' if I don't rob them of their ability to connect themselves

    When I expand my ebike fleet to a second residence here in a few months, I don't plan on buying another $300 Satiator. Instead I will use a Mean Well HLG-185-54A. They are essentially a Grin Satiator without the fancy UI. In practice, you can adjust it to be a 3a, 48v or 52v charger. I bought a few of these brand new on Fleabay when they were offered for $30 each and they work great. They also fit into the same pouch above just fine. there is a thread on a different version that is less powerful in the Chargers area. FYI they are meant to be used for street lighting in hazardous/outdoor areas. So pretty sturdy.


    • AZguy
      AZguy commented
      Editing a comment
      I guess I'm missing something. From the meanwell site for the HLG-185H-54:

      Voltage adjust range - 49 ~ 58V

      52V 14s battery - 14 x 4.2V = 58.8V

      So good enough for 13s but not quite enough for 14s.

      That's not saying they won't do it but they aren't specified to do it and the engineer in me won't subscribe to using devices outside their recommended operating conditions - I've seen too often the problems with that - in fact was just dealing with it last week.

      A customer has a product they've been building for over a decade and suddenly 30% failure rate on the last build. They called me in not solve.

      Turns out a part was being used successfully outside its specified operating range in the past. They got a lot that didn't this time. They still function just fine within their specified range but since the product designer wasn't mindful of it they had a hugely costly problem a decade later... Their bad...

      My concern here is that I buy one and it doesn't work for me either right off-the-bat or even later in it's life or at different temperatures, etc., whatever, even though it works exactly as the manufacturer states... Or that operating it higher than specifications just because it can and it fails, maybe taking out my battery or worse yet starting a fire... That would fall into the category of.... My bad...

    • MoneyPit
      MoneyPit commented
      Editing a comment
      My bad. You're right the spec is limited to 58v. Myself personally, I save my monthly 58.8v balance charge days for the Satiator. I would argue the diff between 58.0 and 58.8 (95% charge more or less) is about a block on throttle and not worth worrying over, especially given my personal aversion to 100% charging and battery wear. Again a personal choice.

      I keep a pair of chargers in three separate regular stopover locations (simplifies life if I am riding the bike that has two batteries that day). I have a regular garage of sorts in each location that I can just plug into. All of those chargers are set to 55.4v and the minimum dialable amperage, which on the 150's is right at 1a and on the 185's is about 0.85a. Thats a really low charge rate... a personal choice that works for me and also works out to minimal load on the device. Its never putting out anywhere near its rated watt output.

      I travel with the Satiator as a just-in-case thing. But soon I will be based in two separate towns so I will have a resident bike and 'road kit' for each location (tools, charger etc.). The traveling charger for that bike will not be another $300 Satiator. Its a 185 that I will set to 3a and 58.0v, which will want 174 watts. I was planning on sticking to 58.0v just to be conservative, but your points about dialable vs. rated specs are well taken.

    • AZguy
      AZguy commented
      Editing a comment
      No worries I miss plenty of stuff so in a way I'm happy.

      The really *big* problem with not reaching the full voltage is that you easily don't get the cells balanced properly. That is super important to do - not every charge but every few. More often than not I only charge to 80-90% but every week or so I'll be charging at least one of the several batteries I have to 100%.

      These are likely fine. Even some of my customers occasionally think I'm overly cautious but I'm old and I've seen (and made $$$ fixing the mistakes) what can happen when things are operated outside their specifications.

      I suppose running 1500W through a BBSHD might be considered operating out of the recommended operating specifications but then again, it's not like they document them very well and I think we all know we're playing games with these. About the only written specification is 750W! Typical for chinese stuff though. If it dies it's not that big a deal either as long as it isn't taking out other stuff and we all know that motors and controllers fail even when used within specifications. I also don't often run more than ~750W at all let alone continuously too...

    I had a nice chat with a guy who worked for a start-up trying to sell ((a) install universal charging stations in Chicago and (b) sell memberships to use them. Not enough user base at this time. Plugs not compatible with Tesla. Times were tough,

    Ebike batteries charge at a few amps. Their chargers can plug in anywhere. Owners can remove the battery and take then inside for charging. I don't think you can make any money with a charging station for ebikes. Forcing people into a proprietary charger that has to communicate to the station. that all-is-well will be unpopular with bike manufacturers. Over 600K ebikes were sold in Germany last year. With the huge embedded base in many countries, you aren't going to force the market to retrofit to a more expensive and restrictive charging scheme.

    The cost of electricity is just pennies anyway. And think of all the real estate needed for a aisle wide enough to hold 20 e-bikes and run cords to their batteries. It just doesn't make sense. How do you pay for that unless you charge $5-10 to park them.


      HarryS I think this is the reason the OP's positing of an onbuilt battery/charging system is overly complex, with an additional negative being it includes a heat-averse product that already suffers from the heat it generates itself, and then mates it to another device that generates heat. Having both devices integrated together is highly undesirable from this aspect alone.

      A carry-on charger sitting in a pannier or trunk is the only solution I can see that makes practical sense. KISS principle applies. The technology has to change fundamentally in ways that cannot come to market for decades to change this.
      Last edited by MoneyPit; 04-15-2018, 12:07 PM.


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