Battery Charger Fun - Sans 42volt 2amp

Discussion in 'Electric Bicycles' started by grahamx, Jan 29, 2018.

  1. grahamx

    grahamx Finding my (electric) wheels

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    I'm running a standard Sans 42Volt 2 amp charger as supplied with an Oxygen S-Cross w/ 36V 13amp battery. I understand the Sans from google search is a basic/ cheap charger.

    The bike is a year old and had covered 40 miles when I purchased it. I have put another 80 miles on it since ownership.

    Charger outputs 42.1v (tested with multimeter) and has successfully (on 3 occasions) charged the battery up to 42v . Charger shows green light plugged into mains only/ red light during charge/ green light at finish.

    Did notice the charger was getting particularly hot to touch during charging so I raised it on a wire baking tray in attempt to assist with airflow. Also I noticed that the final stage of charge ramping down took 90mins! determined with my plug in watt meter which btw is a great way to know what the charger is up to:)

    Unfortunately the charger failed to charge the battery on the last charge & just stayed on green light when connected to battery....I didn't realise this untill following days ride where I had been lazy to check final volts!

    Have taken a look at the inside of the charger but cannot see any obvious evidence of blown components

    UPDATE

    More luck then anything else .....after connecting and disconnecting the battery a few times this afternnoon I saw a brief red flicker from the charger and now it appears to be back up and running again:eek:. I've left the top section charger case off to assist with the heat issue and am carefully monitoring battery charger with my watt meter as well as battery volts with multimeter.

    Will update how the rest of the charge goes...... and will definite not be using this charger unattended:mad:

    Has anyone else similar issues / fixes/ modifications of this charger:)?
     

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  2. Benjahmin

    Benjahmin Pedelecer

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    Don't know about that charger in particular, but all 2A fanless chargers get hot. I have two, one supplied with a Big Bear the other supplied with a Panda kit, both get hot to the touch. Conversly the 4A fan cooled charger supplied with my Ezee kit doesn't get even warm.
     
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  3. grahamx

    grahamx Finding my (electric) wheels

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    Thanks for reply yes certainly very hot to touch. On opening up there is a crude heatsink of sorts soldered into position but with no air ventilation its like an oven in the enclosure.

    Update: good news the charger went through charging process and has successfully charged the battery to 42v though noticed a very slight whistling noise from the unit towards the end of the charge...will definite be keeping an eye on this charger o_O

    Am going to leave the top cover off for future charging (careful where to position charger in this respect as open circuit board) though will consider moving to an enclosure with additional heat sink and fan.

    Also found a couple of very useful posts from @cyclebuddy on this forum about replacing replacing 2 of the capacitors. I've no experience of doing this though do have an old soldering iron some where.

    http://www.pedelecs.co.uk/forum/threads/carrera-crossfire-ebike-battery-charger.28670/#post-391471

    http://www.pedelecs.co.uk/forum/thr...bike-battery-charger.28670/page-2#post-417365
     

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  4. cyclebuddy

    cyclebuddy Pedelecer

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    Unvented chargers do get hot - especially when running flat-out at just 2Ah for an extended period of time charging a bigger 13Ah battery. Changing the capacitors does (subjectively) keep the charger somewhat cooler: Sticking bigger rubber feet on it to keep it off a flat surface and allow air around it helps too. The cooler it runs, the longer it should last.

    It sounds to me as if your charger/battery connector may be dirty/not making as good a contact at the battery end as it should; that may explain the seemingly erratic nature of the RED/Charging GREEN/Full LED. A wiggle when charging will tell.

    Once the charger LED turns green the battery is mostly full, but yes, Current will continue to ramp down gently whilst Voltage is kept constant to slowly balance/equalise the cells. That is the nature of a CC/CV charger.
     
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  5. Fordulike

    Fordulike Pedelecer

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    I agree with cyclebuddy about the charging connector. I've noticed that if the charger is connected to the battery before the charger is energized, a spark occurs at the contacts. This could tarnish the contacts to the point of making a bad connection.

    I too have a Sans charger, and have always energized the charger before connecting to the battery. No spark and never any problems charging.

    It gets very warm too, so wouldn't worry too much. I should imagine it's got some type of thermal cut-out.
     
    #5 Fordulike, Jan 30, 2018
    Last edited: Jan 30, 2018
  6. grahamx

    grahamx Finding my (electric) wheels

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    Thanks for the reply and much appreciate the advice. I notice that most of the heat from the charger appears to be emanating from the large coil? attached to the underside of heatsink > see photo.

    Regards charger /battery connector will check the connections.

    Have you any recommendations of a replacement charger...... a 2 amp with a fan would be good
     

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  7. grahamx

    grahamx Finding my (electric) wheels

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    I have not seen any sparks...connect the battery per oxygen manual i.e. connect battery to charger > than connect charger to mains.

    Maybe @cyclebuddy can confirm if there is a thermal cutout in charger....theres definite no removable fuse.
     
  8. cyclebuddy

    cyclebuddy Pedelecer

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    Most of the heat comes from the switching transistors/MOSFETS (rather than the transformer you've arrowed) - the large heat-sinks being intended to dissipate that heat. Even though the charger gets "hot" it is designed to cope with that heat so I wouldn't worry too much about it. The draw-back with the unvented design is that the high internal temperature tends to dry-out capacitors and make them fail early. The uprated Panasonic caps I mentioned are specifically designed to work in hot, stressful high-frequency switching situations so should cope far better for longer than the cheap, marginally rated generic ones used.

    A fan-cooled charger generally uses much smaller internal heat sinks because it relies on air being drawn through the charger to keep it cool. The catch there is the fan is (most often) cheap, noisy, and (having no bearings) very prone to failure over time... resulting in a rapid overheat and component meltdown when that happens. So both types of charger have inherent failings.

    I would speak to Oxygen to see if a higher powered 4-amp charger could be used with your 13Ah battery: It would cut the long 7-8 hours charging time to a little over half that, and be less stressful on the charger too.
     
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  9. JPGiant

    JPGiant Pedelecer

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    Is it possible that the cables/plug ends to/from the charger have a fault or broken cable?
     
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  10. cyclebuddy

    cyclebuddy Pedelecer

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    That is a possibility, especially if the cable has been snagged or stressed; You can check continuity of the lead easily with a multi-meter. I don't know what type of connector is being used here, but my thought was the sprung tongue within the barrel connector losing contact - oxidation, road dirt, electrical pitting, corrosion... losing sprung tension against the plug... sometimes just everyday use can cause the solder joint of the socket to become broken (dry joint). All are common issues with many barrel-type sockets that give the appearance of a charger intermittently connecting and charging or not.
     
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  11. cyclebuddy

    cyclebuddy Pedelecer

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    I forgot to mention: In your picture of your charger, there is a 3.15 amp fuse (marked with green arrow), and 2 thermistors (red arrow); they can be used for a variety of reasons, but usually in this kind of circuit, to tame inrush current, suppress surges, or to limit/reduce/shut-down the charger output when it gets too hot... generally, current limiting applications.

    Sans Std 42v ebike Charger -grahamx int pic 2.jpg
     
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  12. grahamx

    grahamx Finding my (electric) wheels

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    Thanks yes I did spot the fuse and was somewhat annoyed to note that it was soldered in place i.e no easy means to replace for the average owner.

    Bearing in mind the average cost of an e-bike that the charger is connected to i'm surprised there is not a more superior 2amp charger available...would suggest there is definite a market for one i.e

    heavy duty aluminium bodied
    quality fan cooled/ ventilated
    changeable fuse
    changeable connectors etc
     
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  13. cyclebuddy

    cyclebuddy Pedelecer

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    If it's any consolation, the Bosch 2A charger is much the same: Unvented, and gets very hot in use.

    BMSbattery.com seem a well liked supplier on this forum: They also offer a range of metal cased, fan cooled, accessible fuse chargers in a range of power outputs, and pre-fitted with a charge lead of your choice (probably possible to request an intermediate connector where you could change those leads around). I have no idea how good these chargers are, but they do appear very good value.

    I'd like to add to your requirements for an ideal charger (features which seem readily available on many RC chargers):
    A voltmeter/wattmeter.
    An ability to part-charge a battery to a settable cut-off point at a lower voltage for storing the Battery.
    A discharge ability to measure actual capacity available (using the wattmeter above).
     
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  14. I've found that the plastic box chargers that don't have a fan are much more reliable than the aluminium case ones.
     
  15. cyclebuddy

    cyclebuddy Pedelecer

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    I don't see why they just can't put ventilation slots into the plastic cased, sealed chargers to allow natural convection. That'd solve a lot of the heat issues.

    When equivalent 42v/2A hover-board chargers retail at around the £10 mark, even if e-bike sellers were to charge £20 retail, they might be considered disposable items easily/cheaply replaced.

    But when e-bike sellers are reselling these same chargers for £50 to £100, it really does grate.
     
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  16. grahamx

    grahamx Finding my (electric) wheels

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    I'm using mine with the top part of case unscrewed and removed...subject to careful placement as exposed circuitry and yes uk prices to be a ripoff with 42v 2amp chargeres avaialible on aliexpress for £7

    UPDATE: after all the concerns with the charger appears issue may possibly lie with the oxygen battery pack as the original issue re-occurred at my last charge up.

    No switching the charger on/ off or fiddling with the connection leads (terminals appear in good condition) would get the red light on however I noticed by chance that a tap of the battery pack on the worktop equated to red light and normal charge

    Am thinking an internal loose connection within the pack? I'm experiencing slight shifting of the cells within the pack when holding pack vertically and turning upside down if that makes sense.

    With regard the charger despite the heat issue it has always shown (green light unconnected) 42.1v at the output connection...is that enough to rule the charger out?
     
  17. cyclebuddy

    cyclebuddy Pedelecer

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    I would agree a loose wire/connection in the battery likely (I've had that previously too). Nothing sounds wrong at all with your charger. Best have a chat with your dealer/Oxygen.
     
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  18. grahamx

    grahamx Finding my (electric) wheels

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  19. Nealh

    Nealh Pedelecer

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    I have 3 sans + another similar made one all get quite warm and give little issue except for some reason 2 started to over volt, so a small mod and adjustment of the trimming pot has now got them back to 42v with a small vent hole above the pot to allow future adjustment and heat to escape.
     
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  20. grahamx

    grahamx Finding my (electric) wheels

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    Hi cyclebuddy

    Now my pack is back up and running I still feel the charger is getting too hot even with the top cover removed.

    After playing around with a digital thermometer confirm am getting the highest temps of 60c at the two 50v caps...can only imagine what temp they are getting to with the cover on...must be like an oven in there! Am also seeing 45c on the main aluminium 'heat sink'

    Playing a simple desk fan onto the bare circuit board see this value drop to a more desirable 30c and appear to be getting better charging performance as a result.

    2018-05-22 20.40.07.jpg

    Am going to upgrade the two 50v caps to the Panasonic 63v 470UF 105C EEUFC1J471 per your post

    Carrera Crossfire ebike Battery Charger

    Though will still likely use the desktop fan to keep things cool.....not an issue as charging at home.

    upload_2017-8-11_12-49-23.png
     
    #20 grahamx, May 25, 2018
    Last edited: May 25, 2018
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