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Reliable but silent charger for 48V battery?

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  • MoneyPit
    replied
    ykick thank you very much for your help walking us thru this. Looks like a fun DIY project! I have to dig up my multimeter now.

    Leave a comment:


  • Rider
    commented on 's reply
    Thanks you!

  • ykick
    commented on 's reply
    When the pack reaches the desired Vo - Amps will no longer flow which is effectively OFF.

    I have no problem leaving it connected overnight or days on end if I want a BMS equipped pack to balance.

  • Rider
    replied
    So, because it is just a simple converted "power supply" I take it that it never shuts off, right? Will it damage the battery if you leave it connected after the battery is charged to the setting level? Or overnight if you forget it?

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  • ykick
    commented on 's reply
    Good old electronic nomenclature I=A, right?

    btw, for us cheap skates, myself and others have bought these (used surplus eBay) as low as $15 shipped. Whenever they're under $30 shipped I can't help but grab one or two. Can't have too many charger systems, IMO.

  • Rider
    commented on 's reply
    Thanks. Saw lo and assumed the other one blocked by your hand was hi. What's the old saying about assuming? Lol...

    Does it shut off when at full charge?

  • ykick
    commented on 's reply
    Vo = voltage output

    Io = current (Amps) output

    One adjustment for each.

    When the pack reaches the desired Vo - Amps will no longer flow which is effectively OFF.

  • MoneyPit
    commented on 's reply
    Got it. Thx!

  • Rider
    replied
    I think one is a LOW adjustment and one is a HIGH adjustment, but ykick can explain that...

    I have another question: Does this power supply used as a charger (said to be the same thing) shut off once the battery is charged?

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  • ykick
    commented on 's reply
    Vo = voltage adjust. And yes, merely crank it up/down with a meter attached. For lithium ion/poly packs: 36V=42V, 48V=54.6V, 52V=58.8V As mentioned, my units only adjust up to 58.2V or so. That will work for 52V packs but not quite full charge.

    Io = current adjust. This is where a power meter is needed to prevent too high of charge current setting. Output power adjusted below 150W throughout the entire battery pack charge range. I use resistive load to set initial current (Amps) and then I check it frequently as the battery pack charges.

    The lowest current I was able to adjust was about 1A. It's not a very touchy adjustment pot.

  • MoneyPit
    replied
    Thx ykick! I have both 36v and 52v systems so sounds like adjustment would be fairly straightforward, although I .would only use this on my 52v systems.

    Here comes a dumb question as I'm only familiar with these from this thread: You adjust voltage up or down via the two adjustors in tandem? Not a procedure I'm familiar with.
    Last edited by MoneyPit; 09-18-2017, 07:45 AM.

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  • ykick
    replied
    Here's the top voltage on one of those units - 58.1V Slightly under for full 100% 52V pack but very close and probably not more than 1 mile difference practical range compared to full 58.8V
    Click image for larger version

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    Here's low end of voltage range which works for 36V packs (42V) - Click image for larger version

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  • ykick
    commented on 's reply
    That's a 12S RC Lipo pack so I'm going for 50.4V top charge voltage. Adjust current using a resistive load (oil filled heater element) and then check it on the battery pack throughout the charge cycle from low-high voltage. I simply try to maintain 150W as the Amps will vary depending on Voltage.

    The main trick is to have connectors and power meter.

  • ykick
    replied
    Sorry folks who asked for more info - this will no doubt be a mess but here's some pics to better understand wtf I'm talking about:

    Click image for larger version

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    Attached Files

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  • Kocho
    replied
    I'm thinking that any 48V power supply that has constant voltage output should work. Just need to solder or add an adapter to match your battery's connector.

    Like this? Any other considerations?

    https://www.amazon.com/gp/aw/d/B01HE...2xL&ref=plSrch

    Although, 48V is not going to fully charge a 48V pack. It will "half-charge" it, unless as suggested you can adgust the output voltage up a bit. Or you are OK with 1/2 charge to the nominal 48V...
    Last edited by Kocho; 09-16-2017, 07:05 AM.

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