question

matejs avatar image

MultiPlus installation - connecting battery

Hi,

I am in the process of installing MultiPlus II (48V).

I have 4x 12V AGM 150mAh batteries, connected in series to get 48V. I have connected VE.Bus Smart dongle to it and it reports 50.66V. So far, so good.

I have connected battery cables to the MultiPlus (correctly) and positive only on batteries (there is fuse on positive). No AC connected on MultiPlus.

Now, I have tied to connect negative but I get sparks! And I do not dare to do a full connect. Is this due to the high current at connection time (capacitors?) or do I have something wired wrong. I cannot imagine what I have done wrong.

Any idea?

Thanks.



installation
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4 Answers
markus avatar image
markus answered ·

:o) yes, your assumption is right. You can slowly precharge the capacitors with a DC power supply for example.

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Bah, I was 6 seconds too late ;)

wkirby avatar image
wkirby answered ·

You should expect some good sparks. You are right, there is a bank of capacitors inside the Multiplus at the DC input.

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Ha, this time it was me :o)

matejs avatar image
matejs answered ·

I have used a 600ohm resistor (10x 6k 0,6W) and connection was a spark-less nirvana.

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Good work, glad you've sorted it.

Yeh, those 48V sparks can actually damage terminal threads too. But you should really be running a batt isolator (& fuse) too, so then you may never have noticed.

But agreed, can be an underwear-changing experience. :)

So you gave your chance away, to ask somebody innocent for help, asking like: Can you please take a close look for me to the plus terminal, while I am connecting this? But concentrate and watch closely...


For any onreaders, I am just joking... :o)

I was looking for a resistor online to pre-charge my Quattro 48/5k-120V, and I remembered I had some unused 600Ω 100W power resistors left over from a project. I was pleased to see someone with that exact resistance!


I'm concerned how long it will take. My system is remotely located, so I can't try it for a couple weeks. How long does it take to pre-charge the capacitors?


Thanks,


Steve


matejs avatar image
matejs answered ·

Thanks. So, how do you connect batteries? Precharge with DC power supply? Via switch? Or have fun with the spaks? :D

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Depends on. If you do it in front of another person (e.g. a female), it could make a bit more fun, letting the sparks flow :o)