Electrical "Splitter"

kanesas45 · May 9, 2016

Hi, so I'm working on a little project, and I just need a question answered - it may seem stupid, but I am just checking, I don't want to get it wrong.
I have an 240V 50/60HZ UK wall socket output going into a transformer module to step it down to 18V DC. I need to have that 18v split three ways to charge 3 6V rechargeable lead acid batteries.
Would the way to do that to be just simply having the batteries all connected in series, and just charge the series circuit by putting voltage through it (18V DC).
I have included an image to explain in more detail.
Thank you.

davesparks · May 9, 2016

Personally I would use a separate charge controlling circuit for each battery, but that's more personal preference than anything technical.

You should be able to have all three in series on one charge controller, after all a lead acid battery is just a number of smaller cells in series.

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Lucien Nunes · May 9, 2016

You cannot charge 18V-worth of batteries with 18V. A 6V battery requires a minimum of 6.9V to charge and 7.25V to charge quickly, but it must be correctly controlled or it will overheat. Also, you cannot effectively charge batteries in series that are in differing states of discharge - some will be overcharged and prevent the others charging properly. You need three 6V battery chargers of a type suitable for the type and size of batteries you are using. Anything else will lead to frustration and dead batteries, or possibly minor acid eruptions.

kanesas45 · May 9, 2016

Thankyou, that makes sense haha. But apparently you have to charge 6v batteries with 1.5v or you'll overcharge it. Thankyou again.

davesparks · May 10, 2016

kanesas45 said:
Thankyou, that makes sense haha. But apparently you have to charge 6v batteries with 1.5v or you'll overcharge it. Thankyou again.

You can't charge a 6v battery with 1.5v, the current will flow the wrong way!!

In order to charge a battery you need current to flow in to it, so there needs to be a potential difference between the battery and the charger with the charger being at a higher potential.