paparts

I have 8 Ni-MH batteries and I am putting it fixed to a mobot. I'm just confirming whether it is possible to connect the batteries this way? or the other way w/c is connecting the batteries in series.

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Krumlink

this would increase the Amperage, so for example if they were 1000ma each, it would now be 8000ma. The voltage would remain the same, at 1.2 volts.

To increase the voltage, put them positive to negative, over and over so that you can increase the voltage to 9.6V

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MechTronics

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Sceadwian

Batteries in parallel will add their capacity but the voltage will stay the same.
Batteries in series will add their voltages but the capacity will stay the same. It's generally a bad idea to mix batteries in series and parallel together without advanced charger design.

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iONic

I guess it depends on what voltage your "mobot" runs on, 1.2V to 1.4V or 9.6V to 11V.

Your circuit, however, shows a charger connection. If you charge them in series you want to apply aproximately 10.8V and a max current of 100mA, given a hypathetical 1000mA battery. If you are charging them in parallel then you would apply between 1.3V and 1.4V with a current of 800mA as it will devide amound the 8 batteries to be aproxamentally 100mA each.

paparts

I am using 9.6 volts. Can it be charged if I connect it in series?
How will I do it?

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iONic

Although the battery is rated for 1.2V x 8 = 9.6V you would want to charge each cell to between 1.3V and 1.36V giving a combined charge voltage of between 10.4V and 10.88V, at a maximum current of .1 x the cells current rating. For a 1200mA cell you want 0.1 x 1200 = 120mA. Full charge can take up to 12 hrs. After that to maintain their capacity you would tricklecharge them at .01 x the cells current rating or 0.01 x 1200mA = 12mA. This charge is genrally save to keep on indefinately without damaging the batteries.

The battery layout can stay the same as your parallel circuit but just wired as in the attached image.

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paparts

I am using a an adaptor. Input 220AC0-50Hz Output 7.2V 200mA. Can I use this in charging 8 Ni-MH batteries?

picasm

No, that adaptor is not good enough for what you need to do.

Please read the previous post by iONic - showing that you will need to supply about 10.88 volts to the cells in series in order to get the required charge current.
You also need to include circuit to ensure that the charging current is regulated to be constant as specified and it must cutoff or reduce to the trickle charge rate when charged as Ni-MH batteries don't like being overcharged.

Here is a useful guide to using Ni-MH batteries:
http://www.steatite.co.uk/batteries/..._technical.pdf