Model Boat Mayhem
Technical, Techniques, Hints, and Tips => Batteries & Chargers => Topic started by: portside II on November 21, 2007, 12:04:00 am
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ok a little assistance required here please chaps .
i have just got four 6v 4.5a batterys from Maplins ,why? cos they were cheap :)
can i wire them up in pairs to give me 12v 9a? and if not then why?
Daz
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In a word yes.
Just ensure the connectors and cable is bigger than required.
Bob
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The fist time I wired a model up this way it worked fine for about 6 months O0 I found the running time was diminishing after each charge and after about 6 months I was getting approximately 25% less. :( Charging the batteries individually instead of charging them together cured the problem and running time was restored.
Gary.
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Can you do it? If done as in the diagram, yes. Batteries in series mean that the voltages 'add' and the current is 'averaged'. Batteries in parallel mean that the voltages are 'averaged', and the current's are 'added'.
There are draw-backs. If the batteries are not at least 'nominally' the same size, then the smaller (ones) are going to discharge quicker, which means problems.
The size of the conductors used to do the connecting are determined by the current handling capacity of conductors. A 'safety-margin' in size is very nice, bigger is better, sort of, to some ridiculous point. 'Where' those conductors are doing the conducting means that a smaller size might be possible since the amount of current handled might be smaller.
Can you charge those batteries while they are still connected? Yes/maybe, depends on how 'nominally' the same they are, and just how 'dead' each battery is.
Can you mix different 'kinds' of batteries? The 'quick-n-dirty' answer is, maybe. Just depends on the rate of discharge. 'Simplest' answer is no. The 'complicated' answer is, yes, if done correctly. "KISS" is very good (Keep It Simple, Stupid!) with that sort of thingy... so don't.
- 'Doc
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hi the other draw back is if a battery dies through age or other. The good battery's will try and power the bad battery as well as the boat. Imagine you 4 batterys are 4 brake calliper on a car. Through age 1 calliper sticks this will have a negative result on the other 3. The result will be battery's with diffrent charge rates in them and less sailing time. While all 4 batterys are fine there is no problem. john
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As Gary noted, even a set of batteries out of the same box are not guarranteed identical, and over time the difference will be exaggerated to the point of a performance reduction. You can do it, just remember that once in a while, they are going to need charging independantly.
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Make sure you charge batteries independently and never in situ in the boat.
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thamks lad's ,that was the intention if i could do it wired that way .
I will remove the batterys every couple aof charges and give them a good charge individualy.
daz