Model Boat Mayhem - Forum

Technical, Techniques, Hints, and Tips => Batteries & Chargers => Topic started by: tizdaz on November 14, 2016, 11:23:00 PM

Title: 2 or 4 batterys?
Post by: tizdaz on November 14, 2016, 11:23:00 PM
Hi guys,


Motor i'm going to use will be 24 volts, i was going to buy 2x 12v 40Ah batterys & run them in series. But i got thinking, the size of these batterys are pretty big (not really an issue with the build i'm doing at mo) but if & when i decide to do another build which is smaller, these batterys may not fit in the hull or be too heavy which would mean i would then have to buy more batterys of a smaller size, so i've been thinking of getting 4x 12v 20ah batterys which are about half the size of a 40Ah & wire them up so I have 24 volts & 40Ah.


Is there any drawback in linking up 4 batteries this way instead of just using 2 batterys or is it fine?


Also when it comes to charging, do i have to charge 1 battery at a time? or is there a charger that can do mutiple batterys (12v 20Ah) at a time?


Cheers!
Title: Re: 2 or 4 batterys?
Post by: tizdaz on November 14, 2016, 11:48:49 PM
Could i use 2x P103 boards from Action Electronics to wire them up, or will these P103 boards only multiply the Ah (I need the Voltage & Ah doubled) ?
Title: Re: 2 or 4 batterys?
Post by: malcolmfrary on November 15, 2016, 09:24:32 AM
The only real problem with combining batteries is ensuring that they all carry the same charge all the time that they are connected.  If they are connected in parallel, they do their best to even out their charges on connection in the shortest time possible, which involves a LOT of current flowing.  If in series, the one with the lowest charge runs out firs and starts to reverse charge, which is not good. 
Having a series + parallel arrangement combines the options for error.
Using a combining board reduces the chance of one battery trying to charge the other, but at the cost of there just being one battery taking the load until it discharges down to the state of its companion.
Title: Re: 2 or 4 batterys?
Post by: jackyoung on November 27, 2016, 02:16:22 AM
Hello ,

It's very great for using 2*2s instead of 2s lipo battery. wow half the size!

You can charge them at the same time, There are a lots of chargers can charge 12v 20Ah, you can find them on bestbuy ebay etc.