# Battery help

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#### Jayjay

##### New Member
I need to no can I use two 12v batterys to make 24v I no how to do that
- to + but can I add a 3d battry 12v but keep it at 24v total. So two battrys 12v each = 24v then add a 12v but keeping it at 24v can it be done . I no how to make 12v into 24 & so on . & how to put 4 / 12v battrys to make a big 24 v pack but I not sure on using 3 battrys to 12v each but make 24v . Can it be done

#### Ian Rogers

##### User Extraordinaire
Forum Supporter
For what purpose..... lets assume you have 3 x 40Ah put two in series and one in parallel with any of the other two..

Two batteries..
12v 40Ah + 12v 40Ah = 24v 40Ah....

Three batteries..
12v 80Ah + 12v 40Ah = 24v 40Ah....
Once the single battery is spent, the two remaining batteries will have the current impeded by the dead single battery...

#### spec

##### Well-Known Member
I need to no can I use two 12v batterys to make 24v I no how to do that
- to + but can I add a 3d battry 12v but keep it at 24v total. So two battrys 12v each = 24v then add a 12v but keeping it at 24v can it be done . I no how to make 12v into 24 & so on . & how to put 4 / 12v battrys to make a big 24 v pack but I not sure on using 3 battrys to 12v each but make 24v . Can it be done
Hi Jayjay,

just to answer your question directly: you can connect three batteries together as you describe to make 24V but, as Jim says, there would be no advantage over just two batteries in series.

But you can connect any even number of batteries in parallel/series: 2, 4, 6, 8 ...

spec

#### ronsimpson

##### Well-Known Member
You can connect two 12V batteries to make 24V. (oV, +12V, +24V) or you can use them as (-12V, 0V, +12V) or you can use them as (-24V, -12V, 0V)

In big trucks; some times we use two batteries and a 24 volt starter. But the radio and lights run from the bottom battery at 12V. In this case the load is very different on the two batteries. So charging can be a problem.

#### Jayjay

##### New Member
They are for a scooter each battry is 12v 7ah so Iv got it runing on two battrys at the mo 24v 14ah but the controller will not take 36v so I was hoping to make it run for longer. Do I had hoped of using the 2 / 12v 7ah = 24v 14ah then add the other 12v 7ah making 24v but 21ah keeping it on 24v making 21ah will that not work. Thank u both for getting back to me so quick as I do need to finish this scooter for my son .
We will in the end do a 36v and overvoult the motor as 350w 24v = 700w and could not believe the speed when we tryed it, but melted the controller lol.

#### Jayjay

##### New Member
Hi Jayjay,

just to answer your question directly: you can connect three batteries together as you describe to make 24V but, as Jim says, there would be no advantage over just two batteries in series.

But you can connect any even number of batteries in parallel/series: 2, 4, 6, 8 ...

spec
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#### Jayjay

##### New Member
Thank u all for helping . I now no it's 2 /12 = 24 but to make it run longer I will need 4/12v to make a 24v bigger pack . Thanks again for all the help

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