Battery Dilemma

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Private Nukem
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Battery Dilemma

:? Okay, I am in the process of doing some upgrades to our Rad2Go E-36 Great White scooter during the cold winter months. In addition to adding a battery level gauge and an ignition switch I started looking at the cheap little Jintong batteries that came with the scooter when I got it used off of eBay ($170 - killer deal).
I would like to get more range on the scooter by upgrading the batteries from the 3, 12V/12AH bricks that are in there to something with a little more reserve capacity. I was looking at 3 of B&B's HR15-12T2 which is a direct drop-in for my current battery with 15 AH (listed) as opposed to 12 - that would bump the available A/H from 36 to 45 - not too shabby. HOWEVER - I also see that B&B has a 6V, 12 A/H cell ( BP12-6T1) which has the unique feature of being only 2" wide - I measured the battery tray of the scooter chassis and I could fit 6 of these in the space of my existing 3, 12V units. So.....
Is there any downside to using 6, 6 volt cells in series to give me 36V and 72 A/H instead of 3, 12V 15A/H cells with a total of only 45 A/H? I'm not enough of an expert on battery technology, but it sure seems like the right way to go - the cost difference at www.electricrider.com is only $3 more for the 6V cells. Now, the weight is about double but I'm not sure that would not be worth the huge jump in available Amp-hours.

So experts, whaddya think?

Thanks in advance,

Nukem.

Fechter
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Re: Battery Dilemma

If you put 6 6v, 12Ah batteries in series, you'll have 36v at 12Ahr.
If you put 3 of the 15Ahr batteries in series, you'll have 36v at 15Ahr, which is slightly more.
I think you might have to raise the deck to fit the larger batteries.

There's no real advantage or disadvantage to using the 6v batteries. Twice as many connections to go bad, but if you do a good job on the connections, it won't be a problem. If they fit better, go for it.

chas_stevenson
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Re: Battery Dilemma

Private Nukem,

I am not sure if you were misinformed or you made a simple mistake but your battery calculations are incorrect.

When you put batteries in parallel then you add the amp hours and the voltage stays the same. Since the voltage stays the same this is why you can not add different voltage batteries in parallel.

When you place batteries in series the voltages is added and the amp hours stay the same. This is why you should not mix batteries of different amp hours in a series string.

Here is a graphic which shows 3 - 12-volt 12-AH batteries.

The more important number to compare is the watts per hour (w/hr). You take the voltage (E) and multiply it by the amp hours (AH) to get the w/hr.

So in this case 12-volts and 36-AH yield 432 w/hr
and 36-volts at 12-AH also yields 432 w/hr
This make since because we have the same number and type of batteries in both cases and the total storage capasity does not change so the watt hours should be the same.

The 12-volt 15-AH batteries you reference in your post yield 540 w/hr and the 6-volt 12-AH yield 432 w/hr. As you can see the 6-volt batteries gives you the same w/hr as the 12-volt 12-AH batteries but with more weight. This would be a loss. The 12-volt 15-AH batteries would give you more overall power.

I hope this helps you decide which battery to purchase.

Good Luck
Chas S.

Private Nukem
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Re: Battery Dilemma

DOH!!

....ummm....nevermind. I'm gonna go stand over there and try not to look so stupid. I'm not sure what I was thinking, but I'm pretty sure it wasn't right. I'm gonna go buy those 15 AH B&B's now - "nothing to see here, citizen, move along......."

Thanks, fellas.

Yeesh. See, my parents were right - beer does have that affect on you.... :?

"In order to get to the truth, the first thing you have to do is get all the liars in one room."

[i]"In order to get to the truth, the first thing you have to do is get all the liars in one room."[/i]

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