Go Back  DoItYourself.com Community Forums > Electrical, AC & DC. Electronic Equipment and Computers > Electrical - AC & DC
Reload this Page >

Quick battery question (Series Vs. Parallel) + Voltage/MAH

Quick battery question (Series Vs. Parallel) + Voltage/MAH

Reply

  #1  
Old 08-31-12, 12:47 PM
CircuitBreaker's Avatar
Member
Thread Starter
Join Date: Jan 2009
Location: Trumbull, CT, USA
Posts: 351
Quick battery question (Series Vs. Parallel) + Voltage/MAH

I recently was given a set of six (6) of those halogen flashlights with the 6Volt SLA/AGM battery. Most of the flashlights were dropped and have a bad halogen lamp or a bad switch but all but one (1) of the batteries seems to be in great condition. The batteries are 6Volt 4.5AH
My question is I know I can use 2 of them to get a 12Volt source but I forgot how to do that (I know I have to wire them in series) but will the MAH increase or just the voltage. what about wiring them in parallel?
I only need one 12Volt battery
One last thing if I do wire them in series can I charge the batteries with a 12V charger

Thanks
 
Sponsored Links
  #2  
Old 08-31-12, 12:49 PM
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 18,759
Series gives you the voltage sum but the amperage will not change
Series and parallel circuits - Wikipedia, the free encyclopedia
 
  #3  
Old 08-31-12, 02:08 PM
Banned. Rule And/Or Policy Violation
Join Date: Jan 2010
Location: KS
Posts: 1,896
If you put two in series, you will get 12v/4.5Ah. If you put two in parallel, you will get 6v/9Ah. If you put two batteries in series, and then put those in parallel with two more in series, you get 12v/9Ah.

Batteries in series you add the voltages, but Ah rating is of a single battery.
Batteries in parallel you add the Ah ratings but the voltage is of a single battery.
When you do series AND parallel you add the voltages, AND you add the Ah ratings.

Here's a couple diagrams to make it clearer..
http://www.batteriesinaflash.com/wir...eries-parallel

And yes, you can use the 12v charger on either a series or a series/parallel setup, because those are 12v . You would not use it on a parallel only setup because that needs 6v.
 
  #4  
Old 08-31-12, 04:11 PM
CircuitBreaker's Avatar
Member
Thread Starter
Join Date: Jan 2009
Location: Trumbull, CT, USA
Posts: 351
Are my batteries scrap?

I think I was just given a box of junk (That I now have to recycle )
I hooked up two batteries (Following the series diagram correctly)
but I only get 5.5 Volts?
and I just noticed that someone already helped them self to 3 of the batteries so I only have three total (No wonder the box was so light )
Would it do any harm if I try to charge the two batteries that I connected in series? I don't want an exploding battery or anything dangerous like that just a charged battery
Thanks
 
Attached Images  
  #5  
Old 08-31-12, 06:50 PM
Banned. Rule And/Or Policy Violation
Join Date: Jan 2010
Location: KS
Posts: 1,896
You can try trickle charging them (they won't explode), but if you're only getting 5.5v out of two in series, it's a pretty good bet they've flatlined. What are the voltages individually (of all three)?
 
  #6  
Old 08-31-12, 06:56 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,399
Those are probably gel-cells rather than AGM batteries. I just refurbished three Streamlight rechargeable lanterns and found each of them had a dried-out battery that rattled when shook.

Now for the bad news. Unless you have a constant voltage power supply it is probably not safe to attempt to charge those batteries. Most common battery chargers do not have a constant voltage output.
 
  #7  
Old 08-31-12, 08:24 PM
Banned. Rule And/Or Policy Violation
Join Date: Jan 2010
Location: KS
Posts: 1,896
You don't need any special charger for them.. Any slow rate charger with a trickle function (like a 1.5A lawnmower/motorcycle charger-maintainer) will work. You just don't want to use a fast charger or an unregulated 'dumb' charger (one that doesn't shut off/float when it's done), because that will cook them.
 

Last edited by JerseyMatt; 08-31-12 at 08:41 PM.
  #8  
Old 08-31-12, 09:21 PM
CircuitBreaker's Avatar
Member
Thread Starter
Join Date: Jan 2009
Location: Trumbull, CT, USA
Posts: 351
OK Here are the voltages of the individual batteries
Battery 1 = 3.73 V
Battery 2= 1.75
Battery 3= ol (Which according to my DMM means open circuit)
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes