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48 volt charging solution

PostPosted: Wed Feb 01, 2012 11:43 am
by Reco
hi all

off topic i know but i have an issue that perhaps could be solved here due to the nature of the question. anyways i have a 48volt battery bank created using 4 12volt motorbike batteries in series, they are used to power my electric go cart. my question: is there away to charge all 4 batteries at the same whilest they are still wired in series. my current solution means i have to disconnect all 4 batteries and charge them individually with a 12 volt car charger.

i was thinking along the lines of using diodes to allow for charging off different wires whilest still being wired up in series. can anyone assist?

cheers

reco

Re: 48 volt charging solution

PostPosted: Wed Feb 01, 2012 12:09 pm
by BillGriffiths100
Are you using four chargers?
If so are the outputs floating i.e. not referenced to / connected to earth?
If they are not you can series them up in the same way as the batteries to produce a 48 volt charger!

Re: 48 volt charging solution

PostPosted: Wed Feb 01, 2012 12:44 pm
by Reco
car chargers are pretty expensive so i only have 1. it would be great if i could charge them similar to the way my 3 cell lipo batteries are charged. using 1 charger for all 4 through 1 plug and all the batteries were charged equally. cheers.

Re: 48 volt charging solution

PostPosted: Sat Feb 04, 2012 10:00 pm
by ergocentric
Reco wrote:car chargers are pretty expensive so i only have 1. it would be great if i could charge them similar to the way my 3 cell lipo batteries are charged. using 1 charger for all 4 through 1 plug and all the batteries were charged equally. cheers.


several routes you could take:

The last automotive battery charger I bought was $13 CDN (Black and Decker computerized charger)

get some quick disconnects for your batteries

lead acid batteries are self balancing

design a 48 Volt charger, you don't need anything fancy for lead acid batteries

Re: 48 volt charging solution

PostPosted: Sun Feb 05, 2012 12:35 pm
by Reco
so just to be clear, i can purchase 4 12volt battery chargers, then connect them in series to effectively get 48 volt output? will this damage the chagers? or my house power grid?

as for "lead acid batteries" even if they were self balancing i would still need a 48volt battery charger to charge them all at one time whilest still in series. 48volt chargers aren't cheap or easy to find.

cheers

Re: 48 volt charging solution

PostPosted: Sun Feb 05, 2012 1:04 pm
by BillGriffiths100
A lead acid battery charger consists at its most basic of a mains transformer and a rectifier.
To make a 48 volt one all that is required is an appropriately rated transformer say (55-60 volts secondary at 10 amps) and a rectifier bridge a resistor to limit the current and a fuse. And Roberts your avuncular.
If you use 4 chargers they must have no common link to a ground reference then you can series them up to get your 48+ volt charger.

Re: 48 volt charging solution

PostPosted: Sun Feb 05, 2012 2:53 pm
by ergocentric

Re: 48 volt charging solution

PostPosted: Sun Feb 05, 2012 3:02 pm
by ergocentric
Texas Instruments makes a one chip solution, all you would need is big transistor and a power supply capable of about 60 Vdc at a current suitable for the size of battery. (I've only charged my motorcycles at 2 A)

http://www.ti.com/product/bq24450

The bq24450 contains all the necessary circuitry to optimally control the charging of sealed lead-acid batteries.
The IC controls the charging current as well as the charging voltage to safely and efficiently charge the battery,
maximizing battery capacity and life. Depending on the application, the IC can be configured in various ways:
examples are a constant-voltage float charger, a dual-voltage float-cum-boost charger or a dual step current
charger.