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Topic Title: 120 volt battery charger needed
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Created On: 10 January 2013 10:59 AM
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 10 January 2013 10:59 AM
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broadgage

Posts: 1267
Joined: 07 August 2007

Can anyone recomend a supplier for a cheap and basic float charger for a 120 volt nominal sealed lead acid battery ?

The float charge voltage would be 137 to 138 volts for a nominal 120 volt battery.
A fraction of an amp output would be ample.

Any ideas ?
 11 January 2013 11:26 AM
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dlane

Posts: 690
Joined: 28 September 2007

It depends upon the requirements for the charger.

If it is a basic charger only requirement then the above would work. However, if you need the charger to also supply the load and that load can vary you will need a load compensation circuit to prevent overcharging of the battery cells during low loads.

You may also need a temperature compensation circuit if the ambient conditions around the cells can also vary as during higher ambients a fixed charger will again overcharge the cells.

It ultimately depends on the cost of your cells. If these are only small cells then it may be viable to live with the decrease in cell life from overcharging against the cost of a specific charger, but if the cells are larger capacity and more expensive and have a high criticality then spending more on a charger may be prudent.

I have used Powernetics in Loughborough in the past, but I wouldn't apply the term 'cheap' to them, although they can build bespoke chargers.

I have also used some rack mount units from PB Design in Clevedon, but again probably not what you would call 'cheap'.

I am sure there used to be another company around Bristol aswell, but my little brain just cannot remember the name of them. I am not back in the office until next Tuesday, so if you can wait until then I will dig out the name for you.

You can also ask the battery manufacturer's as they can usually point you in the direction of charger companies.

Kind regards

Donald Lane
 11 January 2013 12:06 PM
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broadgage

Posts: 1267
Joined: 07 August 2007

A simple transformer and rectifier circuit wont be suitable because this is for sealed batteries which are easily damaged by overcharge.

Definatly needs to be regulated, constant voltage at 137 to 138 volts.

No load needs to be supplied by the charger, it is simply to keep a battery charged and slowly recharge after any discharge.

Very cheap, mass produced chargers exist for lower voltages, but for 120 volts they all seem rather expensive, presumably due to low volume or "one of" manufacture.
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