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kevinloh
Apprentice
Brunei
121 Posts |
 Posted - Oct 24 2003 : 03:18:36 AM
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How long does it taked to charge a car battery rated 12V40Ah using a 12V 6A Transformer and what is the formula.
Thanx
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cirvin
Nobel Prize Winner
USA
1542 Posts |
Posted - Oct 24 2003 : 07:00:48 AM
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well, if the charger was 1 amp, then it would take 40 hours to charge it from dead, divide 40 by six and that willn get you your time
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Oct 24 2003 : 10:08:53 AM
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Not quite....But I would say 8 hours off the top of my head. You charge the battery to 13.8V. If you want to boil it a little, go to 14.4V to get a nice finish charge.
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kevinloh
Apprentice
Brunei
121 Posts |
Posted - Oct 28 2003 : 8:00:37 PM
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Is it alright if my charger gets burnin hot while charging? Should I put a cooling Fan?
By the way, if my charger is rated 12Volts 40amps so it would take about 2 hours for a full charge or is the current an overkill?
Thanks
Edited by - kevinloh on Oct 28 2003 8:02:49 PM |
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cirvin
Nobel Prize Winner
USA
1542 Posts |
Posted - Oct 29 2003 : 3:50:55 PM
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your charger is very good. the higher amperage, the better. personally, i would use a fan, i don't much like things getting hot like that, but it is your cxall
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kevinloh
Apprentice
Brunei
121 Posts |
Posted - Oct 29 2003 : 10:43:04 PM
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But a too high amperage transformer to charge a car batery is also not very goog right cirvin? Correct me if i am wrong :)
PS that charger cost nearly US$200.00
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cirvin
Nobel Prize Winner
USA
1542 Posts |
Posted - Oct 30 2003 : 06:46:52 AM
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well, the only time you will damage the battery, is if you keep it connected to the charger too long. the higher amperage, the better. it charges your battery much faster
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Oct 30 2003 : 09:40:06 AM
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If the charger gets very hot, then it was probably designed that way and I doubt it hurts. However, no problem with adding a fan.
As for the battery, you can charge it as fast as you want AS LONG as you don't heat it too much. It can be warm after charging, but if it is boiling or HOT then you are putting in too much current.
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kevinloh
Apprentice
Brunei
121 Posts |
Posted - Oct 30 2003 : 7:28:11 PM
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Well that large current charger its ok its only warm but if I charge the battery using a charger say 2A it will get extremely hot. Do you think its alright to let stay that way? Could the windings in the transformer get melted and ruin the charger?
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Oct 31 2003 : 10:32:30 AM
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A 2A charger [i]should[/b] have an internal current limit that prevents more then 2A from being drawn. That is probably why the transformer gets hot. I wouldn't worry too much, unless you start to smell something...
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kevinloh
Apprentice
Brunei
121 Posts |
Posted - Nov 04 2003 : 7:49:58 PM
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What if it was just a transformer or adaptor and not a charger, will it work too or it will it melt?
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Kale
Nobel Prize Winner
Canada
795 Posts |
Posted - Nov 05 2003 : 2:14:25 PM
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That would depend on whether or not there is any limiting circuitry built into the adapter. Good ones have an overload protection system built into them that keeps them from melting themselves. Cheap ones often do not.
As for heat, if something is designed to run hot, then it's ok to do so, however electronics generally have longer lifespans if they are kept cool. As a result I like to use fans whenever practical.
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kevinloh
Apprentice
Brunei
121 Posts |
Posted - Nov 08 2003 : 7:47:52 PM
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There is one charger/adaptor that I wanted to buy it costs here BND$41.90 in US it is around $25 it has these specifications Adaptor and Charger with glass fuse protection. Variable 12V -24V. 12V 8000ma max 24V 4000mA max. Do you think this is a good charger? It says it can charge all types of car batteries, lead acid batteries and gel cells. I'm not quite sure of the name of the think but I think it is NEWSTAR. Any opinions are welcome.
Edited by - kevinloh on Nov 09 2003 7:47:46 PM |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Nov 10 2003 : 09:37:07 AM
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That sounds like a nice unit for the price....Do you know where I can look it up? I am interested in one (or several).
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kevinloh
Apprentice
Brunei
121 Posts |
Posted - Nov 10 2003 : 7:15:35 PM
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Unfortununately, I can't find any picture of it even though I searched for google and yahoo. :( Sorry about that. It sells in here Brunei in 220Volts but it could be changed to 115V at a flck of a button. And why is it that there are two choices Adaptor and Charger Flick a switch to the left is for adaptor and to the right is adaptor. Aren't it all the same?
By the way are the charging times the same(using the same types of charger) for Ni-cd. Ni-Mh and Lithium Ion and Lithium Ion Polymer?
Edited by - kevinloh on Nov 10 2003 7:17:41 PM |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Nov 12 2003 : 2:52:48 PM
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Proper chargers are a lot more sophisticated then an adapter. An "adapter" is generally just a transformer, bridge rectifier and small filter capacitor which outputs a voltage approximately close to it's rating. The voltage will be low during high load, and high during light load. Works reasonably well for charging lead-acid batteries if you manually monitor the state of charge.
Chargers are much more complicated supplies, that function as both constant current and constant voltage sources. They contain the charging algorithm for the type of battery which they are designed for. Most nowadays use microprocessors.
Charging other types of batteries gets more complicated, especially lithium-anything. Temp and current must be closely monitored, otherwise they burst into flame.
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How long does it takes to charge...
