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| John Rudd:
I wouldn't endorse the use of a car battery charger as a power unit for your charger.....generally their output is raw dc with no smoothing....not something it will like..... |
| S. Heslop:
Dang. I might look at a PC power supply with a dummy load then. There's a million sketchy half-assed looking guides on the internet about converting them, and that usually puts me off. But as far as I know a PC supply would have no problem delivering 5 amps at 12 volts. |
| vtsteam:
Yes you can charge a 5000 mah R/C Lipo power pack at 5 amps -- it is in fact the norm. You need a supply to the charger of more than the output amps though -- the charger isn't 100% efficient. An 8 amp or better rating on the computer PS would probably be okay. Basically to convert one the yellow and black wires carry +12V and ground respectively. Most newer supplies also have a ON-Off switch sensing wire that turns the PS on or off. On mine it is a green wire in the biggest connector (might be a different color on a different supply) this gets connected to ground (black). I just inserted a hairpin piece of wire in the connector to make that connection. The PS own switch still works to shut it off. Some people say you also need a dummy load across a red wire (+5V) and ground so the supply can do a good job of regulating -- and to extend longevity. You can use a 6V light bulb. That 's about it. |
| awemawson:
Simon, if you do end up with an old style car battery charger with no regulation then all you need do to keep it's volts in range is to put it across a car battery and draw your charging source from the pair of them. |
| DMIOM:
--- Quote from: S. Heslop on July 30, 2014, 11:36:34 AM --- ......In other news, i've still had no luck finding laptop batteries at boot sales. I need to move on to other stuff though so I suppose i'll have to save the batteries for later, whenever I find any. --- End quote --- Hi Simon, I must admit I don't think I'd be looking for boot-sale laptop batteries. Two reasons really - the main one is that batteries that are that far down the chain may well have limited capacity. Most laptop users leave their machines on mains power almost all the time. Susceptibility to 'memory effect' is reducing - but the batteries are likely to have limited usable capacity. Secondly, the management of charging laptop batteries is handled in different and sometimes quite sophisticated ways by the host laptop - so unless you gut the battery for individual cells, you may need the host laptop to charge the battery pack. Dave |
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