What amperage does a car charge its 12v battery at?
- Thread starter Fordulike
- Start date
D
Deleted member 4366
Guest
They always used to be around 3 amps, but your alternator can charge it at 60 amps or whatever the battery's internal resistance allows. Basically, any current that 14.4v will push into it.
D
Deleted member 4366
Guest
You know when it's on its way when it struggles to turn the engine over on a cold morning. I only use my car about once a month, so the battery keeps running down if I don't remember to charge it. I keep meaning to get a solar trickle charger/ in fact, you've just reminded me. I'll do it now.
Short answer yes.
The longer answer ... Those battery chargers from Halfords, could buy you an extra years usage. Car batteries don't like extremes of heat and cold, vibration, and really hate being left discharged for long. The best place for a car battery is where the original Renault scenic had it. Under the driver's seat.
It takes about 5 minutes of motoring to make up the charge lost in starting under good conditions, and could be longer if the engine was very cold, diesel, and the battery also cold.
Hi Dave, you will probably already know, but depending on the vintage of your car, the cigarette lighter socket , into which these panels plug, may be isolated from the battery. On my Peugeot, it switches off after a while in order to protect the battery discharging. .. so you may have to resort to wiring directly to the battery.
Thanks for the replies guys. Just bought a replacement Bosch battery, so I'll be getting the socket set and spanners out this weekend.
Saw a few dubious branded batteries for much cheaper, but from what I've learnt on electric bikes, it's a good idea to go for quality when it comes to batteries.
Saw a few dubious branded batteries for much cheaper, but from what I've learnt on electric bikes, it's a good idea to go for quality when it comes to batteries.
... Warning.... If your car has protection devices like an immobiliser, you may need to keep power from the battery or engine at all times. Otherwise you may need to bring it to a garage to get it reset. If the engine is running it will supply the power .. I remember having to ensure the power was on for my son's ford focus if you want to do the battery transfer without the engine running,. Just use ordinary domestic electric wire to parallel the old and new new batteries together at the cable connector s . .. plus to plus neg to neg.. or you get a big bang. Then unloosen the connectors and replace...
Thanks, I've already thought about that and did some research. It appears to be fine just to swop straight over without maintaining power.
D
Deleted member 4366
Guest
If we could elaborate on this Dave. I tested the voltage of the four and a half year old battery and also the new one. Both batteries off the car with nothing attached. Both read 12.67 volts. Obviously, give or take for inaccuracies in my multimeter.
Now you mentioned internal resistance. Could the old battery have deteriorated internally, creating a higher resistance, and still show a healthy voltage? If this is the case, would the alternator have a harder time pushing more amps in, therefore affecting fuel economy?
. A fully charged lead acid battery should go above 13.6 volts, so if yours at 12.7, it is seriously depleted., Inaccuracies in your meter notwithstanding.
A battery could be severely knackered (technical term) and still give a full voltage off load. What happens is that lumps of the active material fall off the grids and form a mush at the bottom of the cell. Vibration helps this happen. The sulphuric acid gets diluted or poisoned, the water evaporates. The nett result is an increase in internal resistance so that the battery is no longer capable of driving 100amp into the starting motor... If you were to look at the kit the old garage guys use, it consists of a voltmeter and a loop of resistance wire.. very heavy gauge. They stick this momentary accross the battery and see the on load voltage
Yeah, I remember using one of those to test 12v vehicle radio batteries in the forces. Made a lovely little spark when you touched the terminals lol.
A lead acid battery is usually charged at max 0.1C so a 100 Ah battery could be charged at 10 Amps and a 40 Ah battery at 4 Amps and so on.
12.67 V isn't a healthy voltage for a diesel car...
12.67 V isn't a healthy voltage for a diesel car...
I've been looking around the web for info and the general consensus is that 12.67 is ok.
This is just one of the sites.
http://www.thebatteryshop.co.uk/car-battery-voltage-guide-34-w.asp
This is just one of the sites.
http://www.thebatteryshop.co.uk/car-battery-voltage-guide-34-w.asp
No .. voltage will depend on sulphuric acid concentration, and time from being left on charge, temperature
My Bosch liteature says 12.6 is fine.. Above 13 for a lead acid IMHO is high...???
Yeah, got in touch with Bosch, and their tech guru sent this reply:
"There are variables such as temp but a fully charged batt at 20 deg will have a specific gravity of 1.27, which happens to relate to 12.65v"