Electronics > Beginners

Is there a way to safely charge a car battery with this equipment? If not, why?

<< < (9/12) > >>

Simon:
well I expect cars err on the side of caution. You can't drive around indefinitely at 14.4V as you will knacker the battery. Given that the battery just works to start the car in most use cases 13.8V float is probably deemed to be a compromise. If i am manually charging i too will use in excess of 14V for speed with a current limit but unless the vehicle has a BMS they have to compromise. The alternator current limit is to protect the alternator not the battery. Modern Audi's have a load of BMS gear attached to the battery i am told and it looks after the battery to the point of restarting the engine if it's off and the ignition is on and the battery voltage is dropping.

tautech:

--- Quote from: T3sl4co1l on October 20, 2019, 06:29:37 pm ---Well, so what? It's taking current at a lower voltage because it's in a discharged state.  As the concentration of Pb-->PbO2 and PbSO4-->Pb rises, the cell potential also rises.  (In fact it's up to 13.74V already.)  When all surfaces are fully charged, the voltage levels off somewhere around there (when under some degree of charge, because again, overpotential).  I'm going to float it at 14.2 for a while (preferably 12-24 hr, not sure if I'll get that much time on it tonight) to ensure a full charge (desulfation, to the extent that it can be performed at all).

Tim

--- End quote ---
You don't get a maintenance charge until 15V (gassing charge) where you'd get any benefit from desulphation and really you don't want to go there with the modern sealed FLA.

IMO the old noisy generators and their spikes where better at battery desulphation than the modern alternator.

Simon:
I thought the old "generators" or dynamos were supposed to be smooth DC. It's all you hear about from the old cranks that want to keep their dynamos that they are better because of the smooth output. In reality the 3 phase that get rectified are pretty good

soldar:
Old (dynamo) regulators were extremely simple. Two relays. One would close above a certain voltage and would disconnect the generator below that. This was to prevent the battery from discharging through the generator. A diode could do the same job today.

Another relay kicked in above a certain charging current and opened the NC contacts which put a resistor in series and this limited charging current.

That's it.

You could have all sorts of problems if contacts got stuck or voltage or current activation got out of whack.

Simon:
yea, but all the old farts still harp on about the good old days of dynamo's

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod