Confused

[silverseal]

A couple of days ago, it was posted that an "ordinary" car battery charger can only charge to 12.7 volts, whereas an intelligent marine charger can achieve 13.4 volts approx.
I spoke to a friend of mine who designs car electrical systems, and he is also equally confused.
Could someone please explain the physics of the charging process for the smart charger. Does it , for example cause gassing.
Finally is this a bit academic, the most likely source of charge is the engine alternator, and is that charge from an alternator smart?

 

[KREW2]

Hi
There are some very comprehensive answers to your question on the post entitled "battery power"posted on 28/03/05 its on page 2 at present.William H has gone into great detail on the subject
regards KW

 

[TigaWave]

I have used three different mains chargers regularly and monitor the voltage, the cheap simple halfords chargers will go up to over 16 Volts but the poor battery will be gassing and suffering. With a flat battery they will be running at 12.5-13 volts and as the charge comes up to keep pushing current in they will go up to 14.5 anything above this and the battery is just gassing...but they will do it so you have to monitor the state of charge. Unless they have a trickle setting which will limit the voltage/current. So no idea where the 12.7V and 13.4 came from?
My marine charger Inteligent thing would go up to 14.5, but it had a more complex charge cycle of changing the voltage and current during charging. I'm sure thats no help whatsoever....but reminds me I need to put some batteries on charge...thanks

 

[muchy_]

As for the alternator, if you have a smart regulator on it then yes, it is smart charging.

 

[boatmike]

It's quite simple really. Car systems are very basic and the alternator is designed to maintain the battery at about 80% charge as you only use current briefly for starting which is put back fairly quickly. The main load is taken by the alternator when the engine is running and the battery has very little to do. This also means the battery requires only low maintenance. Most trickle chargers only charge to about 80% capacity for the same reason and are designed to restore a discharged battery to a usable state only. BOOST chargers on the other hand are designed to smack maximum charge in over a short time at higher voltages. This gives the capability of charging a totally flat battery in a short time. In fact if you have a very flat battery a trickle charger will often not charge the battery at all. It needs a boost charge to wake it up first.
On a boat if you have a car type alternator you will only get car type charging. You will never get that boost that you need to put maximum charge into a deep cycle battery that is designed to be deeply discharged when the engine is not running.
The "smart regulators" (Stirling, Adverc etc) are designed to convert the output of the alternator to boost rates to achieve higher states of charge. The only downside is thjat you will get some gassing and need to maintain the electrolyte levels by topping up more often. Hope this clears the confusion!