How long to charge a battery?

[She_websitetoolbox_import3114]

I was looking through the list to see if it was here sorry if I missed it. How long generally does it take to charge a battery thats connected to your alternator? Battery that has 50% power left. I need to know with the kind of driving I will be doing if its worth it. Thanks!

 

[bee]

<p>It will vary depending on your exact batteries and the voltage that the batteries are charging at. &nbsp;If your alternator is charging at 14v it will charge faster then one at 13v. &nbsp;My two wet cell standard 6v golf cart batteries (hooked up in series for 12v)at 50% will charge to 80% in about very roughly 2 hrs. &nbsp;My alternator charges high, don't know why but my batteries see 14.5v and that is after any voltage drop nearly 20 ft of cable. &nbsp;Most vehicles charge at lower voltage so they will take longer. &nbsp;My batteries are pulling 35 amps from the alternator at 50% charge. &nbsp;To get from 80% to 100% will take about another 5hrs.<br><br>If you cannot charge a battery to 100% after every discharge it is recommended to fully charge at least once a week.<br><br><br>AGM batteries are different, if you have a way of supplying them with high amperage they will accept it at least for the bulk charge. &nbsp;They should charge quite fast from 50% to 80%, they can max out an alternator, maybe even damaging it.</p>

 

[She_websitetoolbox_import3114]

OK everything looked good on your answer until I got to the bottom. Damage? First I heard of that. So what battery would not get damaged?

 

[bee]

Sorry if I wasn't clear. &nbsp;I don't have first hand knowledge with AGM batteries, but I have read a lot about them. &nbsp;My understanding is that when bulk charging they will draw basically whatever amperage is available, where as wet cell batteries self regulate. &nbsp;When I say that my batteries draw 35amps at 50% that is regulated by the battery itself, my alternator is rated at over 100amps. &nbsp;If I replaced my batteries with AGM they could draw double that which MAY overload my alternator. &nbsp;Most alternators are not designed to run at full output for more than a minute. &nbsp;With that being said if that was really true then there should be tons of angry people posting on the net complaining about cooked alternators which I haven't really seen.

 

[Zil]

There are many posts about cooked alternators on the boat cruising forums. Yes if you pull too much currant for too long the belt and or the alternator will fry.

 

[Willy]

&nbsp;It's rather amusing watching people fire up their rigs for 5 minutes and figuring they've charged up their battery. Guy I know, who lives in a minivan, sits on his laptop ALL day playing a facebook game.. till his battery is near pooched (inverter shuts down). Fires up his rig for a few minutes and back at it. ..Willy.&nbsp;

 

[She_websitetoolbox_import3114]

Had to laugh at that comment Willy. I can't see that one working. Its not going to be worth it to me to set a house battery on the alternator. Its not worth the hassle or worry that I may damage the&nbsp;alternator&nbsp; I have a place at work that I can charge a battery up when I need to. I only need to charge it for one thing and thats only in the summer. I already do not use much electric. Yes a laptop which will be charged in the company car I use and my cell phone and thats it. Easy peasy!!! Thanks for your answers <img src="/images/boards/smilies/smile.gif" border="0" align="absmiddle">&nbsp;

 

[Willy]

I have a Surepower battery isolator charging both my starting battery and the house set, with roughly 10 A of solar going to the house set or the fridge battery. Been doing so for over a decade with no problems. ..Willy.