Fall Battery Use

[searat]

Battery question: We have a camp (in Maine) where we installed a small solar system (200w) currently with (2) 6v batteries golf cart batteries (soon to be 4).  We are up there very frequently during the summer, but in the fall we are up there only about once a month and then we close the place up in late November (we will take down the panels for the winter- trees, ice, etc).  

I am a little reluctant to leave the batteries hooked up to the solar system unattended for a month, even if it is only running at a float charge.  I was thinking about buying one of those solar trickle chargers from Northern Tool (5w), but maybe that's not worth it if it is only running at a float charge anyway.  I plan on lugging the batteries home when we close up, and sticking them on a trickle charge in my basement.  Any advice if I should just leave the system hooked up or do something different?

[ghurd]

I would leave it hooked up. The charge controller takes care of everything.

The low quality, small 5W PV won't count for much, if anything, for batteries that size.

Watch out for 'standard' trickle chargers, as they can overcharge a battery,

no matter what the box says.

G-

[whatsnext]

I would bring the batteries home but I would skip the trickle charger. As long as the voltage of each bat does not go lower than about 5.3VDC there is nothing to do because that is the point sulfation starts. Because I'm paranoid I would check the voltage every couple of weeks and if it got down to 6VDC I'd put a charger on it and bring it up to 6.6VDC or so. If the batts are stored someplace warm I doubt you would have to charge them more than once over the course of the winter. The trickle charger is really a waste as it's not that important that the batteries stay at absolute full charge. The sun will bring them back to full charge next spring.

John.........

[Volvo farmer]

Hey, where do you get this information about sulfation and battery voltage? The reason I ask is I have about $2K worth of brand-new L16s waiting for me to build a power shed. I put series cables across pairs of them and charge them up, two at a time with a Vector smart charger every week or ten days. I haven't checked lately but there's no way they are below 5.6V by the time I get the charger on them.

I'm glad to hear this info about sulfation, because I've been worried about it. Just wondering how you know the specific voltage at which sulfation begins.

[whatsnext]

Trojan's site pretty much tells all but I'm sure all the links are here at FL. To the best of my knowledge 10.5VDC is the point to avoid, loaded or unloaded, I'll try to dig up a link for you.

John.......

[ghurd]

Not trying to argue.

But I read (somewhere) that it is 11.9V for 12V, or 5.95 for 6V when sulfation gets faster.

Personally, I would try to keep them above 12.4V, but I can't say why I chose that number.

G-

[Flux]

That 12.4 figure rang a bell with me as well. I found it after looking through things that I have saved over the years.

http://www.batterystuff.com/tutorial_battery.html

Seems as though it starts at 75% charge or 12.4 v.

Flux

[Bruce S]

Hey All;

   There's a website that is from the guy who wrote the defacto book on all types of batteries. There's enough reading there to tire out an insomniac.

I found it from the back of his book, that came with our companies super-duber battery tester.

http://www.buchmann.ca/

Hope it helps;

Bruce S

[whatsnext]

I'm pretty sure that the 10.5VDC number is when the 'hard' version of sulfation forms but like I said I'm paranoid enough to keep things above 12. I've been trying to chart self discharge in post EDTAed batteries and it's just taking forever for the voltage to come down. I really have not run this stuff on enough batteries to say, scientificly, that it's as good as we sometimes hear but, so far, it seems pretty amazing.

John..............

[wooferhound]

 Here is another great link about Batteries . . .

http://uuhome.de/william.darden/carfaq.htm

[steak2k1]

Just as an aside.

The link that Woof has above this post is about the best (IMHOP), FAQ one could ever want for information on batteries: Deep cycle and SLI types.  I have DL'd and printed it (about 147 pages for what I needed), and yea it has been of enourmous value in saving my 2 - 2yr old trojans (t105's).  

thanx woof.!

They were sulphated a bit. (80% capacity). I am now in the process of trying out a water based retail product called Battery Equaliser. (cheaper than buying a pulse charger),  The manufacturer professes that it will desulphate a battery to some extent. We shall see how that works.

www.batteryequaliser.com (no I am not an agent for them by any stretch...but some interesting testimonials on this stuff.) any comments on this stuff from previous experimentors would be welcome BTW..??

Bottom line is that all batteries need to be kept charged and not with a trickle but rather a float charge.  As noted a trickle charge will in fact overcharge batteries and likely destroy them.

for what it's worth.

stk