Storage Life

[Midrover170]

Hi all,

My solar kit arrived this past week, and it includes 4 UB8Ds. I'm leaving them at my house while I get the cabin wired up and ready, about halfway there. It's cold up there and I don't think I want the batteries sitting there without juice or heat. Is there anything I should do in the interim to protect the batteries other than keep the garage warm? I have a 12v Battery Tender that I used for a motorcycle... Is it worth putting that on them in rotation? Will that damage them?

Thx

[Sunking]

Charge them up.

[Logan5]

depending on how many AH the batteries are, I suspect that battery tender is only 1 to 1.5 amps. too small for off grid batteries. If they are new batteries you plan to use on solar they need to be hooked up to a smart charger until they are fully conditioned. If you do not have a good quality bulk charger, you will need to purchase one. 100 to 200 bucks. If you take new batteries on put them on solar the will never get fully charged and you will be replacing in 6 mo's

[PNjunction]

The Battery Tender will just time out. One doesn't use a BT on 250ah batteries I'm afraid.

The best solution since they are not wired up for their final configuration is to just charge them up individually with a 25a charger, and then get back to them when you can, since agm's have very low self-discharge. No more than 3 months - 6 months TOPS.

It is highly likely these batteries have also sat around in retail, or are truly older than 30 days from date of manufacture. So it is vitally important to get them fully charged.

A cheap way to do that would be to go to any hardware store, and pick up either a Stanley BC25BS benchtop charger, or it's twin, the Black and Decker BC25BD. The point here is not so much to get the absolute best charger in the world, but to save your major investment in batteries from sulfating - especially since the clock started running the day they were manufactured, NOT when you received them.

Using less than 25A for charge, ie less that 0.1C, which for an agm is not really efficient if you go too low. Sure, you'll eventually charge, but because it is not efficient, secondary PCL issues arise which you don't want to saddle your brand new batts with from the get-go. So don't skimp on the current. 25A just to get them topped off is fine.

Charge each battery to full INDIVIDUALLY, preferably allowing for about 6 hours of float afterwards with each. Since you won't be around, unplug charger and leads. Don't be tempted to wire them all up in parallel to shorten the process. They are not balanced, and the fact that they are new means that each has it's own "first birthday" character to being charged.

If you are gone longer than 30 days (60 days tops), return and repeat. It will likely take much less time.

[Midrover170]

Thanks all. I picked up a charger today and hooked it up to the UB-8Ds. Reading full but great to have charger around while install wraps up. A great little battery shop here had a 26amp Noco Genius, about got that but it dawned on me that it probably would have thrown every breaker in my 1931 garage... And I wasn't about to lug these batteries throughout the house. Opted for the smaller Noco and it's working well.

[Logan5]

I would have purchased a battery charger for the voltage of the solar battery system you plan to build. If you are planing a 24v system you should have a 24v charger. 48v same thing, a 12 volt charger is good if you need it for other things, but in the future when you need to do maintenance your going to need a proper volt charger. to use this 12v charger would require you to break the buss. lot of work just to balance your solar batteries.

[Midrover170]

It is a 24v charger

[Logan5]

Very good.

[PNjunction]

Er ok, you gotta do what you gotta do. If that is the G15000 instead, just know that at 24v, it can only supply 7.5A, far below the 0.1C current charge spec should be for an agm if you want it to stay healthy. However, if they were already near topped off, and just using it as a temporary tool - good deal - you got much of the retail storage self-discharge sulfation under control.

Unfortunately, both my newer 15000 and 26000 failed with the major mode button.

I STILL would have preferred using the 12v charge (15A now) on them individually for their "first birthday". At 7.5A at 24v for the G15000 that represents about a .03C charge current, so my advice is to never use the Noco for coming out of a deep, or in fact even moderate discharge on these batts.

Put it this way - that would be equivalent to using a 3-amp charger on a 100ah agm. Something even Schumacher warns against doing with their smaller maintainers.

I mean you seem to have gotten them topped up - ok.

And if you didn't charge them individually when they first come out of the gate - like many people do - you are just crossing your fingers, and NONE of them get a REAL good first charge to help ensure balance and health down the road when charged as an array - until after the fact.

Hint: Like their automotive dual-purpose / marine "thin plate" brethren, they aren't really made for deep-cycling. In order to get 3-4 years of "moderate" daily cycling from them, never discharge beyond 25% DOD each cycle:

http://upgi.com/Themes/leanandgreen/...oads/45964.pdf

Take care of 'em with proper maintenance.