Got a 2nd battery, AGM, 2 questions?!

[dylanear]

1: How can I tell how old this battery is??

2:How do I hook it up to my converter along with another battery of a different type (flooded, not glass mat)?

So I was passing a large battery warehouse like place. So I stopped into to price AGM batteries. The guy I was talking to said, "I have a great deal today", takes me in back and shows me a "scratch and dent" half price group 24 Interstate AGM battery. $75, and it shows "good" on the tester. Then he says, "oh wait", and shows me a larger 100AH AGM and says I can have that for $75 too. But turns out someone else says, "No that's a warranty return." But now I'm left wondering about the state of the first battery.

The guy slapped the EconoPower label on top of the Interstate label before taking out to my car. I moved it so I could still read the original label.



So Interstate has a page on factory ship dates, but the instructions do not match the only markings I can find on my new battery. And my markings are far from clear, look at the large version of this image and read the interstate instructions, does this make any sense to anyone?



http://www.interstatebatteries.com/c...ur_battery.pdf

Interstate Batteries FAQ :: How can I tell the age of my battery?

I may have to call interstate.

And can I just get an intelligent, high quality battery charger that works on 12V? So it can charge from AC (through the converter) or tow vehicle DC? I do have a spare AC powered Battery Tender/charger. Or are there converters that support multiple battery banks that are not too large for a 13' Scamp?

My solar charger does support charging to batteries or battery banks.

I plan on putting the AGM under the rear seat by the converter, I'll leave my flooded 80AH on the tongue.

[Darwin Maring]

Go to the factory web site and ask them. More than likely the STAMP is a code of the manufacturing date.

The dates on the sticker on top is used for the purchase date.

[dylanear]

That's just the thing, the info on the Interstate web site does not match these markings. They say there would be a number as one of the two left characters, all these marking look like letters, except that last one on the right might be an 8, or a B.

[Darwin Maring]

I can not read the stamped letters/numbers. Are they upside down? What do they say.

[dylanear]

I talked to Interstate, and it's possible it was made August '11. But there's enough ambiguity that there's no guarantee.

Hey, $75 for a 75AH AGM, I'll try not to worry too much. Well, there was tax and a $17 core charge since I didn't want to give them my working 80AH flooded battery.

Now if I could just figure the best way to wire this thing in!

[dylanear]

Replacing my current converter with this one and the distribution panel I think will do the trick. Not cheap, but looks like a nice solution.
PD2130 30A Marine Battery Charger

PD5000 AC/DC Power Control Center


Or maybe, for now, just adding another battery charger to my converter, but then how would I get power FROM that batter in conjunction with the tongue battery?

DC Input Battery Chargers for 12 volt Lead Acid and SLA Batteries useful for electric golf trolley

Oh it makes my head hurt.

[Roy in TO]

Most things I've read about using multiple batteries state that the batteries should match for best results. Dual 6V will typically give better results than dual 12V.

[dylanear]

Yes, matching would make my life easier. I could treat them as one battery that way. I never seem to make things easy.

Ideally I'd like a grp 24 on the tongue and a larger in back.

[Ryan P R]

Since they are not matched in age, capacity, type or brand.... Perhaps you should use one of those heavy duty red isolation switches that folks tend to use with camper vans. It will allow you to isolate the batteries from on another, and/or the converter charger and solar charge controller.
That way neither of the batteries would get over or undercharged as a result of being run in parallel with each other.

[dylanear]

Do you mean a simple manual toggle between batteries? Use one or the other? Probably not an awful solution in the interim. I ran across "diodes" for isolating batteries, not cheap. But that might let me put one on the converter charger, one on a secondary 12V to 12V intelligent charger and, have both feed back to the converter to power the trailer DC circuits. A total mystery how that would actually work or be wired up.

I really do think the Progressive Dynamics marine unit and a fat AC/DC breaker/fuse set up will happen eventually. Yum. But probably not before I'm getting paychecks again. And I can't add to my current to do list. Although, since there would be little mystery about how to wire that up, replacing my converter entirely might be faster than trying to figure out how to cram this 2nd battery on my current one! I have more money than time right, now, but not tons of either sadly.

Any serious DIY electronics whizzes? Maybe an EE around? Are there devices that can go inline or a hall effect type sensor that can feed power measurements to serial for monitoring and logging? Or am I getting entirely too nerdy here? I'd love to log all my power use, an AC power measurement/logging unit would be cool too. Just a project I'd find fascinating and rewarding to dabble with at some point.

[Ryan P R]

I don't have any suggestions on power consumption/charging metering.... But I currently charge my "other" trailers 2 batteries with a hobby grade smart charger. I bought the charger to charge lithium polymer batteries for my RC cars and RC SURFER- but it works great for charging the trailer batts.
It tells me exactly how much capacity it puts into the batteries, which I find very helpful and comforting. It's nice to know how much you've really used.
I'd also like to have system that fully monitors all power use/charging. But I'll probably just end up with a PD 4045 unit for cost and simplicity.

[honda03842]

Dylan, Went to HarborFreight and bought two moose-like battery switches for about $3 a piece. Installed them on a panel between the two batteries.

[Patvetzal]

I have a feeling that the different type of batteries all have a slightly different voltage when fully charged. Doesn't effect anything when only one is used, but as soon as you connect two types in parallel the voltage will settle out at the lowest one.

[dylanear]

Funny Norm, I was holding a $65 rotary, lockable battery switch and looking at $10 simple style battery battery disconnect switches and was thinking they'd effectively do the same thing. But the expensive one looked cool, so I got it. This is why I'll never have the money to retire.

Yeah, I could probably just get by wiring them in parallel and leaving it at that. The charge voltages between flooded and AGM is only like a volt. But I just like the idea of being able to charge separately. And the switch I got will also let me have them both attached too, if I want to see how that works. There may be times I'll want to have both connected.