AGM or not ???

2Guido · January 2013

I have set up my continuing project with a combo of glass panels and flex solar mats..approx wattage total = 2000. They feed into a coleman 440 diversion controller then into banks of 6v AGM's to power 3 prosine 3k inverters. After reading many posts on batteries, I am beginning to wonder if I am spending too much $$ on the AGM's and go a different type of battery. Can I get a definitive answer from the mods as to which batteries are best for both performance and life ?? ..Oh, in bright sunshine, the controller reads around 50amps at 24volts
Thanks guys !!!

BB. · January 2013

Re: AGM or not ???

Us moderators are here to, mostly, help with spam patrol--There are lots of folks here with more experience than I.

Agm batteries are very nice, but if you can do the monthly watering and cleaning, then flooded cell batteries may be a better buy... Also, there is a good chance that flooded cell may last longer too.

-Bill

waynefromnscanada · January 2013

Re: AGM or not ???

Would be good if you could keep it all in one thread so we could easily check back on previous info re this system.
That aside, you'll pay more, perhaps twice the $ as for the same capacity Flooded. Also Flooded are much more forgiving of overcharging etc.
AGMs have their place, but I definitely wouldn't recommend them as "learning batteries".
And you're aiming for 9000 watts worth of inverter? WOW!!!

Cariboocoot · January 2013

Re: AGM or not ???

My personal opinion is that flooded cells are better to start with because they are usually cheaper per Watt hour and easier to "keep an eye on" by looking inside and actually measuring specific gravity. Too often people think AGM's don't need watching because they are sealed, when really it's that they can't be watched because they are sealed. That's why a battery monitor is almost essential with AGM's. Along those lines the flooded cells will be more forgiving of mistakes (incorrect charge Voltage/time) whereas the first clue you get with the AGM could be "dead battery".

On the other hand there is sometimes a need for the AGM's advantage of being sealed (such as having to locate it in living quarters, no hazardous shipping), lighter weight (some mobile applications), and greater current handling (need to charge very fast or take heavy discharging).

You're not going to find people saying "this is better than that always" because it isn't so. Got to consider all the circumstances of the application.

vtmaps · January 2013

Re: AGM or not ???

As you design your battery bank, remember that parallel batteries are a bad idea.
read: http://forum.solar-electric.com/showthread.php?14674
not mentioned in that thread is that AGM batteries are even more susceptible to to the problems of current sharing because of their lower internal resistance.

--vtMaps

BB. · January 2013

Re: AGM or not ???

Even though I am a major proponent for one series string of batteries, with possibly two to three parallel strings as my recommended upper limit for normal systems (each string should be fused/breaker to limit short circuit current)--Others here with lots of experience (Windsun, our founder/admin of this forum from NAWS) has stated before that he has not seen a difference in battery bank life between single series and multiple parallel battery banks. Lots of happy customers with both

For me--If you choose to go with multiple parallel batteries, I would suggest getting a DC Current Clamp Meter (this version of AC/DC clamp meter + DMM functions is only ~$60) so you can monitor current flow in parallel battery circuit paths (can be used on parallel solar strings too). This will make it easier and quicker to identify problems (open/shorted cells, loose/dirty/corroded connections/etc.) before they get so far out of hand that it damages one or more battery cells.

Like anything, more connections means more complexity and maintenance (each string is another set of cells to water once a month). It does not mean do "B" (parallel battery bank) will instantly crash and burn--It just means that there are, usually, alternatives that make installation and maintenance a bit cheaper and easier to do if you can design a system that tends towards one series string.

-Bill

solar_dave · January 2013

Re: AGM or not ???

2Guido wrote: »

I have set up my continuing project with a combo of glass panels and flex solar mats..approx wattage total = 2000. They feed into a coleman 440 diversion controller then into banks of 6v AGM's to power 3 prosine 3k inverters. After reading many posts on batteries, I am beginning to wonder if I am spending too much $$ on the AGM's and go a different type of battery. Can I get a definitive answer from the mods as to which batteries are best for both performance and life ?? ..Oh, in bright sunshine, the controller reads around 50amps at 24volts
Thanks guys !!!

SO are your panels all the same Spec? Is it a single charge controller? The solar mats and glass panels have me a bit worried as to how they are hooked up. What are the specs for your panels? What are the specs for your proposed batteries?

2Guido · January 2013

Re: AGM or not ???

The panels are all the same voltage but different wattages. The array has been an experiment, hence the different size panels. I get the most current from the flex mats. All panels feed down to a circuit breaker box where they are combined before being fed into the Coleman 440 Diversion Controller (PWM) Currently I have 3 banks of four 6volt AGM's (260Ah) feeding into three ProSine 3k inverters. The system goes off the grid at 6am then auto-returns at 6pm when the inverters kick in their chargers to top off the batterires. It is obvious i need more batteries to sustain this system...

westbranch · January 2013

Re: AGM or not ???

2Guido wrote: »

at 6pm when the (Prosine) inverters kick in their chargers to top off the batteries. ...

???

Prosine inverters do NOT have built in chargers. http://www.xantrex.com/power-products/power-inverters/prosine.aspx

2Guido · January 2013

Re: AGM or not ???

Yes they do.these are the 3k inverters (older models before Xantrex put their name on them)
http://www.wholesalesolar.com/products.folder/inverter-folder/pros3000-12.html

Cariboocoot · January 2013

Re: AGM or not ???

Most likely they are these: http://www.xantrex.com/documents/Discontinued-Products/DataSheet/DS20070503%20Prosine%202.5-3.pdf
Or a similar, older model.

Photowhit · January 2013

Re: AGM or not ???

westbranch wrote: »

Prosine inverters do NOT have built in chargers. http://www.xantrex.com/power-products/power-inverters/prosine.aspx

Just for the record they still make a ProSine with a charger;

http://www.xantrex.com/power-products/inverter-chargers/prosine-2.aspx

Just have to look under inverter/chargers! Actually I was surprised i didn't find any 24 volt versions, they can't be long discontinued.

Shadowcatcher · January 2013

Re: AGM or not ???

I went with an AGM battery with our trailer, in part because it is in a closed space and I wanted a battery that was basically maintenance free. If I were going with a stationary system I would not have gone that route, so my vote is wet cells.

AGM or not ???

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