Woo Hoo..New AGM Batteries

pnichols wrote:
Reading this thread makes me wonder what "floating" batteries means. I thought it meant maintaining some particualar voltage on the batteries at all times after they have been fully charged using whatever method.

I believe you have it correct. To float means to hold at a static SOC. A float-charge would invoke a slightly higher Voltage.

ME! on Mar 13. wrote:
It is 2:39PM CDST in OKC and I just checked and my 48F temperature AGM is being floated at 14.24V by the MS TS 45 PWM solar controller.

That it is floating means that the solar controller has completed its daily Bulk and Abs stages. Generally Abs Voltage is ~1V higher than float. My bank gets goosed daily.

In this situation your 13.8V float would be too low for me.

Do you have temp coefficient specs for your batteries?

HTH;
John

Electricity: Understandable controllable with microprocessor algorithm

Chemistry: Understandable controllable with microprocessors algorithm

Electrochemical: Almost Voodoo, "auto" controllable with dead chicken nailed upside down on door, juju beads, chanting and virginal sacrifices.

My batteries only spend a few days of the year at actually floating with shore power , and some afternoons at float with solar
IF I'm not using more than the solar is producing
Basically my batteries are either being used or being charged
Resting or floating could be measured in tenths or even hundredths of percent time
Compared to use time

Reading this thread makes me wonder what "floating" batteries means. I thought it meant maintaining some particualar voltage on the batteries at all times after they have been fully charged using whatever method.

At least in my case that's what float means when camping with hookups or when the RV is in storage .... plus this caveat: My "float" voltage is also the voltage the RV batteries usually get charged with from our generator whenever drycamping. The spec on our AGM batteries calls for 13.5 to 13.8 float volts, but they also of course can be charged up to a < 1.0 acceptance amps state using only 13.5 to 13.8 volts - if the charging time is long enough. We usually only charge the batteries with higher voltages than those when on the road or for faster generator-less charging when in drycamp.

We can only get by using the above approach because of our particular type of AGM batteries.

5:30 A.M. Still dark, before sunrise
90 percent SOC
12.73v
2 amps load

With an AGM battery, modestly increasing the float voltage -should- result in a mere momentary rise in amperage then flatten out. But the higher setting would be too high..................................because................................

If it was too low, amperage would rise then stay risen for a considerable length of time. This is a BS detector for AGM float voltage settings. The particular battery design has an inherent "correct" float voltage characteristic that proves to be useful for those whom battery lifespan is critical (long term maintenance float). The testing and tweaking should be done with a fairly new battery then adjusted once a year as the battery ages.

I have a 31 Lifeline on float. Because of its mass it greatly resists ambient temperature "tracking". An 84F to 59F daily spread, yields a seven degree Delta T temperature spread. Only a battery post thermistor compensation could resist exaggeration under this condition.

MEXICOWANDERER wrote:
Ohhhhhh Señor,

May I ask a favor of you?

Tweak your 14.24 float to 14.40 and note the amperage amplitude and duration to sag back to <1% total amp hour bank capacity. This would be merely to satisfy my curiosity. Zank Youse!

I can't observe DC Amps.

I have no doubt that increasing Volts will result in additional Amp flow as you describe.

HTH;
John

I can let my 150 Ah Telecom sit for 3 or 4 months, and when I put the MegaWatt on it at 14.40V, amps will start at around 4 amps, and within 40 -50 min, I will be down to .75 to .60 amps, in 70F temps. Zapping it briefly to 14.8V makes hardly any change at all in the amps it takes, still under 1.00 amps charge rate.

It's an unusual critter, that surplus telecom battery. It does not like high amp rate withdrawal rates either, or high recharge rates. I've never seen it take over 20 to 21 amps at 14.4V. I do need to discharge it to around 50%, just to stir up the chemistry inside. Maybe just run the unit with the fridge on for 2 days and some TV at night to lose 50 or 60 amp hours, then recharge it with the MegaWatt and the Eu1000i. 2 to 3 hours of run time should do it, then bring it home for a top charge in the garage, on the grid.

Ohhhhhh Señor,

May I ask a favor of you?

Tweak your 14.24 float to 14.40 and note the amperage amplitude and duration to sag back to <1% total amp hour bank capacity. This would be merely to satisfy my curiosity. Zank Youse!

My buggest regret regarding solar was not buying the controller that had a BTS. but I am coastal S california so temperature swings are not wild.

My voltage goosing was perfomed after sundown via Meanwell power supply, and who in their right mind does not enjoy turning a 10 turn potentiometer? Goosing is fun!