voltage drop

pianotuna wrote:
Hi,

Do you mean agm battery?

Self discharge can be as little as 1% per month or as great as 1% per day. It depends on the chemistry that the battery maker is using.

How does the chemistry vary? They are all lead/acid batteries.

As mentioned, the higher voltage reading from a freshly charged battery that has had no drain applied is know as "Surface Charge." It will quickly drop to the 12.6v range once a load is applied.

12.8 or higher is the DEKA AGM 100% charged resting voltage.

http://www.dekabatteries.com/assets/base/0139.pdf see pg 13

thanks smkettner for the info. I copied a page from my inverter/charger manual about charging. will this type of charger charge my batteries correctly and not shorten their life?

There are 3 charging stages:
Bulk Charging: This is the initial stage of charging. While Bulk Charging, the charger supplies the battery with controlled constant current. The charger will remain in Bulk charge until the Absorption charge voltage (determined by the Battery Type selection) is achieved.
A software timer will measure the time from A/C start until the battery charger reaches 0.3V below the boost voltage, then take this time asT0 and T0×10 = T1.
Absorb Charging: This is the second charging stage and begins after the absorb voltage has been reached. Absorb Charging provides the batteries with a constant voltage and reduces the DC charging current in order to maintain the absorb voltage setting.
In this period, the inverter will start a T1 timer; the charger will keep the boost voltage in Boost CV mode until the T1 timer has run out. Then drop the voltage down to the float voltage. The timer has a minimum time of 1 hour and a maximum time of 12 hours.
Float Charging: The third charging stage occurs at the end of the Absorb Charging time. While Float charging, the charge voltage is reduced to the float charge voltage (determined by the Battery Type selection*). In this stage, the batteries are kept fully charged and ready if needed by the inverter.
If the A/C is reconnected or the battery voltage drops below 12Vdc/24Vdc, the charger will restart the above cycle.
If the charge maintains the float state for 10 days, the charger will deliberately reset the cycle to protect the battery.

That system works fine. Check that absorption and float voltages are not more that 0.1 too high.

smkettner wrote:
That system works fine. Check that absorption and float voltages are not more that 0.1 too high.

I do not know about the absorption but the float voltage is .1 below. so i'm guessing that is ok?

AIMS Power www.aimscorp.net
Switch setting Description Boost / Vdc Float / Vdc
0 Charger Off
1 Gel USA 14.0 13.7
2 AGM 1 14.1 13.4
3 AGM 2 14.6 13.7
4 Sealed lead acid 14.4 13.6
5 Gel EURO 14.4 13.8
6 Open lead acid 14.8 13.3
7 Calcium 15.1 13.6
8 De-sulphation 15.5 (4 Hours then Off)
9 Not use

i am using switch 2 agm 1
after reading the deka page 11 I might want to use switch 3 agm 2

#2 looks better in Summer and maybe #3 in Winter assuming no temperature compensation.
How cold does it get in Jersey?

norm is 25-35, but a few days in the teens, once in awhile single digits. we only need to worry about the winters for 2 more years, then if plans work out we shouldn't be here in the winters any more.

Hi Gau,

For example how much Antimony is in the paste. That affects gassing voltage and charging voltage

Or if it is Calcium (usually a hybrid type). That means less depth of charge.

Is the electrolyte tropicalized? That means a lower specific gravity for fully charged.

There are probably hundreds of variants on the above. So contact the maker and find out what charging routine is best for your battery.

Lifeline can be "hit" with up to C x 3, so a 100 amp hour battery can be charged at 300 amps. Most other AGM's would not survive.

Gau 8 wrote:

pianotuna wrote:
Hi,

Do you mean agm battery?

Self discharge can be as little as 1% per month or as great as 1% per day. It depends on the chemistry that the battery maker is using.

How does the chemistry vary? They are all lead/acid batteries.