another source for agm batteries

Almot wrote:

I think all MPPT controllers over say, $200, have adjustable setpoints and remote temp and volt sensing. Some also have adjustable rate of temp compensation, i.e. how big voltage increment per every degree above/below 77F....

Good point. I do have a Tristar PWM that is smart as well. I don't mean to omit other brands with smarts.

HTH;
John

BFL13 wrote:


That's a strange quote. Usually they base everything on 80F or 25C. If max at 20C is 14.6v it is less at 25C.

If you think about it, when a battery's AH is rated at a lower temperature, 68 v.s. 77F, that battery is going to have more AH at 77F.

It is a marketing blunder to spec at 68F as the unwashed will not understand the temp effect on AH. If the other brand 77F rated battery is 80 AH, which one is better? More may actually be less!

HTH;
John

full_mosey wrote:
A temp comp charger actually simplifies this by adjusting charge stages according to a reference 77F. The charging profile is then based on 77F and you ignore battery temps because that is handled already.

The Tristar models of solar controllers are known for their ability to accept custom parameters that meet whatever your battery manual requires. They can sense both battery volts and temperatures.

Converter/chargers are dumb by comparison.

I think all MPPT controllers over say, $200, have adjustable setpoints and remote temp and volt sensing. Some also have adjustable rate of temp compensation, i.e. how big voltage increment per every degree above/below 77F. I only wish they could generate current at all times :)...

Lifeline provides a formula to estimate charge times:

5.4 wrote:
The time to reach full charge at temperatures in the range of 68 to 86°F (20-30°C) can be estimated from the following equation:
Time to Reach Full Charge = ((DOD/100) x Rated Capacity (Ah) ÷ Rated Output of Charger (Amp)) + 2 hours.
For example, charging a 100Ah battery at 50% DOD with a 25A charger would take:
((50/100) x 100 ÷ 25) + 2 = 4 hours to reach full charge.

If a 10A charger is used, it would take:
((50/100) x 100 ÷ 10) + 2 = 7 hours to reach full charge.

A temp comp charger actually simplifies this by adjusting charge stages according to a reference 77F. The charging profile is then based on 77F and you ignore battery temps because that is handled already.

The Tristar models of solar controllers are known for their ability to accept custom parameters that meet whatever your battery manual requires. They can sense both battery volts and temperatures.

Converter/chargers are dumb by comparison.

HTH;
John

I can't name names, but when I had contacts in various battery manufacturing plants, the degree of knowledge varied from mediocre to quite satisfying. Some plants operated purely by rote. Reminds me of doctors who scribble a prescription then emit a clear signal to hit the road. They do not want to talk about how and why they arrived at their conclusion and decision. Thank god doctors do not have a sales department.

Here are some key questions to ask a manufacturer. They are sensitive. A response or lack of one is telling.

Do you use virgin lead? Recovered lead? Refined recycled lead?
Do you manufacture your plate paste from scratch here on site?
What is the percentage of antimony in the positive plate?
What is your percentage rate of destructive sampling and testing?

If "the competition" wanted to know succinct precise information they would purchase a new battery then analyze what's hiding beneath the lid. There really is no valid justifiable reason for a battery manufacturer to balk at providing comprehensive answers to these questions. A trustworthy OEM would be proud of their numbers.

BFL13 wrote:


What is a constant potential charger?

Lifeline Manual 5.6 Deep Discharge Recovery explains this in detail.

HTH;
John

I agree, strange quote and different from what we hear about some other AGM's.
Perhaps we are seeing Mex's description of the battery marketers thinking the engineers 'gobbledygook' will hurt sales
Here is where I pulled the quote from if you have not found it already:

http://www.dekabatteries.com/assets/base/1143.pdf

landyacht318 wrote:
I am still AGM shopping. Was seriously considering the Deka Intimidator/ Sears DiehardGoldAGM group 65 until I saw the max charging voltage of 14.6. My Vehicle will do 14.7 and occasionally higher, though usually short lived.

Constant under- or overcharging will damage any battery and shorten its life! Use a good constant potential, voltage-regulated charger. Charge to at least 14.4 volts but no more than 14.6 volts at 68°F (20°C). The open circuit voltage of a fully charged 12-volt AGM battery is 12.8V at 68°F (20°C). As the battery charges, the building internal pressure (voltage) causes resistance to the charge. Therefore, the on-charge voltage must be higher (at least 14.2V) to overcome this internal pressure (voltage) during charging.

Now back leaning toward the DHPlatinum/Odyssey that lists 14.8v, for more CCA a few more A/h, and a bigger wallet hit.

Noticed my nearest battery distributor carries US Battery AGM. They have 27's slightly smaller than my current flooded crowns. Will call and check prices manana

That's a strange quote. Usually they base everything on 80F or 25C. If max at 20C is 14.6v it is less at 25C.

What is a constant potential charger? Is that like my constant current charger in Bulk, where charger voltage stays ahead of battery voltage as battery voltage climbs to maintain the "spread"? You only want constant voltage for the Absorption stage, so I don't know where along they mean "voltage regulated."

I am still AGM shopping. Was seriously considering the Deka Intimidator/ Sears DiehardGoldAGM group 65 until I saw the max charging voltage of 14.6. My Vehicle will do 14.7 and occasionally higher, though usually short lived.

Constant under- or overcharging will damage any battery and shorten its life! Use a good constant potential, voltage-regulated charger. Charge to at least 14.4 volts but no more than 14.6 volts at 68°F (20°C). The open circuit voltage of a fully charged 12-volt AGM battery is 12.8V at 68°F (20°C). As the battery charges, the building internal pressure (voltage) causes resistance to the charge. Therefore, the on-charge voltage must be higher (at least 14.2V) to overcome this internal pressure (voltage) during charging.

Now back leaning toward the DHPlatinum/Odyssey that lists 14.8v, for more CCA a few more A/h, and a bigger wallet hit.

Noticed my nearest battery distributor carries US Battery AGM. They have 27's slightly smaller than my current flooded crowns. Will call and check prices manana

For the timing to work as a standard, you need the same assumed capacity, which unfortunately, is temperature dependent. You need a good Temp vs Capacity chart to follow the play. (Sadly they are wildly different, so only use the same one every time) But then if your charger has temp comp that can muddy the water too.

You have to keep good notes on the temp, etc at the time of recharges so you are getting the right picture for comparing recharges. After a while, you get to "know your rig" and can spot those "trends and tendencies" despite the variables.

You are still RVing, after all, not running a science lab! Even so, you should still have some sort of clue as to what is going on. :(