Matching batt. voltage for pairs in bank

Re: Matching batt. voltage for pairs in bank

Cariboocoot wrote: »

That is not good.
Nor should it be possible with a solar charge controller.

As usual, I have to agree with you, Sir.

Sunbunny, pay close attention to what he says. I don't post here very often, but I most certainly respect cariboocoot's knowledge and experience!

With a 1040T at a stable temperature between 65F and 85F:
Charge it at a constant 14.2v to 14.4v (no more than 14.6v) until the current draw drops to .5 to 1.0 amps. THAT is when it is fully charged and NOT before that.
(Use temperature compensation when outside of this range - it is NOT optional)

I will grin while adding: Hitting them with 15v+ was a good move to desulfate your used batteries. Some of these swap-out batteries are a good deal, some are not. Here is how I would qualify it, based on a Concorde battery:

- Fully charge the battery at the PROPER voltage, with a high available current if the battery wants it
- Let it stand for 2-3 hours
- Look for 12.8v to 13.0v

1) If the battery voltage is a bit low after charging, it is MOST LIKELY sulfated. Time to equalize it gently with a constant voltage, or to smack it with a constant current recondition. Depending upon severity, it may take several runs of "equalizing" to bring it back - if it is possible at all.

As a gross generalization, when a customer brings in a PVX-1040T sitting at 10v or higher, I can bring them back up to 60% to 95% caapacity, depending on how long they sat

2) If the battery voltage is VERY low, and/or continues to pull a high current when it shouldn't - you may have lost a cell. Time to replace.

3) If the battery static voltage is in the proper range, but the capacity obviously just isn't there, it is either worn out from cycling - or it was overcharged over a long time period and it dried out. Time to recyle it.

Just my opinion,
The other Marc

Re: Matching batt. voltage for pairs in bank

I'm not a fan of IOTA chargers for a whole bunch of reasons, but I'm not here to promote or bash a product. (They make a good converter, but look closely at how their Bulk phase voltage is higher that the Absorb - then think about it)

I will say that:
- Your batteries pulling over 8 amps at 28.4v is a good sign - they are taking a charge at the specified voltage. This is a good thing to see when dealing with used batteries! Hopefully, your charger has the IQ :-) to drop to the float voltage when the load drops very low - like under 1 amp. Keep an eye on them - be sure you see a tapering current being drawn by the batteries. My bet is that they will drop to float too soon, leaving the battery undercharged.

- IOTA's float voltage of 13.6v is a tad bit high at 75F to 85F for the PVX-1040T. Short term, no big deal at all. For longer term, I'd rather see you top off the charge and let the batteries stand alone. When the voltage drops to 12.65v or 12.7v, boost them again. That will take 3-6 months if the batteries are healthy.

- Undercharging causes more premature failures than any other two things that we see. Undercharging can be too low of a voltage, too low of a current, not charging long enough to see the reduction in amperage, or leaving the battery sitting at lower charge levels.

Based on the voltages that you are reporting, the ambient temperature of where your batteries spent their previous and future time will determine how much life they have left.

The other Marc

Re: Matching batt. voltage for pairs in bank

Just some information about a IOTA with IQ-4. I find they work quite well and even if their algorithm and voltage's seems weird, it works fine. While they do not follow the traditional 3 stage format they do use the 3 variables of Battery charging, Voltage, Time and Current. I have installed them for many customers in the last 3-4 years and find them bullet proof. They will maintain their rated output hour after hour.

ABSORPTION STAGE
After the Bulk Stage, the IQ4 then moves to the Absorption Stage (14.2V for a 12V battery). This mode will continue for up to 480 minutes (8 hours) to ensure that the battery receives a complete charge.

FLOAT STAGE
During the Float Stage, the IQ4 reduces the DLS charge voltage. This reduced voltage maintains the full charge while minimizing 'gassing' of the battery. The IQ4's float stage prevents boiling and bulging of the battery caused when the battery is exposed to higher charging voltages for too long.

EQUALIZATION STAGE
If the batteries remain in a "float stage" for a seven-day period, the IQ4 will switch the DLS charger into a pre-programmed Equalization Stage. This protects the life of your battery by dissolving any sulfate layer on the battery's internal plates and avoids stratification that can occur when a battery has not been in use for extended periods.

Absorption Phase
(2.366V per cell) 14.2V 28.4V 56.8V
Float Phase
(2.266V per cell) 13.6V 27.2V 54.4V
Equalization Phase
(2.466V per cell) 14.8V 29.6V 59.2V

My preference is for buying the plain DLS and the IQ-4 as a plug in option. As I posted before there is a 10 turn potentiometer where the voltage can be adjusted. The only issue is the output voltages are a ratio to each other. If you lower the voltage say .2 it lowers all 3. If you crank it wide open and and insert the hi plug in the jack you can adjust it to a true equalization voltage ( 15.5 V or 32 V ) I have never tested the 48V model. The way I judge it is the batteries maintained by them use very little water and the SG's stay spot on. Just a little .02 on them.
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