Varying on charge voltage problem!

[Jemplayer]

You are welcome, but don't get to worked up about it. As for pricing both Trojan and US Battery are made in the USA. Going rate for a T-105 here is $130 to $140 per unit. The US Battery equivalent 2200 XC2 is slightly higher capacity of 232 AH (7 AH more than the T-105) going rate $105 to $115 or about 18% less than the Trojan. US Battery are not bad batteries, they just are not Trojan. Don't go away thinking Trojan is the best, because they are not. FLA battery prices in the USA have a wide price range from 6-cents per watt hour on the low end, and up to 24-cents per watt hour on the high end. In the USA US Battery and Trojan weigh in around 7.8 cents and 10 cents respectively. The mistake people make which is understandable is they come away with the US Battery is a better value because it cost less per unit. But that is short term thinking because in application the Trojan is a far better value in the long term because they are going to have 50% more cycle life.

If you look at your Kwh cost is where it counts over the life of the battery. If you use 20% capacity daily from each battery, and assume the US Battery last 2 years, and the Trojan last 3 years, your battery Kwh cost are:

US Battery = $110 / [.278 Kwh x 730 days] = $0.5421/Kwh
Trojan Battery = $130 / [.27 Kwh x 1095 days] = $0.4566/Kwh

As you can see in this calculation Trojan is a better value.


Moving on to your situation you state cell voltage are 7.1 on the low end and 7.7 on the high end right? If correct that is troubling as that means your cell voltages range from 2.37 vpc up to 2.57 vpc. That is a huge difference. But let me ask you this. How and when are you taking those measurements?

If you are taking them while the batteries are charging or discharging is invalid results and what US Battery may be thinking. Voltage measurements are only valid on a rested cell that is not being charged or discharged. In other words disconnected and allowed to rest a few hours. So let's shift our attention away from voltages and use the only true measure of a battery SOC by measuring the Specific Gravity which can be done anytime. So what is the spread from high to low? If less than .030 points, then there is no problem. If more than .030 points they equalized. If they will not equalize the batteries have a problem.

Have you ever spilled any electrolyte? Have you ever charged too fast causing electrolyte to bubble or boil out? If so you have lost acid, and those cells will forever have a low specific gravity because you replaced acid with water.

As to your last question of how much more time do you have. Heck I do not know. Maybe 6 months... When you start to notice loss in performance, then you know it is time to replace them.

I have never seem the SG within such close tolerance. By your 0,03 variance, the cell would need to 1,270 - 1,273 as an example.

What I get is more like 1270 - 1,285 on some cell, there is an average but still from the highest to the lowest even when the batteries were newish 5month old, I didnt have anywhere near the tolerances you mention.

Thank for all your help. It took me 5 months to get a handle on how everything operated and since then have been monitoring the SG etc, and have not as yet seen any decline in those numbers.

I think today I will after I reach float take Sg's acrross the bank and see where I am, I did do a good 2,5 hour eg last Sunday.

For interest sake I will let you know.

Another question, what is thought of lead crystal. This seems to be being used here and there, with claims about dod ect, but curious if there is more tangible real world info regarding charge rate and time, and dod vs life etc.

[Sunking]

I have never seem the SG within such close tolerance. By your 0,03 variance, the cell would need to 1,270 - 1,273 as an example.

You failed your math test.

A fully charged cell specific gravity at 25 Celsius is 1.277 EQ should performed if there is more then .030 variance from low to high. After EQ the variance should be no greater than .010 low to high.

It would look something like this:

EQ Needed: 1.262 - 1.292 {1.277 - .015 = 1.262, and 1.277 + .015 = 1.292}

After EQ: 1.272 - 1.282 { 1.277 - .005 = 1.272, and 1.277 + .005 = 1.282}

[paulcheung]

I have chatted to us batt at length regarding the cond and state of the batteries and told they are still fine and per new spec according to Mike at thier Georgia office, and to go ahead and add the second string and I would loose a bit of life long term but nothing to drastic.

How long do you recon I have left to support the loads mention above?

If I am a battery salesperson, you come to me for advice, I would tell you to go ahead add the second bank as I won't push the business out of the door.

If I were you, I just use these batteries to the end and don't care about the state of DOD just make sure not over 70% DOD. and when they are done. Go buy a set of the Trojan L16RE batteries, a single string of battery is much batter than two strings.

[Sunking]

If I were you, I just use these batteries to the end and don't care about the state of DOD just make sure not over 70% DOD. and when they are done. Go buy a set of the Trojan L16RE batteries, a single string of battery is much batter than two strings.

+1 Good advice

[thastinger]

you seem to have been discharging this battery bank to 50% since they were new?

[Jemplayer]

If I am a battery salesperson, you come to me for advice, I would tell you to go ahead add the second bank as I won't push the business out of the door.

If I were you, I just use these batteries to the end and don't care about the state of DOD just make sure not over 70% DOD. and when they are done. Go buy a set of the Trojan L16RE batteries, a single string of battery is much batter than two strings.

Yes, I think I am seeing that just using these up is the smarter way to go. To answer the other guys question, I only use 50% (not quite) of the capacity in summer, and given that the battery is much warmer you do get a bit more capacity anyway. In winter around 30% is average.

The batt are seemingly still fine. I don't see that my voltage is getting pulled down any more than when new, I.e. Say At 10pm after taking out 1600 odd watts the voltage is the same as it was a years ago.

I didn't mention earlier, but about 4 month ago, two of the eight batts were replaed under warranty, so 6 are 20 months and two 4 mths.

[thastinger]

I didn't mention earlier, but about 4 month ago, two of the eight batts were replaed under warranty, so 6 are 20 months and two 4 mths.

Yeah, that is critical info to know and probably why Sunking had questions on your SG readings.
Why were the 2 replaced?

[Sunking]

Yes, I think I am seeing that just using these up is the smarter way to go. To answer the other guys question, I only use 50% (not quite) of the capacity in summer

There is a great part of your problem. Between yoi\ur math and usage it is wonder your batteries lasted as long as they have.

Example a T-105 is only discharged 20% per day can get up to 3000 cycles. At 50% discharge drops 1000 cycles. Each time you allow your battery to go down to 50% DOD you are putting more nails in the battery coffin each day you do that.

The good news is you bought cheap batteries to learn with. Do not repeat your mistakes.

[Jemplayer]

Yeah, that is critical info to know and probably why Sunking had questions on your SG readings.
Why were the 2 replaced?

Give me a bit of credit. I am talking before those were replaced, in regards to varying on charge voltages on the same age batts. I obviously don't compare old batt to those new ones. I expect higher everything with those.

To be honest I too am surprised these batteries are still giving me good service. I get a full 4.5kw out over 12-13 hours and still have a voltage of 48,4 odd in the morning, at rest I.e no load.

Them seems just as they were then new, go figure!

[thastinger]

Give me a bit of credit. I am talking before those were replaced, in regards to varying on charge voltages on the same age batts. I obviously don't compare old batt to those new ones. I expect higher everything with those.

To be honest I too am surprised these batteries are still giving me good service. I get a full 4.5kw out over 12-13 hours and still have a voltage of 48,4 odd in the morning, at rest I.e no load.

Them seems just as they were then new, go figure!

How often do you EQ them and how do you do it. I.E. what are your CC eq program settings.
Have you tried starting the generator early in the AM to charge up the bank then letting the solar take over to finish the eq charge? Although my CC has an auto eq feature I turned it off because there isn't enough sun time to finish the cycle so now I use a charger to as described above. You know to check the SG every hour and stop the eq when either the target SG is reached or the SG no longer climbs correct?

[Jemplayer]

How often do you EQ them and how do you do it. I.E. what are your CC eq program settings.
Have you tried starting the generator early in the AM to charge up the bank then letting the solar take over to finish the eq charge? Although my CC has an auto eq feature I turned it off because there isn't enough sun time to finish the cycle so now I use a charger to as described above. You know to check the SG every hour and stop the eq when either the target SG is reached or the SG no longer climbs correct?

Yes I do, However, I am over panelled for 232ah bank, so I can and do use my panels to EQ. The other issue, is that for some reason, my inverters charger only allows a max of 62v to be selected, and it over reads a touch so more like 61.5, and this is not enough to EQ.

So have to use the MPPT.

My last EQ was at 63.5 vote for 2.5 hours. I do this manually once a month for 2-3 hours.

[thastinger]

63.5 is to high for EQ huh? I'm not familiar with those batteries but is 2.64VPC IAW the batt manufactures directions?

[Sunking]

63.5 is to high for EQ huh? I'm not familiar with those batteries but is 2.64VPC IAW the batt manufactures directions?

2.55 vpc, +/_ .05 I would go with 2.6 vpc on this battery.

Thatsinger are you aware of Trojans newly release set point voltages. There is no more Bulk Setting.

Absorb = 2.45
Float = 2.2
EQ = 2.58

Source Info

For Solar you want to run higher voltages.