Alcatel Lucent 12AVR145ET Telecom 12 volt AGM batteries for off grid

bobertcom · April 2016

Been a while since I have posted, but I have been lurking

NAWS is my go-to forum!

Anyway, newbie charging error: I killed my x16 6 volt golf cart batteries over the winter. They are still going, but the SG after multiple charges and equalize shows I murdered them. The AGS support kicks on alot to make up for the battery issue.

They are wired series/parallel for my 24 volt weekend off grid cabin. I have a Schnieder 4024 inverter, 60 amp MPPT solar charger with x10 180w solar panels, 5500 watt generator backup on autostart.

I happened across 12 Alcatel Lucent 12AVR145ET Telecom 12 volt AGM batteries, see attached photos. Great price, 6 months old, and load tested. Gonna series/parallel them to 24 volt as well. I understand the issues with telecom batteries, but since this is a weekend cabin, I think they will work fine for us.

Soooo.... I'm new to the battery thing as evident by my murder of 16 golf cart batteries (RIP). Can I get some advise on charging these AGM batteries? Should I just use the Schneider AGM charge profile on the inverter and MPPT charger?

Thanks all!

Bob

mike95490 · April 2016

Telecom batteries are rated for about 100 cycles of high power usage. Then they die. if they are free and you can carry them twice (once to your place, and then shortly to the recycler) then go for it, you will get a couple months out of them,

vtmaps · April 2016

One of your mistakes with the 16 6-volt golf cart batteries was that you had 4 parallel strings.   If you buy 12 12-volt batteries you will have 6 strings in parallel.   Parallel batteries are a sub optimal design choice that will shorten the life of the battery bank.     NOTE: batteries that seldom get cycled are the exception to the rule.   Telecom batteries are often put in parallel because they do NOT get cycled often. As Mike pointed out, it will be a mistake to use telecom batteries for daily cycling (whether or not they are in parallel).

The problem with parallel batteries is that the current does not divide equally between the parallel pathways. Here's a good link to get started on understanding this:
http://forum.solar-electric.com/discussion/13179/series-rule-of-thumb

There are many other reasons to have a single string. For one thing there are stochastic considerations.   The capacity and lifespan of your battery bank is NOT the average capacity and lifespan of the individual cells... rather it is the single weakest cell that will set the capacity and lifespan of the entire bank.

If you have a single cell (2 volt) system, you have a 1 in 2 chance of buying an above average cell. If you have a 4 volt system (2 cells in series) you have a 1 in 4 chance of getting 2 above average cells. If you have a 6 volt system (3 cells in series) you have a 1 in 8 chance of getting 3 above average cells. For a 24 volt (12 cell) system it's 1 chance in 4096 of getting 12 above average cells. Don't count on it!

A more useful way to look at it is to consider the below average cells... you will get some. But how far below average? The cell quality has a Gaussian distribution... The more cells you have, the greater the chance that you will have a far below average cell, an outlier on the Gaussian curve. If you have 4 parallel strings you have almost 4 times the chance (compared to a single string) of getting a really weak cell. The more cells you have, the shorter the lifespan of the entire battery bank.

The optimal design for a system has as few cells as is practical.   If you have a 2 volt system, you have a battery with an expected lifespan longer than a 12 volt battery.... but of course, 2 volts is not practical for the power levels you will use.

As mentioned in the thread I linked to, each of your parallel strings should have a fuse or non polarized DC circuit breaker. Fuse size is tricky... if one string (of 4) develops high resistance all of its current will pass through the other three strings... the current is unlikely to divide evenly, causing one of the other fuses to blow, and then the current will be forced into the remaining 2 strings and cause their fuses to blow.

And then there are points of failure. Every cable, crimp, bolted connection, circuit breaker, etc. is a potential point of failure. Four strings of batteries has many more potential points of failure than a single string.

--vtMaps

bobertcom · April 2016

I agree with your assumption about the prior failure. My charger was not set up correctly for winter and continually undercharged during many below freezing days on the mountain. That added to my too large of strings= murder. Further, I discovered 2 batteries that were 10 months older than the other 14, I suspect they were the weak link? Another rookie error i think...

Regarding the telecom batteries: it seems they are well suited for my application because they will only be cycled ounce a month for 3 or 4 days. The rest of the 25-28 days they will be sitting idle powering my sat internet, cameras, fridge (during summer), and being charged by solar during the day. AGS is turned off while I'm away...

Newbie thinking: I though the extra AH capacity and setting the AGS gen support a little higher for when we are there, they would work fine for me... I'm I wrong? I guess thats the core of my question: Any suggestions for a charge profile for the 25-28 days the system is sitting idle (or almost idle)? Then a profile for when we are there...

For what its worth from the guy I got them from: he said his he has successfully used these batteries for both off grid and back up. They will even replace or upgrade them if they fail in the next year. I know...take with a grain of salt.

Thanks again

vtmaps · April 2016

bobertcom said:

Any suggestions for a charge profile for the 25-28 days the system is sitting idle (or almost idle)? Then a profile for when we are there...

If (and only if) you can get them fully charged before you go away for a month, I would suggest that you disconnect them... no load and no charge. It is a virtue of AGM batteries that they have low self discharge.

If you are planning to discharge them deeply and then go away and let them charge back up, I'm not sure what the best advice is... I have no personal experience with telecom batteries.

--vtMaps

BB. · April 2016

Check the manual for charging set points. In general, at 75F you do not want more than ~14.4 volts (12 volt bank) at the battery terminals... And you do not want that for (probably) more than 2-6 hours.

After that, check the "float voltage"... Something around 13.4 to 13.8 volts (maximum).

Or, as vtMaps says--If mostly fully charged (over 90%)--Just disconnect loads and charging sources and let them sit. Should be fine for 3+ months without much problem.

Note that Lead Acid batteries do very well when stored cold (45F and colder)--Stored hot (95-115F), they are not going to be happy (rapid aging).

Fully charged Lead Acid Batteries will not freeze in normal winter temperatures. Fully discharged lead acid batteries will freeze near 32F/0C. AGM's are supposed to be "freeze tolerant" (not crack cases/break plates if frozen--However, you cannot charge them when frozen--Would not recommend freezing AGMs on purpose).

-Bill

bobertcom · April 2016

Thanks for the advice, I'm going up this weekend to install...Wish me luck!

bobertcom · April 2016

Last question:

145AH @ 8HRS... what would that be in AH in a parallel/series of 12 batteries at 24 volts total in 20HRS? The 8HR this is messing me up!

The plan is to keep the SOC high and not cycle them too deep. From what I have read, that seems to work well with these batteries.

Thanks again!

littleharbor2 · April 2016

145 AH @ 8 hour = 175 AH @ 20 hour rate so at 24 volt x 6 = 1050 AH @ 20 hour rate

bobertcom · April 2016

You rock sir, thanks!

Vic · April 2016

bobertcom said:

Last question:

145AH @ 8HRS... what would that be in AH in a parallel/series of 12 batteries at 24 volts total in 20HRS? The 8HR this is messing me up!

The plan is to keep the SOC high and not cycle them too deep. From what I have read, that seems to work well with these batteries.

Thanks again!

As always, the Capacity of a battery does depend upon just how deeply one wants to discharge it. And the differences between the Capacity verses the discharge interval does depend upon the actual battery construction ...

I might say that those batteries might have closer to about 150 Ah, BUT, that is based upon recollection of the following Date Sheet,:
http://www.eastpennmanufacturing.com/wp-content/uploads/12AVR145ET-Flyer-1398.pdf

FWIW, YMMV, and so on. Vic

bobertcom · April 2016

I am thinking of not going below 50% SOC...is that too much or too little in ones opinion?

mike95490 · April 2016

occasional discharges that are that deep are not generally a problem, but even twice weekly discharges of that depth will shorten it's service life

H2SO4_guy · April 2016

I have been living with used telcom batteries full time for over 31 months. These are actually stationary 2 volt cells. They are Panasonic 2 volt cells and 1040 AH @ the 8 hour rate. I bought 56 cells so I could have 2 strings of 48 volts (2080 AH @ 48 Volts @ 8 hour rate) and have a 12 volt string kept charged to swap in as needed when cells fail. They were all within .01 volts of each other when I got them used. They were headed to the smelter, but I just diverted them for the time, but once they fail they will still get smelted.

I have used Lucent cells before just to mostly run lighting and some tools. They worked very well and I got rid of them to trade in for the Panasonics I have now. I did abuse them pretty bad and they took it well, but I do lots of stuff not reccomended doing off grid.

Good luck and let us know how it works out.

bobertcom · April 2016

Thanks all, they are installed and for now (fingers crossed) and holding 60-70 SOC overnight with refrigerator, video system, and satellite internet router running. The sun has not been good since install, so I expect charge profiles to get better...

The SOC reading is via the internet using my Combox with the system on and running, so I think that 60-70 SOC may be a bit high... Am I correct in that assumption?

I do have a Schneider Battery Monitor, but I did not set it up correctly...

westbranch · April 2016

Try to get an Ahr reading to do your assessment... if you had a MidNite WBjr ( along with a Kid or Classic) you would be smiling...

bobertcom · April 2016

This is what my Combox came up with for last night into this morning...

westbranch · April 2016

OK good... can you zero that info so you can see just what you have used since changing the batteries from the old set? I look at both output and input to verify my Ahr settings for my bank... since change over at midnight I have to assume that the use from sundown to 12:01 AM yesterday is the same as tonight's use.. I usually end up with a small + AHr reading at sundown if I reach Float that day...

bobertcom · April 2016

Copy that, I'll do that and post up

bobertcom · April 2016

heres yesterdays:

.8 KWH used
3.2 KWH solar in

not too shabby?

westbranch · April 2016

if you only used .8 and the batteries took 3.2Kwh then they REALLY need a full charge and an EQ if they will take it...
rule of thumb for recharge is ~ 110% of use is needed for a full recharge...your number give ~ a 400% ratio... something is just not right, don't know what right now

ADD: What are your charge parameters and times for Absorb etc.

bobertcom · April 2016

bobertcom · April 2016

I think that has what you need. Thanks again for the help

westbranch · April 2016

Check Batt temp coefficient, seems a bit large, mine is 3.5, yours 42....???

Default bat temp ....can you set it to 25*C? that is the normal reference temp AFAIK

bobertcom · April 2016

It has the battery temp sensor installed, so that should be automatic...???

The default for the Batt Temp Coefficent was -42. So -3.5 would be ok for AGM batteries?

westbranch · April 2016

The BTC is the adjustment your charge controller will make to the Absorb voltage based on the actual temp of the batteries...and it is from the reference temp ( most use 25C) a colder battery needs a higher V and a hotter battery needs a lower V while charging, and you need a battery/remote Temperature sensor (BTS or RTS) to make/allow the CC to adjust the Voltage it sends to the battery...

Chekck the makers web site for the coefficient % setting... it is maker specific, FLA is around 5 AGMs less...

westbranch · April 2016

a similar thread http://forum.solar-electric.com/discussion/21763/help-finding-battery-information-on-alcatel-lucent-12avr145et-for-midnite-classic-setup

Vic · April 2016

westbranch said:

Check Batt temp coefficient, seems a bit large, mine is 3.5, yours 42....???

Default bat temp ....can you set it to 25*C? that is the normal reference temp AFAIK

I have not used the Combox, BUT, would bet that the --42 mV is for all 12 cells of the 24 V battery bank ... which is, --3.5 mV/Cell/degree C.

Just guessing, FWIW, Vic

bobertcom · April 2016

copy that I will research. I do have the BTS sensors installed for all the schnieder gadgets I have. U guys rock!

bobertcom · April 2016

so vic, you think the --42mv is correct?

Vic · April 2016

bobertcom said:

so vic, you think the --42mv is correct?

Typical AGM batteries are in the range of --3-ish mV/Cell/C, but you should contact the manufacturer for the exact value for your batteries.

And, you might consult the documentation for your Schneider system to confirm that the noted Temp Comp value is the total compensation for your system voltage that you have entered, or that the system has guessed as your battery voltage.

Vic

Alcatel Lucent 12AVR145ET Telecom 12 volt AGM batteries for off grid

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