Will Stationary (telco) batteries last in a cycling application

[diesel]

I can get some ex telco batteries at a good price which have been on float for 3-5 years. Batteries are "Hawker supersafe 12T155F" Valve regulated lead acid type.

I know the batteries are designed to maintain a float charge rather than regularly cycle. Has anyone had experience using stationary / float / telco (call them what you will) batteries for a cyclic application?

[BioHazard]

What type of batteries are they? Some standby type batteries will be "lead calcium" batteries which don't like to be cycled. But not all telco batteries are this way, some are just standard AGM batteries or other types.

[diesel]

What type of batteries are they? Some standby type batteries will be "lead calcium" batteries which don't like to be cycled. But not all telco batteries are this way, some are just standard AGM batteries or other types.

Original post edited with battery type. Cheers

[BioHazard]

If they're just standard VRLA batteries...then yeah, they should make a great battery bank. You can probably look up a spec sheet from Hawker on the specific battery. I bought a ton (quite literally) of ex cable company Hawker batteries that had been on float for 8 years. The ones I saved worked quite well for cycling, even put one in my Jeep and it's still working great at about 13 years old.

[diesel]

That sounds promising 
What bulk current and absorption voltage do you use on them? The spec sheet only gives a float voltage (as that's what they're designed for).
Cheers

[rcavictim]

I can get some ex telco batteries at a good price which have been on float for 3-5 years. Batteries are "Hawker supersafe 12T155F" Valve regulated lead acid type.

I know the batteries are designed to maintain a float charge rather than regularly cycle. Has anyone had experience using stationary / float / telco (call them what you will) batteries for a cyclic application?

Good score!!! Those very expensive batteries are designed for cycling in high demand modern UPS systems.  For longest life don't cycle them deeply.  In your system try to keep max discharge to not more than 50% of capacity and you should get years out of those used batteries.

How many did you acquire?  What voltage do you plan to use them at?  12 volt  in parallel or series parallel for 24 or 48 volt for example?

Some info here.
http://www.enersysreservepower.com/documents/AS-TFT-RS-007_0506.pdf

I use an auto shutoff automotive charger to condition my similar valve regulated AGM batteries before they get put into float service.  My charger shuts down at about 14.5 volts.  You won't hurt these doing that like you would gel cells which such an overcharge would destroy.  These AGM's are actually wet lead acid cells inside, it's just that the acid is kept in an absorbent fiberglass type finely woven matting so it won't spill or slosh around.  Outgassing bubbles can still escape unlike from gelled acid.

[BioHazard]

I use an auto shutoff automotive charger to condition my similar valve regulated AGM batteries before they get put into float service.  My charger shuts down at about 14.5 volts.  You won't hurt these doing that like you would gel cells which such an overcharge would destroy.  These AGM's are actually wet lead acid cells inside, it's just that the acid is kept in an absorbent fiberglass type finely woven matting so it won't spill or slosh around.  Outgassing bubbles can still escape unlike from gelled acid.

Yep, I've actually cut a few in half to recover the lead, and they still didn't leak!  I just used a good automotive battery charger for them, I remember something from Hawker about never, ever, ever letting them hit 15 volts.

I don't know about yours, but the ones I got were rated for an amazing amount of discharges as well, I believe something like 400 cycles at 100% depth of discharge and 500 at 80% DOD.

[Tom Reed]

The Hawker batteries in my basement (pv-1's) are rated for 1200 80% discharges. I hope they last because there is $8k tied up in them.

[Lloyd]

The Hawker batteries in my basement (pv-1's) are rated for 1200 80% discharges. I hope they last because there is $8k tied up in them.

Hey Tom,

If you want those bats to last, never take em to 80% discharge. All the telcos use those bats and never discharge below 70% State of Charge, which means they work in the top 30%. I posted a study on this exact topic here at Micro-Co-gen...I'll see if I can find the link.

Also a tightly controlled charge regime is imperative to getting the full life out of theses bats...they can take high current, they just can't take high voltage. A Valve Regulated Sealed Acid VRSLA bat will off-gas electrolyte, because even though they're sealed, they have a high pressure vent for safety, and anything over about 14.4 volts could cause them to gas...and there is absolutely no way to add back the missing electrolyte...because they are sealed.

An 8k bat bank is a big investment...so be sure and take care of them. I would never charge them without a temp compensated charger.

Lloyd

[diesel]

I haven't bought them yet. Was going to buy 8, so 2 48V strings. Price was AU$1200 for the lot, which seemed good value.

However I've been able to get in touch with some people who work for our local rail network. It looks like I can have my pick of the used substation batteries at no cost. These are changed out every 5 years on a regular replacement program, so should have at least another 5 years of life left in them.

This is looking like a more attractive option 

[Tom Reed]

Lloyd, those batts are FLA technology. I don't they have ever been taken down below 60% state of charge, so yes they are being babied only using the top 30%. The system was purchased without a bat temp sensor. The thinking was that since they are located in a heated basement with stable temps the compensator would not be needed, wrong. The batts would boil out the water in a month. So the temp sensor was added and the water lasts consistently about 3 months all year.

[Lloyd]

Hi Tom,

Some how I got confused, I thought the discussion was and VRSLA bats, so I just assumed that's what you meant.

A three stage smart charger is only smart if you're using a temp sensor, and the charger is in fact temp compensated. A bat bank once the charging process has started and if the bank is healthy, can take almost all the current you can throw at it, even FLA's...ON ONE CONDITION. It's voltage is tightly controlled, and the chargers temp sensor is working...that way if the bats start to get to hot, the temp sensor tells the charger to cut back the current, then when it's cool enough it tells the charger to give it all shes got.

The temp censor is the little general standing at the bats giving orders to the charge source...that's what makes it a smart charger.

A charger by design, is add enough voltage controlled current to reach absorption, heat, and a problem cell  or loose terminal, may not let the voltage of the bat rise... so the charger minus the temp sensor, does what it's programed to do, and that's try to raise the voltage...so it just keeps pouring in the current, which causes the bats to heat more and gas.

Lloyd

[DanG]

Recommended float charge voltage:
2.280Vpc at 20°C (68°F) = 16.68V. 27.36V, 54.72V
2.265Vpc at 25°C (77°F) = 13.59V, 27.18V, 54.36V

Look at the voltage limits - they mean what they say, temperature correction ABSOLUTELY required.

These batteries are float only - and they require large currents  (C/2, C/4, check their literature) to circulate the semi-gelled electrolyte.

Can you provide 40 to 70 Amps of 12, 24 or 48VDC that is precise voltage limited from zero to max amperage with negligible ripple?

I have 10-year telco batteries, they are extremely user unfriendly if one does not have the required technology - they are easily murdered!

[rcavictim]

Recommended float charge voltage:
2.280Vpc at 20°C (68°F) = 16.68V. 27.36V, 54.72V
2.265Vpc at 25°C (77°F) = 13.59V, 27.18V, 54.36V

Look at the voltage limits - they mean what they say, temperature correction ABSOLUTELY required.

These batteries are float only - and they require large currents  (C/2, C/4, check their literature) to circulate the semi-gelled electrolyte.

Can you provide 40 to 70 Amps of 12, 24 or 48VDC that is precise voltage limited from zero to max amperage with negligible ripple?

I have 10-year telco batteries, they are extremely user unfriendly if one does not have the required technology - they are easily murdered!

DanG let a typo slip by. This number marked in red above should be 13.68 volts.

[diesel]

Change of plan. I didn't buy the hawkers because I got in touch with a contact of a contact. I now have access to pretty much all the batteries I want for free 
I'm Picking up 8 x Exide marathon M12V90's on Monday, about 5 years old out of a substation DC supply. VRLA / AGM batteries.

Datasheet is found at http://www.networkpower.exide.com/exidepdfs/Section%2022.60%202010-12.pdf

Is there any requirement for a multi-stage charge for these batteries? The literature seems to point to a single charge rate (and bloody fast one at that).

The Recharge Characterization says that they should be charged at approx 2.27V/cell = 13.62V for the battery. It gives an acceptable range of 2.25-2.3V/cell. It's hard to make out the charge current draw in the lower regions of the graph, but it's pretty high. My charger is good for 60 amps (Trace 4548E) which will be C/3 for 2 parallel strings. This won't quite give the quickest recharge, but will give sufficient to get them going. The trace is also temp compensated.

I'm expecting the daily discharge won't be more than 20 or 30% max.

I am proposing a bulk charge limited to the max setting of the trace (60A), an absorption voltage limit of 54.6V, and absorption time at a couple of hours. If they're not getting enough juice I'll extend the absorption charge time, and may drop the charge voltage down to 54.5V or 54.4V. It'll take a bit of trial and error to see how the batteries respond.