AGM (Lifeline) Batteries and voltage question

System · February 2008

Hi. I have a matched set of four Lifeline AGM 12V batteries in the basement of my little 5th wheel, together with a Heart 2000 Inverter. Last spring I fully discharged the batteries (long story). They seemed to fully recover, but now I have my doubts about them.

In the morning, before the sun comes up, the meter indicates that we've used about 20 amp/hrs during the night. I turn on one 12V light, drawing around 1.5amps, and notice the voltage on my meter is around 11.9V. I seem to remember that, before I fully discharged the batteries, the voltage when we'd get up in the morning would be quite a bit more.

Also, when the sun finally drops down and we're fully charged, the voltage drops immediately to 12.5 or so. I think that it used to just drop into the 13.5 range. This is with only the 'background' amps being sucked out (frig and CO2 detector, around 0.5 amps). Is this a clear sign that my batteries need to be replaced? They are spendy critters.

Solar Guppy · February 2008

Re: AGM (Lifeline) Batteries and voltage question

What are you using to think the batterys are fully charged?

What are you using to think "only" 20 amps were used?

I have never heard of a frig that only uses 0.5 amps, so thats what makes me doubt the numbers you have posted. 11.9 volts is close to dead and 12.5 indicates the batterys are NOT fully charged.

As a guess the batterys are never getting more than 50% charged ( based on the 12.5V ) and your sucking them dry every night with loads that are not being accounted for ( based on the 11.9 v), as a guess your using +2kWh a night based on having 4 batteries and killing them every night.

Now a 0.5amp load at 120V would present about a 100+ watt load on the batteries and overnight that would explain the numbers you posted

System2 · February 2008

Re: AGM (Lifeline) Batteries and voltage question

Hi, Solar Guppy. Let me take your questions one at a time.

What are you using to think the batterys are fully charged?

I have a Solar Boost 2000 and a Link 1000. When the sun shines and the amps used gets set to zero and the battery voltage is around 13.9V or so, the instrumentation and past experience makes me think they're fully charged.

What are you using to think "only" 20 amps were used?

Well, that's what the Link 1000 claims. Besides, we only run one (1) 12V light for about 4 hours at night and 3 hours in the morning. That, plus the 0.5amp constant drain kinda makes me agree with the 20 amp reading.

I have never heard of a frig that only uses 0.5 amps, so thats what makes me doubt the numbers you have posted. 11.9 volts is close to dead and 12.5 indicates the batterys are NOT fully charged.

My refrigerator runs on propane, but the little circuit board takes a little juice, hence the 0.5 amp/hr figure (includes the CO2 detector).

As a guess the batterys are never getting more than 50% charged ( based on the 12.5V ) and your sucking them dry every night with loads that are not being accounted for ( based on the 11.9 v), as a guess your using +2kWh a night based on having 4 batteries and killing them every night.

I don't think we're sucking them dry, unless they were damaged by the incident last spring. Incidentally, that's the only time they were flat-lined. My instrumentation is accurate, and I know beyond all shadow of doubt, that we're not using 2kWh a night. We're not running on batteries for the most part - the batteries are just powering the 12V stuff. We're plugged in to 120 AC.

Now a 0.5amp load at 120V would present about a 100+ watt load on the batteries and overnight that would explain the numbers you posted

We haven't run the inverter at all since last fall.

Thanks for the reply. Your observations made me think a bit before answering, and that's always good.

Solar Guppy · February 2008

Re: AGM (Lifeline) Batteries and voltage question

AGM's should be charged to 14.3 volts, 13.9 is to low, also you didn't mention if this was tempature compenstated, if the batterys are colder that 77F, they need about 25mv more per C, but this is dependant on the battery manufactures recommendations.

So looks like your undercharging the batterys and by your readings about 50% at a minimum

System2 · February 2008

Re: AGM (Lifeline) Batteries and voltage question

Solar Guppy wrote: »

AGM's should be charged to 14.3 volts, 13.9 is to low, also you didn't mention if this was tempature compenstated, if the batterys are colder that 77F, they need about 25mv more per C, but this is dependant on the battery manufactures recommendations.

So looks like your undercharging the batterys and by your readings about 50% at a minimum

We're charging the AGMs up with our solar panels. The Solar Boost controller is controlling the current to the batteries. 13.9V is the maximum voltage we've seen so far, but we're in Oregon and there's too many clouds, I think, to keep up some good solar pressure.

Yes, we've got a temperature compensator in the circuit.

During a few weeks here when it was either foggy or thick clouds all day every day, we did resort to using our converter to charge them back up when they'd be more than 100 amps down, which would happen about once a week. Since the converter is, essentially, a one-stage charger, I wonder if we should have used the 3-stage in the Heart to charge them back up instead. Hindsight and all that.

mike95490 · February 2008

Re: AGM (Lifeline) Batteries and voltage question

Even 3 stage chargers, need to be configured with settings (jumpers/switches) for AGM batteries, otherwise, it will still charge at flooded cell voltages.

The outdoor temperature has the influence on PV panel voltage, the clouds/brightness, affects the amps coming off the panels. What are your panels rated to put out? Maybe if they are only 16V under load, minus loss across the controller, you only get 13.9V 20V panels would give the controller something to regulate.

You didn't let the chargers run an Equalize Cycle did you ?

System2 · February 2008

Re: AGM (Lifeline) Batteries and voltage question

mike90045 wrote: »

Even 3 stage chargers, need to be configured with settings (jumpers/switches) for AGM batteries, otherwise, it will still charge at flooded cell voltages.

The outdoor temperature has the influence on PV panel voltage, the clouds/brightness, affects the amps coming off the panels. What are your panels rated to put out? Maybe if they are only 16V under load, minus loss across the controller, you only get 13.9V 20V panels would give the controller something to regulate.

You didn't let the chargers run an Equalize Cycle did you ?

I have three panels - Kyocera 120W ones. I know that in AZ last winter the panels would kick the batteries up to 14.25V by early afternoon. I had them tilted. I don't know what the voltage ratings are of the individual panels.

No, I've never equalized the AGM batteries. Bought them brand-new in the summer of 2003. They're Lifeline 1040T, I think. 105 amp/hrs. When I bought them I'd read a lot of warnings against equalizing. Now, even the Lifeline site seems to say it's OK - 15.5V at 8 hrs once they're fully charged. I'm still a little leery about doing it, however.

EDIT: Right, the controller and Link 1000 are both set for AGM batteries.

Solar Guppy · February 2008

Re: AGM (Lifeline) Batteries and voltage question

Well, sounds like there is your answer then, your NOT fully charging the battey's at 13.9V, its more likely the charging source is limited for some reason, flat panels in the Northwest this time of year = almost no power!

The zero amps is odd, you can try and bypass the charger and get a full day of readings to see if thats part of the problem.

Also the charger is its own 24/7 load on the batteries of about 0.4 amps

If you don't get 14.3 for a few hours everyday ( compenstated for tempature ) your going to have a slow death for your batteries.

mike95490 · February 2008

Re: AGM (Lifeline) Batteries and voltage question

silverjim wrote: »

Now, even the Lifeline site seems to say it's OK - 15.5V at 8 hrs once they're fully charged. I'm still a little leery about doing it, however.

Yikes, that would surely kill them. Even flooded cell is only about 2 - 3 hours
Do you have a link to that doc ? I'd like to read that.

Mike

System2 · February 2008

Re: AGM (Lifeline) Batteries and voltage question

mike90045 wrote: »

Yikes, that would surely kill them. Even flooded cell is only about 2 - 3 hours
Do you have a link to that doc ? I'd like to read that.

Mike

Sure do. Here it is.

http://www.lifelinebatteries.com/charging_procedures.php

mike95490 · February 2008

Re: AGM (Lifeline) Batteries and voltage question

Wow.
well, if they appear to be toast now, I suppose it can't hurt. Now to find a constant voltage source, that can accomplish that level of charge.

These are 4, 12V battereris in parallel ? Maybe you can pull 1 at a time, and EQ it, and then the next till all 4 are done. Then re-install the set. (don't connect 1 EQ'd battery to one that was not)

Maybe when 2 are done, you can swap the other 2 and let the fridge idle off 2 batteries for a day.

System2 · February 2008

Re: AGM (Lifeline) Batteries and voltage question

mike90045 wrote: »

Wow.
well, if they appear to be toast now, I suppose it can't hurt. Now to find a constant voltage source, that can accomplish that level of charge.

These are 4, 12V battereris in parallel ? Maybe you can pull 1 at a time, and EQ it, and then the next till all 4 are done. Then re-install the set. (don't connect 1 EQ'd battery to one that was not)

Maybe when 2 are done, you can swap the other 2 and let the fridge idle off 2 batteries for a day.

I can't equalize the four all at the same time with the Heart? It has a setting for AGM, and a setting for equalizing.

Solar Guppy · February 2008

Re: AGM (Lifeline) Batteries and voltage question

You have to have the batterys 100% charged before you do the "EQ" cycle.

To acheve the batterys 100% charged, they need to be at 14.3 volts ( tempature compenstated ) until the charge amps is down to 2% of the aH rating, so for your bank, charge at 14.3V constant voltage and when the amps gets down to ~8 amps the batterys should be near 100% charged.

I know of NO charger that has a "EQ" for AGM's, its considered a 100% no-no as the battery has nowhere to gas out as they are seal. Now 15.5 really isn't an EQ, that more than bulk, but not a Pba EQ.

As for what your inverter/charger does you will have to read the manual, but for sure DON'T USE THE CHARGERS EQ SETTING ON AGMS

mike95490 · February 2008

Re: AGM (Lifeline) Batteries and voltage question

Try it and see if it can. It all depends on how much "headroom" was designed in at the factory. If it only has a 16V transfromer, it may not do it. 18V transformer would do it

niel · February 2008

Re: AGM (Lifeline) Batteries and voltage question

silverjim,
i shuddered to read what they said for eqing the lifeline batteries and i believe that they did make a mistake as they mention gassing and there shouldn't be any gassing from your agm batteries as that damages them. the sunxtenders are similar agms and here's the advice for them from the website:
CHARGING INSTRUCTIONS
Initial charge or recharge: 2.37 to 2.40 volts per cell at 25°C (77°F). Float charge: 2.20 to 2.22 volts per cell at 25°C (77°F). Equalize charge: 2.40 volts per cell at 25°C (77°F). Temperature compensation = ±3.75 mV. per cell per degree C [Reference to 25°C (77°F)]. This is for battery temperature (not ambient temperature) and is useful for battery temperatures from 0°C (32°F) to 40°C (104°F).

note that most eq charges are for an hour or 2, but individually charging the batteries or rearanging them in the bank helps. no agm likes excessive charge voltage applied to them as it causes them to outgas and that can't be replaced in a sealed agm battery. with leaving 14.4v on it with the battery temp sensor for a few hours will have the effect of diminishing current through the batteries as charge increases. (note: editted to correct eq voltage as 14.3v is a good regular charge voltage setting.) those that are low will have a slightly higher current and this could in fact be under 100 milliamps while it's eqing, but i never tried it to know for sure.
i do agree that you may be under charging those batteries and you need to allow them to get their full charge without loads being applied that may rob them of their full charge. you may have shortened their life with the deep discharge, but don't further depleat their life with deficeit charging. when the sun isn't there you can't expect from your batteries to come up with this power from out of thin air. i don't recommend discharging your lifelines further than 80% under any circumstances and the approximate depth of discharge point would be about 60% unlike many other battery manufacturers specs that are at 50% dod. do know that concorde had told me a few years back that their sunxtenders and lifeline batteries are rated for an input charge current equal to their ah rating at 20hrs if you'd ever need to pump that much into them.

System2 · February 2008

Re: AGM (Lifeline) Batteries and voltage question

We finally got a sunny day, so I was actually able to do a few things. We were 15 amp/hrs down this morning when we shut the 12V light off. The morning sun doesn't give us a lot of power, as it's low in the sky and some bare oak branches are casting some shade on the panels.

The voltage worked its way up to 14.00 around noon, so I decided at that point to turn the 3-stage charger that's built into the Heart on, after checking to make sure it's set for AGM batteries (yes, it's right in the manual).

The charging light on the Link 1000 zipped right past bulk and stayed on acceptance for 20-30 minutes (sending the voltage up to 14.20) and then switched to float. I waited until the amps used display had counted up to zero, then turned the charger back off to let the solar gain keep it at float, at which point the battery voltage dropped back to 14.00

It's been a couple of hours now, and the controller has gradually throttled the solar gain back to 4.0 amp/hrs. The voltage is stil right at 14.00. The forecast is for another couple of sunny days. I'll just leave things be for the time being, then the next string of sunny days we get I'll draw the batteries down 60-70 amp/hrs and see how they react. Thanks for all the comments, guys.

mike95490 · February 2008

Re: AGM (Lifeline) Batteries and voltage question

You need to see what the battery temperature is, and use the right voltage for temperature conditions. It still does not look like you are getting 14.4V into them, and maybe give them the night off, and run off "shore power" In the AM, hit them with the link charger, and let the PV finish topping them off.

I think you are still in decifit, regardless what the monitor thinks.

Practice with the remnants of this battery bank, before you buy new ones.

What is the "link" AGM voltage?
What is the "Hart" AGM voltage? should be in the manuals.
What's the nameplate voltage on your PV's ? 16V ? 19V ? 23V ??

System2 · February 2008

Re: AGM (Lifeline) Batteries and voltage question

mike90045 wrote: »

You need to see what the battery temperature is, and use the right voltage for temperature conditions. It still does not look like you are getting 14.4V into them, and maybe give them the night off, and run off "shore power" In the AM, hit them with the link charger, and let the PV finish topping them off.

I think you are still in decifit, regardless what the monitor thinks.

Practice with the remnants of this battery bank, before you buy new ones.

What is the "link" AGM voltage?
What is the "Hart" AGM voltage? should be in the manuals.
What's the nameplate voltage on your PV's ? 16V ? 19V ? 23V ??

Thanks for the response. I'll take your advice and do all that tomorrow, since the forecast is for another sunny day. FYI, I've been running off of shore power since last fall. Anyway, in response to your questions:

I did some looking in the manuals, and I hope this is what you were looking for. The Link 1000 Charged Voltage setting for the AGM batteries is 13.5V, which I verified by stepping through the menu of the Link 1000. The Heart, since it's controlled by the Link 1000, is the same. The voltage on the Kyocera panels is 16.9V (120 watts, 16.9V, 7.1A).

crewzer · February 2008

Re: AGM (Lifeline) Batteries and voltage question

Link to related discussion: http://www.outbackpower.com/forum/viewtopic.php?t=2384&highlight=lifeline

HTH,
Jim / crewzer

System2 · February 2008

Re: AGM (Lifeline) Batteries and voltage question

I did kick on the equalizer circuit in the Heart. Well, the manual says that it'll just charge at the acceptance voltage (14.15) amps for 8 hours, as it's set for AGM batteries. I'm doing that, but in the meantime after looking up my battery specs, there's an interesting difference that I think I'm going to need a little assistance on.

My shipping and installation receipt said the batteries were Sun Xtenders PVX-1040T. The batteries themselves say Lifeline GPL-27T. Is there any difference between the two? Would I be safe in ordering the Sun Xtenders (they're a few dollars cheaper). It looks like the terminals are the same and the size IS the same.

Windsun · February 2008

Re: AGM (Lifeline) Batteries and voltage question

The only real difference is the type of connector. Sun Xtenders all have bolt on only terminals.

http://us.st11.yimg.com/us.st.yimg.com/I/wind-sun_1990_7979312

niel · February 2008

Re: AGM (Lifeline) Batteries and voltage question

silverjim,
there is another difference in that they will warrant the sunextenders for renewable charge sources. they are both excellent batteries and if you charge them correctly you will have many good years of service from them. a battery temperature sensor is almost a must have for these batteries and any other agm battery. these batteries do not go by settings on inverters or battery monitors preset or not. they must be charged as the manufacturer says and that means 14.15v is unacceptable as it is not in the manufacturer's charge range spec. this is 14.22v minimum and 14.4v maximum at 77 degrees f.

rplarry · February 2008

Re: AGM (Lifeline) Batteries and voltage question

Silver jim
Niel is 100% correct in his statemnt, do what the manufacturer says, except maybe the eq charge, that does not sound right. Also before you give up on those batteries, you may want to test them with a load tester. Its possible you may have one bad battery that is pulling the voltage down on the other batteries. After fully charging the batteries you can disconnect them and test the voltage individually and see if there is a low one. Sometimes just one bad cell will cause all the batteries to look bad.
Good luck
Larry

System2 · February 2008

Re: AGM (Lifeline) Batteries and voltage question

rplarry wrote: »

Silver jim
Niel is 100% correct in his statemnt, do what the manufacturer says, except maybe the eq charge, that does not sound right. Also before you give up on those batteries, you may want to test them with a load tester. Its possible you may have one bad battery that is pulling the voltage down on the other batteries. After fully charging the batteries you can disconnect them and test the voltage individually and see if there is a low one. Sometimes just one bad cell will cause all the batteries to look bad.
Good luck
Larry

Thanks, Larry. Do you happen to know of a decent load tester for AGM that's under $100?

AGM (Lifeline) Batteries and voltage question

Comments

Categories