bad batteries?

[wine_guy_3]

this is the second time I am trying to post.
The first one must be in deep space somewhere.

I hooked up my 2 x 100 watt solar panels to 2 new 100 Ah batteries.
Connected them to an inverter and my freezer. No idea of the draw, but assume about ½ kWh per day.

Sun was shining, and up to 10 amps from the panels.
After about a day the inverter shut off at about 12 volts.


The solar charge controller uses a pulse width mode:
The closer to full charge, the narrower the pulse.
Float charge is set at 14.5 volts on the solar charger.

I put them on a smart charger that puts a float charge on them up to about 14.6 volts.
The charger cycles up and down around the 2 amp range for the float charge.


I checked the SG of the "charged" batteries, and they were around 1.175.... not good.
I put on a 1 amp charger to try to get the SG to around 1.25 or better.
It took several hours.
Got the SG to 1.25 on most cells, but the voltage was up around 15.04.

No I didn't check the SG of the new batteries, but they were
manufactured only 1 month ago (date stamp)

Question:
Is it normal to have to run the charge up to 15 volts to get the SG in normal range?


I put them on a 300A load test, and then the charger.
They charged overnight.
I broke my hydrometer so I will have to get another to verify the SG.

Hopefully the float charge at 14.6 volts will work after a few cycles.

any thoughts?

[DamonHD]

Float charge is set at 14.5 volts on the solar charger.

I would expect *float* to be nearer 13.7V with *absorption* somewhere a little over 14V depending on battery type (for my gels about 14.1V).

If the batteries are kept over 14V for a long time I'd expect them to lose electrolyte, but as I have never owned anything other than gels, I am no expert.

Rgds

Damon

[OperaHouse]

I don't know what you use your freezer for, as a fridge mine uses about a KWH a day.  A day to stabilize uses a lot more.  If the inverter is on all the time it will be a lot more.  I switch mine on and off and disconnected the fans.  This 2,000W inverter is dedicated to the fridge.  When the motor turns on it draws 120A and settles down to 9A. It may be the batteries are fine and the initial charge condition of the batteries was less than expected and the draw was a little more.  It is likely with your system that the batteries will never get out of the bulk charge mode.  I use a Turnigy, GTPOWER, etc type wattmeter in my system connected to a shunt.  These are only about $10 on ebay and are the handiest things ever to tell you what is happening in your system.

[wine_guy_3]

charged the batteries with the smart charger.
Let them sit overnight.
Got a new hydrometer.

battery cells are all arouind 1.125.
put on another 300 amp load test and running the charger again. Not bothering with the solar panels.
will let you know the outcome.

by the way, the freezer is showing 130 watts while running (I got a kill a watt meter)

[Rob Beckers]

Wine, you need to figure out what your freezer uses in energy per average day (Wattage is not all that interesting unless you also know how many hours a day the compressor is running). The Kill-A-Watt will tell you, just let it run a few days and read it off. I doubt it'll be much less than a kWh per day, likely more (even for a small freezer).

Your 2x 100 Watt panels are very small as a charging source. Not sure where you live, but that little solar PV isn't likely to bring in a kWh per average day, to make up for the losses from the freezer. Similarly, a 100Ah battery bank (I'm assuming it's 12V/100Ah) will last just about a day with 1 kWh of energy use, and at that point is down to 20% SOC (or about as low as you'd ever want to go with a deep cycle battery). To put this differently: That little in batteries will barely get you through the night when there is no solar coming in!

By the way, in your last message I assume you meant an SG of 1.250 and not 1.125? The latter means the cell is empty...

-RoB-

[OperaHouse]

To that, I've been quite successful running a freezer as a fridge for months at a time.  I have massive amounts of liquid as a cold storage mass at just above 32F and this runs only during the day.  I eventually had to get 1,000W of panels to insure I could maintain temps below 38F.  Is your inverter MSW? I've heard Those kill a watt don't like that.

[wine_guy_3]

Yes, I meant 1.250 for the SG; OK, but not good.

I've been putting on a 300 amp load test and recharging the batteries.
Something is goofy.
The battery recharges in less than an hour using the 2 amp range; voltage at 14.6 with the charger on.
Settles to 13.4 within an hour and stays there. SG still at 1.250, no more, no less.
Not making a lot of sense. The battery should not recharge that fast, and/or the SG should not be that high.

The kill a watt meter is on the wall supply. Not using it with the inverter.
maybe later today I will put the inverter and freezer back on to see what happens.

[OperaHouse]

I'd like to get one of those kill a watt.  If it is out of warranty, ship it to me when it goes up in smoke. I got plenty of expensive wattmeters, but would like to look inside this.  I've seen reports that these and refrigerator controls with a capacitor dropping power supply have trouble with MSW.  If designed right it shouldn't be a problem.  But what today is designed right.  I don't think you will learn much by using it with an inverter anyway.  I really think these are one of the neatest devices to have around.  It will record the lowest voltage on a battery along with daily watts consumed.  This one is the cheapest, but they hot melt glue in the board so it is hard to mod removing the power from the sense.  Only one red lead needs to be connected.  Current sense is via the negative black leads.

http://www.ebay.com/itm/100A-60V-DC-RC-Helicopter-Airplane-Battery-Power-Analyzer-Watt-Meter-Balancer-DP/112062067350?_trksid=p2050601.c100085.m2372&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D37338%26meid%3Da39faed91de84b3eb8af06f8a3c506e0%26pid%3D100085%26rk%3D2%26rkt%3D4%26sd%3D172269880717%26clkid%3D7582271106827417017&_qi=RTM2247626

[wine_guy_3]

Called the EverStart hotline to try to get some more info.
They do not publish the SG for a fully charged battery, nor do they have a suggested procedure for charging.
Hmmm.
Still need to hook up the 1 amp charger to get the SG above 1.250, and the voltage still goes up to 15 V.
This just doesn't sound right, but maybe that is the design of the battery.

The freezer uses 1.3 kWh per day according to the kill a watt meter.
Will probably need to hook up the other 2 panels (4 total) to keep this thing running without killing the batteries.

Thanks for all of the inputs.

[Johann]

Under perfect condition 200 watt solar panels will give you about 150 watts an hour times about  4.5 to 5 hours exposes depending on your location = about 700 watts hours per day that your panels make minus your inverter that can use up to about 80 watts per hour, the bigger the inverter the worse the idle power consumption will be.
Also a modified inverter will have to provide more power to the devices that it will power and the devices will turn more power into heat instead of work compare to an true sine wave inverter.
It looks like that your 200 watt solar system is not big enough and the the batteries are not big enough either.

Newer fridges and freezers are using about 1 kwh per day.
Remember you have to run your fridge daytime and still charge your batteries.  You should not discharge your batteries more than 50 % or you will kill them prematurely. So a 100 ah battery will give you 50 ah safely daily use or 600 whr per day max.  Between charging and discharging you loose another 20% or so and you really need to make even more power per day now just to keep the battery happy, but you still need  additional power to run the fridge while the battery is charging when the sun is out.

You should have at least 500-600 watts on solar power and about 400ahr on battery at 12 volts.

[wine_guy_3]

Johann,
Thanks for the input.
I was coming to the same conclusion.
On a good day I was figuring 600 watt-hours from the 200 watt panels, maybe a little more.
Adding the other 2 panels would give me around 1200 watt hours; just enough for the fridge.
I need more panels.

I still need to play with the batteries so see why the SG reads so odd.

Thanks for the inputs.

[Harold in CR]

 Everstart sounds like WalMart marine starting/deep cycle battery ?? If that is what you have, I don't think you have true deep cycle batteries and won't have the capacity to do what you want.

[wine_guy_3]

Yes, they are the Walmart batteries.
I searched around the net before I bought them.
They seem highly rated for trolling motor usage, so I thought they would work fine here.
Trolling motor usage is really tough on a battery.

[ChrisOlson]

Question:
Is it normal to have to run the charge up to 15 volts to get the SG in normal range?

That is completely normal for the Everstart (Johnson Controls) Walmart deep cycles.  15.0 volts is recommended absorb voltage.  Equalize by applying ~2 amps until the voltage rises to 15.5-15.7 once a month.  Used them batteries for years for both off-grid power and in our boats and camper.  Treat 'em right and they'll last just as long as a Surrette or Trojan.

Nice thing about those is that they have a pretty good water recovery system and they use very little water.

[wine_guy_3]

 
thanks for the inputs on the charge voltage.
Where did you find the info on the batteries? I couldn't find any.

any idea what the SG will settle out to be?

[ChrisOlson]

Years of experience with those very batteries   

The SG is on those is low and ends up at 1.250 after an equalize charge, and usually 1.220 - 1.230 (depending on temperature) after a normal charge.  They are actually designed to be charged by common marine chargers that don't have an absorb stage.  Most marine chargers are constant current, and voltage gradually rises to 15.0 for flooded lead-acid then cuts back to float.  The charge process can take 24 hours for a pair of them on a 24V trolling motor.  For off-grid you'll normally have higher charge rates than that.  So set absorb to 15.0 volts and once it reaches that, absorb for an hour then drop to float.  You should have SG around that 1.220-1.230 range.  You can adjust your time in absorb to get the proper SG.

EQ once a month to 15.5-15.7 at about 2 amps equals the cells out so they stay healthy.

They are lead-calcium plate, designed to take heavy vibration or pounding in marine applications.  So they do not have the capacity to hold their voltage at levels of discharge much below 70% SOC.  Under load from 70-50% SOC their voltage will rapidly drop to 10.8-11.0 volts, which is no problem for 24V trolling motors with them in series, but can be a problem for inverters.  So keep that in mind, as they will start cycling your low voltage cutoff on your inverter if they get below 70% SOC at more than their 20hr rate of discharge.  To compensate for that, just add a couple batteries.  They are cheap compared to lead-antimony off-grid solar batteries, so you can buy four of 'em for less money than two so-called "off-grid" power batteries   

I've got some of those around here in stuff that are 8 years old and still working fine, although they do drop voltage faster than they used on the inverter in the camper if we run the microwave on inverter power.

[ChrisOlson]

thanks for the inputs on the charge voltage.
Where did you find the info on the batteries? I couldn't find any.

any idea what the SG will settle out to be?

wine_guy, keep in mind that a marine charger does a much better job of charging those batteries than an off-grid charger does.  The marine charger, on a 24V or 36V system, will charge each battery individually, and insure they are equal.  Off-grid systems don't do that, so if your setup is series 24V, make sure to keep a check on the balance because no two batteries are ever the same.

The other thing is that the marine charger will charge them at 2% C for a very long time and they will spend a lot of time in absorb and gassing at 14.4 - 15.0 volts before it cuts back to "maintain".  Off-grid systems don't do that and are more "wham bam thank you ma'am" type of charge systems.  Where a marine charger won't get your batteries hot, ever, an off-grid system can.  And I wouldn't charge them over 10 amps during bulk.  So if your system is bigger than that, add more batteries to keep the charge rate at 10% C.

It's a sad fact that the marine folks usually have more experience with batteries than off-grid folks do.  And the nature of off-grid charging is not battery-friendly.  But if you adjust a few things to make them happy, they will work fine for you.

[wine_guy_3]

Thanks again.
These are batteries used in a 12 volt system.

I seldom go over 6 amps on the charger, and mostly use the 2 amp setting.
The charger does not seem to go above 14.6 volts before it seems to put on a float charge.
It then cycles between 2.5 and 0.5 amps for several minutes.
maybe I need to look at a marine charger?

[ChrisOlson]

Just a different solar charger is all you need if you are charging from panels.  I imagine you have one of the more economical PWM chargers and many times those aren't real adjustable.  MidNite solar makes some good ones that should work nicely.  Check out their 30A MPPT Kid charger.  It's a real good unit and is rated for marine use.  We had one on our sailboat.