Are my batteries shot

mountainman

I have 208 amp hrs 12 volt in rv full charged.1.27 sg 12.8 volts If I run my 9.5 amp furnace 15 mins my voltage drops to 11.5 turn off the furnace back to 12.4.  in an hour or so back to 12.8

westbranch

Not sounding good.....Need more info....
how old is the battery?
what are the ambient temps the batt is situated in?
how is it charged? type and capacity of charger.
Have you ever Equalized the batt.?

softdown

208 Ah 12 volt battery? That is massive. 

Should go more than 15 minutes I would hope. 9.5 amps at 12 volts or 120 volts? 

mountainman

2 6 volt golf cart Batterys are less than a year old.12 volts rv furnace around 40 degrees f. 400 watts at 22 amps solar. 35 amps on generator to 14.8 volts. I equalize when sg varies by .005. after a full charge for about 3 hrs 

mountainman

I Equilize On 6 amps

mcgivor

The batteries should have little voltage drop with a 9.5 amp load, I have a 200Ah 12V monoblock which gets a daily load of 80A for 9 minutes total, espresso machine, the voltage sags to 11.9 to 12 V recovers to 12.5V, done this every day for over 2 years without change. Something is not right, the SG indicates full charge but capacity is down, perhaps plate damage from over equalization ??, based on 0.005 difference between EQ, Trojan recommend EQ when differences of > 0.030 in SG. How frequently dose this translate in terms of days and at what voltage?

Estragon

Certainly sounds like something not right. Does the bank have trouble with other loads? I'm wondering if the problem could be a problem with the furnace, such as gummed up fan bearings?

mountainman

I meant to ssay. .050  between cells buttons seem to be sticking. I equalize at 15.5 volts a couple times each month. Gonna try testing with a different load.

softdown

I think it may be possible that your batteries are stored in a cold location with the furnace showing 40F. The furnace bearings also may not like 40F and create a lot of friction. 

My trailers furnace was noisy and had "permanently lubed" bearings which means that users can not readily lube the bearings when the factory lubrication fails...which it will. I took mine apart and never got it put it back together again. It was not made to be worked on. 

Battery output at 40F is much lower than 70F. On the bright side, cooler temperatures are ultimately very favorable for long term battery life. However....it will not seem that way when using a battery in cold temperatures.

mountainman

I've done more battery testing 2 car headlight bulbs 7.3 amps 85 watts 1 hr on a 45 degree day.down to 11.96 volts. Unhooked 12.28. I started with full charge.Also checked my furnace 9.6 amps batteries are 10 months old I use 75 to 80 amp hours per day.always stay above 50%soc.I think I need to see my battery man? Any other ideas?

Dave Angelini

Just a comment, I do not see anywhere in your thread that you measure accurately 100% Soc or even 90%. 
Are you really charging them and is your hydrometer accurate?
An EQ will do very little if the battery has lost capacity from chronic undercharging.
Might be time for a trip to Costco

mountainman

Yea maybe some trogens. Hadn't thought about  my hydro being off.  In my first post i stated 12.8 volts  sg 1.27 sg 100% charge. The voltage drop was what ive been concerned with. I'm gonna fully charge on grid . Run 3 head lites 10.8 amps run the battery  down to 10.5 volts and time it I should get a little over 7 hrs x10.8= 75 amp hrs. My batteries spec 75% at 45f.   then check sg with a different hydrometer. Wait 12 hrs and check Voltage 11.90 50% soc sg 1.190.    Is there a better way to check capacity?

mcgivor

It would appear they have already failed the load test, based on information provided, doing the suggested load test to 10.5V would be akin to flogging the dead horse. If time and grid allows, I would suggest leaving them on charge/float  for an extended time, around  a week,  carefully monitoring voltage, temperature and current, this would allow the capacity to reach its maximum, whatever that may be. Having to perform an EQ twice a month due to SG drift would indicate, to me at least, that the charging regime may have been insufficient, perhaps this is something that needs to be addressed in order to recover the batteries you have, or prevent the same happening to the replacements, should they be needed. Providing information of charge controller type, voltage settings, bulk/absorb times, float voltage etcetera, would be helpful, there may be something you overlooked that others may see.

mountainman

Yes I agree 10 months and my batteries are toast. I'm for now using 2 12 volt group 27 starting batteries. I never have taken the batterys below 1.17 sg!! As far as charging 4 100 watt 5.29 imp 18.9 vmp. 70 ft on 8awg from panels to a 30 amp pwm 14.6 absorb for 2 hrs. float 13.8 auto eq 28 days at 14.8 volts for 2 hrs. From day 1 my golf cart batteries never had the same voltage 6.3 and 6.5 but 1.27 on all cells. And fully charged would drop instantly to 12.4 with a 10 amp load. The starting batteries I'm now using
Drop to 12.6?. I manually eguilized when one or more cells were 0.050 lower which happened once or twice a month. After fully charging To eq I use the 10 amp setting on a car charger. I know that's not the best way. checking the amps with my multimeter shows 6 amps 3% of my bank at (16 VOLTS. for 2 hrs COULD BE THE PROBLEM.) On cloudy days I charge on 35 amp setting until voltage reaches 14.8. I have never had to add water to the batteries. They are used outside unprotected from 0 f to 100 f. also had a panel stop producing amps but still produced full voltage at 8 months old.

softdown

Panels producing voltage with no amps are really quite a problem to troubleshoot. I have four solar banks so may be more experienced than I seem....in some ways.

mountainman

I noticed lowered amps so short circuit tested each panel found one dead sent it in for testing.They replaced it. But they couldn't give me an answer of why or what happened.

softdown

mountainman said:

I noticed lowered amps so short circuit tested each panel found one dead sent it in for testing.They replaced it. But they couldn't give me an answer of why or what happened.

Gosh...I was unaware of that procedure....short circuiting a panel. Is it easy to do? I like easy.

westbranch

Yes, there are some tell tale items showing in your post:
1. I have never had to add water to the batteries......  this tells us there has not been a good charge or an EQ achieved... EQ is identified by a need to add water monthly or so...
2.checking the amps with my multimeter shows 6 amps.... from panels that should be putting out 10 Amps+...tells us you may have a poor connection in the wiring or the wire may be too small for the distance.
Have you retorqued all your wiring connections since first assembled?

Struck part of #2 as noted below, those values were for a 110 AC charger. additions in bold

mountainman

Westbrance coming out my cc I've seen 24 amps and 344 watts with loads on. I use a car battery charger to equalize 6 amps at 16 volts.

mountainman

Soft down really?

westbranch

Corrected previous post about 110V charger..

mountainman

Ive found out from volt drop calculator 10% drop on my 8 awg cable I'm gonna fix that before putting in new batteries. Any suggestions for a battery charger that won't break my pocket

mountainman

Yes Ive checked connections but if I'm not losing water. seems as I'm not getting enough charge. Some one suggested my hydrometers off.

westbranch

When you get your replacements batts. tell the vendor you want new batteries with matched manufacture dates, to the day if possible, and that they be fully charged and equal SGs on all cells.  If not get them to do an EQ charge. have them record the SG  on all cells and have that noted on the bill of sale.   A knowledgeable vendor will be able to do the tests, if not go elsewhere...

Charger: you need to have a charger that will put out ~ 10% or more of the battery Ahr rating, at the recommended EQ Voltage. In winter if you need to EQ, the standard recommendation is to run the generator or charger before sunup if possible so that the BULK  phase is complete and ABSORB has started when the sun rises and then just let the  PV finish the EQ. Bsically only the mid to highend chargers have an EQ ability, Not usually available at a auto-supply store.

Estragon

Lack of need for watering is related to voltage. Late stage absorb and all EQs should cause some gassing in flooded batteries. The gassing is what causes the need to add water. If not gassing, that's a sign absorb voltage and/or EQ voltage is too low and/or too short.

Both Vabs and Veq voltages are temperature sensitive, requiring higher voltages at lower temps. OF to 100f is a large range, so temp compensation in controller/charger is important in your situation. Temp also affects how SGs should be interpreted.

littleharbor2

Running high voltage/low amperage from series wired panels to your controller will fix your voltage drop problem. Need an MPPT controller to do this though.  I'm not seeing what controller you have. 

mountainman

Cheap pwm cc all panels in parallel

littleharbor2

There are some fairly inexpensive REAL MPPT controllers on the market. Should take care of your voltage drop problem and, as a bonus, gain you better production from your existing array

westbranch

this is the forums sponsors store and the show 238 Residential  MPPT charge controllers, you might give them a call to shorten the list for you.  I have found the prices pretty  good for what I have bought ... I think something in the MidNite KID 30 A class / size would work well for you.

https://www.solar-electric.com/catalogsearch/result/index/?cat=722&q=mppt+charge+controller+12v