Specific Gravity - are my batteries charged or not?

11 Posts
Jan 19, 2009 02:12 pm
Specific Gravity - are my batteries charged or not?

Still learning my system: I have 2x 6 volt 400Amp hour Rolls/Surrette deep cycle batteries. Unfortunately, they stood unused for 4 months before they were installed and had some sulfation issues. My supplier, at Christmas, was able to put them through discharge, re-charge, equalisation cycles and get them back to holding charge and so I re-installed them.
After a period of 2 weeks of varied cloudiness (I am at 55 latitude in Canada, about 3500 feet) and the batteries were between 50 and 65% charges, I got 2 full sunny days. First day my Solar Boost Charge controller told me that voltage was about 12.85v (after allowing time for batteries to "settle") and then Day 2, full sun the same charge controller flashed batteries as charged in the morning. Yahoo I thought to myself. Also, my GoPower 1000Watt inverter signaled that it was getting maximum charge to it. Yahoo again. BUT I checked my cells specific gravity this morning, all of them registered on the border of RECHARGE and fair (ie sp gr of 1.196 to 1.216). Why are they not reading as charged or at least a higher spec gravity?Huh
 My hydrometer is only a month old. Something is not measuring things correctly (hydrometer also allows for temperature variation). Both the charge controller and inverter tell me batteries are significantly charged (13.15v for example this morning) but the specific gravity gives me the opposite.
Any ideas???
351 Posts
Jan 19, 2009 03:26 pm
Re: Specific Gravity - are my batteries charged or not?

Meters can lie to you, for various reasons. Idiot lights are even worse. Hydometers generally do not. Trust it.

Were any of the adjacent cells more than 0.05 apart?
Also, what temp did the hydrometer give you when you took the readings?

If your system is still 2x80 watt panels, they are not going to charge that battery in 2 days.  You are probably getting no more than 2 hours of full sun equivelence at this time of year. That means you can only charge about 5-6% a day.  It will take over a week to bring the battery up from 50% to full.

I would suggest you get a charger on them. Get the batteries up to full charge and then monitor them.

« Last Edit: Jan 19, 2009 03:31 pm by ken hall »
Jan 19, 2009 03:45 pm
Re: Specific Gravity - are my batteries charged or not?


Maybe this site will help to clear things up a little.
Take notice of the volts per cell on the graph, how it shoots straight up at first upon the beginning of recharge then starts to level off more or less. Compare that line to the specific gravity line and how it does not start a significant incline until voltage is much higher.

How do the SG readings compare from cell to cell? Are they the same or very close to each other? Is the electrolyte level correct? Just how cold is the environment where the batteries are kept? What is the high voltage set limit on the charge controller?
Its a possibility that the voltage is high as shown on a meter when charging starts in the morning, but the amphours replaced are still low.
Compare the SG readings and voltage shown, first thing in the morning when charging starts to evening measurements as charging comes to an end. 
Most importantly, keep us up to date. I for one would like to know how this all turns out for you. I just bought some of those same batteries recently too.

11 Posts
Jan 19, 2009 07:45 pm
Re: Specific Gravity - are my batteries charged or not?

Thanks Thomas and Ken,
I'm a visual learner so that graph helped explain where the batteries are at in terms of the charging process and Ken's comments concur with that (ie, still a long way to go for full charge).
To answer the questions..
*** I have the Solarboost Charge Controller set at a higher average, of 15.2v (vs default 14.2) given the winter season and the shorter hours, to make the most of any bright sunshine.
***I have just got an IOTA 55 amp charger wired and will get that rigged up tomorrow. That will be interesting to see how long it charges.
***The cells have similar sp. gr, one battery all are exactly the same. One battery one is significantly lower and always has been by 0.4 this time. This is where the cables go on to the positive terminal. I should equalize after I charge?? (will be charging from gas generator)
***The ambient temperature is 5C and the hydrometer said to subtract 0.004 from each reading. I understand the colder temps affect battery performance and I am working on a solution to that.
***Electrolyte level is correct.
It is dusk now and I am seeing that when I walked in it was 14.05v and now that sun is gone the reading has droppped to 12.95v. I'll check all specific gravities again tonight.
I will also phone solar boost tomorrow as I am also concerned that the charge is "trickling" in based on the fact that the unit thinks the batteries are close to 100% charged which is NOT the case.
Thanks for your help guys, any other comments welcome.
351 Posts
Jan 20, 2009 03:35 am
Re: Specific Gravity - are my batteries charged or not?


Which voltage did you set to 15.2 ?

I am assuming that your charge controller is a Blue Sky Solar boost.  Either a SB2512i or SB2512ix.  Please confirm the controller model.

11 Posts
Jan 20, 2009 12:48 pm
Re: Specific Gravity - are my batteries charged or not?

Good morning Ken
A solar boost 2000E
351 Posts
Jan 20, 2009 03:26 pm
Re: Specific Gravity - are my batteries charged or not?

Good afternoon Sally.

A couple of suggestions for you.

I think you should dial back the charge voltage setpoint (I am assuming that is what you raised to 15.2) to something around 14.5.  That should still reduce the charge time without stressing the battery as much.

Watch your electrolyte levels like a hawk.  Running higher voltages can boil it away. It hasn't really been much of an issue because your panels have been working on a big battery that has generally been in a lower state of charge. Now that you have a charger, they will see a higher state of charge more often, and the higher voltage will actually come into play. 

You have not mentioned the optional temperature  compensation on the charge controller, so I assume that you do not have it.  I think it would be a wise investment for you, particularly with the wide range of ambient temps that you see during the year, and your use of higher than default voltage settings.

Until you get a few more panels, I would opt to run equaliztion charges with the charger.  You dont have enough panels to drive a really effective equalization charge.

Which charger did you decide on ?


Jan 20, 2009 03:42 pm
Re: Specific Gravity - are my batteries charged or not?

*** I have the Solarboost Charge Controller set at a higher average, of 15.2v (vs default 14.2) given the winter season and the shorter hours, to make the most of any bright sunshine.

Where you use the word "average" does that mean the same as high limit? 15.2 is an equalizing voltage on a 12 volt nominal system. Are you having to replace lost water very often? Or alternately, are the batteries reaching 15.2 on a regular basis?

***The cells have similar sp. gr, one battery all are exactly the same. One battery one is significantly lower and always has been by 0.4 this time. This is where the cables go on to the positive terminal. I should equalize after I charge?? (will be charging from gas generator)

Technically, equalizing is done when cells show very different values, but to answer your question I would run the ICE genset at night and let it take over the loads as well, just to get more from the fuel burned. Assuming there are VAC loads that it can power directly.

This is curious. I started out using a hydrometer while still in the learning process. Now I just rely on a Bogart TriMetric. I just know from years of compiling data from it, first in a log book and then mentally, that my batteries are being treated and working properly. Not very scientific I know but it works for me. Once a month I run an equalizing charge on them anyway. The Trace C-60 has an automated function for this, all I have to do is initiate it, and it resets when done.
 Just a note, when my bank of S-530's arrived I checked the voltage with a multimeter and they were all at 6.3+ and, just out of curiosty, I cleaned the dust off of my hydrometer and checked the sp. gr. on two of them, it showed them as being low. I had always doubted its accuracy anyway. Thats why I quit using it. I wouldn't be surprised at all if I went down and checked mine with a hydrometer and it showed conflicting data as compared to the TriMetric. I think as time goes by and you get more comfortable with maintaining your own system, you will learn your systems characteristics and you'll settle into a routine that your confident in. Of course knowledge is power. One of things, in a manner of speaking, that "settled my mind" about dealing with batteries is when I happen to read in an old high school chemistry text book that "batteries do not store electricity, they convert electricity into a chemical energy and store that until such time as they or called upon to deliver electricity again." It worked for me anyway.   

A few more more question. (I don't mean to be nosey Miss Sally, just trying to learn for myself what is going on with your system)
When you sized the battery bank, did you size it for what your needs are or for the size PV array that is recharging it and, what percentage of depth of discharge per cycle, did you plan on?   
Jan 20, 2009 04:58 pm
Re: Specific Gravity - are my batteries charged or not?

Just so you know, where I live there is very few people I can relate to, in person, about this stuff. Everytime I try its as though I am speaking Greek to a Chinaman. Also, my writing skills needed serious help so... I put 2 and 2 together and luckily found the Alt-E store forum.
Thanks Alt-E Store!

I don't know if this will help you any but here it is anyway.

In an ideal world, all things being equal budgetwise, and always rounding up, I would take the watthour load estimated over a 24 hour period and convert it into amphours at a nominal voltage.
Then multiply that by at least 5 to get the size battery bank needed. Then I would take that same watthour estimate and divide it by - the number of hours of equivalent full rated charge per day - with a given PV array orientation for a given region on the shortest day of the year. This may seem bare bones to some but glutonus to others. To each their own.

Estimated load - 4,000 watthours or 4 kW h's over 24 hour day/night cycle. 24 volts nominal system.

4000/24x5= 833 amphours @ 20 hour rate minimum battery bank.
(I might would go up to a 1200 amphours bank for future use and/or more days of autonomy.

2 hours of equivalent full rated charge from a PV module.
4000/2= 2000 watt PV array 
(I might even double this. A lot would depend on site specifics.) The idea of course is to replace what was taken from the batteries as soon as possible.

Undoubtedly though, budget restraints can and will come into play for a lot of people, including myself. Personally, I am disappointed with the PV industry and its pricing. I had expected better prices as PV become more main stream. Oh well, I guess that was just a pipe dream.
« Last Edit: Jan 20, 2009 05:01 pm by Thomas Allen Schmidt »
220 Posts
Jan 22, 2009 12:04 am
Re: Specific Gravity - are my batteries charged or not?

 hi folks,

 sally, i agree with the advice to get those batteries back up to full charge and take it from there. i would try to get those set points back to the default settings and watch how things run. did you see the technical bulletin issued for that controller? i believe it deals with the issues you are experiencing. looks like all adjustments should be made with the bank right at the top of its charge for the readings to be accurate.


 this tech update was issued back in 01 and revised in 03,  one would think that the issue has been resolved by now..but who knows?

 hang in there, you will be up and running in no time..you just have look at these things as learning opportunities!

best regards, dave
Jan 23, 2009 05:30 pm
Re: Specific Gravity - are my batteries charged or not?

Well, I for one am glad it had nothing to do with the Surrette S 530's. I just bought 8 of them a couple a years ago. I am hoping to, not even think about having to change them until 2026.

So, the Solar Boost 2000E's would appear to the culprit. Let me see if I got this right.

 In order for Miss Sally to set the high voltage limit set point of her Solar Boost 2000E, the batteries have to be at that high limit voltage?

Or make an additional purchase of the device that Mr. Ames, so graciously gave us a link to, in order to set the high voltage set point at any battery state of voltage?

And I thought it was wierd to, have to, have a conversion chart to set my old Trace C-30-A on/off type charge controllers high and low limit set points.

Thanks Mr. Ames
578 Posts
Jan 23, 2009 06:46 pm
Re: Specific Gravity - are my batteries charged or not?

good thread, here is the link to that tool i think.



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220 Posts
Jan 24, 2009 01:38 pm
Re: Specific Gravity - are my batteries charged or not?

 hi folks,

 things are getting curiouser and curiouser, has anyone else had time to read through some of the product documentation for those blue-sky controllers? and this is not to pick on or single out the blue-sky people but some of the "fixes" they have come up with are beyond the average "consumer" to have to deal with.

 on the "fix" for a clicking relay they want you to go in and chop out a diode from the circuit board!

 this ones even better...

 in the above tech update they tell you how you have to build your own voltage offset circuit to trick the controller into an equalization voltage!

 it appears the attitude with manufacturers and/or their engineering departments is. as long as there is an aftermarket fix to the problem they can just hum along business as usual.

we can do better.

edit: note that these examples are "old" fixes from the sb2000 model. but according to the 01 date on the first tech update blue-sky has been aware of the set point issue on the sb2000e since then. and as a favor they will be happy to sell you a tool to make up for their design flaw.
« Last Edit: Jan 24, 2009 03:42 pm by david ames »
11 Posts
Feb 3, 2009 06:28 pm
Re: Specific Gravity - are my batteries charged or not?

Hello everyone,
I'm back on the map here after a business trip to Vancouver. Wow what a "rabbit hole" this has turned out to be!!
Am a little overwhelmed with all this set-pint stuff, but will take some time to read and digest it.
I have been successful in running the IOTA 55AIQ4 charger and charging the batteries from the gen. Altho it is still a bit of a mystery as to when they are 100% (no equalize option on this baby either).
Thomas, what is a Bogart Trimetric? and yes..I totally understand about having some people to talk to about this. I am the only one in my community with solar.

Now, about the voltage setpoint on the solar boost. I thought the solar boost simply controlled current into the batteries based on what it reads the voltage as...simplistic I know. I must get a volt meter next to match what SB2000E tells me vs actual voltage. When I recently disconnected the system, got the batteries fully charged artificially (return to vendor). When the fully charged batteries got rehooked to solarboost, would it have reset itself correctly?
The solar boost manual sure seems simplistic now that I am reading these other articles!
Ironically, I feel that the sun is recharging my batteries, that my charger is re-charging them, and that my household system runs well (altho I am not using it at full capacity yet). It's a lovely 0 degrees C outside, and I am on my laptop and hooked up to the internet!
Yes, I agree, the concept of solar is so darned attractive but there are too many glitches for the average household that may not have some one passionate and with the time for monitoring and compete understanding of system.
That's enough of the rant! off to buy voltmeter tomorrow Smiley

11 Posts
Feb 3, 2009 07:06 pm
Re: Specific Gravity - are my batteries charged or not?

one other piece of the jigsaw puzzle. when i re-charge using my IOTA 55A IQ4 it is independent of the solarboost2000E. ie. the wiring goes from genset to IOTA and direct into battery. The SB2000E does continue to then record the increase in voltage as the batteries charge (but it does not control that charge).....Miss Sally
11 Posts
Feb 4, 2009 12:55 pm
Re: Specific Gravity - are my batteries charged or not?

also found some other tidbits re: hydrometer
The Real Goods Solar Source book has what looks like my graduated hydrometer with the clause "Use Tip: The color-coded red, yellow, and green zones on the hydrometer are calibrated for automotive starting batteries: ignore them. Just look for differences between cells." Altho, my source told me mine was for deep cycle batteries, and I can't really tell from the picture any difference, other than mine is red, green and white.
Looked at Bogart items, so I know what they are now :)Way cool anddefinitely for the christmas list.
and also found interesting battery info at
http://www.windsun.com/Batteries/Battery_FAQ.htm The first of the Mini Factoids (near end) was also interesting about 10-30 cycles before full charge. Mine are still pretty "new" in that regard.
Feb 4, 2009 03:17 pm
Re: Specific Gravity - are my batteries charged or not?

Bogart Tri-metric 2020 I think is the lastest edition.
May as well get the 500 amp shunt.
At first it can be a real head scratcher to program but once it is, there is very little to do afterwards. Whats so great about it for me is its history abilities and the reminders.

I have yet to read the manual on the SB2000E but I do know that most (if not all) PV charge controllers will have different voltage limit set points, at the very least for different types of batteries, ie. flooded cell lead acid, sealed gel cell, yadda, yadda, yadda...

I think I'll take a gander at that manual now.

Back again. Sounds like a good controller. One thing about it that raised my eyebrows was the equalizing charge doesn't automatically turn off when done. I've burn a pot of beans on the wood stove more than once. Pages 9 and 10 read, easy to understand. But in all honesty, it would be for someone who reads manuals as a part of their job chores. Try replacing an Hitachi L300P with a Yaskawa V1000 after the Hitachi has blown and all of the parameters were lost. Just kidding. I troubleshoot industrial motor controls (among other things) for a living.

I agree about the glitches but in time I think you'll forget about them or maybe at least put less importance on them and go about your life as you would with just a few more chores. Or maybe just different chores. I don't miss filling the Kerosene lamps, but sometimes I miss reading by them.
« Last Edit: Feb 4, 2009 04:25 pm by Thomas Allen Schmidt »

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