[RE-wrenches] Trojan L-16 charge settings

Tue Jan 19 07:06:13 PST 2016

William,

Sounds like the Trojan rep  

#1 Doesn't know off-grid equipment if they are giving you a different voltage for absorption than the bulk voltage setting. 

#2 Says that "Absorb Time needs to be increased, maybe from 3 hours up to 4 or 5 hours" - that is unrealistic for day to day off-grid PV charging. Sounds like Trojan is covering their butt by telling you to do unrealistic stuff.

                And "1.270 to 1.280 for SG" is really high and only obtainable if Trojan is loading their new cells with electrolyte that strong (not what they have usually been doing). 

I vary the settings I program for off-grid systems (and often recommend changing settings for winter vs non-winter pv charging). Typically 29.6/59.2 Bulk-Absorb, 27.2/54.4 Float and 31/62 EQ as a starting point for wet cells.

The biggest determinants of success as I see it are: A) high enough Charge Rate of PV to rated storage of batteries. B) regular logging of SG readings, all cells. C) good back-up generator/charger set up and the knowledge of when and how to use it.

BTW for those newer to wet cell Lead Acid batteries, manufacturer's can tweak the performance of their deep cycle batteries by varying the strength of the electrolyte -  1.265 has been typical for true deep cycle storage batteries for many years.

If you want a battery to have more amp hours of storage and perform well in initial testing then you could increase the strength of the electrolyte to 1.275 or so. BUT these cells will not last as long (all else being equal) because the increased acidity will degrade the plates quicker. I have some German made Hoppecke LA cells in my barn/shop system that were intentionally made with weak electrolyte to enhance the lifetime of the cells. They are 1.240 SG electrolyte. These batteries are 19 years old now and have never given me a peep of trouble. I expect them to last for many more years.

                Back in the late 80's and early 90's there was an electric car rally/race here in New England (American Tour de Sol) where the early winners gained a competitive advantage by removing about 1/3rd of the electrolyte from their  L-16 or T-105 batteries and replaced it with straight sulfuric acid. I don't remember what the SG of this new "Race Mix" was but the racers who did this performance enhancement would typically outperform the field enough to be the top finishers. After a couple of years the word got out and judges spot checked initial SG's to level the playing field. The racers would correct the SG in the batteries after the race and they would sell the batteries at a great discount into the off-grid market.

Some of you will remember that Trojan several years ago was selling their new off-grid Industrial batteries with a lower SG mix of about 1.25 as I remember. Good intentions for a long lived battery. BUT the market had trouble dealing with the low SG and Trojan decided they were spending too much time educating dealers and consumers on this issue, so they changed to a higher SG after the first couple of years. 

                If Trojan has gone to a stronger electrolyte now, I think that this is not a good sign and it will lead to their batteries failing sooner. 

Dave

(semi-retired and not minding it, at all)

David Palumbo 

Independent Power LLC

462 Solar Way Drive

Hyde Park, VT 05655

802-371-8678 cell

802-888-4917 home

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of William Miller
Sent: Monday, January 18, 2016 9:43 PM
To: RE-wrenches
Subject: [RE-wrenches] Trojan L-16 charge settings

Colleagues:

I have an off-grid customer for whom I replaced a set of 8 Trojan L-16s as well as upgrading her inverter and charge controller.  Right after the job, we found several batteries with low specific gravity.  We spoke with the local distributor and received two replacement batteries.

The system continues to perform poorly.  The customer EQs every 30 days to 60 plus volts for 3 hours.  They try to get a full bulk and absorption charge in every day but this time of year may not. The specific gravity readings continue to diverge and generally go lower.

We contacted the distributor who told us they have had problems with Trojan batteries since the company was sold about two years ago.  We were told they had a brand X battery that tested better than the Trojans.  We agreed to try the Brand X but then were told that we had not charged the Trojans adequately.  Below are the settings recommended directly by Trojan

These settings are significantly higher than any I have used before.  Also, I don’t recall it being possible to set different bulk and absorption voltages with any of the equipment I use.  I use Trace, Outback, Schneider default settings of 57.6 bulk, 54.4 float and reprogram to 60.5 for equalization.

I am curious about what charge settings you find successful for flooded lead-acid batteries and what any of you might think about the recommended settings as seen below. Do you feel it is practical to achieve these settings in an off-grid scenario?  Would these high settings cause excessive water consumption?

Thanks in advance.

William Miller

Gradient Cap_mini
Lic 773985
millersolar.com <http://www.millersolar.com/> 
805-438-5600

I looked at the spreadsheet and the SG. readings across each battery are uniform which tells be that it is highly unlikely that anything is wrong with the batteries except for being under-charged. Take a look at our User’s Guide on the Trojan website on page 19  ( Recommended Charge Profile) or FLA batteries.

The Bulk stage should be @ 59.3V, Absorb @ 58.8V, Float @ 54V and Equalization @ 64.8V. When the User notices drops in the SG such as in this document, an EQ charge should be performed in order to get the batteries back up to full charge (full charge SG being in the range of 1.270 to 1.280. When performing the EQ, the user should take SG reading for a “pilot” battery every 30 minutes until the voltages reach that range. Termination should happen when SG reaches full charge range or if battery temperature reaches 112 degrees F, which-ever comes first. SG readings can be taken during EQ, but you have to make sure that you bump the tiny gas bubbles off the Hydrometer float to prevent erroneous readings.

Seeing the SG readings decreasing after each month is an indication that maybe the Absorb Time needs to be increased, maybe from 3 hours up to 4 or 5 hours.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20160119/46103bf6/attachment-0002.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.jpg
Type: image/jpeg
Size: 1460 bytes
Desc: not available
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20160119/46103bf6/attachment-0002.jpg>