Ron,
I had the same problem with my own battery bank last year. It puzzled me
for weeks until I finally started checking battery voltage of each battery
after every change in load or charging. The culprit was an intermittant
failure of one cell in one of my L16 batteries. Since I had a single string of
8 Trojan L16 H batteries, it was easy to see the failure and reconnect with a
sudden change of roughly 2 volts. When charging, the cell reconnects, when
discharging eventually it would fail again. I would guess if you had read all
the individual battery voltages, you would see that the other batteries have an
elevated voltage. I got rid of the battery, reconfigured to 24v battery bank
and eventually changed out my system to new batteries and used the other ones
for upgrading my 12v sub system and for spares. The other batteries are still
working OK.
John Blittersdorf
Central Vermont Solar & Wind LLc
Rutland, VT
-----Original Message-----
From: Ron Young <solarea...@solareagle.com>
To: RE-wrenches <re-wrenches@lists.re-wrenches.org>
Sent: Sat, Nov 12, 2011 11:58 pm
Subject: Re: [RE-wrenches] intermittent battery problem; ...Battery Sulfation
Folks, this one really has me puzzled. The client has done regular two hour
EQ's, at least once a month. When did a site visit and I topped up the
electrolyte (they'd been starving the batteries for water but always just above
the plates) the problem seemed to go away. They were satisfied that the problem
was solved but I wasn't and I told them what I had been hearing from this group
- essentially that the batteries needed a deep EQ, discharge, recharge and EQ
again two or three times to scrub the sulphates. They declined until just a few
days ago when they said the rapid voltage drop was back. Here's a quote:
We had another rapid voltage loss this morning ---it was 25.2 when we got up
and it dropped rapidly to 22.8. We turned on the generator and charged the
batteries until our display showed 30.2 for awhile with the generator running.
We turned off the generator and the voltage settled at about 26.4. We turned
off all loads and wind and solar.
At 9.15 our batteries were at 26.4
At 9:16 we turned on an 8W light bulb, a1600W hair dryer, and a 1.5HP (120V
5.75A) shop vac
The display showed a load of 1.9kw
At 9:40 the inverter shut down---display showed batteries at 18.4
By 9.47 the display showed the batteries at 25.2----the solar and wind were
still shut down.
We turned everything back on (a light, Sunfrost RF16, phone) and all seems to
be normal.
They agreed to do the EQ process but only have a 3kw generator so we started
with 8 hours with the EQ voltage set for 32v (24v system). They completed that
yesterday and here's what resulted:
Before starting EQ the batteries were at 25.8, hydrometer reading 1283 with
temp. correction
Began EQ 32.6 v
Buying 1.5 kw
Hour 1 32.4 v
1283 with temp. correction Buying 1.4
Hour 2 32.4 v
1285 with temp. correction Buying 1.5
Hour 3 32.2 v
Buying 1.7
Hour 4 32.2 v
1290 with temp correction Buying 1.8
HOur 5 32.0 v
1290 with temp correction Buying 1.8
Hour 6 32.0 v
Buying 1.9
Hour 7 31.8 v
1292 with temp correcton Buying 1.9
Hour 8 complete---turned off Gen and turned on loads ---Batteries dropped to
25.4 within 30 minutes and stayed there until this morning---fridge was
running, telephone, internet, wool carding machine, lights. This morning
hydrometer reading was at 1290.
Then today I just got this email:
Just experienced another rapid voltage drop. As soon as the voltage hits 24.8
the voltage drops like a rock if we don't have any input (no solar or wind).
This is not what I expected after a lengthy EQ. I'm getting them to do another
one tomorrow after a discharge cycle and charge but I'm really beginning to
think we have something else going on here, something electrical, not chemical.
The rapid voltage drop is puzzling.
To review, it's an Outback 3524 on an Epanel, Whisper 100 & controller, 6 4KS
25 Surrette batteries in 24v configuration - 4.5 years old, .7kw solar. I know
the charging end is undersized but they have been compensating with the
generator and they get lots of wind in the fall, winter, spring.
Any more thoughts on this anyone?
Best Regards,
Ron Young
earthRight Products - Solareagle.com
Alternative Energy Solutions ~ Renewable Energy Products
On 2011-10-24, at 6:50 AM, Larry Crutcher, Starlight Solar Power Systems wrote:
Hi Ron,
Accurate SG readings are not simple. Was temperature compensation properly
employed? Have they been keeping a log book to identify changes? How accurate
is the hydrometer? How skilled is the person taking the reading?
Most of the Battery Wrench responses suggest equalization but I don't see from
any of your posts that this has been done yet. I suggest this to be the next
step and I recommend that you carefully watch voltage and current. This will
tell you a lot. I use a Fluke ScopeMeter in the TrendPlot mode and track
voltage and current over time. It provides a good visual understanding.
In case others are using this forum to glean information, attached is a chart
for illustration of the charge cycle. You should see a constant, somewhat
linear rise in voltage until the constant voltage setting is reached. If you
see a sudden rise: suspect sulfation. If you see a quick reduction in current:
suspect sulfation. The current should drop to about 8-10 amps at the constant
voltage towards the end of charge cycle. The health and DoD will determine the
time this takes, expect many hours. Begin equalization.
<3s-chart.gif>
A couple other points: Is the MX absorb voltage at 29.6V? Did you program the
MX controller for an extended absorb time (advanced menu, absorb time limits)?
The default setting is poor for large batteries. I use 90 minutes minimum and 4
hours max. This can greatly reduce the possibility of undercharging the battery
but it may use more water. The timer (ChgT) will determine how long it stays in
absorb each day.
Larry Crutcher
Starlight Solar Power Systems
On Oct 24, 2011, at 12:49 AM, Ron Young wrote:
Hi Larry,
I immediately assumed sulphated battery when I heard the customers description
a couple of weeks ago but the hydrometer readings didn't jive. Any sulphated
battery I've encountered, and I defer to your greater experience, has always
revealed itself with a simple S.G. test and these batteries were reading above
1.265. I then thought the possibility of a defective hydrometer and had them
test with another but we just got confirmation of the same thing.
The weird drop in voltage also isn't explained by your description. Why would
this just happen without loads or charging present (except maybe the DC
Sunfrost load) at the same predictable time at 4 a.m. The fact that when the
generator was turned on and sent a surge of current into the system and the
problem went away made the detective in me think there had to be another
explanation. The bank was at rest for several hours through the night and the
voltage dropout was cured by a brief application of charge current.
When I arrived on site my discovery that the client was under watering the
batteries and this chronic condition resulted in a very rich electrolyte,
reading well above 1.265 - into the 1.280 range made me think that was the
problem and it seems to have gone away now that the electrolyte level was
raised and the batteries given a good charge. But it still nags at me that
something else is lurking in the shadows. Your description of the sulphate
converting to a crystalline form has me worried because if this is the case
this expensive battery bank is in danger. I would have to camp out at the site
and monitor the charging over a day or so. I'm going to forward some of your
comments and those of others that have generously offered suggestions and we'll
see if I can convince the client who now believes everything is A-Ok.
Best Regards,
Ron Young
earthRight Products - Solareagle.com
Alternative Energy Solutions ~ Renewable Energy Products
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches@lists.re-wrenches.org
Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
_______________________________________________
ist sponsored by Home Power magazine
List Address: RE-wrenches@lists.re-wrenches.org
Options & settings:
ttp://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
ww.re-wrenches.org/etiquette.htm
Check out participant bios:
ww.members.re-wrenches.org
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches@lists.re-wrenches.org
Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
