Drake,
I'll add just a bit to Jarmo's excellent reply:
You mentioned that you were unsure if the MX60 was set to auto-EQ.
This could be a source of trouble. The MX60 had the unfortunate
characteristic whereby if set to auto-EQ, it would continue to try
to complete an EQ indefinitely once triggered. As such, if the
array was not sufficient to hold the batteries above the EQ
voltage for the set duration, or as the batteries aged and their
internal resistance increased such that the EQ voltage couldn't be
maintained, the controller would never complete and exit EQ mode.
31V, while conservative, is high enough to cause this.
If that is what occurred here, then disabling automatic EQ and
reducing the EQ voltage below gassing threshold should prevent
recurrence.
Allan
Allan Sindelar
al...@sindelarsolar.com
NABCEP Certified PV
Installation Professional
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder (Retired), Positive Energy,
Inc.
505 780-2738 cell
On 11/18/2014 11:03 AM, jarmo.venalai...@schneider-electric.com
wrote:
Hi:
This may not be the problem, but
I wanted
to bring it up as I have heard of a few cases of battery boiling
issues
with various charge controllers and want to suggest a possible
cause.
I'll do this point form. It's
easier to describe it that way:
1. Solar charge controllers are
programmed
to go to bulk charge in the morning.
2. The intensity of the sunlight
starts
off low in the morning and depending on the weather during the
day, the
intensity can reach any level between virtually 0% and 100%.
3. The exit criteria for bulk is
that
the battery voltage reaches the Vbulk/abs volts setting or a
bulk/abs timer
times out.
4. If the sunlight conditions are
just
right to keep the charging voltage just below the Vbulk/abs
setpoint, the
exit from bulk/abs will be the timer.
5. Bulk/Abs timers are usually
set for
rather a long time, many hours is not uncommon.
6. Given the above, it is
possible that
the battery stays at gassing voltages for many hours every day
at certain
times of the year when the sunlight intensity is just right to
support
that.
7. As a consequence the boiling
problem
will show up only at particular sites, particular battery/charge
controller
sizes and particular times of year.
Again, I am not suggesting that
this
is necessarily the cause of battery "boiling" in systems with
solar charge controllers, but it could be a reason.
2nd ps. All manufacturers do
precise
battery voltage/current measurements on the bench with a wide
variety of
conditions, but we will never be able to simulate the 1000's of
conditions
that happen on the 1000's of installs out there. With that in
mind,
on-site battery voltage/current data logging is a very powerful
tool when
investigating these kinds of issues.
JARMO
_____________________________________________________________________________________
Jarmo Venalainen |
Schneider Electric
| Solar
Business | CANADA | Training &
Development Specialist - Senior
Phone: +604-422-2528 | Fax: +604-420-1591 |
Mobile: +604-505-0291
Email: jarmo.venalai...@schneider-electric.com
| Site:
www.SEsolar.com
|
Address: 3700 Gilmore Way, Burnaby, BC V5G4M1
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Hello Wrenches,
An MX 60 boiled a 24 volt bank of 4 Trojan L-16 batteries last
summer.
The batteries all checked out to be in good shape. It is not
totally clear
that the CC was not set to auto equalize, but the EQ voltage was
only set
at 31.0 V.
The battery bank has been replaced by 8 Full River L-16 AGM
batteries.
The parameters have all been reset for AGM with EQ disabled. The
homeowners
are concerned that the charge control may not work, and damage
their new
battery bank.
If there is a problem with the CC, it is very intermittent. Has
anyone
ever seen an intermittent MX 60?
Outback tech support says if we send it in they will update the
firmware
for $90, and do a 24 hour bench test. It appears that the
firmware update
will not do anything useful for this off grid system. There are
no new
boards available for this unit. I'm not sure if the bench test
will show
up an intermittent problem.
Has anyone had this situation before? Would it be better to:
- Replace the CC
- Send the CC to Outback
- Do nothing
Thank you,
Drake
Drake Chamberlin
Athens Electric LLC
OH License 44810
CO License 3773
NABCEP Certified Solar PV
740-448-7328
http://athens-electric.com/
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