[RE-wrenches] intermittent battery problem; ...Battery Sulfation
Ron Young
solareagle at solareagle.com
Wed Nov 16 17:58:11 PST 2011
You're correct Larry, my apologies. Been burning the candle at both ends. Thanks for your input.
On 2011-11-16, at 9:04 AM, Larry Crutcher, Starlight Solar Power Systems wrote:
> Ron, you have misquoted me so yes you are wrong. It is not about getting to 32 volts. Go read it again.
>
> On Nov 16, 2011, at 12:20 AM, Ron Young wrote:
>
>> Hi Daryl. I've got other KS25's in hybrid systems (wind gen & solar) that seem to do fine over the last several years. The Ouback 3524 has an 85 amp charger. There was no problem getting to 32 v and holding it for eight hours. This has been done twice now. Larry and others attribute the ability to get to 32v to a sulphated battery condition and I'm thinking that a healthy battery could get to 32v as well, especially one that's been regularly EQ'd... am I wrong?
>>
>> I'm listening to every opinion here and trying to sort it out but I think John may be on the right track with an intermittent failure of one cell. I just can't seem to find it.
>>
>> Ron Young
>>
>> On 2011-11-13, at 3:51 AM, penobscotsolar at midmaine.com wrote:
>>
>>> Ron,
>>> What comes to mind for me is that Surrette 5000 series batteries like
>>> to have a regular charge of C10. KS25 cells are rated for 1350 ah,
>>> creating a need for a somewhat regularly occurring charge of 135 amps.
>>> I do believe the batteries are not ever getting that, except for very
>>> rare occasions. We have seen this before in undersized systems.
>>> Is the bulk charge set to 29.6? I would try a couple more eq's over the
>>> next month to loosen likely sulfation. Get it up to as close to 32
>>> volts as possible and taper the charge down, then eq at that voltage
>>> for four or five hours, even more if the client will do it.
>>> That would be how we would deal with this. It does seem ultimately to
>>> be sulfation that is the problem.
>>>
>>> Daryl DeJoy
>>> NABCEP Certified PV installer
>>> Penobscot Solar Design
>>>
>>>
>>>
>>>
>>>> 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
>>>>>>
>>>>>
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