[RE-wrenches] intermittent battery problem; ...Battery Sulfation
Larry Crutcher, Starlight Solar Power Systems
larry at starlightsolar.com
Wed Nov 16 09:04:45 PST 2011
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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