[RE-wrenches] intermittent battery problem; ...Battery Sulfation
Ray Walters
ray at solarray.com
Wed Nov 16 09:50:46 PST 2011
I completely agree with Larry, Trimetrics are not an option. You're
learning the hard way why (and why most grid tie solar companies stay
away from off grid). Yes, the meter helps the customer better
understand the system, but more importantly it saves you needless trips
to look for what is usually a load side (customer) issue. The meter pays
for itself in one service call. Trouble shooting over the phone while
they look at the Trimetric is a joy for both of you. When you quote the
system, you don't let the customer decide whether or not they ground or
use breakers, or get enough modules and batteries for their loads, the
meter is the same.
I do use a cheaper meter on smaller systems (under 8 golf cart
batteries). I used to use the SCI mark 22, but since it was
discontinued, I've had good luck with the new Midnite battery meter
($59). It is not enough info for a larger system, though, as it doesn't
have a shunt to track loads. As soon as you're looking at expensive
batteries, a Trimetric will also pay for itself in improved maintenance
of those batteries.
Ray
On 11/16/2011 10:02 AM, Larry Crutcher, Starlight Solar Power Systems
wrote:
> We are only on your back until you to do the advisable thing: Sell
> them a battery capacity monitor. It is a hard fact that NO off grid,
> battery based power system should be without a battery capacity
> monitor. They are cheap (only $150!) and not an option. Apparently, it
> is also hard learned fact. ;-)
>
> Larry Crutcher
> Starlight Solar Power Systems
>
>
>
>
> On Nov 16, 2011, at 12:20 AM, Ron Young wrote:
>
>> Hi Larry, no amp hour meter installed yet as the customer is penny
>> pinching. We're trying to solve the problem first and I've been out
>> there twice, once to do general diagnostics and check all
>> connections, try to load test the batteries, and so on; the second
>> time I 'dropped in' to try a different load test on the batteries to
>> see if I could replicate the problem _and_ to resolve some other
>> problems with a Whisper controller that had given up the ghost when
>> disconnected & re-connected to the batteries (all precautions taken).
>> It's a seven hour round trip and with time spent on the job makes for
>> an expensive service call. I only charged for one call and I have to
>> go back at least once more. So customer wanted to save some money on
>> the installation of the TriMetric until the spring... sorry for the
>> long winded reply. I know, it's false economy. So I'm thinking I'll
>> just put the meter in and tell them to pay me when they feel like it.
>> It'll help solve the problem and get some of the Wrenches off my back
>> ... ;-)
>>
>> Ron Young
>>
>> On 2011-11-13, at 8:26 AM, <larry at starlightsolar.com
>> <mailto:larry at starlightsolar.com>> <larry at starlightsolar.com
>> <mailto:larry at starlightsolar.com>> wrote:
>>
>>> Ron,
>>> I stick by my evaluation as seen here:
>>> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/msg10694.html
>>>
>>> The #1 reason for my opinion is that you can NOT drive up voltage on
>>> a healthy bank _that size_ in just 5 minutes. It is impossible with
>>> a 2500 watt generator.
>>>
>>> Here is the pertinent part from my post:
>>> You mentioned that the the battery drops to 24.5 in the early AM
>>> without any heavy loads on. For the 4KS25 battery this equates to
>>> about 800AH at the 72 hour rate. Then you said that the customer ran
>>> a 2500 watt generator for 5 minutes and drove the voltage up to 29
>>> volts. Here's the Ah-Ha moment: That is EXACTLY the behavior of a
>>> heavily sulfated battery bank. A fast rise in voltage indicates
>>> sulfation. It is impossible for that tiny generator, or any charge
>>> source they own for that matter, to replace the hundreds of AH it
>>> would take to drive a healthy battery up to the absorb voltage of 29
>>> volts. The bank is about 45,000 watt hours (72h rate). There would
>>> have to be over 20,000 Wh removed to be at that voltage. How many
>>> Wh's are replaced in 5 minutes by a 2500 watt genny? I'm sure you
>>> are getting the picture.
>>>
>>> Also, why have you not installed a battery monitor yet? It will give
>>> you "eyes" into the battery and spare countless hours of time
>>> diagnosing the problem.
>>>
>>> Larry
>>>
>>> -------- Original Message --------
>>> Subject: Re: [RE-wrenches] intermittent battery problem; ...Battery
>>> Sulfation
>>> From: Ron Young <solareagle at solareagle.com
>>> <mailto:solareagle at solareagle.com>>
>>> Date: Sat, November 12, 2011 9:57 pm
>>> To: RE-wrenches <re-wrenches at lists.re-wrenches.org
>>> <mailto:re-wrenches at lists.re-wrenches.org>>
>>>
>>> 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 <http://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 <http://Solareagle.com/>
>>>>> Alternative Energy Solutions ~ Renewable Energy Products
>>>>>
>>>>
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