[RE-wrenches] intermittent battery problem

[Darryl Thayer]

I think David id correct as usual.  By your description the solar array sounds too small, the customer is depending upon the wind genny and even in a good site the W100 can not supply the load.   .  
 
I have a customer with similar simtoms   batteries seemed to diacharge very quickly, the solar would seem to recharge during the day but batteries go flat quickly, (batteries 5 years old)  customer was sure the battrery bank (Surretts) was DOA.  When I arrived my optical hydrometer said the batteries were low.  I set the genney (with Outback inverters) to charge at C/20 and let it run all day, 8 hrs, at end of day batteries were still not charged.  So I let genney run all night, next morning (20 hrs run time) batteries were close to full charge (on some of the cells)   I set it to charge at C/30 and let the Genney run all day and all night again.(total run time over 40 hrs) I explained to the customer that during the winter the sun is less than summer and the system had probibly been low for quite some time.  The Customer has been trouble free for three years on the same battery set.   (these batteries have been in service over 8 years).
 BTW I had him set the charge efficiency at 80% from then on.     


________________________________
From: David Katz <dkatz at aeesolar.com>
To: "'re-wrenches at lists.re-wrenches.org'" <re-wrenches at lists.re-wrenches.org>
Sent: Saturday, October 8, 2011 8:55 PM
Subject: Re: [RE-wrenches] intermittent battery problem


How many years have they been off grid. It is pretty common for people to have problems when the days get shorter and the nights get longer in the fall. My guess is he gets about 30 amps of charge using a 2500 watt generator and probably less if loads are on when they charge.  You should tell them they need to run the generator for 40 hours to catch up.  Customers never like to hear that.  A trimetric will help them keep up.
David Katz
 

From: Ron Young [mailto:solareagle at solareagle.com] 
Sent: Saturday, October 08, 2011 06:42 PM
To: RE-wrenches <re-wrenches at lists.re-wrenches.org> 
Subject: Re: [RE-wrenches] intermittent battery problem 
 

Thanks Bob but he has a tubular type hydrometer, not the pointer type. They're usually ok but I'll check it against mine when I go there which looks like a certainty.

They EQ the batteries on a regular basis as per my instructions (they say) but will have to nail them down on that. The small 2500w generator worries me but they have 800w solar and a Whisper 100. The wind blows a lot. Inverter is a 3524 Outback.

Ron


On 2011-10-08, at 5:07 PM, bob ellison wrote:

I bet he has a cheap pointer type hydrometer, I have seen them be way off from reality.
>My guess is that the gravity is low the voltage changes quickly, specific gravity changes slowly in a battery bank.
>To fully charge a 24 volt bank you need to get it to 29 + volts and keep it there for several hours, depending on the battery bank size.
>Charging it to 25.4 is nothing in the long run.
>Give them a LONG full charge, what are the inverters? Does it ever get an EQ charge?
> 
>Bob Ellison
> 
>From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Ron Young
>Sent: Saturday, October 08, 2011 2:02 PM
>To: RE-wrenches
>Subject: [RE-wrenches] intermittent battery problem
> 
>Howdy Wrenches,
> 
>One of my customers that lives 3 hours out in the back country is having an intermittent problem that I haven't encountered before. The batteries drop rapidly in voltage but hydrometer readings are in the green. Turning off the inverter and just using DC doesn't change anything. Meters on the Mate, Outback MX and Whisper controller are all the same so it's not a metering problem. On the way to bed the batteries were at 25.4, overnight with no loads they dropped to 22.9 then a short 15 min. charge with a generator brings the batteries back up and two hours later they are at 25.8. This scenario has occurred several times and then doesn't appear for a day or two.
> 
>It doesn't seem to be sulfation as the batteries are reading good on the hydrometer every time. All cells check out. The inverter doesn't seem to be the problem. They have a Sunfrost on a separate DC circuit. It sounds like an intermittent circuit problem or electronics issue. Customer has checked and tightened all the connections he can get at but hasn't been inside the components. Would appreciate any suggestions or clues before I make the trip.
> 
>Ron Young
> 
>earthRight Products - Solareagle.com
>Alternative Energy Solutions ~ Renewable Energy Products
> 
> 
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