[RE-wrenches] intermittent battery problem

Tue Oct 11 17:05:52 PDT 2011

I once saw a brand new L16 battery that would read the proper voltage (6.3 VDC) and had good hydrometer readings, but the voltage would drop to zero when a load was applied. We were even able to do a dead short with a piece of #10 wire with only a faint spark visible upon connection, and then nothing.

The manufacturer replaced it (after much haggling and the usual “that’s not possible”) so I never found out for sure what caused it, but I suspected a fracture in one of the internal bus bars. Could be what you are seeing here since the voltage change is about 2V.

I second Mark’s suggestion to load test each battery

Brian Teitelbaum
AEE Solar

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of mark at hurshtown.com
Sent: Tuesday, October 11, 2011 4:55 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] intermittent battery problem

I would load test each battery individually using a common "toaster heating element" tester.
I'm betting on a bum battery in the string.
-------- Original Message --------
Subject: Re: [RE-wrenches] intermittent battery problem
From: Ron Young <solareagle at solareagle.com<mailto:solareagle at solareagle.com>>
Date: Tue, October 11, 2011 3:00 pm
To: RE-wrenches <re-wrenches at lists.re-wrenches.org<mailto:re-wrenches at lists.re-wrenches.org>>

Wrenches,
I received some additional info from the customer this morning. They have asked me to hold off my visit until they get a few more clues but some of what they are telling me doesn't necessarily jive with a sulphated battery. Would appreciate comments - here's a quote from their email:

Hi Ron
Still having problems with system.  If the batteries are sulphated would the system return to full charge when you remove the load???  Checked our hydrometer against another and it is working fine. Batteries are all either in the green or on the line between green and blue this morning.  Display showed the batteries at 25.2 when we got up this morning. About 10:30 this morning---I had just tested all batteries with the hydrometer---the readings dropped to 23.8.  Retested batteries---they were in the green.   I turned off all loads----the readings returned to 25.2.  I turned on the Sunfrost---readings immediately dropped to 23.8.  I turned off the Sunfrost--- readings returned to 25.2.  I turned on all lights in the house and the readings remained at 25.2.  I turned the Sunfrost back on and the readings again stayed at 25.2.  The one other thing that happened in the meantime is that the sun came out and we started buying power from the solar system---.1-.3kw.  This all seems to be part of a pattern where as soon as we start buying power---whether from sun, wind or gen. the system returns to normal---But we are still suspicious of the Sunfrost because of our problems a few months back.

Ron Young
earthRight Products - Solareagle.com<http://Solareagle.com>
Alternative Energy Solutions ~ Renewable Energy Products

On 2011-10-09, at 11:56 AM, Ron Young wrote:

As always, impressed and gratified by the number of thoughtful replies from Wrenches, thank you again! It looks like a hefty EQ is in order. I've successfully recovered badly sulphated batteries by putting them through multiple charge/EQ/discharge cycles on more than occasion. Will check out that Sunfrost as well. My mistake was believing that the hydrometer could tell the truth, the whole truth and nothing but the truth but apparently it takes an amp hour meter to keep it honest.

Ron Young
earthRight Products - Solareagle.com<http://Solareagle.com/>
Alternative Energy Solutions ~ Renewable Energy Products

On 2011-10-09, at 11:12 AM, Jonathan Hill wrote:

Ron-
We've seen this issue before,and it is almost always due to badly sulfated batteries. I'd try a LONG (8-12 hrs) EQ charge at 32 volts. We've done this with Hawkers and fixed the problem. I believe the Surrettes could handle this kind of charge, though you might contact Jamie Surrette.

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Sierra Solar Systems
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On Oct 8, 2011, at 6:42 PM, Ron Young wrote:

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> [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<http://Solareagle.com/>
Alternative Energy Solutions ~ Renewable Energy Products

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