This is really an interesting thread.
A few years back, I saw almost exactly the same thing happen with a
PV-direct water pumping system, no batteries. PV Voc read fine, pump ran
fine off a car battery and jumper cables, but pump controller/LCB acted
haywire....status lights said it was fine, but no current to the pump.
The problem ended up being an improperly sealed buried PV wire
connection that had turned to green slime from galvanic action.
Why do I bring this up here? Because the symptoms were the same. Voltage
measured just fine and dandy all throughout the system. Big pump load
ran just fine when hooked up to a reliable power source (my truck
battery). But every time the bad PV cnx hit about 250ma in current, the
corroded connection opened. Once current demand dropped, the cnx closed
again and voltage read just fine and dandy throughout the system again.
I don't envy you in trying to find the bad microfractured battery, or in
getting the mfr to replace it.
Dan Fink
Executive Director;
Buckville Energy Consulting
Buckville Publications LLC
NABCEP / IREC / ISPQ accredited Continuing Education Providers
http://www.buckville.com/
[email protected]
970.672.4342 (voicemail)
970.373.1311 (fax)
Brian Teitelbaum wrote:
Funny story: we once had a brand new L-16 that came back to us from a
customer who said that it was bad. We checked the voltage and it was
6.2VDC. We tried to run a small 6V motor with it to no avail. Checked
the voltage again at 6.2VDC. Then we did the unthinkable: we shorted
across the terminals with a short piece of #10 wire. Only a very faint
spark was noticed, and the voltage dropped to zero. Took the wire off
and read the voltage at 6.2VDC.
Upon calling the manufacturer we got the expected response of “that’s
not possible”. It took forever to get the manufacturer to replace it.
We never cut it open to take a look, but I suspect that it was a
micro-fracture in one of the internal buss bars, with enough continuity
to provide voltage but not enough for current flow. We didn’t measure
the SG either, but I doubt that it was anything other than normal.
Brian Teitelbaum
AEE Solar
*From:* [email protected]
[mailto:[email protected]] *On Behalf Of *Bob-O
Schultze
*Sent:* Wednesday, April 20, 2011 12:16 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] 2 volt Trojan RE series L16 Batteries
Rich,
It sounds like you've got a rotter or two. Given the short age of the
pack, that's my suspicion. Try checking the individual battery voltages
when under load and fairly well discharged. I've seen a new battery bank
all show good SG and individual voltages while resting but one or more
batteries tank badly under load. Poor manufacturing QC is the cause.
good luck, Bob-O
On Apr 20, 2011, at 12:03 PM, Rich Nicol wrote:
RE Wrenches
My question regards a system (installed by homeowner / friend) where
they recently upgraded their t105 battery bank to Trojan RE series L16 2
volt cells. The battery bank consists of 6 batteries in series for a 12
volt system. The interconnects are 12” long 4/0 cables with crimped and
soldered lugs. Main cables are 6’ long 4/0 cables.
The first issue is high terminal temperature during periods of heavy
draw (~100 amps @ 12v when water pump is on). Due to the issue the
owner has been only running the water pump when charging the batteries
with his generator since the transfer switch on the Outback inverter has
transferred his household circuits from the battery bank to the
generator. Obviously this is an inconvenience. Before the end of life
on his T105’s he had no issues with the 6 volt cells in series/parallel
using only #2 AWG interconnects.
Most recently he’s experienced an issue where the inverter will not come
on at all and when attempted to come by switching on his main DC breaker
the voltage at the batteries sags from 12.5 to ~5V! This issue is not
with the inverter since I loaned him a back up Trace DR I keep around as
a loaner but it too would not come on and voltage sagged as well. This
sag is with no demand since it sags immediately when the DC breaker is
switched on when connected to the inverter even though the inverter has
not been switched on.
I stopped by this AM to check out the situation, specific gravity of all
cells is good, open circuit voltage on each cell is matched at 2.12
volts. The battery bank is only about 4 months old.
Any insight would be greatly appreciated.
Battery specs:
2 volt, Rated Capacity @ 5 Hr rate=909 AH, 20 hr rate = 1110 AH, 100 hr
rate = 1235.
Thanks for your help!
Rich
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