I have seen very hot batteries infact batteries that melted. and caught fire.
the problem was that the string was several strings in parallel, and one of the
strings had thermal runaway. during charge one battery got hot, and it has
lower voltage and gets more current. then it get hotter because of the more
curent. soon it is so hot the other batteries start to discharge through the
hot battery.
A similar event will occur when one battery in a string of batteries develops a
bad cell, and the othe batteries in parallel strings will force current
backwards through the cell. and thermal runaway occcurs in the hot battery.
________________________________
From: Jason Szumlanski <ja...@fafcosolar.com>
To: RE-wrenches <re-wrenches@lists.re-wrenches.org>
Sent: Monday, April 2, 2012 11:53 AM
Subject: Re: [RE-wrenches] Hot Trojan Batteries
There must be some confusion here about the charging rate. C/20 refers to
capacity divided by 20, so in the case of a 325aH battery (capacity @ the 20
hour discharge rate) we’re talking about charging at a 16.25 amp rate. I’m sure
John is not referring to a maximum rate of 10-15% of 16.25 amps, but 10-15% of
the 325aH capacity.
Jason Szumlanski
Fafco Solar
From:re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of John DeBoever
Sent: Monday, April 02, 2012 12:14 PM
To: allso...@scswifi.net; RE-wrenches
Subject: Re: [RE-wrenches] Hot Trojan Batteries
Jeremy, Wrenches,
165°F is definitely too high and you should stop immediately any charge to
avoid further major problems. I recommend you contact our Trojan Tech Support
for help at
http://www.trojanbatteryre.com/Tech_Support/Tech_Support.html?tab=0#TabbedPanels1#top
Below are few perspectives to help the diagnostic:
o System issues:
ü Check Charger setting: the C/20 rate mentioned is definitely too high and
will damage the battery. The maximum recommended current rate is 10-15% of C/20
for a deep-cycle flooded lead acid battery. Other C/rates are possible but are
application specific and not typical.
ü Check Voltage settings: these are provided on Trojan datasheets, see here:
http://www.trojanbatteryre.com/Tech_Support/literature.html
ü Check Temperature compensation: -0.028VPC for every 10°F above 77°F (add
0.028 VPC for every 10°F below 77°F or subtract 0.020VPC for every 10°F above
77°F. See here:
http://www.trojanbatteryre.com/PDF/Signature_Trojan_ProductLineSheet.pdf
ü Check Voltage sensor status and connection. Dedicated wiring is recommended
ü Check temperature sensor. It shall be well positioned, typically in the
middle of the battery bank at the warmest point.
ü Check if air circulation between the battery units.
ü Check if adequate air ventilation of the battery room.
o Battery issues:
ü C/20 charging rate is too high (see above)
ü How old are the batteries? Ageing batteries will face micro-shorts that will
decrease the battery turnaround efficiency over time that translates in higher
temperature generation. Typically the battery temperature range is about 20oF
above ambient temperature, and typical min and max limit are -4°F to 113°F.
See here:
http://www.trojanbatteryre.com/PDF/Signature_Trojan_ProductLineSheet.pdf
165°F is way too high and will damage the units
ü Maybe you are facing one or more shorted units: check the voltage and it
will quickly indicate if a unit is shorted. Shorted units will generate heat
and will jeopardize the charging of other units. Remove shorted units and
consult tech support your charger supplier if possible to reconfigure of your
battery bank with fewer units, configured at a lower battery bank voltage,
using same voltage settings recommended by Trojan Battery Company. Typically 1
to 3 units less would be acceptable, depending the charger manufacturer
settings.
ü Maybe you are facing sulfated batteries, resulting from low charging, thus
resulting in lower overall turnaround efficiency. This will heat some healthier
units of the battery bank, accelerating corrosion damages. The max temperature
acceptable being 113°F, please consult Trojan Tech Support:
http://www.trojanbatteryre.com/Tech_Support/Tech_Support.html?tab=0#TabbedPanels1#top
ü Please deal directly off-Wrenches list, with Trojan Tech Support for better
fine tune resolution:
http://www.trojanbatteryre.com/Tech_Support/Tech_Support.html?tab=0#TabbedPanels1#top
I hope this help,
John
John F. DeBoever
Global Technical Director – Renewable Energy
Trojan Battery Company
12380 Clark Street
Santa Fe Springs, CA 90670
Tel: +1-562-236-3000 Ext. 3139
Cell: +1-845-514-7600 – NY office time zone: USA EST (GMT-5)
Skype: john.f.deboever
Fax: +1-562-236-3239
jdeboe...@trojanbattery.com
www.trojanbattery.com
-----Original Message-----
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of
allso...@scswifi.net
Sent: Sunday, April 01, 2012 7:20 PM
To: re-wrenches@lists.re-wrenches.org
Subject: [RE-wrenches] Hot Trojan Batteries
Wrenches,
Can anyone explain why an L16 bank would be at 165F at rest. Over a C20 charge
rate, but I have a feeling there might be an internal short
Jeremy
All Solar
Sent via BlackBerry. Sorry for typos and shorthand!
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