[RE-wrenches] Hot Trojan Batteries

Mon Apr 2 12:43:48 PDT 2012

There are a lot of forums and circles where C/20 refers to the capacity
divided by 20, or 5% of the battery capacity. This may be the more informal
interpretation of the term, but you will find many examples where people
consider C/20 to be 5% of the capacity (wrong or right). For example, look
at the most frequently accessed deep cycle charging FAQ on the Internet:
http://www.windsun.com/Batteries/Battery_FAQ.htm

To be clear perhaps we should just use plain English and say “the
recommended charging rate is 10-15% of the capacity of the battery at the
20 hour discharge rate.”

Jason Szumlanski

Fafco Solar

*From:* re-wrenches-bounces at lists.re-wrenches.org [mailto:
re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of *Allan Sindelar
*Sent:* Monday, April 02, 2012 1:46 PM
*To:* re-wrenches at lists.re-wrenches.org
*Subject:* Re: [RE-wrenches] Hot Trojan Batteries

Wrenches,
I attended John DeBoever's Friday afternoon presentation on battery
technology and care at the NABCEP Continuing Education conference this past
weekend. It quickly became clear to me that John seriously knows his
batteries, at all levels: chemistry, physics, RE use and care, etc. It was
an advanced-level presentation, and I learned a lot.

The first thing John told us was that English is not his native language;
he's a Belgian raised in South Africa (and more that I didn't catch). He
was bursting with knowledge and good information, but occasionally we in
his class would back him up to better explain a point.

In short, I think he will be a real asset to the Wrenches list as a
manufacturer's representative. And occasionally there will be something
confusing, such as what just happened here. I too wondered about C20 versus
C/20. I appreciate that he quickly cleared up the confusion, and look
forward to learning quite a bit from his posts about battery issues.
Allan

*Allan Sindelar*
Allan at positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
*Positive Energy, Inc.*
3201 Calle Marie
Santa Fe, New Mexico 87507
*505 424-1112*
www.positiveenergysolar.com

On 4/2/2012 11:00 AM, John DeBoever wrote:

Jason, Wrenches,

C/20 means C over 20 hours discharge rate = capacity @ the 20 hours
discharge rate. C/20 often is mentioned as C20, so the confusion here.

Max recommended is 10& to 15% of C20 of the battery bank.

John

Trojan Battery Company

*From:* re-wrenches-bounces at lists.re-wrenches.org [
mailto:re-wrenches-bounces at lists.re-wrenches.org<re-wrenches-bounces at lists.re-wrenches.org>]
*On Behalf Of *Jason Szumlanski
*Sent:* Monday, April 02, 2012 12:53 PM
*To:* RE-wrenches
*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-bounces at lists.re-wrenches.org [mailto:
re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of *John DeBoever
*Sent:* Monday, April 02, 2012 12:14 PM
*To:* allsolar at 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

jdeboever at trojanbattery.com

www.trojanbattery.com

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org [
mailto:re-wrenches-bounces at lists.re-wrenches.org<re-wrenches-bounces at lists.re-wrenches.org>]
On Behalf Of allsolar at scswifi.net
Sent: Sunday, April 01, 2012 7:20 PM
To: re-wrenches at 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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