Commuting Bicycle commuting is easier than you think, before you know it, you'll be hooked. Learn the tips, hints, equipment, safety requirements for safely riding your bike to work.

SLA Battery freezes

Reply

Old 12-19-04, 03:37 PM
  #1  
cmarkey
Je suis un ananas!
Thread Starter
 
Join Date: Sep 2004
Location: Washington DC
Posts: 30

Bikes: Surly LHT, K2 Mach 1

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
SLA Battery freezes

Just wanted to post this for anybody using an SLA battery for their bike light. I built my own, and have a hefty 5 AH SLA battery permanently attached to my rear rack, which I park outside at work. It was on the bike rack for probably 8-10 hours one day last week, at about 34F, when I came out that night it had stopped working. Took almost a day to thaw out, but is now running fine, and for the time being I bring my bike inside, though I'm thinking of getting a NiMH pack that I can just detach and bring in during the day.

I'm posting this mostly for the information of night-time bikers, but I was also wondering if anybody knows what kind of damage this does to my battery, I've heard it's bad for them, but my battery seems to works fine for now. Will it just have a shorter life?
cmarkey is offline  
Reply With Quote
Old 12-19-04, 03:46 PM
  #2  
andygates
Just riding
 
andygates's Avatar
 
Join Date: Oct 2004
Location: Exeter, UK
Posts: 651

Bikes: Cannondale Bad Boy / Mercian track / BOB trailer / Moulton recumbent project

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Most things that damage SLAs effectvely just shorten its life, quite radically in some cases (we have batteries that used to run 2h now lasting just 30min!) - so I guess your workaround is to bring the battery indoors for the day.
andygates is offline  
Reply With Quote
Old 12-19-04, 05:28 PM
  #3  
GeezerGeek
Senior Member
 
GeezerGeek's Avatar
 
Join Date: Sep 2004
Location: Minnesota
Posts: 224

Bikes: 1993 Infinity LWB, Bacchetta

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I don't think that your lead acid battery was frozen. If they are charged they don't freeze until the temperature is way colder than that. I used to park my car outside and it would go to -40 and the battery did not freeze. I have heard that if a battery goes dead it can freeze but it would still have to be far colder than 34 degrees F. Water won't even freeze at that temperature.

The electricity in a SLA battery is produced from a chemical reaction. When it gets cold, the reaction slows down. I think your battery was almost dead and then when you warmed it up it was able to produce enough electricity to work for you. The chemical reaction is an exothermal process so your battery warms up in cold weather after a bit and can improve performance.

There are two types of SLA batteries, deep discharge and other. If you have then normal battery, you will shorten its life by deeply discharging it and then recharging it. For a remote power source you should be using a deep discharge battery.
GeezerGeek is offline  
Reply With Quote
Old 12-19-04, 06:49 PM
  #4  
Map tester
I am not a car
 
Map tester's Avatar
 
Join Date: May 2004
Location: Decatur, GA
Posts: 747

Bikes: Giant Revel 1, Surly Ogre

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
From http://www.unionbattery.com/batterycare.htm:
"The temperature limits for SLA batteries in operation are as follows:
Charging: 5F to 122F (-15C to 50C).
Discharging: -4F to 140F (-20 to 60C).
The ideal operating temperature for SLA batteries is approximately 68F to 77F (20C to 25C). Operation at temperatures below -4F could result in physical damage."

Here in Atlanta it rarely drops to into the single digits (9 to 0F), so I haven't worried about the battery freezing. Does anyone know if a trickle charger keeps a SLA battery warm? (I'll try to do some testing this week!).
__________________
"Bad facts make bad laws." FZ
Map tester is offline  
Reply With Quote
Old 12-19-04, 10:51 PM
  #5  
cmarkey
Je suis un ananas!
Thread Starter
 
Join Date: Sep 2004
Location: Washington DC
Posts: 30

Bikes: Surly LHT, K2 Mach 1

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Well, frozen or not, the battery would not work, and would not take a charge or react in any way until about 12 hours after I brought it inside. Not sure why this is, I just bought it maybe a month or 2 ago. It seems to be working fine now when I keep it indoors, so I sort of figure it has to do with temperature, and I've read many website that metnion SLA batteries freezing below 32F.
cmarkey is offline  
Reply With Quote
Old 12-20-04, 07:16 AM
  #6  
bnet1
'Bent Brian
 
Join Date: Jun 2004
Location: Wellington Ohio
Posts: 560

Bikes: Trek 1000, Rans Tailwind

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Was the temperature 32 deg below zero or just 34 degrees? A SLA if fully charged will not freeze at -40 degrees F. However it may not work evwen thought it is fully charged because the chemical reaction, well, can't react with sufficient vigor to produce much power. A discharged battery or even a partially charged one can freeze at -34F. In fact it can freeze at 0F. Freezing damages a battery and you should never attempt to charge a frozen battery. Fully thaw it out first. If the battery is partially discharged when you get to work bring it into a warm place and keep it there until you head home. Putting a small charge on it will while you are at work will not hurt it either.

'bent Brian
bnet1 is offline  
Reply With Quote
Old 12-20-04, 08:45 AM
  #7  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 20,952

Bikes: Some silver ones, a red one, an orange one and a few titanium ones

Mentioned: 82 Post(s)
Tagged: 1 Thread(s)
Quoted: 2202 Post(s)
Originally Posted by cmarkey
Well, frozen or not, the battery would not work, and would not take a charge or react in any way until about 12 hours after I brought it inside. Not sure why this is, I just bought it maybe a month or 2 ago. It seems to be working fine now when I keep it indoors, so I sort of figure it has to do with temperature, and I've read many website that metnion SLA batteries freezing below 32F.
The other posters are right in that your battery can't "freeze" at 34 F. Lead acid batteries are used in automotive applications at that temperature, and much below, all the time without problem. The operating temperature range of SLA are -4F to 140F. The optimum operating temperature of SLA are 70F.

That said I would suspect that you may have a weak cell in your battery. The chemistry (and that's what we talk about when we talk about batteries) of all batteries is affected by cold. The transfer of electrons during the chemical reaction that is carried out in all batteries is slowed by cold. Some battery chemistries are affected more than others however. The lead/acid battery is slowed more than most and a heavy current draw, like lights, puts a lot of strain on the cells of the battery. When the battery was warmed back up to room temperature, the weak cell doesn't have to work as hard and the battery performs as it should.

Be warned, however, that this is a symptom of a battery that may be in trouble. It might fail on you when you least expect it. Watch your lights carefully. If they are dimmer than usually or if they brown out on you, get a new battery! This is especially important with SLA because drawing them down to far will kill the battery very quickly particularly if one cell is weak to begin with.

Stuart Black
"I don't build batteries, I just use them."
cyccommute is online now  
Reply With Quote
Old 12-20-04, 11:43 AM
  #8  
cmarkey
Je suis un ananas!
Thread Starter
 
Join Date: Sep 2004
Location: Washington DC
Posts: 30

Bikes: Surly LHT, K2 Mach 1

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Sounds like I got freezing and failing to discharge confused. Is it the case then that an SLA battery is likely to not be able to discharge when it's around 34F (not -34)? Either way I am definitely keepin an eye on the battery and in fact I'm going to order a NiMH pack so I can make it portable and still leave my bike outside in the cold. Thanks for all the tips.
cmarkey is offline  
Reply With Quote
Old 12-20-04, 11:52 AM
  #9  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 20,952

Bikes: Some silver ones, a red one, an orange one and a few titanium ones

Mentioned: 82 Post(s)
Tagged: 1 Thread(s)
Quoted: 2202 Post(s)
Originally Posted by cmarkey
Sounds like I got freezing and failing to discharge confused. Is it the case then that an SLA battery is likely to not be able to discharge when it's around 34F (not -34)?.
Yes. I'd say that is true.

Originally Posted by cmarkey
Either way I am definitely keepin an eye on the battery and in fact I'm going to order a NiMH pack so I can make it portable and still leave my bike outside in the cold. Thanks for all the tips.

Watch out for the NiMH packs. Their cold performance is not as good as a NiCd. I've used them in the past and I stick with NiCd because it's more rugged. Look at http://www.buchmann.ca/ for details. (I'm beginning to sound like a broken record.)

For battery packs look at http://www.batteryspace.com/. I just found them today and their prices look great.

Stuart Black
"No. I don't own stock in Cadex."
cyccommute is online now  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service