Question re old batteries

[br2an]

I recently received (free) four Exide type 3CA-7 batteries (6V 150A/Hr). They were removed from a local power utility switching station. While they have been well maintained they are at the end of their life cycle as far as the power company is concerned.

My question, is there some way to check their 'health'?

A quick voltage check of each cell showed 2.07V each. That seemed low but they were all consistent. Looking at the tops of the terminals, it appears each cell was load tested regularly. Wish I had their tester! There is a very small amount of sediment at the bottom of the cells but no apparent discolouration of the plates.

They are currently connected and working fine (tried them for one evening at the cabin) but I was wondering if there was any way to gage the remaining life left in them.

[Sunking]

They are currently connected and working fine (tried them for one evening at the cabin) but I was wondering if there was any way to gage the remaining life left in them.

Well there is but not really a DIY thing. It is called a Load Capacity Test where you fully charge then up, then put on a calibrated load and measure the time it takes to discharge them.

Those batteries are made for emergency standby systems to be float charged. Not really good candidates for cycle service.

[br2an]

Well there is but not really a DIY thing. It is called a Load Capacity Test where you fully charge then up, then put on a calibrated load and measure the time it takes to discharge them.

Those batteries are made for emergency standby systems to be float charged. Not really good candidates for cycle service.

Thanks, Sunking. Can you briefly explain what unfavourable characteristics they have? Are they similar in construction to a car battery?

I just assumed because of their physical size and amp/hour ratings they would be ok for my purpose. Btw, they will likely only be discharged 50 times per year, the cabin isn't used more than once a week.

If this has been explained before, a link to the thread would be much appreciated. (search didn't find anything for me)

[Sunking]

Thanks, Sunking. Can you briefly explain what unfavourable characteristics they have? Are they similar in construction to a car battery?

Correct they are made for Emergency Standby applications not cycle service. If you press them into cycle service you will only get a 200 to 300 cycle out of them depending on how deep you discharge them. Like a car battery there plates are thinner and more of them to enable them to deliver very high charge and discharge rates.

That does not mean you cannot use them, all it means is do not expect them to last long. When used in Emergency Standby Float service they last up to 10 to 20 years. However in that time may only be used a few times. Utilities like the POCO and Telco have plocies to change out station batteries depending on type (FLA or VRLA) every 5 to 10 years.

[OregonSolar]

Correct they are made for Emergency Standby applications not cycle service. If you press them into cycle service you will only get a 200 to 300 cycle out of them depending on how deep you discharge them. Like a car battery there plates are thinner and more of them to enable them to deliver very high charge and discharge rates.

That does not mean you cannot use them, all it means is do not expect them to last long. When used in Emergency Standby Float service they last up to 10 to 20 years. However in that time may only be used a few times. Utilities like the POCO and Telco have plocies to change out station batteries depending on type (FLA or VRLA) every 5 to 10 years.

Heck, i'd install them and run em into the ground for free!

A 300 cycle life at about 50 cycles a year = over 5 years! For that kind of small system, sounds good to me for free.

[br2an]

Correct they are made for Emergency Standby applications not cycle service. If you press them into cycle service you will only get a 200 to 300 cycle out of them depending on how deep you discharge them. Like a car battery there plates are thinner and more of them to enable them to deliver very high charge and discharge rates.

That does not mean you cannot use them, all it means is do not expect them to last long. When used in Emergency Standby Float service they last up to 10 to 20 years. However in that time may only be used a few times. Utilities like the POCO and Telco have plocies to change out station batteries depending on type (FLA or VRLA) every 5 to 10 years.

I was concerned about their age, never realized they were a high charge/discharge type of battery. I will continue to use them and see how they perform, hard to argue when they are free. I can always sell them to the recycling station when they fail so I figure I can't lose. Thanks again, Sunking, for sharing that information.

[br2an]

Sorry if I seem to be beating this to death but another question. I searched the net and found what I believe are the battery specs here: http://www.makopower.com/site/assets...78/5210_ca.pdf

I'm not positive it is the same battery construction as mine are probably around 10 - 20 years old. However, the model number appears to be the same (Exide 3CA-7). Anyway, it shows a + plate thickness of 0.280" and - of 0.210". That seems a lot thicker than an automotive type battery. Also, I remember reading that lead-antimony plate construction (which this has) was preferred for deep cycle.

Is it possible these are true deep cycle? Or am I missing something, it wouldn't be the first time.

[SunEagle]

Sorry if I seem to be beating this to death but another question. I searched the net and found what I believe are the battery specs here: http://www.makopower.com/site/assets...78/5210_ca.pdf

I'm not positive it is the same battery construction as mine are probably around 10 - 20 years old. However, the model number appears to be the same (Exide 3CA-7). Anyway, it shows a + plate thickness of 0.280" and - of 0.210". That seems a lot thicker than an automotive type battery. Also, I remember reading that lead-antimony plate construction (which this has) was preferred for deep cycle.

Is it possible these are true deep cycle? Or am I missing something, it wouldn't be the first time.

That battery looks more like one used in an emergency lighting fixture or a control power system backup. They are not usually rated for a lot of cycles but more towards being used to generate a lot of energy for a short duration like a power outage in an office building. I don't think it is a good candidate for a solar RE system.

[Sunking]

Sorry if I seem to be beating this to death but another question. I searched the net and found what I believe are the battery specs here: http://www.makopower.com/site/assets...78/5210_ca.pdf Is it possible these are true deep cycle? Or am I missing something, it wouldn't be the first time.

If that is your battery is a good candidate for cycling. You have nothing to loose.

[SunEagle]

If that is your battery is a good candidate for cycling. You have nothing to loose.

You are the battery expert so I bow to your statement but what did I miss about this battery?

It looked like one used for fast discharge during a power outage but I didn't see anything about high cycle capabilities.

[Sunking]

It looked like one used for fast discharge during a power outage but I didn't see anything about high cycle capabilities.

Look at the spec sheet under description.

I would not recommend it for cycling as it is made for float service as indicated in the specs, but with those thick plates makes it suitable. The high current capability is a bit misleading as it wil have significan voltage sag. However those heavy battery post means it can deliver very high current without damage if voltage sag is not an issue.

It states clearly the batteries are for Emergency switching, telecom, and utility float service.

[SunEagle]

Look at the spec sheet under description.

I would not recommend it for cycling as it is made for float service as indicated in the specs, but with those thick plates makes it suitable. The high current capability is a bit misleading as it wil have significan voltage sag. However those heavy battery post means it can deliver very high current without damage if voltage sag is not an issue.

It states clearly the batteries are for Emergency switching, telecom, and utility float service.

Ok, I understand now. It is not "designed" for high cycles but has thick plates which will stand up better to cycling. Thanks for the clarification.

[br2an]

Thanks, guys. I appreciate your time and effort. I have them in use now and with luck they will last a few years or so. Still good bang for the buck.

[Naptown]

If they last 6 months you got your money's worth out of them.

[br2an]

I feel like a fool for asking but here goes: How do I calculate how much amp-hour capacity my battery bank has?

I have four 150 amp-hour 6V batteries connect 2s, 2p for a 12V output. (yes, I know 24v is preferred, just need to order my 24V inverter)

I thought I had 4 x 150 = 600 amp-hours but I've convinced myself it is only half of that. When I do the c/12 c/8 calculations they make no sense.