Question concerning Flooded cell batteries

[alumna Turtle]

I just ran across a (imo) a good buy i have just purchased @ 35.00ea a set of 8 sealed lead acid batteries that are new, and rated at 175 ah reserve capacity to use as a base for my solar setup. now gurus please help me design the rest of my system. Open to all Ideas but for instance don't understand how the ah reserve translates to what controller, and how many watts capacity i have.

 

[DLTooley]

What's 'reserve' capacity? The size of your battery bank is a somewhat separate question from your solar panels, the size of your controller depends on how much solar you have.

The place to start is your use. What sort of loads do you plan on - wants and/or needs.

 

[Trebor English]

If the reserve capacity is 175 minutes that means the battery can give 23 amps (used to be 25) for 175 minutes.  That's 4025 amp minutes.  Divide by 60 and you get 67 amp hours discharging to the dead 10.5 volts.  

Reserve capacity is a specific technical term.  Is that what you meant?  

Sealed lead acid could mean maintenance free starter batteries that have calcium added to the plates to reduce water loss due to electrolysis.  

VRLA, valve regulated lead acid, are seald and could be gel or AGM.

 

[alumna Turtle]

I just ran across a (imo) a good buy i have just purchased @ 35.00ea a set of 8 sealed lead acid batteries that are new, and rated at 175 A reserve capacity to use as a base for my solar setup. now gurus please help me design the rest of my system. Open to all Ideas but for instance don't understand how the ah reserve translates to what controller, and how many watts capacity i have. the batteries are rated @ 950 CCA and 175A reserve capacity, group 31. I don,t know how to convert that to watts but understand the 175 to be 50% state of charge.

 

[Trebor English]

Again, reserve capacity is minutes at 23 amps to 100% discharged at 10.5 volts.  You have switched description from 175 ah to 175A.

Can you post the brand and model?

 

[tx2sturgis]

Reserve capacity is normally stated in minutes...get back to us on this.

 

[alumna Turtle]

Again, reserve capacity is minutes at 23 amps to 100% discharged at 10.5 volts.  You have switched description from 175 ah to 175A.

Can you post the brand and model?  FVP 31 TXXHD CCA 950 RC175 is all i can find on the battery i think it is an Exide commercial duty 31 series battery manufactured for fvp.

 

[tx2sturgis]

RC175 is reserve capacity in minutes. There is a formula to convert to approximate ah.

Multiply rc times .4167

Roughly 73 ah.

Figure less than half of that in real use. 35 ah per battery, usable...maybe.

 

[alumna Turtle]

I am going to try to make my scrambled mind behave to make it easier to understand what i am asking.
They batteries are  Exide commercial duty 31 series battery manufactured for fvp. Numbers that i can find are FVP 31 TXXHD    Cold Cranking A 950    Reserv Capacity 175 They are 12v.

i have just purchased @ 35.00ea a set of 8 sealed lead acid batteries that are new.

What information i am looking for hopefully is to figure how much in wattage i would need in solar to keep them charged and if i wanted to hook them up as a 24v system what items and what charge controller i would need for 12v and 24v system. all help and suggestion's are appreciated.

I am sorry that i didn't know what I was asking and wanting know. I want to power my air-stream with power for  2 12 v refrigerators 1 as refer and 1 as freezer and some lights and use the power in my tow vehicle for my laptops and my ham radio. and normal little items that all  would use Phones, Boost, etc.

 

[alumna Turtle]

so is my thinking right 175 X 8 =1400x .4167=583.38AH x12v =7000.56W

 

[Weight]

They are starter batteries and will not last being used as deep cycle as in a house bank. They can be used. The approximate amp hour capacity would be about 85 each. It would take a lot of solar to charge a bank of eight of them from 50% discharge.
Connections. Eight batteries as 12 volts would be + to + to + to + to + to + to + to +, for eight batteries, the same with negative. For 24 volts would be two batteries connected one positive to the other negative. Make four sets like that and then the 4 sets would be connected as I listed for 12 volt system using the other battery terminals. Here is a detailed explanation: http://www.smartgauge.co.uk/batt_con.html
There are many rules for how much solar you need to charge a given bank. But the hard and fast is you need to replace what you use. Those starter batteries want to be kept fully charged at least every day. I have about that many amp hour capacity in six 6 volt GC2 batteries. I have a fridge, microwave, coffee pot, and stuff. 45 amp TriStar solar controller with four 100 watt Renogy solar panels on the roof of a cargo van. My system works for me.

 

[tx2sturgis]

Yes, so call it 500 ah total, round numbers and peukerts, all that jazz.

The rules of thumb call for 100 watts of solar per 100 ah, to balance out modest loads on good solar days. (I use this set up and configuration in my comm trailer)

Figure 200 watts per 100 ah, for heavier loads and some cloudy days at mid lattitudes. (I have this in my pickup topper)

Figure 300 watts or more per 100ah if you live (or boondock) way up north and want good performance even in the winter. Or if you plan on using heavy loads. (A/C, microwaves, toaster ovens, etc)

Again, rules of thumb to get you in the approximate ballpark.

 

[highdesertranger]

yep not deep cycle batteries. they are starting batteries. true deep cycles don't list CCA. highdesertranger

 

[tx2sturgis]

True, since the CCA is listed on the label they are not 'true' deep cycle. 

Starting batteries are spec'd with CCA and RC numbers. 

So we de-rate them in deep cycle service, or in other words, treat them gently, and try not to actually 'deep cycle' them.

 

[alumna Turtle]

I understand that the batteries are not the ideal batteries for solar, but should do hopefully 2 years with the anticipated loads that i will need. I was the newbie at RTR that pestered highdesertranger and jim in denver. one who lost his teeth!

What i had in mind was a morningstar 60 controller and three or four 325 w panels. according to what i am reading it will work.

Alumnaturtle

 

[alumna Turtle]

for the price i couldn't go wrong!!
Alumnaturtle

 

[tx2sturgis]

for the price i couldn't go wrong!!
Alumnaturtle

Yep...roughly 500 usable ah for about $280 is not a bad deal at all.

And if you 'shallow-cycle' them they should last for many years.

 

[highdesertranger]

ah ok how you doing. speaking for myself you didn't bug at all, that's why I am there to answer questions. you are always welcome in my camp. highdesertranger

 

[alumna Turtle]

Thanks highdesertranger
I learned a lot and enjoyed it more!!

Just trying to get everything done here that needs to be done to get a house ready to sell after living here for 45 years.

Alumnaturtle

 

[wmyers4u]

you don't want to heavily discharge those batteries so the answer on the solar....IMO.......is cram as much solar as you can so they charge up as fast as possible (also discharge less due to lots of solar). I'd wire panels for 24 volts and use an MPPT controller to max out amps. All depending you will probably need a 40 or 60 amp controller. You can run more solar watts through the controller at 24 volts than at 12.