current cost of t-105's?

levsmith
levsmith Solar Expert Posts: 56 ✭✭
in Off Grid Solar & Battery Systems #1
Hey everyone,
I'm just getting ready to start on my first system, for now just to run a fridge and sump pump during power outages. I'm looking at batteries and figure I'll get two 6 volt golf cart batteries for now. I'm curious what you guys are paying locally for t-105's. There is only one dealer within 50 miles of me and they are closed on the weekends and open weekdays the same time I work so not very convenient. One other place I've found for golf cart batteries (not sure what brand) is 40 miles away and wants $90 plus $25 core. local Oreillys wants $125 for their brand. Are these good prices? Neither are trojans. Thanks
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,654 admin
    #2
    Re: current cost of t-105's?

    Walmarts/Sam's Clubs/and some Costcos will carry golf cart batteries... $90 is probably not a bad price (from what little I have seen here).

    You can also see if there are any battery distributors near your place. And sometimes you can get them drop shipped to your place without additional charges (probably more that two batteries though).

    And back to the beginning, have you measured your loads and figured out how long you want them to run? A kill-a-Watt meter is very handy for this (and conservation measures around the home).

    For "emergency usage" with deep cycle golf cart batteries, you are probably looking at:

    2 batteries * 6 volts * 220 AH * 80% discharge * 0.85 inverter eff = 1,795 Watt*Hours at 20 hour rate
    1,795 WH * 1/16 hour discharge cycle = 112 Watts average load

    So, two "golf cart" batteries will probably run a single energy star refrigerators for about 1 day (~24 hours) ... Is that what you are looking for?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Photowhit
    Photowhit Solar Expert Posts: 6,011 ✭✭✭✭✭
    #3
    Re: current cost of t-105's?

    Staab Battery usually has pretty good prices on T105 and Trojan batteries in general and they are at $150 each, for T105 now(I don't think they require a core). I purchased 4 Energizer(?) golf cart batteries from Sam's Club in December at @$75 each, Sam's club is very liberal on exchanges I actually used 2 marine batteries, 1 auto battery and took along a tiny 12v lawn tractor battery which they were happy to take as 'cores'. Your mileage may very but it's been my experience in 2 states and 3 Sam's clubs now. I think their exchange is $15 as well now.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • levsmith
    levsmith Solar Expert Posts: 56 ✭✭
    #4
    Re: current cost of t-105's?

    Thanks BB. I have checked the load with the riobi equivalent of the kill-a-watt. The fridge uses about 2kw/day. I will be happy with 12 hr run time on the batteries for now. Average power outage is around 4-6 hours around here.

    Also to clarify on the batteries, the $90 is from a distributor but I would have to add $25 since I dont have another core. I just found out the $125 ones from oreillys has an $18 core charge. So either 115 from the distributor thats 40 miles away or 143 from the local oreillys
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  • Volvo Farmer
    Volvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    #5
    Re: current cost of t-105's?

    We all love to crunch numbers around here.

    2 golf cart batteries are 1200 watt/hrs? If you're running that fridge AND a sump pump for 12 hours, you're gonna run those batteries completely flat, and that is not generally recommended for good battery life.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #6
    Re: current cost of t-105's?

    There is No Way that a T-105 @ $140 + would ever compare to a Sams Club Batteries @ $80 + in Cost vs Return. When T-105's were priced $50 they were a better than some of the others and everyone bought them. In one year they doubled the price from $75 street price to what they are now and they are still a 5 year service battery. Not a good investment in my opinion, If a customer insists I'll still put them in, but it's a waste for the ROI you get.
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  • levsmith
    levsmith Solar Expert Posts: 56 ✭✭
    #7
    Re: current cost of t-105's?
    Volvo Farmer wrote: »
    We all love to crunch numbers around here.

    2 golf cart batteries are 1200 watt/hrs? If you're running that fridge AND a sump pump for 12 hours, you're gonna run those batteries completely flat, and that is not generally recommended for good battery life.

    Not sure what you mean by completely flat but if I'm doing the math right, 2 6v 220ah batteries would make 12v 220ah. I realize drawing down to 50% is not recommended but is ok every now and then. If I drew them down to 50%, that would give me 110ah usable power, or ~1300 watts.

    The fridge uses average 2kw/day or about 1000 watts in 12 hours. During the latest flooding, the sump pump used .5kw or 250 watts in 12 hours. So thats a total of 1250 for both. I know there are losses but 12 hours would hopefully be a worse case senario. Am I wrong to assume they could be run off of 2 batteries until the money comes to get a couple more?
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  • levsmith
    levsmith Solar Expert Posts: 56 ✭✭
    #8
    Re: current cost of t-105's?
    Blackcherry04 wrote: »
    There is No Way that a T-105 @ $140 + would ever compare to a Sams Club Batteries @ $80 + in Cost vs Return. When T-105's were priced $50 they were a better than some of the others and everyone bought them. In one year they doubled the price from $75 street price to what they are now and they are still a 5 year service battery. Not a good investment in my opinion, If a customer insists I'll still put them in, but it's a waste for the ROI you get.

    Thanks for your thoughts blackcherry. We dont have a sams local so i dont have a membership but found out my parents do so i think they will be getting me some next time they go.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
    Re: current cost of t-105's?
    levsmith wrote: »
    Not sure what you mean by completely flat but if I'm doing the math right, 2 6v 220ah batteries would make 12v 220ah. I realize drawing down to 50% is not recommended but is ok every now and then. If I drew them down to 50%, that would give me 110ah usable power, or ~1300 watts.

    The fridge uses average 2kw/day or about 1000 watts in 12 hours. During the latest flooding, the sump pump used .5kw or 250 watts in 12 hours. So thats a total of 1250 for both. I know there are losses but 12 hours would hopefully be a worse case senario. Am I wrong to assume they could be run off of 2 batteries until the money comes to get a couple more?

    The Math:

    110 Amp hours @ 12 Volts = approximately 1320 Watt hours DC.
    Inverter consumption is how much? Expect 20+ Watts to power that alone, over 12 hours = 240 Watt hours. You are now down to 1080 Watt hours DC available.
    Inverter conversion efficiency typically 90% = 972 Watt hours AC.

    You're in trouble.

    How much the 'frige uses depends on the time of day in use too; usually it will consume less at night when no one is opening the door and the interior of the house is cooler. This is a good thing! :D
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,654 admin
    #10
    Re: current cost of t-105's?

    In my calculations, I used 80% discharge (to 20% state of charge)... While this is not great to do--If this is for emergency operation, then it is not the end of the world.

    If this is for daily or multiple times a week/month cycling--Then cycling below 50% is not something I would recommend. Batteries will probably not last long if cycled to 20% state of charge (couple hundred cycles???).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Volvo Farmer
    Volvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    #11
    Re: current cost of t-105's?

    My calculations were incorrect. I think BBs are pretty appropriate for this situation.
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