Which Battery types?

higgins
higgins Solar Expert Posts: 56 ✭✭✭✭
hi all,i'm new to the forum,i think it's a fantastic forum to learn new concepts.
My question is which type of technology is the best all round battery to use in a small to medium off grid system in terms of performance and life/cycles,drain etc,and what is the best way to efficiently get the most from them,thanks Higgins.

Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Which Battery types?

    The best battery for 'starting out' is the golf-cart type, such as the Trojan T105. They are true deep cycle, and are more forgiving of 'mistakes' like over or under charging than are AGM's or gel-type. You can open the tops and check the Specific Gravity - best way of telling what state a battery is in. They are also relatively cheap on a cost-per-amp-hour basis. You can often get 'generic' versions from Costco or Sam's club for quite low prices.

    Don't waste your time with automotive batteries or 'hybrid' Marine/RV "deep cycle" types; you will be disappointed in performance.
  • higgins
    higgins Solar Expert Posts: 56 ✭✭✭✭
    Re: Which Battery types?

    Thanks Cariboocoot,is this a personal opinion based on facts or experience and do
    most people use these types for their systems?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Which Battery types?

    It is based on how the batteries are designed... Different batteries are made for different service conditions.

    A car battery is made to be "light weight" and provide very high current for short periods of time (starting, lighting, ignition). Designed for a 15% maximum discharge cycle (85% state of charge).

    A Deep Cycle Storage Battery is designed to provide less peak current, but cycle down below 50% (even down to 20%) state of charge without causing the plates to fail/wear out.

    There are also Fork Lift/Traction batteries that are designed for very deep cycles, long life, and fast charging.... But they they tend to have more self discharge (loss of internal power) and can require more solar panels to make up for the losses (upwards of 1% per day loss of power as the batteries get older)... But they can have a 20 year cycle life.

    Deep Cycle Battery FAQ
    www.batteryfaq.org

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Which Battery types?

    I think it would be safe to say most people start with a "golf cart" battery set-up.
    Of course those who don't soon regret having either wasted their money on the wrong kind of battery or having just fried a very expensive set of AGM's! :p

    Like I said, the T105's or their like give you a good performance value. Some people keep on running them for years (right, Icarus? ;) )
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Which Battery types?
    BB. wrote: »
    I forgot to add some information about Thermos Cooking...

    Here is one site that uses a standard wide mouth thermos to cook grains:

    www.thermoscooking.com

    My wife (and many other Asians) really like to cook stews, meats, and such in these ~4.7 QT thermos cookers. There is a stainless "pot" inside that you throw all your food in and fry the meats, boil the liquids--then put the hole thing in a thermos container and let sit for a few hours (sometimes, for cooking stew meats, I will reheat and let sit again).

    I don't know why they appear to be so difficult to find (Target, Amazon don't appear to have any)... If you have a local Asian market nearby--you might find them there too.

    They are not cheap ($100 or so?)... But very nice for what they do.

    -Bill

    :confused:

    I know I'm old and senile but ... Was this what we were talking about?
  • john p
    john p Solar Expert Posts: 814 ✭✭✭
    Re: Which Battery types?

    I :confused:also thought it was just me being old and not understanding where the thread was going
  • Kamala
    Kamala Solar Expert Posts: 452 ✭✭
    Re: Which Battery types?

    Bill.... Bill? BILL!

    This is the Solar Forum. Not the Gourmet Chinese Cooking Forum.

    Or maybe just wrong thread.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Which Battery types?

    Sorry, the thermos pot cooking was intended for the Ready, Fire, aim ooops! thread... Where there was discussions about using an electric crock pot cooker on solar PV.

    I will move the "low power" cooker over there...

    I am sure it was a software bug in the forum software that that put my post in this completely unrelated thread.... :roll: ;):blush:

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • higgins
    higgins Solar Expert Posts: 56 ✭✭✭✭
    Re: Which Battery types?

    thanks for the replies and links fellas,i wasn't sure where my thread was going either:blush:.But getting back on the subject of batteries i was looking for something which could give me the most amps in one small size which i could connect 2 or 3 to increase amps at the best price for the most reliable types and which could stand a bit of abuse,the golf cart type don't have high enough Ah's and would mean i have to connect a lot of these together which i'm trying to avoid!What are most people using as tried and tested in a solar/wind setup?
    Also is it neccessary to let the batteries discharge for the first few times or should i keep it charging a much as possible to avoid any reverse/memory effects etc?
    Higgins
  • Kamala
    Kamala Solar Expert Posts: 452 ✭✭
    Re: Which Battery types?

    How many AH do you think you'll need? The golf cart (~200AH to 250AH) size is very popular with many folks here.

    Lead acid batteries do not have "memory." Keep them charged. Full capacity might not be realized until after the first few charge/discharge cycles
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Which Battery types?

    To add to what Kamala has already said;

    When you get new batteries, fully charge them and check the Specific Gravity to start with. If it's off by more than 0.050 per cell, equalize them. Let them rest, and check again. WRITE THESE NUMBERS DOWN! You need this baseline to compare future readings to, so that you know how they are holding up.

    A few comments on charging levels/procedures. Keep the Absorb and Float Voltages as high as possible - without excess water loss. This is a tricky 'balancing act' and is a good reason to start with inexpensive batteries so you can get a 'feel' for it without risking too much $. Only equalize if the cells are out of balance. Regular equalizing just uses water and shortens battery life. Only equalize for an hour; let rest for 3 hours, check the SG and re-equalize if needed. Too much Voltage is as bad as too little.

    Don't rely on any 'absolute' numbers from other sources: your readings are taken with your equipment at your location under your conditions. That's why you need to get your own baseline figures: "this is what the batteries were like when brand new and fully charged."

    Frankly, there's a LOT of 'golf cart' battery set-ups out there all functioning nicely for many years.
  • higgins
    higgins Solar Expert Posts: 56 ✭✭✭✭
    Re: Which Battery types?

    My apologies Cariboot,thanks Kamala,i did a quick search on Ebay for some Golf Cart Batteries and almost all of them were quoting 28-36 Ah so i thought that was all that was available.Will do another search for some bigger batteries,thanks to all,lots of interesting links and info from everyone here,looks like learning about batteries is better than 'knowing it all',
    Higgins.
  • Kamala
    Kamala Solar Expert Posts: 452 ✭✭
    Re: Which Battery types?

    The Trojan T-105 (almost a standard on this forum) has a C/20 rate of 225AH. It is a flooded cell battery. The kind that 'Coot talks about where you can measure the specific gravity of each cell and thereby have "a finger on the dial" of maintenance.

    I use AGM batteries which cannot be "maintained," except through stringent usage rules. They are more expensive and the reason that I use them is that I have them installed in a location where I cannot tolerate outgassing. Which they might still do if I were not absolutely certain that my charging protocols were accurate. Which I am.

    BTW, my batteries are 8AGC2's from East Penn. C/20 rate is 187AH.

    Have you visited our host's site? It is Northern Arizona Wind & Sun (or NAWS.) They have lots of batteries. Some are HUGE. There is also a great Battery FAQ.

    Good Luck!
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Which Battery types?

    Also, Lead Acid batteries will increase capacity the first 10-20 discharge/charging cycle... So some use up front is a good thing.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • dagr51
    dagr51 Solar Expert Posts: 72 ✭✭✭✭
    Re: Which Battery types?

    If you have a Sam's Club nearby, they sell a 220 AH, 6v Golf Cart battery that can be a great "training" battery. You will, of course, need at least 2 for a 12v system. I checked this past week and they were going for $74 each.
  • bryanl
    bryanl Solar Expert Posts: 175 ✭✭✭✭✭
    Re: Which Battery types?
    They are true deep cycle
    Old myths die hard, don't they. This might have been true many years ago but not now.

    The facts are that there is no objective definition for 'deep cycle' lead acid battery and the 'golf cart' battery offers nothing special. You won't find anything in the specifications for batteries where you can draw a line that clearly delineates deep cycle from non deep cycle or golf cart from others designed for similar use.

    Lead acid batteries are designed trading off between cost, capacity, and ruggedness. If you look at the specs for modern batteries, you'll see that, while there are differences, the differences aren't really all that great.

    Yes, SLI batteries will generally not last as long as 'deep cycle' in terms of discharge cycles for a given discharge depth and they will generally be better at providing current. For 80% discharge levels, the range is about 200 to 600 cycles or so. For 20% discharge levels, they all tend towards the thousands of cycles. Compare that to typical use patterns over the 4 - 7 years you can expect from a properly used and maintained wet cell (see the FAQ).

    It is your use and maintenance of batteries that is going to make the difference more than anything else.

    Do get batteries intended for the type of service you plan. Do buy from a reputable retailer who sells a lot to folks like you and will stand behind what he sells. Do use specifications, price and warranty and avoid letting things that have no measurable meaning, like deep cycle or golf cart, influence you.

    Once you get your batteries, take care of them and the odds are they'll give you good service.
  • higgins
    higgins Solar Expert Posts: 56 ✭✭✭✭
    Re: Which Battery types?

    i suppose any battery would do the job,as long as it's never discharged too deep and as long as you regualrly keep it charged and maintained,is this what you mean?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Which Battery types?

    Quoting myself from earlier today and previous months... Batteries are not the same. They are "tweaked" to best fit the application:

    I ran across this page on why different types of batteries have different starting s.g. fills... Is pretty interesting:
    Specific Gravity vs Applications
    1.285 Heavily cycled batteries such as for forklifts (traction).
    1.260 Automotive (SLI)
    1.250 UPS – Standby with high momentary discharge current requirement.
    1.215 General applications such as power utility and telephone.

    As mentioned earlier, the specific gravity (spgr.) of a fully charged industrial battery, or traction battery, is generally 1.285, depending on the manufacturer and type. Some manufacturers use specific gravities as high as 1.320 in an attempt to gain additional Ah capacity, but at the cost of a shorter cycle life.

    ...

    Higher Gravity = vs Lower Gravity =
    More capacity / Less capacity
    Shorter life / Longer life
    Higher momentary discharge rates / Lower momentary discharge rates
    Less adaptable to "floating: operation / More adaptable to "floating" operation
    More standing loss / Less standing loss
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Kamala
    Kamala Solar Expert Posts: 452 ✭✭
    Re: Which Battery types?

    Hmmm... so specific gravity, which can be measured, is meaningful with regard to application. Cool. Now all we need are names for the applications.;):roll:
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Which Battery types?

    I think the UPS (oops) application is good for here. ;)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bryanl
    bryanl Solar Expert Posts: 175 ✭✭✭✭✭
    Re: Which Battery types?
    Hmmm... so specific gravity, which can be measured, is meaningful with regard to application. Cool. Now all we need are names for the applications.
    We can measure specific gravity, life cycles versus discharge in controlled conditions, Peukert coefficient, and many other things about batteries. We can even design them to favor certain aspects of the cost, capacity, and ruggedness primary trade-off factors.

    The key for a user to keep in mind is that there is variety but there isn't clear delineation.

    Even applications have fuzzy definitions. Many solar installations tend towards a near float use profile with occasional high variance instances (and those are where failures are most often noted) but some solar installations have more regular discharge cycles. And then there is the RV solar use depending upon whether full timing or occasional weekending.

    If your use goes towards float, then gel cell batteries might be worth considering. If you need low self discharge rates, low internal resistance, and high charge acceptance, then an AGM should be on the list. If you are looking at cost effectiveness in general service, then a wet cell might be the right direction. After those basic considerations, other factors can then be put into consideration.

    But there ain't no magic bullet when it comes to batteries (yet) as far as I have been able to find out.