best way to check battery for state of charge

[B and C]

well, i'm looking at my current batteries (two, used gel, 51ah each) as a learner set... probably... 

Yes, not much capacity and you have already discharged below the 12.2 threshold.

so i put one of them, which i charged fully, on my 50L fridge (on an inverter). i left it connected for 6 hours. the voltage gradually dropped to 11.61. i disconnected it.  i'll see if the voltage rebounds... so, it works......... for awhile........... 

You should have plugged it in as a 12V device because inverters are inefficient.  They can waste 20%.  Plug it into the house to get it to temperature before trying to run it on battery.

it seems like knowing the total amps going in and out, over time, would be good to know. do controllers keep track of that? i know a couple people here (hdr) mentioned a trimetric device, and then there are various cheaper devices, but don't no if those just give a reading of what is happening right then, rather than a log. soundslike the trimetric keeps a total. what is a shunt?

A shunt is a known value resistor that one side is connected to the battery negative and the other side is connected to ground.  Two little wires attach to the shunt that goes to the meter.  Maybe three little wires, it has been a few years.  The trimetric does have  a data logger that I have never looked at.  The trimetric will show how much battery is remaining and how fast you are using electricity as well as how many amps in and out.  Someone else may be able to help with the data logger.  My solar charge controller is a midnite kid with the whiz bang jr.  I don't use the trimetric charge controller.

and now i'm starting to think of what type of battery i'll eventually get. i'm thikning agm vs liion phosphate... but leaning to agm because of the cost of a 100ah liion, which is like $900. as i said, i'd be worried about them getting stolen, or me doing something to break it... windy nation 100ah agms are less than $200 ea. i'm thinking if my fridge needs approx 30ah a day, over 3 days that's 90ah, so i'm thinking of trying to get 200ah of battery.... i'm figuring agm will be half the price of liith ion? i'm leaning away from flooded lead acid cause of the spillage potential, and off gassing in my living compartment.......... i've read they can last longer if you take care of them.... i think i might not want that burden.

Two LA 6v LA golf cart batteries are probably the longest lasting battery in the LA chemistries.  I have two 125Ah AGM batteries that weigh 100# each and another 100 Ah AGM battery that I added because it was lying around doing nothing.  Not the best way to connect batteries.  Ideally, they would all be the same age and size.

i do like the size of my current batteries. securing four of them, since i want 200ah, and wiring them, might be harder than two large 100ah batteries. but i'd prefer working with lighter batteries. i think they're 40#. 60#, for the 100ah agm's, is heavy.

Two 12V batteries


Four 12v batteries

 

[doublegregg]

hi brian
thanks for the reply!... ok, so a shunt seems clearer... i just looked it up... i might get a trimetric, at some point. 

i kind of didn't care that the inverter was inefficient. i just wanted to test the battery....... should i have not let it go below 12.2v? i thought it would be okay since i'm going to recharge it uh tomorrow... also --- the fridge was already cold, from house power....

in terms of 6v golf cart batteries, there's Universal Power Group UBGC2 Gel Deep Cycle 6V 200AH Battery Golf Cart batteries - $269 each... so $540 for 12v 200ah...  there's trojan t 105's but they are a lot more expensive...$440 each, which gives 12v and 225ah... at $880.... i'd be thinking of lithium at that point........

 

[highdesertranger]

I would not use GEL batteries, i have never had good luck with any GEL battery. around here I can get T-105's for 120 bucks each so something ain't right, where are you? I am using Sam's Club 6v GC batteries at 89 bucks each so I got 4 of them for under 400 bucks. yes you shouldn't let the battery go below 12.2v. you are ruining that GEL battery taking it down that low. highdesertranger

 

[doublegregg]

oh, planning to get agm. i just happened to be given gels. is a t 105 a trojan battery? i thought they seemed more expensive... i'm near the bay area... are there any good places to get batteries, or solar, actually, around here?

 

[Trebor English]

Battery prices vary.  If you are looking for 10 or more years of service, lithium can make sense.  I'm 71 so I'm not looking for ten year batteries.  If you figure the cost of replacing AGM batteries a few times over a ten year period then their price goes up 2x, 3x, getting them right up there with lithium prices. 

If you want low cost, flooded lead acid golf cart batteries are what golf course managers buy.  They need many watt hours stored with plenty of time (over night) to charge the batteries and they want to keep costs low.  The golf cart battery size and shape are manufactured in large volume so manufacturing costs are contained.  Anybody can make and sell them so there is actual competition. 

I have a group size 24 flooded deep cycle trolling motor battery.  That has characteristics similar to the golf cart battery, common size, shape, capacity, good sales volume, low price.  It is possible for a vendor to put a deep cycle sticker on any group size 24 battery and some people have had poor performance.  No one ever says my battery gave poor performance because I under charged it and let it run out of water so you never really know.

Lead acid batteries suffer more from the Peukert effect than LiFePo4.  That's where taking out 10 amp hours at 10 amps for one hour has a greater effect on the state of charge than taking one amp for 10 hours. 

All lead acid batteries suffer from partial state of charge cycling where LiFePo4 are alleged to be immune.  That's where you take a 100 amp hour battery and charge it to 90% full then discharge again.  Repeating the 90% partial charge gradually decreases the capacity of the battery.  A 100 amp hour battery can be reduced to 50 amp hours capacity in less than a year.  If you don't discharge it more than 50% what does it do to a 50 amp hour battery that used to be (new) a 100 amp hour battery when you take out 50 amp hours?

T105 is a Trojan golf cart battery, a common size.  Look at the trojanbattery.com web page.  They have lots of details about their batteries.  If you get some other brand of battery and that vendor doesn't specify, for example, charging voltage temperature compensation, look at the trojanbattery.com page to see what they say.  Because the vendor you bought your battery from doesn't specify something doesn't mean it isn't there. 

Given Peukert, don't run your fridge one one battery, use two.  You have two. 

You said your fridge is 50 liter.  That's 1.7 cubic feet.  That's the common size of cube shape dorm room fridges.  The insulation on those is intended for 10 cents per kilowatt hour commercial power, the grid.  Do not expect that fridge to work with less than 200 watts of solar and 200 amp hours of battery in a sunny place like Arizona.  Anywhere else you'll need 300 or more watts of solar.

 

[doublegregg]

thanks, trebor, for the info... now i'm considering FLA... can i ask what about gases produced by it, along with spills? i would gather people have decided they're comfortable with the risks... i've got a cargo van, so they'd be --- right there with me. i'll also be heating with propane, a wave 3. so - not sure about all this FLA. i found these, and i like the price. they're local to me, but kind of confusing all the variety in this one type. i notice their weight is 66# - a little heavy for me. i'm 64 and have chronic pain. i much prefer my gels, which are 40#. but i don't think i'll be using them when i'm out there. they're 51ah, 12v..... i'm still trying to figure out how much capacity is in them....  i still might get agm's... 

https://www.batteriesplus.com/search?facets=Voltage:6|Categories:Golf Cart&q=6V Golf Cart Battery

i think i've ruled out lithiums due to cost. i could afford them, but damaging them or theft are big concerns.... otherwise, they sound terrific....! and they're so light...

actually my fridge is an iceco.... i'm hoping, and expecting better performance than a dorm fridge... but i'll have 300w solar (although in a suitcase style) and i want probably 200ah of batteries........ i may add solar on the roof - i just am not crazy about getting a wire from it into my van, and i wanted to not be noticed as a camper. i might use a panel on top when i'm just boon docking. that might work...along with my suitcase solar.

have a great week!

 

[doublegregg]

i don't prefer my gels, i just prefer the weight, which is 40#. ultimately, i'm trying to decide between agm, lithium ---- and now FLA. should i start a thread on battery choice? i'm researching, but batteries seem more uh.... art than science........altho the science is a lot to absorb.

 

[B and C]

You will only need to move your batteries in and out, once each way. You won't be moving them weekly, monthly or yearly. You could always ask for help getting them into place.

You seem real concerned about theft. Do you plan on staying in a high crime area? I have never considered theft of batteries but mine weigh 100# each and are hidden away.

From what you are saying, AGM is the way to go. FLA batteries are for those that like to tinker. I like set it and forget it.

 

[highdesertranger]

yeah I don't mind the once a month service at which time I also inspect the cabling for tightness, corrosion and such.

also mine are mounted outside so flooded was an easy choice.

highdesertranger

 

[rokguy]

+ 1, FLA

 

[Trebor English]

thanks, trebor, for the info... now i'm considering FLA... can i ask what about gases produced by it, along with spills? i would gather people have decided they're comfortable with the risks... i've got a cargo van, so they'd be --- right there with me. i'll also be heating with propane, a wave 3. so - not sure about all this FLA. i found these, and i like the price. they're local to me, but kind of confusing all the variety in this one type. i notice their weight is 66# - a little heavy for me.

Gases, H2 production, happens mostly when the charge is finishing and the almost full battery is still getting current.  There is very little gassing during discharge.  If there is ventilation the hydrogen gets diluted and there is no explosive mix of H2 and O2.  Some people use a small computer fan to help move the H2 along.  Some people make sealed boxes vented to the outside, some just shove the batteries under the bed. 

If you use the vehicle alternator as a charging source, drive with the windows open.  A 45 MPH breeze will keep them well ventilated. 

It is important that any battery be bolted in place so that the batteries don't become missiles inside the van during a crash.  With that in place a spill would have to start with using tools to get the battery loose.  They are heavy and have flat bottoms.  Accidental tipping isn't a problem.  

At 66 pounds it is possible for a person to put 6 of them into a golf cart, one at a time.  The 8D size batteries are like two golf cart batteries together, twice the weight.  Those are too much for me.  Mounting the batteries to the floor in a van requires sliding them around more than picking them up.  If you start with two of them on the ground outside the van you can lift, one at a time, a short distance onto a crate.  You get yourself in a good position, one arm to support your upper body leaning against the van, one hand on the golf cart battery and you bring it up one foot.  Then you reposition yourself.  Get comfortable and do a second lift from the crate to inside the van side door.   The batteries have plastic loops molded into the top at each end and the guys at battery places have a rubber strap handle with a hook at each end.   Do not pick up a battery without a handle.  The steel wire that comes attached to the top of a bucket can work, be careful to avoid shorting out the battery. 

I recommend a plastic box to contain a battery.  Once upon a time I had a starter battery case break and the acid leaked. 

Flooded lead acid batteries need distilled water once a month.  Sealed batteries can't have water added.  Being able to add water makes it so that charging mistakes can be corrected.  Flooded are more robust, AGM and gel are more easily damaged.  Adding water is not difficult but I have a friend who has a grandson who filled up the batteries in his golf cart with a hose, full, to the top.  Don't over fill or use tap water.

I found these on the internet.  Flooded batteries aren't going to be shipped by FedEx.  You need to find them locally.  You may have a golf cart repair shop near by.  Places like Auto Zone and O'Reilly are likely to not have them in the store but can order them in a day or two.  Batteries Plus Bulbs used to offer a lower price if you ordered them online and picked up in store.  They may still do that.  People who use boats often use batteries too.   Expect to have to pay a core charge, $15 to $30 each, unless you have some old batteries to trade in.

$89.88
https://www.samsclub.com/p/duracell-golf-car-battery-group-size-gc2/prod3590228?xid=plp_product_1_1

$98.99
https://www.costco.com/Interstate-6-Volt-Golf-Cart-Battery.product.100476406.html

$119.99
https://www.batteriesplus.com/productdetails/sligc110

124.99
https://www.oreillyauto.com/detail/...ry-group-size-gc2/gc110tj/4742595?q=gc2&pos=1

$142.95
https://www.interstatebatteries.com...olf-car&subcategoryKey=&ignorecategoryid=true

$144.00
https://www.lowes.com/pd/Deka-6-Volt-448-Amp-Golf-Cart-Battery/50183775

$146.00
https://www.napaonline.com/en/p/NBP8143?keywordInput=Golf+Cart+Batteries

 

[doublegregg]

brian, yeah, i live in a high crime area (urban bay area) and leave my van on the street. it's the kind of place where people smash out windows just to see what's available. but, yeah, i'm also concerned about theft on the road, maybe overly so, but that's kind of how i am. being in a cargo van with a bunch of tools, computer, batteries, solar panels, etc,... it's definitely a worry... i kind of doubt i can insure the stuff, since it is kind of like an rv, but isn't. i may install a locking job box inside...

any comments for or against FLA's in the interior - i no bob wells does this... one site commented FLA"s let out exess gas if they're over charged... i read hydrogen sulfide smells like rotten eggs. but is that reliable as a sign of gas being present?

 

[doublegregg]

thanks so much, trebor for the detailed info........... it's helpful to have practical details about what people do with their FLA's and where they store them.... i'll have to think about this..... i do have a batteries plus near me, so that is a positive, and i noticed the duracell golf cart batteries while surfing the net... and thanks for the info on how to muscle the bigger (to me 60# is bigger) batteries around..!

everyone have a good rest of the week.........

 

[Trebor English]

any comments for or against FLA's in the interior - i no bob wells does this... one site commented FLA"s let out exess gas if they're over charged... i read hydrogen sulfide smells like rotten eggs. but is that reliable as a sign of gas being present?

I wouldn't count on  there being no H2 present because of no smell of hydrogen sulfide.  If the alternator is alternating or if the solar panel is collecting, H2 is possible.  No smoking.

Hydrogen sulfide has the foul odor so it should be noticeable. It is poisonous, corrosive, and flammable.  It isn't as poisonous as carbon monoxide.  H2 can displace oxygen causing hypoxia but isn't poisonous.  It doesn't attach to hemoglobin and block oxygen like carbon monoxide does.  

If your total battery price is $180 to $240 and then someone steals your van the battery is not going to be a big concern.  If you paid $800 to $1000 for the battery and then someone stole the van the battery would be a concern.

 

[doublegregg]

I wouldn't count on  there being no H2 present because of no smell of hydrogen sulfide.  If the alternator is alternating or if the solar panel is collecting, H2 is possible.  No smoking.

Hydrogen sulfide has the foul odor so it should be noticeable. It is poisonous, corrosive, and flammable.  It isn't as poisonous as carbon monoxide.  H2 can displace oxygen causing hypoxia but isn't poisonous.  It doesn't attach to hemoglobin and block oxygen like carbon monoxide does.  

If your total battery price is $180 to $240 and then someone steals your van the battery is not going to be a big concern.  If you paid $800 to $1000 for the battery and then someone stole the van the battery would be a concern.

ty................. weighing the gas possibilities...........if too troubling, i'll lean to agm...

 

[Spaceman Spiff]

ty................. weighing the gas possibilities...........if too troubling, i'll lean to agm...

Hydrogen has to be 4% by volume to be flammable.  In a volume the size of a van that would be almost impossible to obtain.  You would need to boil the batteries very hard with no outside air exchange. [font=Tahoma, Verdana, Arial, sans-serif](For comparison gasoline vapor only needs to be 1.5% to be flammable.)[/font]

I am on year 6 with 2 GC2 FLA batteries, stored under my bed.  I don't loose any water in the 6 months between equalizations; I don't even check them anymore.  I've never smelled sulphur inside.

 

[doublegregg]

ty for all replies... i'm still a bit concerned about the gases released by the lead acids... i guess at night, not an issue -- ever? since they're not charging. i'm also wondering about just how long it takes to fully charge the lead acids every day. it seems like you'll always be having to charge them fully --- i'd guess many or most alternators don't have the voltage to top them off? or it seems you'd need your solar panels on the roof of the vehicle to charge them every day --- if you're driving during the day. at this point i have the portable unit, 300w, but may get a roof top panel.

in terms of lithium --- idk --- the cost is so great... it would be a plus to be able to use them in my stix and brix, i guess that's possible. that might come in handy. i'd probably lock them in a box in my van, with the wires coming out.... yeah, i'm maybe overworried about them. i see the benefits of lithium as i'd maybe need only a single 100ah battery to power my 50L fridge and lights, etc... i could discharge it to -- is it 80 or 90%? and then the charge up time is reduced by hours, plus they don'[t have to be fully charged. i've been considering getting an induction cook top. since i'd only use that during the day -- maybe that would work out... i can't see the induction working with lead acid - simply a lot of watts and the peukert effect, but at this point the induction is a new thing i just am thinking of..

i could see lead acids being great for a house, i mean simply in terms of they're just sitting there, getting charged - unless it's raining, etc.. but a van seems harder to keep them fully charged.

hope you're all having a good weekend.