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Borrego
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# Posted: 13 Dec 2017 14:34
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It's close to time for me to make a decision on batteries and I've come to the conclusion that sealed AGM are the best for me.....I think...I would go lithium if they were more affordable, but....
I need the sealed style because the closet where i house the inverter etc... is the same place I will have the batteries and it is on my screen porch (somewhat a living area) so i don't want gasses/corrosion etc...
Budget is about $200 per and I need (8) 6 volt batteries....
Any and all input helpful as always...
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littlesalmon4
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# Posted: 13 Dec 2017 16:39
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Best lead batteries i can find online.
rollsbattery.com/renewable_energy/
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ColdFlame
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# Posted: 13 Dec 2017 18:03
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The Costco golf cart 6V batteries are often a good bargain, and Costco has a great warranty on their batteries. I can't speak to their performance, though I'm sure you'll find hundreds of posts about the topic if you are to go looking.
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Just
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# Posted: 13 Dec 2017 18:58
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I have a small EV .I switched from SLA batteries to Lithium ,I have had a marked ( 50 %)improvement in performance . If the promised increase in logevity comes true the lithium will prove to be a far better value. IMO just
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Kamn
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# Posted: 13 Dec 2017 19:05
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I don't think its as expensive as you think for Lithium
https://www.ebay.com/itm/2011-Chevy-Volt-Battery-2kWh-48V-Li-ion-pack-Solar-Golf-cart /222552892596?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D49454%26meid% 3Da5aeb728e01e49e5b38dc0d996e547e4%26pid%3D100675%26rk%3D3%26rkt%3D11%26mehot%3Dpp%26 sd%3D253305735903&_trksid=p2481888.c100675.m4236&_trkparms=pageci%253A5f43e07c-e062-1 1e7-b70b-74dbd180dbe9%257Cparentrq%253A525651051600a68826cbd6effff838fd%257Ciid%253A1
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Borrego
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# Posted: 13 Dec 2017 22:20
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Quoting: Kamn I don't think its as expensive as you think for Lithium
Hmmmmm, ya got me thinkin;....
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Kamn
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# Posted: 14 Dec 2017 07:49
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Maybe get in touch with Creeky about Lithium and your setup
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Mike 870
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# Posted: 14 Dec 2017 09:14
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I was able to get scratch and dent batteries from my local manufacturer for half price. 6v flooded 260 AH Crown batteries for $99 each. Same warranty. Worth checking if you have a manufacturer near by.
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creeky
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# Posted: 14 Dec 2017 14:12
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Okay. i wasn't gonna touch this one.
but if 3 volt modules is 900. My bms with harness another 550 or so. And you have a 15-20 year pack. Less than the lead acid from the gate. much less after 3-5 pack replacements. And more usable power. with, as Just aptly puts it. Much better efficiency.
I have a local guy. Scratch and dent surrettes. 3 years and he's begging me for a Leaf pack 'cause he's all in on an older inverter/charger. it can't do the 48v on charge. Has to be "lead acid" 56v. everything else is fine. I'm trying to tell him. Just dump the charge function. but. you know. it cost $$$.
the best battery is lithium.
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ICC
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# Posted: 14 Dec 2017 14:25 - Edited by: ICC
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Quoting: creeky it cost $$$. the best battery is lithium.
No doubts on that. the best battery is lithium. it cost $$$.
Quoting: Borrego I need (8) 6 volt batteries....
Is that for 24 VDC system or 48?
The salvaged Volt batteries are 48 volts, so if the existing system is 24 volts there also needs to be different hardware at least for the inverter. maybe for the charge system too. Lots more $$$
Do you have a SamsClub or Costco near enough? One that sells golf cart batteries. The Sams nearest to me has GC-2's for around $85 with core exchange. Hard to beat that for a tight budget.
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ICC
Member
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# Posted: 14 Dec 2017 14:27
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Ooops! Those are NOT sealed. But they work well for a location with batteries outside.
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creeky
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# Posted: 14 Dec 2017 15:58 - Edited by: creeky
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ICC. The 3 volt batteries gives you 5kw usable. Take your amp hrs on your lead acid and calculate at 20% dod how much power you have. The lithium is cheaper. Way cheaper.
Now factor in you will use 3-5 lead acid packs in the time you go through 1 lithium pack.
Since 2013, on a cycle basis, lithium is cheapest. And with prices dropping so fast. Now its basically cheapest right out of the gate.
Lead is dead.
FYI 48v is the way to go for the future. High voltage is coming. Mfct are still producing 48v for the home market. Don't get saddled with "ye olde solar." that will prove expensive. .02
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95XL883
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# Posted: 14 Dec 2017 17:48
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Okay, stupid newbie questions here.
First, if I were to use a 48V lithium pack, then I would need an inverter to convert the 48V DC to 120V AC, right? And that inverter would need to be sized to supply the pulling wattage of whatever I expect to run on it, right?
Second, with a 48V lithium pack, then I wouldn't be doing any 12V DC usages, such as lights or computer fans, right? (I'm assuming the computer fans are DC, they may be AC stepped down to 12V for all I know.)
Third, if I were to use a 48V lithium pack in an occasional/week-end use cabin, then do I have to take the pack back home each time I leave (or at least disconnect the charger) when temps are expected to go below freezing?
Fourth, in terms of figuring out how many watts of solar power I would need, I would be trying to compute how much time I will have to charge it between uses, right? In other words, if a 300 watt panel will fully charge a 48V lithium pack over a five day period, then all I would need is one 300 W panel, correct?
Fifth, how does one protect the panel, charge controller, battery pack and inverter from extreme power surges? (I'm in eastern Kansas where we have strong lighting storms that can be frequent especially during spring, summer and fall months.)
Thank you very much for the help.
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Borrego
Member
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# Posted: 14 Dec 2017 19:21
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I will have a 48v system....so I need (8) 6 volts, right?
Dumb question......can you use just one 48v battery?
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Just
Member
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# Posted: 14 Dec 2017 21:34
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Yes in lithium. not in lead .
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Just
Member
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# Posted: 14 Dec 2017 21:40
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Actually most lithium packs are made up of 3 v cells,many 3 v cells..
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Borrego
Member
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# Posted: 14 Dec 2017 22:06
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So (1) lithium 48v battery = (8) lead 6v batteries?
Then they would be waay cheaper...I must be missing something. Sorry to be so thick....
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Just
Member
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# Posted: 14 Dec 2017 22:27
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I m no expert all i know is my 20 amp hr lithium battery has 60 flashlight size batteries sodered to gather . and it works great .It replaced 4 12 volt SLA ,It weighs half as much and about half the size. It cost about 35 % more than the lead.
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creeky
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# Posted: 15 Dec 2017 09:31
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95xl. To answer some good questions:
Yes. 48v battery you need a 48v inverter. The advantage is a 48v inverter is more efficient. Most 12v are 88% efficient. 24v are 92. And by 48v you're up to 94.
Yes. You give up using 12v appliances. You wire for 120 and forget the 12v wiring. If you need 12v. There are many small "wall warts" that convert 120 to 12v. The new switching types are very efficient. (the small ones). These are also available to convert 48v dc into whatever. I have a friend that converts 48v into 5v to run his monitoring camera at the cabin. Cost less than $5 if I remember correctly.
Leave the battery in place. I mean you can move it. Its much lighter than lead and so easier to move.
Lithium can be discharged down to -25C (-13F). Lead should not be discharged below -17C (0F). This is for solar storage.
Most lithium shouldn't be charged below 0C (32F). This is to avoid "plating" the anode. So, come to camp, turn on the power, heat the battery before turning on the solar panels.
Off grid we're using well insulated battery boxes (my case) or storing them in conditioned (ie. heated) space. Battery blankets are popular. Mine's running right now. (-20C / 0F outside)
There are also lithium chemistries that aren't vulnerable to cold. The Nissan Leaf uses one. The titinate or nano titinate batteries too. Some of these are available online. They are a bit more expensive. But they should last in neighborhood of 50 years. So there is that.
Saying lithium is like saying chocolate. there are a lot of flavours. Lifepo4 like Just uses is 3.2v/cell. Is super safe. And pretty reasonable price. NMC from LG Chem (chevy volt-NMC) is 3.85v/cell. Titinate is 2.3v/cell. To give some examples. All these chemistries are very safe. There are less stable chemistries. Like in cell phones. where they are trying to cram as much power as possible into tiny spaces. These have had some issues. smile.
Each has its benefit and drawback. Sort of like flooded/sla/agm.
On 48v. You have to watch your voltage on the solar panel. You need to be higher than the battery to charge. So you may need 2 panels in series to get a high enough voltage to charge the battery. Oddly, a solar controller (mppt) will lower the voltage (turning volts into amps) to charge a battery but won't raise the voltage.
Borrego. You really need to calculate the size.
Lead is Amps * voltage @ 20% dod = usable power.
Lithium is Amps * voltage @ 80% dod = usable power.
Then deduct for efficiency if you want to get really fussy ...
Lead efficiency is typically rated at 1.26 or more.
Lithium is usually stated as 1.
Note Justs true life experience. 35% more for a battery that lasts 3 times longer.
I hope this helps. Happy solar everyone.
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Borrego
Member
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# Posted: 15 Dec 2017 09:43
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Just - Which batteries do you have exactly?
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Just
Member
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# Posted: 15 Dec 2017 10:26
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Lifepo4 48 v 20 amp hr. $ 520.00 all in canadian funds Ebay 6 week delivery..
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rachelsdad
Member
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# Posted: 23 Dec 2017 06:09
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My installer called out of the blue and came in about 6 weeks early this year.
I was in a hurry and a friend owns a battery wholesale store and had Trojans, used but in great shape for $50 each, including new cables...so I figured I'd run them until I got my fat head around Lithium.
OK
Let's see if I have the math right.
My 8 x 330 x 6v is 15.8 kwh x 20% DOD = 3kwh
If I buy 2 of the Volts:
2 x 2kwh = 4 kwh x 80% DOD= 3.6kwh??
So I can replace my 1,000 lb battery pack with 2 45 lb Volt batteries??????
If this is true Creeky I'll be calling for the BMS and assorted goodies I need to make the transition.
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Borrego
Member
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# Posted: 23 Dec 2017 21:00
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And then there are these.....
https://www.solar-electric.com/simpliphi-phi-2-6kwh-48v-lithium-ferro-phosphate-batte ry.html
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Ontario lakeside
Member
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# Posted: 23 Dec 2017 23:49
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Rachelsdad
That basically what Creeky set up for me.
https://www.youtube.com/watch?v=yCudeUYf52Q
https://www.youtube.com/watch?v=ZfilBtej3t4
https://www.youtube.com/watch?v=LuSJTvH94EU&t=3s
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rachelsdad
Member
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# Posted: 24 Dec 2017 06:51
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Ontario,
Great use for the old battery~!!!!
Creeky really got to you huh??
So, does my math make sense?
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creeky
Member
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# Posted: 24 Dec 2017 23:50
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rachelsdad. Yup. Your math is right on.
Borrego. The battery you point out is a basic LifePo4. Nice that they add a disconnect and a bms.
Note: disconnects from inverters ... its better to turn the inverter off and then trip the disconnect. Most modern inverters have a shut down sequence to protect the electronics.
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paulz
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# Posted: 25 Dec 2017 23:06 - Edited by: paulz
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I haven't noticed 12v lithium car batteries in stores, are they available and if not, why?
Also, I have these two 12v 10ah scooter batteries I need to replace. $35 for the pair shipped for the same, anything in lithium I could use? It has a wall charger.
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Kamn
Member
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# Posted: 10 Jan 2018 14:08
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Creeky,
how important is mileage on the donor Chevy Volt that the battery pack will come from?
I found one close by that has 22,000 miles
Cheers
Kamn
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offgridjunkie
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# Posted: 11 Jan 2018 12:38
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I love the talk about the new Lithium battery packs for off the grid. After reading some of the posts, I am hearing that they should be warmed up before charging. So my cabin in the winter gets down to below 0F fairly frequently and I leave my solar connected to my charge controller and my AGM Battery so that it always remains topped off.
If I were to go with a Lithium, would I need to disconnect the solar in the winter when I am not at the cabin to make sure I do not damage them due to it being too cold?
My system is very small, and meets all my needs, but my battery is at the age it is going to need to be replaced in the next few years. Any info on this would be great.
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ICC
Member
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# Posted: 11 Jan 2018 13:28
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Quoting: offgridjunkie would I need to disconnect the solar in the winter when I am not at the cabin to make sure I do not damage them due to it being too cold
Disconnect or keep them above freezing. Disconnecting lithium does not have the problems of fairly rapid self discharge that any lead acid type has. Plus lithium can be stored at less than full charge. If they can't be kept warm enough then disconnect the charge controller when leaving.
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