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spencerin
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# Posted: 7 Dec 2014 21:06
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Deka 6-Volt 448-Amp Golf Cart Battery
http://www.lowes.com/pd_599952-50656-GC15_0__?Ntt=golf+cart+battery&UserSearch=golf+c art+battery&productId=50183775&rpp=32
I may have to upgrade my solar batteries soon because their performance has declined recently. This golf cart battery seems too good to be true - wire 2 in series for 12V and 448Ah for <$300!? Specs show some cold cranking amps, making me think it is more hybrid, but it's definitely being marketed for golf carts / deep discharge.
Thoughts?
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groingo
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# Posted: 7 Dec 2014 22:09
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Going to take a closer look myself as the capacity looks good and Deka is a decent brand....what I really need is a battery that will take the higher charge rate so it will charge quicker.
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razmichael
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# Posted: 7 Dec 2014 22:15
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Check the deka specs
Deka
- this is the GC15 model. 20 AH is 230 (20 is the most common rate to compare when considering off-grid batteries). Not saying anything bad (or good) about them as I do not know - just make sure you are comparing apples to apples when looking at capacity. Also, not sure the Lowes specs really match up (terminology) with the DEKA spec sheet.
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razmichael
Member
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# Posted: 7 Dec 2014 22:33
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Sorry, the link was for the google search. here are the specs
DEKA
The 448 figure is for the minutes ar 25 amps. The specs (including weight) are very similar to Trojan T105s. No mention about cranking amps so I think Lowes just messed up.
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spencerin
Member
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# Posted: 7 Dec 2014 23:31
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You guys also mind opining on a charge controller?
I bought a 10A Sunforce charge controller 3 years ago and am using it on 3 marine batteries from WalMart that are probably hyrid and not deep cycle (I got "marketed").
I noticed a few months ago that my batteries weren't holding a charge like they used to, but didn't think too much of it other than the batteries are cheaper and stored outside (dry, but exposed to the temps).
Today I knew the time was upon me to check the water levels. Pried off the tops, and yikes, some tops of the plates were exposed.....not bad, only needed a splash or two to cover them again, but still exposed. That explains the declining performance.
The thing is, I'm not sure if the charge controller is overcharging the batteries and that's why so much water evaporated. Then again, I last refilled them in the Spring, thinking since I don't use them too much, there won't be too much water evaporating.
The charge controller displays its own voltage, and it seems to max out at 14.3V and then dissipates down to 13.6V, back and forth, I guess from bulk to float. I did read that was normal.
Your thoughts on that? Maybe I just taught myself a lesson on checking water levels more often and that's it.
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groingo
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# Posted: 8 Dec 2014 00:19
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Best advice on battery condition I would give is to check battery charge levels with a good multimeter regularly and write the results down and date them, you can also easily check power output on your charge controller to be sure it is working to spec.
Simply put, a good maintenance routine takes the guesswork out.
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MtnDon
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# Posted: 8 Dec 2014 13:26
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13.6 is a little high for float voltage. That will use more water. But face it, if there is a charge source connected the batteries will use water. Monthly is the interval I use for electrolyte level checking. But I do only need to add water maybe twice a year.
Recommended charge voltages, bulk, absorb, float, can vary from one battery manufacturer to another. Check the recommendations from Deka.
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creeky
Member
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# Posted: 8 Dec 2014 16:54
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As Razmichael posted ... it's a 230 amp hr battery. Still. Put two in series for 12v and you'd have a nice battery pack. And for 140/ea. not bad.
Your battery charge levels sound reasonable to me. The float is high, but we don't know what temp your batteries are at, right. So if they're a bit cold, 13.6 is what you'd expect from lead.
I add water 5 times a year. 3 times in the summer and twice in the winter. But I use my batteries to 20% dod daily and equalize monthly. (Love equalizing. Your batteries are super powered for a week afterwards.)
What are you using for solar? You'd probably want around 250 watts of panels making 20 amps for a pack that large.
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Scott G
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# Posted: 10 Dec 2014 16:51 - Edited by: Scott G
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Cool thread. May I interupt a second to ask the reason for 250w at 20amps? I get how you add 250w of panels, not sure how you set amps.
12v panel x 20a = 240w?
Just trying to figure all this out. Thanks.
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spencerin
Member
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# Posted: 11 Dec 2014 01:54
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Thanks for the replies. I run light on the panel watts. I should probably shrink my bank, but I figured since I'm at my place weekly at most for a day, I only needed X amps over the course of a week to get and keep the bank full. I have always had a full bank (13.3V+) whenever I've gotten there.
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creeky
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# Posted: 11 Dec 2014 11:01
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Scott you have the math right.
It's just a rule of thumb I've learned over the years. Basically when you look at folks who rely on solar you quickly see the happy ones have one watt of panel per amp of storage.
Most solar "experts" on the solar sites will cite (sorry) c/10 as the recommended charge rate. So charging at 1/10 of your storage amps. note this is for lead batteries.
So spencerins suggested battery pack is 230 amps at 12v. So to charge c/10 is 20 amps or 250 watts (rounding off numbers ... lol. I mean if you want to get real precise then it's actually 12.7 v etc...).
the reason you want a bit of a kick to the charge is to get the power into 'em. lead has a fair amount of resistance. So higher voltages ... more amps ... keeps the plates in better shape. Most 12v packs actually benefit from a charge v around 14.5.
as I understand it.
a lot of folks here mostly use their systems on weekends and during the summer. living with slower charging scenarios. No big deal. just replace batteries more often. (or getting a better battery not made of lead cough lfp cough)
so, as spencerin points out, with his one day a week use of lamps, he's probably better off with a small cheap 12v deep cycle that he replaces more frequently.
I bring up this rule of thumb to help those who might be new to solar.
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Scott G
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# Posted: 11 Dec 2014 11:49 - Edited by: Scott G
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Thank you good sir. I appreciate the clarification.
Didn't mean to hijack - just easier (for all imo) when in context.
Visited your site today creeky. Wicked. I'll be on that and outbound links for a great deal of time as I work out my system plan. We'll be off-grid 24/7 in the not too distant future.
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groingo
Member
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# Posted: 11 Dec 2014 18:09
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I'm looking at everything from larger deep cell flooded to Lithium and even Nickel Hydride like they use in the Prius batteries but the key thing I am lacking in all except flooded batteries is people actually using them.
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Scott G
Member
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# Posted: 11 Dec 2014 18:24
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Could the cost be the reason?
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spencerin
Member
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# Posted: 11 Dec 2014 20:47
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Hey, I should consider myself lucky, then! I have been using 110W to charge 300Ah for almost 3 years and only now has there been any sort of performance problem.....that may have been fixed. But.....I should probably shrink the bank.
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Scott G
Member
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# Posted: 11 Dec 2014 22:08
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Or addpanels i guess.
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creeky
Member
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# Posted: 12 Dec 2014 11:22
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You can certainly charge batteries slower, geez, we do it all the time with solar. but you know. recommendations and all that. still. seems lead batteries need a good kick now and then...
and I want to whack myself in the head. Spencerin, Regarding your recent performance slump... did your batteries get colder recently? I know I hate winter as my battery bank suddenly weakens. But it's 'cause they are cold. Once summer comes again...
groingo, to research lithium (or lfp) properly you have to go to the RV and the yacht/boaters forums. there a lots of folks out there with lfp battery packs.
and I just deleted a two paragraph rant about leadites...
I have a friend who's had a lfp pack for two years. I hate talking to him. Last week he used 4.5kw (on a 9kw battery pack) overnight and it was cloudy the next day. He didn't care. His solar got some power in and with lfp it's okay to leave your battery part charged for weeks, months. myself. the same day. I used 2.5kw. the next day my 14kw lead acid pack had to be charged with the genny for an hour, due to cold/heavy cloud. Because leaving lead acid discharged will dramatically shorten the lifespan. ya. who's got the better battery pack.
personally I'd happily pay double just for the lack of headaches... when you look at the overall cost increase (before amortization), it's really only adding 10 or 15% to the cost of your solar system ... so. and if you look long term, it's cheaper. and it's proven to be cheaper. anyway. i'm getting on a horse here and I'd better climb down.
oh. and hey scott, thanks for the like on my blog. super appreciated.
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groingo
Member
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# Posted: 13 Dec 2014 22:20
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Creeky:
Currently I am looking at all battery options but actually thus far my Crowns look to be doing quite well being that I don't allow them to go below 60% and their charge temp is rarely below 72 degrees because I am piping heat into the battery box.
Fortunately since installing the panels I have only had to charge by generator twice but am planning on doing it at least once a month the give them a good deep charge.
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MtnDon
Member
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# Posted: 13 Dec 2014 23:14 - Edited by: MtnDon
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Quoting: groingo but am planning on doing it at least once a month the give them a good deep charge.
IMO, the best method is to do a bulk charge by generator early in the AM on a day that looks to be sunny, and then let the PV complete the charge... Assuming the absorb time that is set in the CC is long enough to truly top the batteries to 100%, and as long as the simultaneous daytime loads are low enough to permit the absorb to do its thing that should do it. Generator charging is inefficient for the last 10 - 15% of topping off (absorb charge).
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Scott G
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# Posted: 14 Dec 2014 11:55
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Cool.
So then, please correct me if im wrong... bulk is...bulk, the principle large influx of amps, float is a slower controlled topping off. Both phases are handled by the charge controller without user intervention. Equalize is a charge controller programmed, controlled high voltage to essentially clean the plates on the batteries, reducing build up and extending service life. This rate/ duration is dictated by battery specs. Talking about liquid cells here. Electrolytes must be monitored...monthly? and topped up with distilled water per battery specs. This maintenance coincides with equalizing.
Not sure about that last bit....
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razmichael
Member
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# Posted: 14 Dec 2014 12:03
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Scott, a three way charger will do bulk, absorption and float. Some will also do equalize (either automatically or manual). Here is a good faq on this
Faq on battery charging
If you check websites for most well known brand of batteries, they will also have details on how best to maintain there batteries and for different battery types. Example - Trojan
Trojan Battery Maintenance
I've also like the site "12 volt side of life" part one and two as good reading although some of the stuff is a bit outdated regarding technology
12 volt side of life part one
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Steve_S
Member
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# Posted: 14 Dec 2014 13:15
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@Raz... That 12V Side of life, link is EXCELLENT and duly bookmarked ! Plain Straight English no "bafflegab" or "Feldercarb"... May be a touch dated (last update 2002) but still a lot of good info and explanation.
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Scott G
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# Posted: 14 Dec 2014 15:22 - Edited by: Scott G
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Razmichael, thank you sir. Ill be reading those tonight. I really appreciate the straight talk... Finding so much blahblah online but this community is sooo helpful.
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creeky
Member
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# Posted: 14 Dec 2014 16:30
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I prefer to let my solar panels do all the charging. I have enough of them. lol.
Scott, there are 4 stages. Bulk. Absorb. Equalize and Float. For the most part, Bulk and Absorb are what you care about. Float is just maintaining your battery until night fall. You wouldn't want to run a genny for this phase. Equalize is (by my Crown
manual) a monthly requirement. When you equalize you'll know why. Super power batteries. There is some very good science on the chemistry if you want to spend the time...
A good point to understand: when your batteries enter "absorb" it may take (by example) 700 watts to get out of bulk and into absorb. But by the end of the absorb cycle you'll be using less than 200. By understanding this. Once you get into absorb for an hour you can start adding loads without worry (given that it's sunny). and it's why doing an absorb cycle on a genny is costly...
this is one nice advantage to the solar charge controllers that come with web servers. when you see your panels have 800 watts available but the CC is using 350 to charge the batteries. well. fire up the whatever...
groingo. those crowns should last you for quite a few years yet.
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Scott G
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# Posted: 14 Dec 2014 16:33
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Thanks man. Appreciated.
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