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spencerin
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# Posted: 30 Dec 2014 12:31am - Edited by: spencerin
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So I bought 2 6V golf cart batteries. I'm charging them with a 6A battery charger. They are taking a long time to charge, which is fine. However, once the charger indicates one battery is fully charged, I disconnect the charger from that one and charge the other one until the charger indicates it is fully charged, too. Then, when I go back to "double check" the first one, it doesn't say it is fully charged, but charges it again for another hour until it indicates the battery is once again fully charged.
The charger does this for both batteries. What's going on?
The batteries are made by Exide for Rural King stores. They are cheap, but likely more durable than the Walmart EverStart "deep cycle"s I used before. The setup will be basically the same, and my 100W 12V solar panel didn't have any problems charging the EverStart battery bank. Will the panel have problems charging these 2 Exides wired in series?
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toyota_mdt_tech
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# Posted: 30 Dec 2014 01:16am - Edited by: toyota_mdt_tech
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I imagine the system is seeing the overvoltage from the fresh charge (this is how it knows the batteries are charged). As you remove the charger, the battery settles back down. I suspect they are both fully charged.
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spencerin
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# Posted: 30 Dec 2014 08:51am
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Any chance, in your opinion, the solar panel will have any problems charging these 2 batteries in series?
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MtnDon
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# Posted: 31 Dec 2014 12:08am
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Use a good hydrometer to determine full charge.
A 100 watt panel is a little on the low power side depending on how muchthe batteries are depleted on average andthe number of good sun hours. Ideally you would be able to get 10% of the AH capacity,inamps from the PV. GC2 =220 orsoAH. 220 / 10 = 22 amps. How many AH did you have before?
Why doyoucharge the batteries separately?
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groingo
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# Posted: 31 Dec 2014 01:55am - Edited by: groingo
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Simply take your multi meter and take a reading immediately after charge then another 8 hours or more later to after batteries have settled out.
Full charge should be around 13.06 volts or above and 8 hours later drop to around 12.61 which is 100% charge.
Ideally for healthy batteries.....check your battery manufacturers charge rates but these numbers are pretty generic.
Don't forget, you want to ideally charge at a room temp of 65 to 72 degrees for best results, the colder the less charge is held.
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spencerin
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# Posted: 31 Dec 2014 01:09pm
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I know this is on the low side, but I don't run much, and I also want to have a "reserve" there just in case, or if/when I want to get a bigger panel. I actually had 225 Ah before, and with only weekly use, the panel charged the batteries full each time I came back. This is now 186 Ah I think and, I'm hoping, more durable.
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MtnDon
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# Posted: 31 Dec 2014 03:52pm
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 sounds like itshould run much like the prev setup
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creeky
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# Posted: 31 Dec 2014 04:09pm
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boy this is my day for being a curmudgeon.
but. (i say again) you have to charge your batteries properly if you want them to last. Lead acid batteries need to be hit hard to get the electrons into the plates.
spencerin, you probably need a better solar charge controller and a better genny powered charger. but make sure you get one that takes your batteries to at least 14.5 in absorb.
and 12.6 is 90% charged. not that I'm being ocd or anything 
and an extra 100 watts of solar wouldn't hurt. you can charge your batteries slower but make sure you're at least getting the higher voltages.
ps. most good marine chargers will offer 10 and 15 amp charging and go to 14.5 or even higher if you need to charge off the genny. 13v is a float charge and about as useful for charging as you know, whatsits on a bull.
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groingo
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# Posted: 31 Dec 2014 04:22pm
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Creeky:
Maybe I read it wrong but you tell me....
https://www.crownbattery.com/en/wp-content/uploads/2013/09/Deep-Cycle-Product-Support -Broch.pdf
Page 6
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creeky
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# Posted: 1 Jan 2015 10:54am
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Groingo: note that the 100% at 12.6 is under a 15 second load. So the load reduces the voltage. Standard 100% charge is 12.7.
What will kill spencerin's batteries is consistently undercharging at too low a voltage. First ascertain that you are getting the proper voltages, for the proper amount of time applied to his battery.
The amps he charges with have to do with the amount of time it will take the batteries to reach the correct voltage. So 20 amps gets him to 14.5 faster than 6a. (The higher initial amperage may also be more effective in getting the electrons past the surface layer of the plates, but that's another discussion) Once the battery reaches "absorb" the charge amperage will begin to drop as the voltage remains constant.
For solar, this is where a good charge controller, I know, they are not cheap, will give you much longer life and better performance out of your battery pack. The controller has been programmed by engineers to properly charge your batteries.
See page 3 of the document you posted. Daily absorb charge voltage is 14.5. Float is 13.5. Equalize is 15.5 and Crown recommends doing an equalize at least monthly. More if you are cycling your batteries frequently and heavily.
The equalize softens the plates and there is good science that indicates it can actually pull sloughed off material back up onto your plates. Crown states that your batteries are only fully charged after an equalize charge. I know from experience that after an equalize my batteries are super charged. They seem to charge faster and respond to surges slower. I like it.
So when spencerin says he's charging with a small 6A charger the thing he should be concerned with first is: did his charger take his batteries to something like 14.5 (or 7.3 as he's charging 6v batteries one at a time). Did the charger then stay in absorption for a sufficient period of time before dropping to float? 3 hours is a good amount of time.
The same for his 100 watts of solar. he needs to be sure first that his solar controller is taking his batteries to 14.5 (as he's putting his 6v in series) and holding it there for several hours.
If he can get a solar controller that is programmed for equalize cycles. This too will extend the lifespan of his batteries.
This is what's important. All I'm saying.
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spencerin
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# Posted: 2 Jan 2015 01:28am - Edited by: spencerin
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All I can say is that on the old battery bank, my cheap charge controller did bring it up to 14.3V-14.4V and then down to 13.3V-13.4V, even with the 100W panel. In my humble opinion, my last bank went bad because I didn't pay attention to water levels and because they are kept outside. They were also the Walmart/EverStart "deep cycle"s, and not more durable batteries.
Interestingly, I bought a $10 voltmeter from Walmart and tested both of the new batteries. The meter said both batteries were exactly at 6.0V....which is dead. My battery charger last charged them to 100% (according to the charger) 30 hours ago. Again, these are 2 brand new golf cart batteries.
I don't know what to think at this point. Something ain't right.
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razmichael
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# Posted: 2 Jan 2015 08:24am
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Spencerin, I may be just missing something here so be tolerant: Most of this discussion seems to be around the voltage needed to charge a 12V bank properly but you start off stating you are charging your batteries (6 volt batteries) separately for some reason. I assume for this you are using a 6 volt charger for this (what type?, what capability? - 2 way, 3 way etc). MtnDon asked why you are charging them separably but I don't think you responded. Are you disconnecting the batteries when you do this? I can't even begin to figure out what type of reading you would be getting putting a 6 volt charger on one battery when still connected to the other. Last post you mention each battery is at 6 volts - dead. Are these not 6 volt batteries? Sorry if I'm just being confused here.
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spencerin
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# Posted: 2 Jan 2015 09:34am
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I arbitrarily charged them separately at 6V, and I also charged them together at 12V. My charger does both 6V and 12V. I don't know what you mean by "3-way", but I assume you mean bulk/absorb/float, in which case, yes, it is 3-way.
I charged them at 12V overnight and took a reading just now. Both are now showing fully charged - 6.3V-6.4V each. But, like before, the cables were only off for a minute, and now the charger is charging them as if they weren't just 100% charged.
Maybe I should return the batteries, but I just don't think the batteries are bad. 
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razmichael
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# Posted: 2 Jan 2015 09:56am
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Quoting: spencerin But, like before, the cables were only off for a minute, and now the charger is charging them as if they weren't just 100% charged.
I don't think what you are seeing is abnormal (depending on the extent). As has been mentioned, the reading right after a full charge is much higher than after things settle to a "true" reading. I know that if I plug in my generator my inverter will automatically start charging the batteries and, even if they are pretty full from solar, it still goes through the cycles albeit quickly. If I turn off the generator and start it again soon, the Inverter will again start charging the batteries although it will not take too long to get it back to 100%. It is very hard to determine what is truly 100% when charging and the chargers will all act slightly differently. As soon as you disconnect the charger the voltage will drop fairly quickly. As Toyota stated:
Quoting: toyota_mdt_tech I imagine the system is seeing the overvoltage from the fresh charge (this is how it knows the batteries are charged). As you remove the charger, the battery settles back down. I suspect they are both fully charged.
Assuming your charger is working properly and strong enough, I would suggest you ease your concerns by charging each battery fully, let them sit and then use a hydrometer to validate each cell rather than a voltmeter. If you are not getting a good charge then try to borrow another charger and try this. At least then you should have a better idea of whether or not you have an issue. I really don't think you can validate your batteries by whether or not the charger starts through the charging cycle again.
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MtnDon
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# Posted: 2 Jan 2015 10:09am
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[quote= use a hydrometer to validate each cell rather than a voltmeter[/quote]
Right!! Seems I recommend that a lot and few seem to listen. Apply a temperature correction and it will be the most accurate SOC you get. The Hydrovolt I mentioned above is very good.
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groingo
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# Posted: 2 Jan 2015 10:35am
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Spec:
You have a lot of variables working here.
First you really want the batteries in series to make the 12 volts you will be using.
Second, battery temp will skew results all over the map, you want to let the batteries warm to at least 65 plus degrees for best charge.
Check your battery charger output, be sure it is not tapering down charge too early resulting in a long duration trickle charge.
Remember, information from the internet will vary, 3 sites will often give three different answers, experience and common sense is the best teacher.
Welcome to the learning process.
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spencerin
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# Posted: 2 Jan 2015 10:57am
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Bought a hydrometer a few days ago, just not here yet.
I did just now charge one of my "old" Walmart batteries I hung onto - last charged to 100% about a week ago. The charger said the battery was 100% 10 minutes after hooking it up. Then, I hooked up the new ones in series that were just charged to 100% overnight - running, and running, and running.....
Temp's not an issue - these are all being charged in 70* temps. The only variable is the battery.
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groingo
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# Posted: 2 Jan 2015 11:42am
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Spencerin:
I just recall the experience I gained earlier this past year while fighting with a lot of problems with my new Crown batteries for three months where they wouldn't hold a charge, finally Crown fessed up that my batteries appear to have fallen through some cracks in their un official recall where a batch of batteries had lead plate problems, returned them and got a new set and problems went away, so defective batteries in todays world where nobody knows where anything came from and made in the USA typically means the parts came from China and some of it was assembled in the US is now the norm.
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creeky
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# Posted: 2 Jan 2015 01:31pm
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Finally. Spencerin. I missed your post on the water levels. Don't worry, you're in good company. If you go on the "solar" forums you will see a "i forgot to water my batteries and..." post frequently. And a useful reminder for me to check my small deep cycle water pump battery.
Your old dead walmart batteries may be showing 100% fully charged due to the resistance coming from the fully sulfated plates. What is the voltage after a day or two of rest anyway?
It's hard to give advice over the internet. The best we can do is give you guidelines. It sounds like your solar controller was working well. As for the 6A battery charger? You haven't mentioned what voltage it's raising your batteries to and how long it's holding them there.
Are you falling into "blinking lights syndrome"? If you're testing your batteries and they are 6.3-6.4 why are you putting the charger back on them? It may be that the charger is (correctly) running a very low amperage "float" charge and that's why it runs and runs and ...
If you're in test mode why not wait 4 or 8 hours and test again and see if there has been a significant voltage drop.
As noted ... consider multimeters for battery charge level testing as a general indication after a substantial rest period.
And, as noted in the 12.6 testing that Groingo pointed out from Crown, a small 15 second load on the batteries prior to testing can help bring the batteries down to their true state of charge.
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spencerin
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# Posted: 3 Jan 2015 02:25am
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Well, I returned the batteries. I just think there was something amiss with one, or both, of them. This experiment is not over yet.....
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