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Old 09-07-2018, 07:13 PM   #21
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I’ll clarify a bit further. While there are many ways to test your batteries, and the manufacturers will recommend some specifically, my comments were meant to clarify what works as a daily check. I have the victron monitor. Unfortunately, the victron does not do a great job of accurately measuring the charge going in to the battery. It will simply call the battery full when the charge rate slows to your specified parameter. The monitor will quickly develop a discrepancy in charge percent if you are unable to top off the system for several days and this issue is described in the manual. Yes, I have properly set up the victron for my system using the specific parameters provided by the battery manufacturer.

I have found that monitoring the voltage on the victron, with no charge voltage, but a light load, gives me the most accurate status of my current charge. Is it perfect, no. But it is better than the readings I get from the Victron for charge status. Since I look at this quite often daily, I am well aware of how my system voltage changes both while charging and while discharging at various rates. Your system charge rate can also tell you a lot about the current charge of your battery. If I am in bright sun, but the charge rate is only 8 amps, I know my batteries are pretty full. On the other hand, if the bulk voltage is only 13.8 and the battery is taking 55 amps, I know they are pretty low, since I am not yet up to full bulk voltage and my amps are maxed.

I have AGM sealed batteries, so checking specific gravity is not an option. Not to mention that it is far more time consuming than a quick glance at the meter.

While a load tester may not be the best way to test a battery, it will in fact quickly identify some bad batteries, whether a starting battery or a deep cycle. It won’t identify deficiencies due to sulfation, for instance, but will identify dead and shorting cells quite effectively.

So , while elitists may find my answer less than perfect, it was designed for the real world use of your battery. If you have a battery test bench which can accurately draw a constant load until dead and measure that time, then that would be ideal. I personally don’t have that and it would be useless for daily monitoring even if I did. However, I do have a Victron and am simply stating from personal experience as someone who is living off the grid with a solar/agm system, what works and what doesn’t. Your mileage may vary.

Charlie
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Old 09-07-2018, 09:00 PM   #22
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Rjpetr65

Some of your questions exceed my "pay grade."
But you hinted at one issue that may be important to explore.

You asked about charging WITHOUT the benefit of shore power.
HMMMM.

Once again, you open the door to sulfation....a problem from routinely UNDERcharging the battery bank.

In brief, sulfation is a problem common in "3rd world countries" that rely entirely on solar but whose users essentially over-tax the system for long periods. I don't mean abuse the batteries...just never let them get fully charged. Demand exceeds supply by just a little. The result is that the batteries, never fully charged, sulfate.

I think I shared this Battery University article on sulfation previously, but pay attention to the notes on solar/wind generated power never quite fully charging the batteries.

Of course, your generator can do the job given enough time...and racket, and gas, and... But nothing quite beats the grid. The short answer is that, with your current configuration, you'd be wise to plug into the grid every few days. The math in your situation suggests undercharging over extended periods.

OR....
Only you know your habits, but I have a recommendation. Upgrade your solar big time. Go from 150 watts to, say, 400. In good sun, 400 watts of solar will deliver 30 charging amps per hour. Even at a conservative 30% overall efficiency, 12 hours at 9 amps = 108 amp hours. In FL, more like 50%, you're hitting the battery bank with 180 AMP HOURS of potential charge. In other words, ENOUGH. If you are consuming 100 to 120 amp hours out of the bank on a daily basis, the solar array will FULLY charge the battery bank, then the charge controller will ease off to a trickle.

Again, deliver ENOUGH charge to overwhelm demand. My 100 watt panel delivers 7.5 amps in good sun. If I consume 40 amp hours overnight, that panel has my battery charged in just over 5 hours. And the CO sun is so strong that in Summer, my panel is delivering almost full power by 9 AM. So, by 1 or 2 in the afternoon, my battery is fully charged, and the rest is gravy. I can use "all the power I want to" during the day...stereo, etc., but if I shut down use by about 6 PM (2 to 3 hours before sunset), I go to bed with a full battery.

My guess is that a few tweaks to your solar array may allow you to add more panels using most of the same equipment. You may need to rewire to a 4 or 6 AWG from the panel array to the controller then on to the battery. A trick I heard is to run panels in series rather than parallel to boost voltage and limit current. Something to explore. This Facebook group, "Boondocking with Solar," might be helpful. There are some people there who, unlike me, actually KNOW this stuff.

Again, this comment is based on the hint that you may go long periods without plugging into the grid. If that's the case, it's time to dig deeper into the nuances of solar and batteries and make sure you don't starve your battery bank of the full charge it needs on a regular basis.

OK, I'm done.
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Old 09-08-2018, 10:18 AM   #23
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Amp Hours or State of Charge

Quote:
Originally Posted by CharlieS3 View Post
Iíve lived exclusively on my solar for the past month. I monitor both the amps in and out,as well as the voltage, daily.



The voltage is the most reliable indicator of your charge status. There are several online charts that will indicate your percent of discharge based on the current load and the voltage at that load. These tend to be most accurate at low loads.



Something is absolutely wrong in your system. Most likely, Either one or both of your batteries are bad, or your charger is not working correctly. What is your voltage right after charging? It should be in the 12.8 range or higher with minimal load. How much battery capacity do you have at 12 volts? Two batteries is typically around 200 amps and your40amp load should draw you down about 20%. If your voltage is not starting at 12.7 or 12.8 with minimal load, your charging system is not working correctly or the battery is bad.



Fully charge your batteries using a different charger, then test them with a load tester. Any battery shop has one. These apply a heavy amperage load. A good battery will maintain good voltage during the test. A bad battery will drop the voltage quickly.



If that passes, check the voltage being put out during charging. Bulk charge should be at least 14.4, depending on the temp.



Iím a power hog. But I have 800 amps of battery and 860 watts of solar. I burn about 170 amps a night. my voltage willtypically drop to about 12.5 by morning.



My 2000 watt inverter actually has about a 5 amp overhead. While watching Tv at night, dish network, with a few lights, I am burning about 15-20 amps an hour. I burn about 60 amps each night with my cpap.



You are starting with less than a full charge. My system tapers to about 4-5 amps when full. However, it is 4 times bigger. Your batteries are not full until it tapers to 1 or 2 amps.



Finally, you may have other battery drains beside the inverter. My motorhome uses about 4 amps an hour with nothing obviously on. Sounds minimal, but thatís a whopping 96 amps a day. The fridge, alarms, etc.



Charlie


Iím at 12.8 after fully charging on shore power. If I use my gen to charge from 11.9v after 3 hrs Iím still pulling 5.0A or so from the gen. Based upon that Iím probably sitting at 12.65v instead of the full 12.8 so I may be undercharging a bit (although most state of Charge charts show anything over 12.6 as 100% so I wasnít concerned at 12.65) but the last few amps takes forever on the gen. 1.5A is considered a trickle charge and it doesnít get there in 3 hours. The charge converter is a 55A at 13.6v. I have been on shore power for a few days and my battery monitor shows 13.7V and 1.5A which is perfect. So my battery monitor appears to be working fine along with my charge converter.

The battery monitor is a cheap one made in China. The Voltage reading concurs with my hand held meter though. So thatís good enough. The monitor simply counts the amps over time used to show AH, it doesnít take anything else into account except that simple calculation. Everything is connected through the shunt for the battery monitor even the inverter and panel.

My panel is a Renogy 150A with a 20A Mppt controller. I usually get 8.5A on a sunny day. I was concerned that running the gen may be leaking current back into the panels instead of the battery and thatís why it was taking so long to charge. But I hear the controllers job is to prevent that. I may pull the fuse on the solar panel and try charging that way to see how long it takes to charge.

My setup isnít great but itís still decent. I had no solar at all when I bought the RV and (2) 12V 80AH marine batteries before I bought the golf cart batteries. When I watched tv with the old batteries, I only got 1 hour max before I had to turn it off due to low voltage. At least I get 3 Hours out of the new 6volt batteries.

I may poke around with a multimeter. Iíll have to buy one with a current clamp tho. When I do that, where should I test current?
Clamp it on to the pos side of the battery with the inverter and tv on?
Where do I connect it to test my charge controller? Also on the Pos side of battery?

You guys have all been great and I appreciate all the info.
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Old 09-08-2018, 11:10 AM   #24
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Quote:
Originally Posted by Rjpetr65 View Post
Iím at 12.8 after fully charging on shore power. If I use my gen to charge from 11.9v after 3 hrs Iím still pulling 5.0A or so from the gen. Based upon that Iím probably sitting at 12.65v instead of the full 12.8 so I may be undercharging a bit (although most state of Charge charts show anything over 12.6 as 100% so I wasnít concerned at 12.65) but the last few amps takes forever on the gen. 1.5A is considered a trickle charge and it doesnít get there in 3 hours. The charge converter is a 55A at 13.6v. I have been on shore power for a few days and my battery monitor shows 13.7V and 1.5A which is perfect. So my battery monitor appears to be working fine along with my charge converter.

The battery monitor is a cheap one made in China. The Voltage reading concurs with my hand held meter though. So thatís good enough. The monitor simply counts the amps over time used to show AH, it doesnít take anything else into account except that simple calculation. Everything is connected through the shunt for the battery monitor even the inverter and panel.

My panel is a Renogy 150A with a 20A Mppt controller. I usually get 8.5A on a sunny day. I was concerned that running the gen may be leaking current back into the panels instead of the battery and thatís why it was taking so long to charge. But I hear the controllers job is to prevent that. I may pull the fuse on the solar panel and try charging that way to see how long it takes to charge.

My setup isnít great but itís still decent. I had no solar at all when I bought the RV and (2) 12V 80AH marine batteries before I bought the golf cart batteries. When I watched tv with the old batteries, I only got 1 hour max before I had to turn it off due to low voltage. At least I get 3 Hours out of the new 6volt batteries.

I may poke around with a multimeter. Iíll have to buy one with a current clamp tho. When I do that, where should I test current?
Clamp it on to the pos side of the battery with the inverter and tv on?
Where do I connect it to test my charge controller? Also on the Pos side of battery?

You guys have all been great and I appreciate all the info.
As I read more of your posts it appears like you are experiencing what I was until I increased wire size from converter to battery. With the #8 awg wire from converter, which is mounted near the rear of my TT charge rate never stayed in boost or bulk very long. Even if batteries were significantly discharged charging current dropped off fast.

I ran a #4 awg wire from converter to batteries and upgraded the chassis grounds on both ends. Total wire length with all the turns and obstacles routed around is just over 25 feet.

Now, when I start my generator I see as high as 55 amp flowing into the batteries and after a short while it starts to taper off to 10-15 amp for the next few hours. It takes a good 8-10 hours before the charger reaches the storage mode where voltage remains at 13.25 v while under generator/shore power.

Before I upgraded wire size voltage drop across the OE wire was "telling" the charger that it had reached max voltage for bulk charge rate and it then switched to absorption rate long before it should have.

Victron has a easy to understand explanation of what happens to a lot of batteries being charged by solar. In summary, sun is only available so long, output is limited, battery is never FULLY charged, it sits in partially charged state for long periods, and eventually it loses capacity.

Call it what you want, equalization, desulfation, peaking charge, at some time one has to either plug in, run generator, or increase panel capacity to both carry load while sun is out and charge batteries more fully.

After I upgraded my batteries power my TV and sound system, lights, and furnace (morning warmup) for up to 3 days (240 ah total capacity) before I had to run generator.

I just added 160 watts of Solar which will more likely than not cut generator time drastically. When I will need to run generator I'll do so until the voltage on my monitor drops to float voltage at least once per week. Most of the time my TV can keep a charge flowing into the batteries while driving. My smartphone show an average charge current of 3-4 amp while driving. In my research this is pretty close to tail current for a fully charged battery along with refrigerator electronics draw, etc.

If you arent getting more than a few hours of TV time start looking at how much current is reaching the batteries and for how long. When inspecting wires and connections dont forget that there are most likely two ground wires and connections to frame. On my trailer the ground connections were rusty and very questionable. I replaced the wires with #4 awg and installed ground lugs with conductive grease to prevent corrosion and improve quality of connection.

Just sharing my experience with factory wiring from converter to battery.
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Old 09-08-2018, 11:18 AM   #25
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Amp Hours or State of Charge

Thanks Titan. I will look at the grounds and cable I suspect that they are probable ok since the batteries charge great on shore power. If I had ground issues or cable probs I would expect the issue to show up regardless of being on gen or on shore-power. I do need to see how much current is reaching the batteries tho and for that I need a clamp on meter which I donít have yet. I will post what I find when I get the meter.
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Old 09-08-2018, 12:39 PM   #26
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A few of you mention sulfation which is probably occurring due to the fact that I have 5.0 amps remaining to go when I turn he gen off however Two things:

1. The voltage dropping to 11.9v after a few hours of tv time has been happening since I bought the batteries 2 months ago. So Iím not sure sulfation is the issue although it could be getting worse. These are the batteries I have https://www.batteriesplus.com/productdetails/sligc110

2. If I am only pulling 20AH overnight, my 150W panel running at 8.5A for 3 hours should be enough to charge it back up. Iím not sure that throwing 450W of solar at this is gonna solve it. It will pump that 20A back in faster but 20A should be easily replaced with a few hours of bright sun and my current solar setup.

I am considering changing the cable from inverter to batteries to a 2Awg from the 4 awg that came with the 1500 watt inverter. Itís only about a foot long cable though.
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