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Old 24-09-2017, 10:18   #1
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inverter issues

I'm having some inverter issues and wondering if someone has some troubleshooting ideas. My house bank consists of 2 golf cart batteries in series, and puts out enough current to start my engine (most of the time. Sometimes the starter just clicks, and then I connect my jump starting battery to the house bank to turn the starter)

1. When I connect my solar panels to the bank, the voltage fluctuates on my analog voltmeter (not the digital voltmeter), and the inverter seems to cycle between on and "shutting down" mode. If I remove the solar panels from the circuit, the inverter stays on.

2. I have a cigarette style USB charger, which charges my iphone fine in my car, but not on the boat. The voltage at the cigarette socket reads 12.4 volts. I also have a cigarette style inverter that turns on in my car, but doesn't in the boat.

Any troubleshooting ideas would be greatly appreciated.
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Old 24-09-2017, 10:32   #2
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Re: inverter issues

It sounds like there is the possibility that your batteries are not getting fully charged from either being too old (cannot accept a full charge any longer) or the charger is not getting up to sufficient voltage to top off your batteries. Standard lead-acid batteries typically do not last more than about 5 years...yes, there are exceptions.

A digital multimeter will get you a clearer picture of the status of your DC system.

Most inverters have the ability to shut themselves down when the DC system voltage drops below a specific voltage so that the inverter does not completely kill the batteries. This is my first guess on what is happening to your inverter. A sudden big load such as what comes from your starter motor can cause a voltage drop in your DC system shutting down your inverter.
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Old 24-09-2017, 10:38   #3
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Re: inverter issues

Ideas? Seriously:
1- Hire an electrician
2- Read two or three of the classic 12v marine electrical system books.

You're going to need to check out all the components and connections, and those are the only two ways to really do it practically and properly.
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Old 24-09-2017, 14:19   #4
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Re: inverter issues

Quote:
Originally Posted by David M View Post
It sounds like there is the possibility that your batteries are not getting fully charged from either being too old (cannot accept a full charge any longer) or the charger is not getting up to sufficient voltage to top off your batteries. Standard lead-acid batteries typically do not last more than about 5 years...yes, there are exceptions.

A digital multimeter will get you a clearer picture of the status of your DC system.

Most inverters have the ability to shut themselves down when the DC system voltage drops below a specific voltage so that the inverter does not completely kill the batteries. This is my first guess on what is happening to your inverter. A sudden big load such as what comes from your starter motor can cause a voltage drop in your DC system shutting down your inverter.
Thanks for your response. I think I've been able to narrow it down.

It's not the batteries, as I checked the specific gravity in each cell, and they were good. Further, I was able to start my engine from them, and if they can start an engine, they shouldn't have a problem putting out enough current to charge a phone.

I checked my inverter's manual, and it had the minimum voltage at 10V and maximum at 17V, and the voltage at my batteries is 12.4V, so I didn't think low battery voltage was causing it to shut off.

I did, however, notice things not working exactly right on various circuits (cigarette outlet circuit, inverter circuit, and voltmeter circuit), which makes me think it's the bus bar or the connections between the bus bar and the battery.

That's it for today, as I'm going to go fishing.
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Old 24-09-2017, 14:39   #5
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Re: inverter issues

A bank may show high voltage at rest but drop very low once a substantial load (high amps discharge) comes online.

Starting an engine doesn't drop a large bank's AH capacity by even .001, yes high amps, but only for a few seconds, no confirmation of AH capacity.

Specific Gravity says nothing about State of Health, both SG and volts look fine but the bank is FUBAR.

Not saying yours is, just that a proper 20-hour load test is the only way to gauge remaining capacity or overall SoH.

By all means test everything else too, just don't think you're out of the woods with the bank.
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Old 24-09-2017, 14:43   #6
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Re: inverter issues

How big are the loads, especially off inverter?

What make/model battery and how old?

How usually charged, make/model controllers?

Any battery monitor? How do you avoid going below 50%, how do you know batt gets charged to 100%?
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Old 25-09-2017, 08:03   #7
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Re: inverter issues

Quote:
Originally Posted by john61ct View Post
How big are the loads, especially off inverter?

What make/model battery and how old?

How usually charged, make/model controllers?

Any battery monitor? How do you avoid going below 50%, how do you know batt gets charged to 100%?
- Off the inverter, the only load is my laptop, at around 45 watts

- I have 2 Trojan T105s that are 2 years old.

- They're charged with 2 ~100 Watt solar panels. The controller is a Sunkeeper-12. When I'm on shore, I also have a multi-stage battery charger.

- I don't have a battery monitor and I don't really check the state-of-charge regularly. I don't draw that much current from them -- it's mostly things like my computer, depth sounder, VHF and cabin lights. Occasionally, galley water pump, bilge pump or tiller pilot.
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Old 25-09-2017, 08:57   #8
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Re: inverter issues

Not sure what's up with the hard wired inverter that is odd. It's possible that the interaction between the solar charger and the inverter is causing an issue. Normally the battery acts as enough of a buffer to eliminate that but it could be an issue. You can put a meter on the solar connection to the Batt and see what is happening when the inverter cycles on and off. You said the voltage fluctuates does it go very high or very low?

On the 12V outlet is the polarity correct?
Do you have a simple device you could plug into the outlet like a incandescent spotlight etc. It could be that any current the circuit drops out do to a poor connection etc.
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Old 25-09-2017, 10:00   #9
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Re: inverter issues

So the inverter works when the solar panels are not connected

The inverter does not work when the solar panels are connected.

If above statments are correct then the solar charging system appeaars to be discharging the batteries rather than charging them. This could be confirmed by measuring the voltage at the battery with a digital voltmeter with and without the solar charger connected. If the battery voltage drops when the charging system is connected, the charging system is defective.
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Old 25-09-2017, 10:05   #10
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Re: inverter issues

Quote:
Originally Posted by asahi View Post
- They're charged with 2 ~100 Watt solar panels. The controller is a Sunkeeper-12. When I'm on shore, I also have a multi-stage battery charger.
This is your problem.

Your solar panel system is not working properly. Either you have multi-crystalline panels that soak load on the shaded cells, do not have a controller, all of the above, or the diodes are screwed.

Try disconnecting the solar panels entirely from the system, charging the batteries using a smart charger to full charge, and see if the problem persists with the solar panels disconnected when you know the batteries are full.

A good smart charger brand is the "Genius" "Wicked smart chargers" brand. They're cheap, you can get a 1.1A for around $40. Might take a week or two to get your batteries to full with shore power, but if it says the battery is full then you know it's full.

Once you add solar to the mix you are likely to have problems if you don't have proper diodes and a proper controller. This problem seems to be quite common.
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Old 25-09-2017, 15:52   #11
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Re: inverter issues

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Originally Posted by mr-canada View Post
A good smart charger brand is the "Genius" "Wicked smart chargers" brand. They're cheap, you can get a 1.1A for around $40
A good marine-quality shore charger is as basic as a bilge pump. 1.1A is barely a trickle, sorry but no.


Quote:
Originally Posted by asahi View Post
I have 2 Trojan T105s that are 2 years old.
225AH pretty small bank, 30-40A would be the minimum I would recommend, double that for future expansion or switching to a high-CAR chemistry, e.g. AGM

Two years is short if well-coddled, long if grossly abused, are you otherwise sure they're in good shape?


Quote:
Originally Posted by asahi View Post
The controller is a Sunkeeper-12.
I suspect this bit if there isn't a miswiring issue.

A Victron 75/15 MPPT is under $100 if you want to try, can buy from an outfit with a good return policy then you'd only be out postage.

But if you decide to keep it, great value, likely get a 15-20% boost in total output from your existing panels, room for expansion, really good adjustability and tracking/logging from your smartphone if you decide to get the dongle later.

But maybe a more certain diagnostic will come along. . .
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Old 26-09-2017, 06:24   #12
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Re: inverter issues

Thanks for all the responses. So I think I've figured my problem with the inverter.

I had some loose connections at my bus bar. This resulted in:
- the inverter to cycle on and off
- the voltmeter to act erratically. It was swinging from like 10V to 13V a few times a second

The issue with my cigarette style inverter was a corroded connection on the back of the cigarette outlet. I was getting 12.4V there, but I guess the corrosion lead to too much resistance.

The reason why I thought it was the solar panels was because they're on the same terminal on the bus as the battery. When I removed the solar panel connection, it must have temporarily improved the loose connection between the battery and bus.

Also, my shore charger is rated at 5 amps, and charging for a few hours usually gets it to the Float stage for me at least.
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Old 26-09-2017, 09:16   #13
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Re: inverter issues

Quote:
Originally Posted by asahi View Post
>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Also, my shore charger is rated at 5 amps, and charging for a few hours usually gets it to the Float stage for me at least.
Why going into float is NOT full: by Maine Sail

Full is when the battery gets to 2% of its amp hour rating.
Actually 2% or less AT ABSORPTION VOLTAGE/14.4V +

AT ABSORPTION VOLTAGE is the part everyone tends to forget. Just because you are in float does not mean the battery actually got full. There are far too many dumb "smart" controllers, chargers, regulators that use simple egg timer programs that may NOT match your bank for the proper transition to float from absorption...

Less than 2% AT FLOAT voltage is not always full unless it previously attained less than 2% at 14.4V +........

It should also be noted that 2% is not technically full for many banks but is rather "cruiser full", which means close enough to deem it full.
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Old 26-09-2017, 12:34   #14
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Re: inverter issues

​Standard ciggie sockets are a dangerous abortion, *avoid like the plague!*

Blue Sea has a nice socket design that twist-locks with the matching plug, but will also accept standard ciggie plugs for smaller (<10A) loads.

Also the BMW/ Hella/ Merit/ Powerlet "Euro-style DIN" (ISO 4165) style is very robust.

Anderson plugs for high amps. If you standardize on one of the last two types, there are adapters for devices with ciggie plugs.
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