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Old 20-08-2014, 13:53   #1
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Charging Batteries

I've not seen this before. When charging my batteries with shore power, the charger ramps up to 14 volts and then drops down to a trickle when the batteries reach their max charge.

When cruising this week, I ran the motor to charge and only saw 13 volts. Here I expected to see 14 volts to start with.

I have a honda 2000 companion generator and hooked that up with my shore power cable. Gen put out 120VAC but the charger would only go up to 13 volts.

So, after returning home, I plugged into shore power, turned on the battery charger and the expected 14 volts is displayed.

Anyone know why this is happening? I used the same shore power cable with shore power and the honda generator.

Thanks

Steve
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Old 20-08-2014, 14:01   #2
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Re: Charging Batteries

What is your shore power amps connection . My charger inverter gives more output at the dock than my Honda 2000 can put out when powering my AC charger . Your motor charging system depends on the regulator for your engine altenator. Some altenators use an external charger that controls the output depending on charge/discharge state of the batteries. Anyhow your engine charging system is different than your AC charger.
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Old 20-08-2014, 17:04   #3
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Re: Charging Batteries

Get a proper marine regulator for your alt and you will see nice 14.3 when motoring.

Plain alt regulators are only good to charge the start battery.

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Old 20-08-2014, 17:17   #4
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Re: Charging Batteries

the question is: why is the charger voltage different when on shore power versus the Honda.

I don't know as that Honda would provide more than enough to max out almost all battery chargers. And even if it didn't once the state of charge got high enough why would the charger be able to get to the same voltage.
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Old 20-08-2014, 18:04   #5
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Re: Charging Batteries

Honda's are invertors? Are they pure sine wave, or modified?
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Old 20-08-2014, 18:10   #6
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Re: Charging Batteries

Does it matter as far as the charger changing AC into DC at 10% of the original wattage and not being able to get it to the same voltage?

It appears it does, but why?

There must be 100s of people on here who have charged with a Honda. I never have used a Honda but have used a cheap 800W portable generator on my boat with the battery charger. The charger put the correct voltage and I used it to equalize my batteries out on the mooring.
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Old 20-08-2014, 18:10   #7
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Re: Charging Batteries

What size is the shore charger?
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Old 20-08-2014, 18:14   #8
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Re: Charging Batteries

It's a 40 amp charger. 30 amp cable. I'm pretty sure the draw on the charger is not more than 13 amps. The generator does not run as hard as it can on the Eco mode
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Old 20-08-2014, 18:21   #9
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Re: Charging Batteries

My only thought is to figure out how to measure the charger AC input at the charger comparing the shore power supply and the Honda supply. Both of course while under load and charging.

This may require the charger cover to be open or something and then you must be extremely careful. If not comfortable with this don't do it and hire an electrician.

I'd start by reading all the tech documentation on the charger and Honda.

Not knowing what impacts charger voltage output, I would guess that input voltage matters and might guess that the dock supply is higher than the Honda.

I would worry about the alternator charging later as it is a separate system.
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Old 20-08-2014, 21:08   #10
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Re: Charging Batteries

Quote:
Originally Posted by sailorboy1 View Post
the question is: why is the charger voltage different when on shore power versus the Honda.

I don't know as that Honda would provide more than enough to max out almost all battery chargers. And even if it didn't once the state of charge got high enough why would the charger be able to get to the same voltage.
Yes, our honda 2000 supplies more than enough juice for my 70 AMP 12 volt charger. You need to make sure that you turn off eco mode... at least when the charger is putting out its full amps. Not doing so will cause fluctuations in the voltages you get on the charger. In fact, mine won't even charge right with it turned on at the beginning. Once the charger ramps the amps down to around 30 or 40 I can switch on the eco mode.

Also, I'm just going to parrot something I have heard mainesail say over and over... check your connections for corrosion. Check the shore power cable, the shore power inlet (and clean them), the battery connections, etc...

Its normal for a charging system of any kind to start out putting a ton of amps in and then as the batteries get full see that go down pretty quickly, since as the batteries get charged they accept less current. For example, on our boat its normal for me to see both a ramp down in the amount of amps being put out by the charger at the same time I see less amps going into the batteries - kinda inverse with the voltage going up. So when you say "drops down to a trickle when the batteries reach their max charge." it would be helpful if you mean volts or amps (and exactly how much trickle are we talking about).

The voltage will change depending on what charging stage you are in. For me, I start out at 14.8 volts but I don't see that on my meter right away. It takes a while for the voltage to ramp up to meet that 14.8 volts. Then, as soon as it sees the batteries hit 14.8 it switches into float mode at 13.2 volts.

I agree you need to solve one issues one at a time by putting the alternator in a separate category. You will go crazy otherwise. Personally, I have found issues that at first appear to be related have completely different causes and solutions once you break the system down into logical components and look at the issues independently.
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Old 20-08-2014, 21:11   #11
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Re: Charging Batteries

Check the power factor of the charger..


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Old 20-08-2014, 21:32   #12
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Re: Charging Batteries

Quote:
Originally Posted by Scott Berg View Post
Check the power factor of the charger..


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Thats true... my mastervolt has power factor correction.
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Old 21-08-2014, 03:23   #13
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Re: Charging Batteries

I've also been reading about neutral bonding with the honda gen. I haven't opened my unit up to see if it is. May that cause this issue?
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Old 21-08-2014, 05:34   #14
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Re: Charging Batteries

Captain Steven,

You may be chasing your tail. That is, you may not have a problem at all.

First, your measurements as noted in the first few posts cited differences you were seeing at different times (while away from the dock and at the dock), maybe with different states of charge (SOC) of the batteries.

Second, there's no way that 40 amp charger draws 13 amps, unless it's the most poorly designed one on the planet. 40 amps @ 14 volts = 560 watts.

560 watts / 120 volts = 4.7 amps AC. Even allowing for only 50% efficiency, that charger isn't drawing more than 10 amps, which the Honda EU2000i can easily put out.

Next, where are you measuring the voltages? Direct at the batteries with a reliable voltmeter?

What kind of battery charger are you using? Make? Model?

I think I'd start over with new measurements -- taken under the same conditions and at nearly the same time with a reliable meter -- before deciding that you have or don't have a problem.

Bill
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Old 21-08-2014, 05:49   #15
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Re: Charging Batteries

I've been charging my battery systems almost exclusively using a Honda 2000 for six years now. I have two banks a 12 volt house bank and a 48 volt electric propulsion bank. They are charged by three stage chargers (promariner 12 volt, Zivan Ng-1 & Dual Pro 4 for the 48 volt bank.). I have never had a problem with the chargers going through a full charge cycle or reaching full charge just using the Honda. Except one time and that was when both banks over drew on the current demands of the Honda output: THE BIANKA LOG BLOG: LESSON LEARNED: Fear and Panic in East Hampton
But, that was due to having both chargers in operation (and a severely depleted 12 volt bank) whose charger was drawing more current than the Honda could provide. If your charger goes through a complete charge using the Honda I doubt you have a problem.
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