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Old 13-03-2014, 21:20   #1
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pirate Float Voltage Drop From 13.8 to 13.0

Question:

I have noticed the voltage of my house bank has been 13.8 or so almost all the time for months, and 100% mostly, but of late it has been hovering around 13.0V. I don't get why.

House bank replaced last Oct: (4) Interstate 6v golf cart batts

Hydrometer readings from 1.25/6 to 1.30 yesterday.

Dist water added to all cells.

On shorepower with Charles 9000 series 20 amp charger on 24/7. I've never seen it producing more than a few amps as my SOC is usually 90% +, just running frig.

I'm disappointed that at least 3 cells of the 12 are reading below 1.30 after just 6 months and the overall voltage drop is of concern.

Digital Xantrex battery monitor, and analog Blue Seas VM seem to read about the same.

I want that 13.8 float voltage back, if possible.

Thoughts on how to get it back?

As a secondary concern, I have a 100 amp Balmar alt and regulator and was just now reading Calder on the hp required to run that bad boy. I only have 18 hp at full military power. Should I start the engine with the alt off, then turn it on?

Also, I've read many of you don't bother with a separate start batt but use the house bank instead. I have two 12v start batts in parallel so I've got it covered, but curious about just using the house bank when the start batteries eventually die.

Thanks for any thoughts; particularly regarding my lowered float voltage.
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Old 13-03-2014, 21:31   #2
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Re: Float Voltage Drop From 13.8 to 13.0

I may be wrong here but deep cycle batteries like to be discharged more like 30-40% then charged up to full, it doesnt seem like your charger s right for what your doing since your constantly drawing on them. I would recc a Iota dls75 with iq, the charger will keep your batteries properly charged and the Iota is a 1000watt 75 amp power supply as well so your 12v systems run off it instead of your batteries. You may have already weakened your batteries from the constant light hammering but im not sure.
Have you equalized them and maybe shaken or knocked them around to break up any sulfating going on? I set my charge controller to float at 13.2ish with our 420 watts of solar and almost never turn on the big ac charger.

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Old 13-03-2014, 21:40   #3
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Re: Float Voltage Drop From 13.8 to 13.0

The Charles 9000 series 20 amp charger is a ferro-resonant charger which I believe is less-than-ideal for use on a boat.

Much better are almost any of the modern smart chargers which have 3 or 4-stage charging and which have adjustable parameters. Among these, the best on the market for the price are the Sterling/ProMariner Ultra series. They come in sizes up to 60 amps and are quite wonderful.

Re: starting the engine with the house batteries, this can be done, of course. And, the 6V deep-cycle battery bank you have is more than capable of performing that role. I much prefer to have a separate start battery, though, maintained automatically by a voltage-follower device like the EchoCharge of the DuoCharge.

What type of regulator do you have with your 100A Balmar alternator?

The external ones are generally programmable to do all kinds of neat things, like reduce draw on the engine when you need more power (via a simple toggle switch), de-rate the alternator to any percentage you like, provide a 30-40 second delay after you start the engine before the alternator ramps up output, etc., etc.

You're right about wanting to maintain the 13.8VDC float voltage. Be sure all your connections are very clean. And, go easy on use of the tester for specific gravity. It's easy to introduce contaminants when you do the measurements and easy to ruin your clothes, too. I don't really believe they are necessary.

New batteries need a number of discharge-charge cycles before reaching their full capacity. If you're at dockside and plugged in 24/7, it might be a good idea to exercise the batteries a few time and, maybe put them thru at least one good equalization session (15.5-16.0VDC for a few hours).

Don't over-fill them, either. Use only distilled water and fill no higher than the bottom of the filler hole, preferably less.

FWIW,

Bill
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Old 13-03-2014, 22:00   #4
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Re: Float Voltage Drop From 13.8 to 13.0

Check to see if your charge controller performs a routine monthly equalization and consider whether a remote temperature sensor would help, ie if your controller and batteries are at different ambient temperatures, especially in extreme temperatures.

Some experts, like HandyBob the RV guy say that 13.8 V is not a high enough float to maintain batteries properly. Make sure your wiring is properly sized (for the round trip length) and the batteries are as close to the controller as possible. It would be worth reading Bob's blog to see if there is an easily fixable wiring situation. If not, it is the batteries themselves. Contrary to what has been suggested, deep cycle batteries don't last longer by being drawn down to near their 50% max but they will tolerate it.

I have read about Interstate batteries having premature failure problems. Check the "born on" date on the battery, sometimes they are many months old already before being purchased.

There are probably other factors that people can come up with, such as wiring the controller to the batteries so that each battery gets an equal charge, instead of the closest battery getting a higher charge. Or placing them next to a darkly colored hull, or inside the engine compartment...
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Old 13-03-2014, 22:07   #5
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pirate Re: Float Voltage Drop From 13.8 to 13.0

Reg is Balmar MC 612 multistage ...

At the moment float V on the monitor is 13.3

But the 12v dist panel analog gauge reads just under 13.

Thanks guys ... I'll be back tomorrow, just became a grandfather. I'm only 72, I guess it's time.
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Old 14-03-2014, 04:06   #6
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Re: Float Voltage Drop From 13.8 to 13.0

I find sometimes the analog gauges to not be of 100% accurate, check with a digital multimeter.
Can someone explain to me why the 13.8v for float? I have read float is ok as low as 13.0?

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Old 14-03-2014, 04:56   #7
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Re: Float Voltage Drop From 13.8 to 13.0

The Charles 9000 is a super "dumb" single voltage charger. They can chronically undercharge deep cycle batteries that NEED much higher absorption voltages 14.6V to 14.8V.

This charger has ONE voltage setting and that is 13.8V.. There is no absorption voltage on that charger just a float level voltage of 13.8V. Using float level absorption voltages is a mind set most charger makers dropped in the 1960's, for good reason.

Don't even get me going on Charle's Marines "smart" charging 2000 & 5000 series chargers which are anything but "smart"...

If the battery starts to overshoot 13.8V, pretty easy with a ferro charger, the transformer simply turns off for a while. This may be what you are seeing... Put a load on the batts and see if the charger kicks back in..

As Bill said these are a really poor choice if you want to maintain your batteries in a good state of health. 13.8V will never get you to gassing level and will result in faster degradation & capacity loss of your bank. Flooded batteries NEED higher absorption voltages to stay healthy. They then need to drop back to a float level. Having only a "float charger" is just bad for the batts.

I see two choices:

#1 Replace the charger

#2 Replace the batteries every couple of years because the charger is murdering/torturing them into an early death..
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Old 14-03-2014, 05:42   #8
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Re: Float Voltage Drop From 13.8 to 13.0

Has the ambient temperature been constant over this time?

Most chargers monitor the ambient temperature and change the output with the temperature.
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Old 14-03-2014, 06:55   #9
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pirate Re: Float Voltage Drop From 13.8 to 13.0

Quote:
Originally Posted by Maine Sail View Post
... I see two choices:

#1 Replace the charger

#2 Replace the batteries every couple of years because the charger is murdering/torturing them into an early death..
That seems an easy choice to make. The old bank looked very clean.

Duh.

Thank you all for the courtesy and comments.

And Bill, my regulator does appear to be the type that does all things mentioned and has the 3 position toggle. Unlabeled. I will now RTFM.

As I am soon to be off the dock anyway, maybe I don't need a charger at all, considering the AirX and Balmar's capabilities on my 500 hour 2GM20F. Gotta think about that. Maybe a portable gas gen would be more versatile. Got to mull that over.

Opinions encouraged.

On a positive note, here's the NextGen, the new Crab on the block, Master Gaius Crab, of Chicago, on day one of his journey:

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Old 14-03-2014, 07:12   #10
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pirate Re: Float Voltage Drop From 13.8 to 13.0

Ya know, Crab isn't my actual surname but I am crabby, esp when folks want to show me pics of their grandkids. But I get it now. Reminds me of how my attitude toward kids on airplanes changed after I became a dad.

Heh.
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Old 14-03-2014, 07:41   #11
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Re: Float Voltage Drop From 13.8 to 13.0

Small Engine Mode - discussion with link to the picture of the toggle switch: Alternator heat, Regulator Controls, Small Engine Mode

Wiring a new charger From Maine Sail: Marine Battery Chargers - Installation Tips & Considerations - SailboatOwners.com
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Old 14-03-2014, 07:54   #12
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pirate Re: Float Voltage Drop From 13.8 to 13.0

Thanks. Will start reading. Have turned charger off.

Live and learn.
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Old 14-03-2014, 12:42   #13
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Re: Float Voltage Drop From 13.8 to 13.0

Crabbie,

Congrats on your new grandchild!

The Balmar MC-612 MaxCharge is a great regulator. It will do all the stuff you need. Read the manual.

Definitely dump the Charles 2000 charger.

Replace it with either a Sterling or ProMariner Ultra charger or an Iota DLS charger. These both come in several sizes. You can get by with a smaller capacity one (20-30A) if you're spending most of your time at dockside. If you ever need fast charging, like an overnite at dockside, get one of the larger capacity ones.

If you're going to get a portable gas generator, don't even think of anything other than a Honda EU2000i. It will handle a 75A Iota DLS-75/IQ4 or a Sterling/ProMariner Ultra 60A just fine, and is very reliable.

Bill
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Old 14-03-2014, 23:53   #14
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pirate Re: Float Voltage Drop From 13.8 to 13.0

Quote:
Originally Posted by wingless View Post
Has the ambient temperature been constant over this time?

Most chargers monitor the ambient temperature and change the output with the temperature.

Didn't mean to ignore this. Temp as been constant enough as all this gear is in my cabin with me running a heater and living aboard.

Again, many thanks to all. I'm pleasantly surprised at the pricing of systems mentioned. How's that for seeing the glass half full?
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Old 15-03-2014, 00:23   #15
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Re: Float Voltage Drop From 13.8 to 13.0

The reason for a separate starter battery is to insure that you have starting juice. If you have just one battery bank, it is easy to inadvertently run down the charge leaving you with not enough electrons to get the engine started, btdt. An 18hp diesel shouldn't need more than a group 24 car battery so it's not a big expense and don't require much space to mount.
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