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Old 27-02-2008, 06:53   #31
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The Hygrometer reading is not good, I think that may say it all
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Old 27-02-2008, 06:58   #32
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Thanks, Mike. I had always thought the hygrometer was the most accurate way to assess a battery's health. Good to see that thought was in the right direction.

Off to Miami to get some new Trojans. Bye bye money!
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Old 27-02-2008, 07:01   #33
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In the interest of accuracy:
Hygrometers are instruments used for measuring Humidity (relative humidity of air).
Hydrometers are instruments used for measuring Specific Gravity (relative density of liquids, such as battery acid).
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Old 27-02-2008, 07:03   #34
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In the interest of accuracy:
Hygrometers are instruments used for measuring Humidity (relative humidity of air).
Hydrometers are instruments used for measuring Specific Gravity (relative density of liquids, such as battery acid).
Thanks, Gord.

I hate mixing those two up. Of course, I was using the HYDROmeter. ha ha
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Old 27-02-2008, 07:04   #35
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Gord,

Point well taken, I was on a conference call as well as dealing with another issue and typing this. That is the problem with multitasking...

One other point Sully, there still may be a problem in there somewhere, be careful putting in new batteries if you still have an issue..You think your pissed know, what if you fry some new batteries.. Good Luck
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Old 27-02-2008, 08:42   #36
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Hygrometer most accurate--but the acid stratefies and is not uniform when batteries are charging, sometimes it can take 12+ hours before the acid fully circulates in a battery cell and evens out, giving an even result in the hygrometer.

You've still got multiple charge controllers (solar & Freedom) connected up to the same banks--and thus to each other--at the same time? They don't know how to play nicely in the same sandbox, AFAIK. They'll drive each other nuts.
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Old 27-02-2008, 08:52   #37
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Originally Posted by ssullivan View Post
Thanks, Mike. I had always thought the hygrometer was the most accurate way to assess a battery's health. Good to see that thought was in the right direction.

Off
to Miami to get some new Trojans. Bye bye money!
Officially, I'm not on this site but I just wanted to tell Sully that he can find condoms fairly cheaply in Canada.
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Old 27-02-2008, 10:30   #38
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And the mystery continues!

Terminal to terminal multimater voltage on house bank: 13V

Voltage as read by the Freedom shore power charger: 12.5V

Hygrometer reading: 1.99 (dead)

Charge controller for solar: one blink, indicating battery well below bulk charge.

#@()*$ #@) &%*@# (tha't me swearing up a storm)
I'll assume that you meant "1.199" on that hydrometer reading since the range for a lead acid battery is 1.10 to 1.265
If so, that represents about 60% charged, not too unreasonable for having the fridge run continuously all night long. Certainly not "dead"
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Old 27-02-2008, 11:40   #39
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Specific Gravity Test

1. Do not add water at this time.

2. Fill and drain the hydrometer 2 to 4 times before pulling out a sample.

3. There should be enough sample electrolyte in the hydrometer to completely support the float.

4. Take a reading, record it, and return the electrolyte back to the cell.

5. To check another cell, repeat the 3 steps above.

6. Check all cells in the battery.

7. Replace the vent caps and wipe off any electrolyte that might have been spilled.

8. Correct the readings to 80 Deg F:
* Add o.004 to readings for every 10 deg above 80 deg F
* Subtract o.004 for every 10 deg below 80 deg F.

State of Charge = Specific Gravity @ 80 Deg. F (Approx. O.C.V.)
100% = 1.265 or more* (12.7V) * Trojan Battery specifies 1.277 ( 0.007)
75% = 1.225 to 1.240 (12.4V)
50% = 1.190 to 1.20 (12.2V)
25% = 1.155 to 1.175 (12.0V)
Discharged = 1.10 to 1.120 (11.9V)
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Old 27-02-2008, 11:56   #40
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Thanks Gord.
Plus to add if not already obvious, you need to test for full charge with the Hydrometer after the battery is fully charged. Just incase you didn't.
Next point. It is usually ver unlikely that a bad battery will ever allow the charger to go to float mode. If the battery is not reaching full charge, the charger will happily keep pouring in the current till it does, which it will never. So as I said, don't go down the road of replacing banks just yet. The charger going to float suggests the banks are OK and some other issue exists.
One major point is, have you calculated how many Ahrs is being drawn off by the Fridge/freezer over night. It maybe that this is not being very efficient. As I said, 11.5V is not an issue if it is being measured under load. It will take some time for the batteries to come back up to there actual rest voltage after the load has been removed.
Sully, go buy a link. The best value for money right now. unless that charger can tell you what Ahr value has been put in and what Ahr value has been pulled out.

Oh and one other point: You need to ensure that chargers charging parameters are all set up correctly. It may not be set to correctly charge FLA batteries and maybe going into absob. adn float mode too early. Temperature setting is critical for a starter. What is the temp set to. This alters the voltage point dramaticly.
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Old 27-02-2008, 12:13   #41
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Hmm, I've got a few random thoughts. (Temporary solution: If you are in the process of moving the boat and need the house bank charged you can use jumper cables, or make a set of cables to parallel the house batteries with the starting batteries so you are charging while underway. I wouldn't do it with a gas engine though, sparks in the bilge are bad.)

It sounds like you have two issues, the first is a drain on the system that kept the 110v charger working overtime, and is your voltage difference. The other is lack of connection between the alternator and the house bank, if the grounds are not shared by both systems the house bank won't charge even if everything is hooked up otherwise. Its like trying to jump start a car with only the positive cable, open circuit.

Do you have a battery switch to start from the house bank, if not you will want a switch that will start from each bank. Ideally you charge only one battery at a time, as the weaker batteries in the bank drag the strong ones down... and the regulator cuts off late when it sees the voltage weaker battery. Ideally the switch is such that you can flip from 1 to 2 without opening the circuit, if it opens its the same as turning off with it running, fried diodes! Start on the starting battery, turn to the house bank once running and the plates of the house bank will thank you.

Turn to off after you are done running the engine and the starting battery will stay charged.

If you already have the switch, take it apart and make sure the contacts are clean! I've seen the knobs pop off and people put them back on wrong so they always charge on both, or one bank is still on when it reads off. If everything is unhooked, ohm out between the poles if the switch is in question.

Check the ohms of the ground cables. The voltage difference between ground at the end, and between the terminal of the battery would show its self if the cable its self is at fault. Clean everything and slather the connections with dielectric grease or other corrosion preventative goop.

I'd also turn everything off and check for discharge at the batteries. Pull one of the cables feeding the fuse box and put a test light between the battery and the cable... if it lights up you've got something discharging. If you've got a multimeter with a fuse you can check the amp draw and an internal resistor. With everything off there should be no draw, or if your meter is excellent less than a three hundred milli-amps. At that rate a single starting battery will still start you up after a month and a half of discharging.

If there is no draw, hook up each of the chargers one at a time and see if they are using power, or if a combination of two causes something funny to happen. I'm betting you'll find something dumb like a corroded bilge pump connection thats trying to make a battery in the bilge...

I hope this helps you...
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Old 27-02-2008, 13:07   #42
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Well, I hadn't seen the responses since I went to Miami to get some Trojans.

I feel good about getting them because now I have to following:

Xantrex shore power charger reading: 14VDC

Batteries across terminals: 14.07VDC

Xantrex Solar Charge Controller: 5 green blinks = top of bulk charge phase (next phase is float)



I still have that pesky 1V difference in potential between the negative battery leg and the engine block. Upon reading through the Xantrex shore power charger/inverter manual, it says *not* to ground the device's output. Wheels, the only ground the device has is for your AC ground, not DC.

In all the installation diagrams for the inverter/charger, however, it shows your house battery bank being grounded at from the negative terminal directly to the engine block. Mine seems to be floating free and wild! It's not grounded at all, even though you can put the house and starting batteries into parallel with a switch. That switch acts on the positive leg, but does nothing with the ground, which they don't share. Investigating this a little further...
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Old 27-02-2008, 14:18   #43
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Sean,

I'm still waiting to hear the 1v story...the "Jeopardy" theme song is playing in my mind...

Steve B.
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Old 27-02-2008, 14:30   #44
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I ended up having to hire someone to hep with the inverter/charger hook up. Couldn't quite figure what was beig said and wanted a second opinion.
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Old 27-02-2008, 17:18   #45
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Don't get wrapped up in thinking that you need to 'ground' your 12V system, you don't. We 'ground' a car's negative to the chassis, and we ground our house AC, but we don't put the battery negative on the engine of a boat because it needs to be grounded. (I'm sure somebody will argue with me over this.) The ONLY reason to tie the negative to the engine is for the starter, and the alternator, and the engine electrical parts. Otherwise a floating 12V system is perfectly fine. If you don't want to charge your house bank with the alternator, or start the engine with the house bank, you can let it float. But if you want to do either of those things then you need to put your house negative on an engine. And make sure that you have a battery cable grounding the two engines together. This is an ABYC standard because if you lose the engines negative battery connection, it will try and draw current through the fuel line, so the engine to engine crossover cable is a safety feature.
It's so much easier when working with 12V to think only in terms of positive and negative. Forget about 'ground'.
As an example, a submarine is completely ungrounded, both the AC and DC systems.
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