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Old 22-03-2010, 06:44   #1
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Electrical Charging Problems

I have a problem and I am hoping someone can help me with it....

1. I replaced my house bank (4-6 volt golf cart batteries) with new batteries before we left the Rio 3 months ago. (the old bank was 6 years old)

2. Recently I can't seem to get the House Bank to come back better than 12.2/12.3 volts. (We have wind and solar...during the day they come back but during the night they drop below 12.)

3. I just came into a marina and thought I'd hook up the charger (Xantrex Truecharge 20+).

4. I set the battery charger on "Cold" and "Bulk/Float" settings.

5. For about 2 hours it seemed like I was getting very little charge. The "Link 10" showed the batteries were accepting 14 amps and then after a short time the production reduced to 3 or 4 amp.

6. A short time later the Link started getting a "0" Amp production reading.

7. As an experiment I took the negative Trucharge lead and hooked it directly to the House Bank's Negative post. (the last one in the group)....(it was on a Negative Bus Bar like the manual says).

8. The instant I did that the amps production rose for about 5 minutes to 15 amps of production. After 5 minutes I started getting a -2.5 amp reading.

9. I turned off everything in the boat (and disconnected the shore power) and my Link 10 showed a 0.00 reading. (so I feel there's not something on the boat drawing power down).
(*) Nothing on our boat draws more than 1 amp except the refer.

10. I woke up early and the Link 10 read 0.00 of production/usage. The amount of amps used throughout the night was perfect for having just the refer on.

11. I then connected the shore power. The moment I turned on the Turecharge it instantly showed a -2.5 amp reading (remember the only thing the Trucharge is connected to is the House Bank).

12. Now whenever I turn the Battery Charger on I get a "-" reading. From -2.5 to -4.0

Any help here would be appreciated.

Thanks,
Ken svpolaris@yahoo.com
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Old 22-03-2010, 07:51   #2
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May seem like an obvious question, but where are you reading the 12.3v? Did you check the batteries with a meter? Occam says you've got problems in your voltage measurement.

Brett
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Old 22-03-2010, 08:04   #3
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By moving your neg. lead from the battery charger to the neg. post on your battery you have bypassed the shunt. That is where the Link 10 gets its reading. Put your battery charger lead back where it was and your readings should be correct.

You may need to equalize your batteries after giving them a full charge. It sounds like they have been left without a full charge for to long a time.
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Old 22-03-2010, 08:26   #4
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DeepFrz...I forgot about that aspect. I just moved the Truecharge ground back to the bus bar and now the link is giving a positive reading.

I think I still have the problem or of not being able to get a daily positive amp comeback with my wind and solar every day. Two months ago I cleaned off every negative and positive lead. I did it again this morning and found a couple of "slightly dirty" ones.

Also I disconnected all the leads to all the house bank batteries and checked all the volts for each separate battery to see if I had a bad one. Each one registered 5.9 volts. So I don't think there's one bad one pulling the rest down.

I was pulling my hair out this morning and slept on the problem last night (poorly) with this negative charge coming when I turned on the Truecharge.

DeepFrz...thanks for being there with my fix. You paid if forward today...Ken
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Old 22-03-2010, 08:32   #5
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The negative reading is quite normal because you connected the negative from the charger to the wrong side of the shunt. You should move it back to the other side of the shunt (probably where you had it before) and start to diagnose with a meter.

First thing is what Brett wrote: measure battery voltage to check those low readings. If the battery is at normal levels you now know to look for a problem with the measurement.
If the batteries are low indeed, I would start with a capacity test overnight. First check all the settings in the Link10, like total Ah etc. All you need to do is weigh the specific electrolyte and confirm they are full in the evening, disconnect all charge sources, note the Ah and voltage readings on the link10 five minutes after stopping charging and check all those readings in the morning again. The link10 will tell you how many Ah you consumed (and the state of charge) while the specific gravity tells you the state of charge.

The batteries are new and new batteries do not have the full capacity yet. You should draw them down to 30% charge or so (check with specific gravity, not the link10) and then recharge to full and leave it on float charge until the charge current goes to a number smaller than 4% of the Ah rating (if your 6V batteries would be 100Ah @ 6V each, you would have 200Ah @ 12V, so half the sum of all batteries). Now, measure values of specific gravity (SG) of each cell and do an equalize until the SG doesn't improve anymore and at least 4 hours. Follow the users guide from Trojan and read how to do this exactly (when to top off the water etc.)

You must also keep in mind that you can have one or more bad batteries.

cheers,
Nick.
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Old 22-03-2010, 18:29   #6
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Just a couple of comments in addition to what Nick has said.

1. A 200 ah battery bank is very low for a cruising boat. It will be very hard to keep it from becoming more than 50% discharged. I suspect that this is the major reason you are having trouble. Don't forget that you probably only have access to 35% of the 200 ah.

2. Are you positive that the batteries you have installed are true "deep discharge" batteries? This is very important as anything less will not last in a cruising environment.

3. It is very important to make sure that your batteries get a 100% charge at least once a month. This is true for both wet cell and AGM batteries.

4. Although I personally don't like the small gas powered generators on a boat, many cruisers are using them and are reporting good results in keeping their batteries charged and healthy. Many cruisers just can't afford or don't have room for a diesel generator. The gas powered generators have the power to kill you with carbon monoxide. Cruisers using them should make sure that they are very careful that carbon monoxide doesn't get into the living spaces and that they have detectors located in the living spaces.

Please keep us informed of your progress. There are many threads on the forum dealing with battery installations on a cruising boat. Could keep you busy reading for a long time...

Thanks for you thanks...
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Old 22-03-2010, 19:30   #7
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Guys...

The OP said he replaced the batteries 3 months ago with four 6-volt golf-cart batteries. That's a total of 450AH capacity, not 200AH. Also, while Jedi's comment about new batteries is true, it's only true for the first few deep discharges and full charges. Surely in 3 months of cruising they have been "broken in".

Ken: Suggest you...

1. Double-check all connections...including connectors on the cables...and make sure they are absolutely clean and TIGHT.

2. Forget about readings you're getting from the Link. Use a quality multi-meter to measure voltages AT THE BATTERY TERMINALS to see what's really going on.

3. Discharge the batteries, as was suggested, to about 12.1 volts. Then, give them a full charge. Charging voltages should be at least 14.4, 14.6 or 14.8 is better.

4. Check the electrolyte level to be sure there's enough covering the plates. A half-inch is enough. Then, if you have the ability to equalize them do so, using a voltage of about 15.5 to 16.0 for several hours.

Now check and see what you've got. With all loads and charging sources removed, check the voltage of each battery. They should be very close to one another. Let them sit overnite with no load or charging source. Measure the voltage again....you should see 12.6-12.7 or better. If not, you've probably got some sulfation going on...it could have happened since you got them or it could have happened before you bought them and put them into service.

Keep deep-cycling them a few times and see if their capacity improves. Again, don't worry about the Link. It's really worthless unless it's been calibrated properly and it can give misleading numbers. You know your boat. You know that with your batteries drawing a load overnight you should be seeing XX.X volts or better in the morning.

Good luck, and please tell us what you find.

Bill
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Old 22-03-2010, 19:54   #8
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There I go with another assumption...
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Old 22-03-2010, 21:55   #9
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Sorry DeepFrz, I just used 100Ah as an easy number.
About the brake in: I had this idea he spend the first time on shore power which can be translated into no cycles at all. That would also have prevented any sulfate buildup so that's good.

cheers,
Nick.
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Old 23-03-2010, 05:43   #10
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Polaris, have you gotten a reality check on your voltmeter? I ask because they can and do go out of calibration, I've seen a "decent" one show 12.2 versus 12.5 from one meter to the next. Since a nominal "6" volt lead acid battery should be charging significantly above 6 volts, a reading of 5.9 on all batteries means either a bad meter, or a charging problem--but no way to tell which without another way to validate the numbers you are getting.
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Old 23-03-2010, 06:07   #11
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I need a new (not expensive) multimeter.... any suggestions for a basic utility one for the boat?

What should I avoid? there are hundreds out there.
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Old 23-03-2010, 07:07   #12
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The Velleman DVM850BL meters are pretty decent for their $19.95 price. Occasionally, I've even seen them at $15. I buy them for client giveaways and for knockabout use. I open them up and adjust them to match the readings on my calibrated Fluke 189 at around 12VDC. They then stay "in calibration" pretty well. Handsome, too. Look like little Flukes :-)

If you want something REALLY useful, look for a good price on a MASTECH MS2108 AC/DC clamp-on ammeter. Very well designed and very accurate, both in amp measurements and voltage measurements. It's a true RMS meter which also measures inrush current, frequency, resistance, duty cycle, and capacitance. Up to 600amps capacity. Sells for about $129 on eBay.

IMHO, multimeters are an absolutely essential item on board. I always carry at least three, one of which is a clamp-on type. Even the good ones are an excellent investment in maintaining the various electrical and electronics systems on your boat, and in peace of mind to be sure things are working as they should.

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Old 23-03-2010, 14:43   #13
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The thing is that when you need a new meter, you don't have a Fluke to calibrate it against ;-) Also, temperature differences throw cheap meters off a lot.

I would recommend a Fluke 113-115 meter which put you in the $100 range for accurate readings, but as a very good (and accurate enough most most jobs) first meter aboard I can recommend this one: Amazon.com: A.W. Sperry DSA500A 5-Function 9-Range 400-Ampere Digital Clamp Meter: Home Improvement

It's clamp meter does AC and DC and it's only $57.-

cheers,
Nick.
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Old 23-03-2010, 14:54   #14
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Nick, that Sperry only does AC amperage, not DC. IIRC someone had mentioned one from Sears? (of all the odd places) that's just over $100 and does DC current as well.

The Sperry is also an example of "Why buy a Fluke?" with an accuracy of 1.5% plus or minus a number of rightmost digits, it comes down to about 2%, so 12 volts could show as anywhere from 11.76 to 12.24 volts. Arguably worthless for working on a 12V system.
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Old 23-03-2010, 15:51   #15
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Quote:
Originally Posted by hellosailor View Post
Nick, that Sperry only does AC amperage, not DC. IIRC someone had mentioned one from Sears? (of all the odd places) that's just over $100 and does DC current as well.

The Sperry is also an example of "Why buy a Fluke?" with an accuracy of 1.5% plus or minus a number of rightmost digits, it comes down to about 2%, so 12 volts could show as anywhere from 11.76 to 12.24 volts. Arguably worthless for working on a 12V system.
Correct. On both counts. The Sperry is NOT well suited for marine use, without DC amperage capability.

The Mastec referenced in my earlier post has a DC voltage accuracy of +/- 0.8%. Full specs are:
Specifications:
  • Display: 6600 counts
  • DC current: 66A/660A 3.0%
  • AC current: 66A/660A 3.0%
  • DC voltage: 660m/6.6/66/600V 0.8%
  • AC voltage: 660m/6.6/66/600V 1.0%
  • Resistance: 660/6.6k/66k/660k/6.6MΩ1.0%, 66MΩ 2.0%
  • Capacitance: 6.6/66/660/6.6m/66mF4.0%
  • Frequency: 10 to 10kHz2.0% (from test terminal)
  • Frequency: 10 to 1kHz2.0% (from current clamp)
  • Duty cycle: 10% ~ 95%3.0%
  • Continuity checking with buzzer
  • Diode test
  • MAX. Diameter for conductor: Φ26mm
  • Power: 1.5V (AAA) x 3
  • Size: 8 1/4" x 3" x 1 3/8
  • Weight: Approx. 340g (w/o battery)
For $129, it's a very good meter which compares very favorably to my top-of-the-line Fluke 337 clamp-on meter which costs three times as much.

There may be others as well, but this is the one I know about and have used. Maine Sail favors this meter also, IIRC.

Bill


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