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I left the lights on

Jan 10, 2011
289
Macgregor 25 Lake Lanier
I left the lights on on the boat. When I return to the boat the battery read 7.1 volts.
I turned off the electricity and left the solar charger hooked up. The battery is red 11.4 volts when I left the boat that afternoon.
I am hoping that the battery will fully charge and last for a while. If it fully charges how do I tell how long it will last?
I plan to check on it this Saturday.
 
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Aug 22, 2021
14
1992 mcgregor 26s san diego
I left the lights on on the boat. When I return to the boat the battery read 7.1 volts.
I turned off the electricity and left the solar charger hooked up. The battery is red 11.4 volts when I left the boat that afternoon.
I am hoping that the battery will fully charge and last for a while. If it fully charges how do I tell how long it will last?
I plan to check on it this Saturday.
Man that's a complicated question... You probably have the OEM lights on your boat which means they probably aren't the most energy efficient.... Age of your battery, lead acid, lithium, size... ideally a good battery should be able to last all night with the lights on... I'm not an expert with batteries I'm just getting into them myself but you didn't give enough data for an answer lol
 
May 24, 2004
6,769
CC 30 South Florida
How long the charge may last depends on the health of the battery. You may conduct a "Load Test" or take to an Auto Parts Store to have it checked. A battery can show to be full at 12.67V and yet have a diminished capacity of Ampere/hours. I would suggest not to rely on the solar charger and take it and have it charge with a strong bulk charger. The way you can approximate how long will the charge of a battery last is to take the rated A/h for the battery and divide it by 2. (a wet cell battery should not be discharged more than 50% to maintain optimum useful life). Find out the power usage rating of the loads (in light bulbs convert the Watts to Amps). Divide the number of available battery Amp/hours by the added total number of amps for each light bulb and that will give you an estimate of how long you can burn those light bulbs before having to recharge. A fully charged battery should show a voltage of 12.67V, at 50% charge the voltage should be 12.06V and at 10.5V the battery is at 0% and considered dead. Your voltage reading of 11.4 volts could be the reading of the charge current coming from the solar charger. For these reasons I recommend you have the battery tested and if deemed salvageable to be charged by a strong bulk charger. Battery maintenance requires that batteries are charged back to 100% after every use to prevent sulfation which reduces the Ah capacity. Check and see if your solar panel has the capacity to fully recharge the battery.
 
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Jan 1, 2006
5,990
Slickcraft 26 Greenport, NY
I'm not a battery guru but there are some who post here. I think it's unpredictable how much your battery was damaged. A one time incident maybe not so bad. It depends a lot on many other factors - age of battery, past charging history, past discharge history, as far as I can tell the phase of the moon and the height of the creek.
 
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Jan 10, 2011
289
Macgregor 25 Lake Lanier
It was the biggest Everstart deep cycle battery from Walmart. EverStart marine battery group size 27dc. It is one year old. all of the onboard lights are LED lights. The lights were left on for a week.

The lowest charge it ever showed before this was 12.4 volts. I ran an electric motor with lights on for a day and the solar charger had it fully recharged a day later.

Would a load test and an auto store tell me how much of the battery is left?
 
Jun 11, 2004
1,203
Oday 31 Redondo Beach
"Would a load test and an auto store tell me how much of the battery is left?"

It would help. Can you take it back to Walmart?

Unless you have a lot of solar you should probably put it on a real charger.

Check this link if you haven't:




HOW DO I TEST A BATTERY?
There are six simple steps in testing a deep cycle battery: inspect, recharge, remove surface charge, measure the state-of-charge, load test, and recharge. If you have a non-sealed battery, it is highly recommended that you use a good quality temperature compensated hydrometer; these can be purchased at an auto parts store for between $5 and $20. A hydrometer is a float type device used to determine the state-of-charge by measuring the specific gravity of the electrolyte in each cell. It is a very accurate way of determining a battery's state-of-charge and its weak or dead cells. To troubleshoot charging or electrical systems or if you have a sealed battery, you will need a digital voltmeter with 0.5% or better accuracy. A digital voltmeter can be purchased at an electronics store like Radio Shack for between $20 and $200. Analog voltmeters are not accurate enough to measure the millivolt differences of a battery's state-of-charge or the output of the charging system. The purchase of a battery load tester is optional; if you use a golf cart or electric trolling motor every day, buy one.
3.1. INSPECT
Visually inspect for obvious problems. For example, is there a loose or broken alternator belt, electrolyte levels below the top of the plates, corroded or swollen cables, corroded terminal clamps, dirty or wet battery top, loose hold-down clamps, loose cable terminals, or leaking or damaged battery case?
If the electrolyte levels are low in non-sealed batteries, allow the battery to cool and add distilled water to the level indicated by the battery manufacturer. If this is not indicated, use 1/4 inch (7 mm) below the bottom of the plastic filler tube (vent wells). The plates need to be covered at all times. Avoid overfilling, especially in hot climates, because heat will cause the electrolyte to expand and overflow.
3.2. RECHARGE
Recharge the battery to 100% state-of-charge. If the battery has a difference of .03 specific gravity reading between the lowest and highest cell, then you should equalize it. (Please see Section 6.)
3.3. REMOVE SURFACE CHARGE
Surface charge is the uneven mixture of sulfuric acid and water within the surface of the plates as a result of charging or discharging. It will make a weak battery appear good or a good battery appear bad. You need to eliminate the surface charge by one of the following methods:
3.3.1. Allow the battery to sit for four to twelve hours to allow for the surface charge to dissipate.
3.3.2. Apply a load that is 33% of the ampere-hour capacity for five minutes and wait five to ten minutes.
3.3.3. With a battery load tester, apply a load of at least one half the battery's CCA rating for 15 seconds and wait five to ten minutes.
3.4. MEASURE THE STATE-OF-CHARGE
If the battery's electrolyte is above 110° F (43.3° C), allow it to cool. To determine the battery's state-of-charge with the battery's electrolyte temperature at 80° F (26.7° C), use the following table. The table assumes that a 1.265 specific gravity reading is a fully charged, wet, lead acid battery. For other electrolyte temperatures, use the Temperature Compensation table below to adjust the Open Circuit Voltage or Specific Gravity readings. The Open Circuit Voltage will vary for gel cell and AGM type batteries, so check the manufacturer's specifications.

Digital Voltmeter Open Circuit VoltageApproximate State-of-ChargeHydrometer Average Cell Specific GravityElectrolyte Freeze Point
12.65100%1.265-75° F
(-59.4° C)
12.4575%1.225-55° F
(-48.3° C)
12.2450%1.190-34° F
(-36.7° C)
12.0625%1.155-16° F
(-26.7° C)
11.89Discharged1.120-10° F
(-23.3° C)

STATE-OF-CHARGE
[Source: BCI]

Electrolyte Temperature FahrenheitElectrolyte Temperature CelsiusAdd or Subtract to Hydrometer's SG ReadingAdd or Subtract to Digital Voltmeter's Reading
160°71.1°+.032+.192
150°65.6°+.028+.168
140°60.0°+.024+.144
130°54.4°+.020+.120
120°48.9°+.016+.096
110°43.3°+.012+.072
100°37.8°+.008+.048
90°32.2°+.004+.024
80°26.7°00
70°21.1°-.004-.024
60°15.6°-.008-.048
50°10°-.012-.072
40°4.4°-.016-.096
30°-1.1°-.020-.120
20°-6.7°-.024-.144
10°-12.2°-.028-.168
-17.8°-.032-.192

TEMPERATURE COMPENSATION

Electrolyte temperature compensation, depending on the battery manufacturer's recommendations, will vary. If you are using a non-temperature compensated HYDROMETER, make the adjustments indicated in the table above. For example, at 30° F (-1.1° C), the specific gravity reading would be 1.245 for a 100% State-of-Charge. At 100° F (37.8° C), the specific gravity would be 1.273 for 100% State-of- Charge. This is why using a temperature compensated hydrometer is highly recommended and more accurate than other means. If you are using a DIGITAL VOLTMETER, make the adjustments indicated in the table above. For example, at 30° F (-1.1° C), the voltage reading would be 12.53 for a 100% State-of-Charge. At 100° F (37.8° C), the voltage would be 12.698 for 100% State-of-Charge.
For non-sealed batteries, check the specific gravity in each cell with a hydrometer and average the readings. For sealed batteries, measure the Open Circuit Voltage across the battery terminals with an accurate digital voltmeter. This is the only way you can determine the State-of-Charge. Some batteries have a built-in hydrometer, which only measures the State-of-Charge in one of its six cells. If the built-in indicator is clear or light yellow, then the battery has a low electrolyte level and should be refilled and recharged before proceeding. If sealed, the battery is toast and should be replaced. If the State-of-Charge is below 75% using either the specific gravity or voltage test or the built-in hydrometer indicates bad (usually dark), then the battery needs to be recharged beforeproceeding. You should replace the battery, if one or more of the following conditions occur:
3.4.1. If there is a .05 (sometimes expressed as 50 points) or more difference in the specific gravity reading between the highest and lowest cell, you have a weak or dead cell(s). If you are really lucky, applying an EQUALIZING charge may correct this condition. (Please see Section 6.)
3.4.2. If the battery will not recharge to a 75% or more state-of-charge level or if the built-in hydrometer still does not indicate good (usually green, which is 65% state-of-charge or better).
If you know that a battery has spilled or bubbled over and the electrolyte has been replaced with water, you can replace the old electrolyte with new electrolyte and go back to Step 3.2 above. Battery electrolyte is a mixture of 25% sulfuric acid and distilled water. It is cheaper to replace the electrolyte than to buy a new battery.
3.4.3. If digital voltmeter indicates 0 volts, you have an open cell.
3.4.4. If the digital voltmeter indicates 10.45 to 10.65 volts, you probably have a shorted cell or a severely discharged battery. A shorted cell is caused by plates touching, sediment (mud) build-up or treeing between the plates.
3.5. LOAD TEST
If the battery is fully charged or has a good built-in hydrometer indication, then you can test the capacity of the battery by applying a known load and measuring the time it take to discharge the battery until 20% capacity is remaining. Normally a discharge rate that will discharge a battery in 20 hours can be used. For example, if you have an 80-ampere-hour rated battery, then a load of four amps would discharge the battery in approximately 20 hours (or 16 hours down to the 20% level). New batteries can take up to 50 charge/discharge cycles before they reach their rated capacity. Depending on your application, batteries with 80% or less of their original capacity are considered to be bad.
3.6. RECHARGE
If the battery passes the load test, you should recharge it as soon as possible to restore it to peak performance and to prevent lead sulfation.
 
Jan 10, 2011
289
Macgregor 25 Lake Lanier
I guess the only answer is lifting at really heavy battery out of the bottom of the boat and taking it to a shop to have a tested.

If it was not so heavy I would just get another battery and carry both on board. I have no use for a battery at home.
 
Jan 18, 2016
664
Catalina 387 Dana Point
A load test can be reasonably done with a simple load (Incandescent light bulbs, 12v heat, the fridge, etc - something close to the 20 hour rate is ideal) , an ammeter and a voltmeter. Pop on the load, measure current and voltage often, figure out how much power was extracted via how much time. Allow charge to stabilize and calc SOC on voltage. Not as good as a constant-current sink, but it'll do.

Automotive shop testing is high-current, short time. IOW, what's needed to start an engine. A house bank is low current, long time. Hence a 20 hour test. You can find out if the batts are toast in 5 hours or so. Won't really know if they're 80%, but you'll know if they're 30%. If they're really gone, the auto shop test will tell you to. but lots of marginal batteries will be fine in the auto shop test.

And... Here's the easiest solution. Do nothing. Use the boat. If you're used to how long the battery lasts, you'll realize soon enough that it's OK or not OK. Then it's new battery time. If I read correctly, it's a single ~$100 battery from wal mart. Not like killing a $5K chunk of LiFePo's.

In suggesting doing nothing I also assume that to motor a Mac 25 you reach behind and pull the cord. So a dead battery does not mean no motor.
 

Ward H

.
Nov 7, 2011
3,093
Catalina 30 Mk II Barnegat, NJ
And... Here's the easiest solution. Do nothing. Use the boat. If you're used to how long the battery lasts, you'll realize soon enough that it's OK or not OK. Then it's new battery time. If I read correctly, it's a single ~$100 battery from wal mart. Not like killing a $5K chunk of LiFePo's.
Yep, agree with jeepbluetj, do nothing and see what happens. In one day your solar brought the battery back up to 11.4. If it comes back up to normal voltage you'll be able to tell pretty quickly if the battery sustains your use for a day of sailing or not. When it doesn't, time for a new one.
 
Jan 10, 2011
289
Macgregor 25 Lake Lanier
The battery is dead. The battery was purchased on April of 2019. Last time the battery lasted 8 years. l think I will make sure to turn off the lights when I leave the boat from now on.
 

Ward H

.
Nov 7, 2011
3,093
Catalina 30 Mk II Barnegat, NJ
Thanks for the follow up.
And, I joined your club.
Went to the boat yesterday and found my batteries at 9.2V. (two GC2 6v FLA)
Turns out I had left my battery charger turned off when I last left my boat Labor Day Weekend.
My fridge ran the batteries down. Luckily I don't get much water in the bilge so that was not an issue.
They appeared to have taken a full charge over 24 hours. I'll be back down this week to turn on all the loads on the boat and monitor the batteries to see if they need to be replaced.
Being they are 3 1/2 yrs old I expect the same outcome you had.
 

jviss

.
Feb 5, 2004
4,627
Tartan 3800 Westport, MA
Boat electrical systems are quite primitive, and are not evolving very quickly. On sailboats we are living with systems that were in use perhaps 50 years ago, maybe longer. Battery technology has improved dramatically, and some boaters are taking advantage, but overall, the systems are still quite primitive.

I find it remarkable that boat DC electrical panels - "load centers" - do not incorporate zones, based on priority, and low voltage disconnects (LVDs), to protect the batteries. Boat load centers should shed loads as battery voltage declines, based on the operational mode, and the priority of the load.

I confess I've designed a system for my boat, and purchased components, but haven't implemented it yet. :(. I got a lot of crap from folks who discouraged using anything other than "marine" components for these applications, but the type of components I sought for this are apparently not available from a marine electrical component supplier. So, there you have it.

That said, you can purchase marine LVD's; Blue Sea Systems had one for about $65. A great investment to protect a vital boat component which can cost much more to replace.
 

Ward H

.
Nov 7, 2011
3,093
Catalina 30 Mk II Barnegat, NJ
That said, you can purchase marine LVD's; Blue Sea Systems had one for about $65. A great investment to protect a vital boat component which can cost much more to replace.
I have one. Unfortunately they don't work well sitting in the To Be Installed bin. :oops:
 
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Jan 10, 2011
289
Macgregor 25 Lake Lanier
This is the McGregor 25. I powered the boat lights bilge pump fans and interior LED lights. I also use an inverter to run computers and charge the phone. There's also a small nav unit that is a fish finder. I have a 55 lb electric trolling motor for quiet evenings or emergencies.
When I leave the boat I shut off All electronics. I have plenty of energy for a three day trip on Sarasota Bay. I have 2 20wat solar panels. This has kept the battery fully recharged.
The Honda 7.5hp outboard has a generator but I have never used the generator.
Everything has a fuse but the wiring is very simple. One battery and a small panel.
 
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Jan 10, 2011
289
Macgregor 25 Lake Lanier
Simple setup. I just need to remember to turn off the lights and not kill another battery.
Just good enough to sail. Just good enough to camp. Great for fishing. I like waking up in the morning and just need to start fishing.
Aqualand Marina on Lake Lanier Georgia.
I will be in Sarasota FL December 18th to Jan 2, 2022.
List:
Replace battery
Check wheel bearings
Trailer boat after Thanksgiving(Turn off lights)
Change Fuel Filter on Diesel Suburban
Head to Sarasota...
 

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Jan 10, 2011
289
Macgregor 25 Lake Lanier
I replaced the battery today and it cost $30. I purchased the battery in 2019. It still had a warranty. The people a the store were very nice. They were amazed that a marine battery was covered by the warranty.
If I knew that it still had a warranty and would only cost $30 to replace I would have done that a week ago.
Puffy wind today. It would blow for 10 or 15 minutes and then quit. Nice day for a slow sail. Anchored for a while and took a nap. Watched a movie. Sailed and drifted for a while and motored back and went home. Relaxing evening.
All I need to do is to remember to turn off the electricity when I leave and I will have a battery.
 
Jan 1, 2006
5,990
Slickcraft 26 Greenport, NY
Can you do something like hang your car keys on the switch or near it to help you remember?
Regarding battery warrantees, it always amazed me that my car dealership would replace my battery about once a year and not even bother trying to figure out why I was going through them at that rate. They'd even send a guy down to jump the car, drive it back to the dealership, replace the battery and would deliver the car if I asked. I was always curious why they didn't care to figure out why I was getting about a year to a battery. I'm sure they wouldn't bother to read MS's website (Compass Marine- OK that's a plug.)