Voltage and charging

[spawnedoutgobey]

How many volts should my battery test when not in use, how many volts do they need to start a motor, and can I charge my batteries hooked up on the boat or do I have to disconnect to charge them?

 

[Barnacle_Bill]

Re: Voltage and charging

You need enough power to spin the motor at least 300 RPM. You don't need to disconnect the batteries for charging.

 

[UncleWillie]

Re: Voltage and charging

A common Flooded Lead Acid Battery with a full charge will measure a nominal 12.6 volt at room temperature after sitting for a while.
12.2 is Half Dead and needs a charge badly.
11.8 is Technically Dead. Any lower will damage the cells.
Some engines will crank at 12.0 some won't at 12.2.
Your experience will vary!

While charging it will measure 14-16 volts depending on the charger.
If you do not see at least 14 volt with the engine running or on the external charger it is not charging.
A smart charger operating in maintenance mode after charging will measure in the 13-14 volt range.

It will measure about 13.0 shortly after coming off the charger and will settle back to 12.6 in a few hours.

You can attach the charger to the battery in the boat without issue.

 

[glenn property of pam]

Re: Voltage and charging

12.6 volts is full charge (leave of charger for 20 mins before testing or it will read higher)
12v is 50% charged which should start a outboard
10.5 is full discharged which means you will be paddling

charging will not hurt the electrical system on a boat but you have to use common sense. You can not hook up a charger next to a gas tank then put the hatch cover down as most chargers (auto) are not spark resistant so any gas fumes would be a problem.

 

[spawnedoutgobey]

Re: Voltage and charging

Thanks guys. One bat is reading 12.8 and the other battery is reading 13.16 neither have been charged for two weeks. I have had a self related mishap last time I took her out and wired it wrong creating some issues. I will try starting it tonight when I get home from work. Or this morning before I head out. And drop back in to let you know what my out come is.

 

[spawnedoutgobey]

Re: Voltage and charging

Ok I put both batteries in boat, hooked them up correctly and tried to turn motor. It tried to work but sounded like tKe battery was dead. On both batteries. I checked althea connections on the batteries and on the motor. All seemed good and tight. So I am now wondering if it is possible for a Battery to read 13+ volts and be no good. Or did I get something else like my starter when I accidentally booked up the negative from my second battery to the positive of my first battery, when I started a and ran it like that?

 

[UncleWillie]

Re: Voltage and charging

Battery IDLE Voltage and LOAD Voltage are two separate numbers.
Measure the Battery Voltage on the Actual Battery Posts, Not the Battery Clamp/Connector, while the engine is cranking.
~11 volts is normal. Less than 10 = Bad Battery; Over 12 = Bad connections.

 

[JB]

Re: Voltage and charging

Connections of battery cables that LOOK clean and tight may be hiding corrosion. Remove and clean them.

Batteries that measure good voltage without a load may fail to provide enough current. Take the measurements Uncle Willie suggests to confirm the battery's ability to take a load.

 

[Auger01]

Re: Voltage and charging

Ok I put both batteries in boat, hooked them up correctly and tried to turn motor. It tried to work but sounded like tKe battery was dead. On both batteries. I checked althea connections on the batteries and on the motor. All seemed good and tight. So I am now wondering if it is possible for a Battery to read 13+ volts and be no good. Or did I get something else like my starter when I accidentally booked up the negative from my second battery to the positive of my first battery, when I started a and ran it like that?

It is very possibile that you did damage the starter and or the charging circuit of the motor when it was run with the batteries hooked up incorrectly.

 

[LippCJ7]

Re: Voltage and charging

Ok I put both batteries in boat, hooked them up correctly and tried to turn motor. It tried to work but sounded like tKe battery was dead. On both batteries. I checked althea connections on the batteries and on the motor. All seemed good and tight. So I am now wondering if it is possible for a Battery to read 13+ volts and be no good. Or did I get something else like my starter when I accidentally booked up the negative from my second battery to the positive of my first battery, when I started a and ran it like that?

First thing I want to know is what motor are you trying to turn over? are we talking an outboard or a inboard V8?

Second thing is you need to load test your batteries, batteries will show a surface voltage appropriate to what you need to start your motor but under load they will drop dramatically, so if I were you have someone attempt to start the boat while you read the voltages of each battery independently if one or both batteries drops immediately upon starting to below 10 volts they are done(provided they were charged prior to this test), or you can take your batteries out and take them to any local auto parts store and have them load tested, takes about a minute each battery, this will tell us the condition of your batteries once you have verified the condition of the batteries we can move on but until we know you have good batteries nothing else matters.

As was stated previously take your battery measurements from the battery POSTS not the terminal they are lead don't worry about hurting them push your probe into the lead post firmly to insure you are making a good connection.

 

[spawnedoutgobey]

Re: Voltage and charging

I have tried the load test and my meter read high 11 low 12 under load. However the starter just slowly turned the fly wheel. I set my meter to 200 ohms to check resistance on wires. A new marine cable 4 Guage tested at 0.5 and so far all others tested the same. I am charging the batteries now and my charger reads low capacity on both of them. I am trying to start a 70 hp Evinrude. Outboard. Frustrating to say the least. I am going to have them tested tomorrow. Guess I'm not boating this weekend.

 

[LippCJ7]

Re: Voltage and charging

ok once you get your batteries tested the next thing I would do is test the length of your power and grounds, from each termination, in other words from the engine block to the negative battery post across your connections do the same for your positive and see what your meter reads, your 200 ohm scale is fine, what were looking for is a bad connection could be between your battery terminal and the battery post, a simple connection but extremely important, once again do this after you get your batteries checked out.

Also a new marine cable 4 gauge that tests at .5 ohms would get me another new marine 4 gauge cable, its not horrible but in my opinion not acceptable for a new cable, this is why I make my own cables and they test at zero ohms. now it may be worth it to have your starter checked as well, a good way to do this on the fly is to gently touch your battery cables (once you know they are good) and see if they are getting hot, a very good indication of a bad starter.

 

[glenn property of pam]

Re: Voltage and charging

remove the positive wire from the battery then remove the positive wire thats on the starter solinoid battery side (there should be 2 small wires also attached to this post). clean all the rings with sand paper then re-land the starter solinoid side then put the positive back on the battery and test again.
0.5ohms on a 12v system is huge when you need to push 150 amps across it.

You can play with this to your hearts content or you can remove all the large cables one at a time and clean then then re-attach them. This also includes the ground cable thats attached to a bolt on the motor. I dont mean to be rude but we see this 100 times a year and some people just dont want to except the advice so we go round and round. The test unclewillie asked you to do shows you have a bad connection. Only when the connections are clean can you get a real test on the solinoid and starter.

 

[UncleWillie]

Re: Voltage and charging

High 11's means a Good Battery, Bad Connection.
The bad connection is going to get HOT! when you crank the engine. A CAREFUL Finger test might find it.

Other wise. Measure the voltage at the Starter Terminals while cranking. You will find the number significantly Different.
Then measure from one end of each cable to the other while cranking. Anything significantly MORE than 0.5 volts is Bad!

You can NOT measure the resistance of any battery cable with a hand meter with any accuracy at all.
Battery wire will measure 0.25 ohms per 1000 feet.
That is 0.001 ohm in 4 feet. 0.5 ohms is 500 times too much; A massive failure.
Touch the leads together and you likely still read the 0.5 and not 0.0

To put it in perspective 0.5 ohms at 12 volt is 24 amps, or 288 watts.
The battery would happily supply that for about 4 hours.

 

[Auger01]

Re: Voltage and charging

Just a hunch here, but after you do what Unclewillie suggested, check the voltage across the starter solenoid.

 

[spawnedoutgobey]

Re: Voltage and charging

I have gotten my batteries tested at a Battery shop. They said they were all good. Now I am cleaning the posts, and going to be cleaning all the cable ends. Would it be advisable to put some Di electric grease on my posts and all the connections when I am ready to reconnect everything?

 

[spawnedoutgobey]

Re: Voltage and charging

I have gotten my batteries tested at a Battery shop. They said they were all good. Now I am cleaning the posts, and going to be cleaning all the cable ends. Would it be advisable to put some Di electric grease on my posts and all the connections when I am ready to reconnect everything? Oh and where do I find my starter solenoid and how do I test. I've taken a picture of what I thought it might be now I just have to fund out to post it

 

[NYBo]

Re: Voltage and charging

Good strategy. People often forget that the connections at the other end of the cables need to be clean too.

Dielectric grease will help slow down corrosion, so that's a good idea. Just a very light coating is all that's needed.

 

[glenn property of pam]

Re: Voltage and charging



bad pic but its the thingy with the strap around it.

if yours leads look as dirty and corroded as this one it needs cleaning as that was a problem i had on this 70 when i first got it.


p.s always a good idea to take lots of pics of the motor before removing anything just in case you forget where stuff goes which is why i have this on file still

 

[UncleWillie]

Re: Voltage and charging

... where do I find my starter solenoid ...

The Starter Solenoid, If you have one, (It may be built into the starter),
Will be at the OTHER end of the biggest wire coming off the Positive (Red) terminal of the Battery.