Batteries in series problem

[poconojoe]

Thinking about that trolling motor, maybe it is the culprit, but why only one battery draining?
So, you said you charge both batteries separately and the trolling motor is always connected. So when you charge them, you must be disconnecting the wires in order to separately charge them. A dumb question, and trying not to insult you, but at any time is the trolling motor still connected to one battery while the other is charging? Probably not since it seems obvious...but I figured I'd throw it out there....
I would take that trolling motor out of the equation, charge both batteries and see what happens.

 

[SonomaScott]

gm280-
I installed a panel meter that operates with a pull switch. It has 10 lights illuminated on a full charge. For example, when my batteries are 30% used, only 7 lights illuminate.

poconojoe-
Don't worry about insulting me- I'm not good with electronics or mechanical things. Learning as I go. :joyous:

No, I don't disconnect any wiring when I charge the batteries separately. The trolling motor is wired to the threaded posts and secured with a nut. I charge each battery by connecting my charger to the lead posts. My understanding is that although the batteries are connected in a series set-up, when I put the charger on one battery, I am not putting a charge into the other battery. Am I wrong about that?

I am really suspecting that for some reason I've been getting a false reading on Battery B. Don't know why, though.

 

[alldodge]

My understanding is that although the batteries are connected in a series set-up, when I put the charger on one battery, I am not putting a charge into the other battery. Am I wrong about that?

Your not wrong, it will only charge one at a time if there is nothing else which can close the circuit to the other battery

I am really suspecting that for some reason I've been getting a false reading on Battery B. Don't know why, though.

I will agree, this is more of the strong possibility. Find a cheap volt/ohm meter and use it to check your battery charge

 

[poconojoe]

Your not wrong, it will only charge one at a time if there is nothing else which can close the circuit to the other battery

Could the (connected) trolling motor "close the circuit" as you stated? Current finding a path through the motor?
Maybe he should disconnect the trolling motor and everything else (including the charge indicator panel) when charging.

 

[alldodge]

Could the (connected) trolling motor "close the circuit" as you stated? Current finding a path through the motor?
Maybe he should disconnect the trolling motor and everything else (including the charge indicator panel) when charging.

Anything is possible but I just don't see how. If it did it to one battery it would do it to the other. The motor is connected but the switch is open

 

[poconojoe]

I would completely disconnect everything from each battery. Then charge each one individually and see if you still have the problem.
Sometimes you just need to start from scratch and get very basic when troubleshooting. Disconnect all variables.
If you do this and the problem is gone, then you can reconnect each device one at a time and possibly find the culprit.

 

[poconojoe]

Anything is possible but I just don't see how. If it did it to one battery it would do it to the other. The motor is connected but the switch is open

Yeah, this is a tough one.
Are both batteries identical?

 

[SonomaScott]

Yes, the batteries are identical. I'm really suspecting that (for an unknown reason) I'm getting a false reading on the second battery. I will disconnect the motor and battery meter when I charge them, and see what happens. If the problem goes away after a few trips to the lake, I'll assume that a false reading was the problem.

 

[Silvertip]

Does this battery indicator have a BAT #1 and BAT #2 selector switch? Is there a separate indicator for each battery? If not, how are you determining the state of charge on either battery?

 

[SonomaScott]

The onboard indicator doesn't read the batteries individually. It gives me a remaining charge for the 24 volt system.
Here is a similar meter to mine:
http://m.ebay.com/itm/12-24-Volt-Aut...481?nav=SEARCH

I am getting the reading for each battery individually when I connect my charger to each one when I get home.

 

[Silvertip]

Are you certain you have the selector switch wired correctly ?

 

[gm280]

Are you certain you have the selector switch wired correctly ?

Good question Silvertip. Knowing the rules and laws of electronics and the FACT that current has to flow equally through every part in a series circuit, there has to be something wired wrong...

 

[Outsider]

Do you have the 3rd terminal of the meter wired to something? I see a red and a green on the right positive terminal ...

 

[SonomaScott]

I'm out of town til Thursday. I'll re-check the wiring & post pics. I wired the meter but perhaps I got something wrong.

 

[Silvertip]

There are positive, negative and a "C" terminal on these units -- intended for external use. I use one of these (digital voltmeter equivalent) to monitor the deep cycle in my cargo trailer. It too has three terminals but the third is a "sense" line for whatever point in a circuit one wishes to monitor. In my case, the sense wire is tied to +12 volts since it's the battery I'm monitoring. I have no idea what the external use would be but it could be for monitoring something other than battery voltage. The switch used to turn this unit on and off is pretty straight forward as it would only need to be inserted in the +24 volt line. But then again, electricity is black magic to many folks and I cannot count how many times I've seen a spst switch wired across positive and negative lines and the owner can't figure out why fuses blow. Since you are using only the battery charger to indicate state of charge, disconnect all wiring to the batteries and then try the charger. Just charge the batteries and then leave them sit unconnected to see if there is a self-discharge thing going on. You would not be the first person to get a bad-new battery.

 

[oldboat1]

interesting mystery. Parasitic drain on one of the batteries? bilge pump wired to one? maybe an auto bilge pump that samples for presence of bilge water. Maybe a boat stereo system?

 

[seadogmike]

I would completely disconnect everything from each battery. Then charge each one individually and see if you still have the problem.
Sometimes you just need to start from scratch and get very basic when troubleshooting. Disconnect all variables.
If you do this and the problem is gone, then you can reconnect each device one at a time and possibly find the culprit.

I agree. Start from the beginning. it should be easy to tell if something is draining one battery over the other, or you have a bad battery. You could always take the battery to the auto parts store and have them check it.

 

[SonomaScott]

I really appreciate all the help I've gotten. Here is an update:

This morning I checked the batteries and both showed 82% after sitting for about 2 weeks, which seems about right. I think the problem has been a faulty reading from time-to-time. Also, the onboard meter and my home charger have agreed when there has been a problem. On the occasions when the meter has shown an accelerated drain while fishing, I've gotten home and my charger has shown the second battery at an extremely low level.

Silvertip, I'm gonna re-check how I wired my meter and post pics and/or a description. Since the trolling motor was wired by a mechanic friend and the meter was wired by me, I'm inclined to believe that the screw-up is all mine. = )

I'll get back to you on the wiring.

 

[Silvertip]

Is your mechanic friend and auto mechanic or a marine mechanic? Electricity behaves the same way regardless, but sometimes wiring of marine accessories can fool even the best.

 

[SonomaScott]

He's pretty well qualified. Taught auto mechanics for many years in the school district and then was a mechanic for the Napa Marina.

So the meter I installed has 3 wires- Red, Green, and Black. As I recall, it didn't come with any instructions which is trouble for a guy like me who is a novice. I wired the Red and Green to the positive post on Battery A and the Black to the negative post on Battery B. (As an analogy, I picture batteries in a series like stacking batteries in a flashlight. Battery A would be the first battery you drop in and Battery B would be the second. In my case, Battery B is the one that "appeared" to be draining.) My assumption was that the Green wire was the one that read the remaining charge, but that was just a guess. The meter has a simple pull-out switch for ON/OFF.

I should also add that the apparent problem has been very intermittent. I had no problems the first year with the trolling motor or the meter. At the end of last year it began to occur. This year I started by buying two new batteries which worked fine for a few trips. Then when the problem started up again, I replaced Battery B. The problem has occurred again, but as I said, yesterday everything tested fine. Very confused!