problems charging battery

[SdDoc]

guys, I have a 36 volt motor and a three bank charger with one of the banks going to the cranking battery. I have one battery not connected to the charger that i usually just put a portable charger on. Well i went to use my motor and every thing was dead. Plugged in the boat one day and came back a week later to charge the other battery and it had reversed it polarity. this has happened twice to me. Do i need to unhook the batteries each time to charge? thanks Doc

[cjbrown]

You're better off just hooking up your cranking battery to the single charger. Or just invest in a 4 bank charger.

[REW]

SD
It wouldn't be a bad idea to have both your charger checked as well as your batteries.

1. If one or more of the banks on your charger has gone bad, you could have these symptoms.

2. If you get one shorted cell in one of your batteries, you could have these symptoms as well.

Generally speaking, the other post is right on, i.e. use the three bank charger to charge the three trolling motor batteries. Depending on the brand charger, you may leave them all connected, or you may actually make the internal connections in the charger itself and thus leave the charger connected all of the time. Follow the procedure that the manufacturer recommends - after checking both the charger itself for correct operation as well as each battery for good life, and no shorts.

Take care
REW

[Hot Runr Guy]

guys, I have a 36 volt motor and a three bank charger with one of the banks going to the cranking battery. I have one battery not connected to the charger that i usually just put a portable charger on. Well i went to use my motor and every thing was dead. Plugged in the boat one day and came back a week later to charge the other battery and it had reversed it polarity. this has happened twice to me. Do i need to unhook the batteries each time to charge? thanks Doc
What type of TM plug are you using? If it's the type with internal jumpers, I wonder if there is a slight short happening in the plug itself, causing a current drain. All it takes is a few strands of wire across the wrong pole to mess things up.
HRG

[SdDoc]

The motor is a ptsv. and hooked up by two wires. pos and neg. its just that the last battery in the series gets the portable charger. I have been thinking of getting a 4 bank, but the three bank works great. Is there much of a market to sell the three bank to purchase a four? thanks Doc

[Hot Runr Guy]

I'm with the other posters, keep your existing 3-bank and dedicate it to your (3) TM batteries, and get yourself a single bank for the starting battery. Then, buy yourself an extension cord that has a 2 or 3 socket female end, and you're all set.
HRG

[28shooter]

I'm with the other posters, keep your existing 3-bank and dedicate it to your (3) TM batteries, and get yourself a single bank for the starting battery. Then, buy yourself an extension cord that has a 2 or 3 socket female end, and you're all set.
HRG

Have a three bank and a single Use an extention cord with the three plug ins and have had no problem. Plus you can get a good one bank charger for under a $100.00.

[REW]

SDdoc,
Here is a thought that I suspect not too many folks have tried.
I wouldn't think that there isn't any reason that all 4 batteries could be connected together in a 48 volt configuration.

Use the first three batteries in the series connection to drive your trolling motor. Then, use the last one in the series connection to drive your motor.

You could then use a 1 bank 48 volt charger to charge all of the batteries at the same time.

Simple and easy.

Here is an example of a single bank 48 volt charger that may be installed on board.

http://www.batterymart.com/p-acc-4820sr-us.html

Take care
REW

[boat nut]

SDdoc,
Here is a thought that I suspect not too many folks have tried.
I wouldn't think that there isn't any reason that all 4 batteries could be connected together in a 48 volt configuration.

Use the first three batteries in the series connection to drive your trolling motor. Then, use the last one in the series connection to drive your motor.

You could then use a 1 bank 48 volt charger to charge all of the batteries at the same time.

Simple and easy.

Here is an example of a single bank 48 volt charger that may be installed on board.

http://www.batterymart.com/p-acc-4820sr-us.html

Take care
REW

2 problems:
You need to run a wire on a switch between the TM batteries and the cranking battery, and you need to remember to turn it on and off each charging cycle.
If any one of your 4 battereis gets a shorted cell, the other 3 will be damaged when you charge, due to overcurrent, and if you get one open cell in any of the 4, none of them will charge. Do it right; get the purpose specific charger.

[REW]

Actually, there is no problem at all to use a 48 volt charger with 4 batteries - one of which is used to run the main motor.

As I said before -= the first three batteries are hooked in series - as is the case right now to power the trolling motor. Two wires are hooked at each end of those three batteries to get the 36 volts for the motor.

Then, an additional battery of the same size and type is added to the end of the string, via a series jumper - (same heavy jumper as is used to connect the three other batteries together.
The Cranking battery is connected to that battery.
So, at the junction between the third and forth battery, you will have the negative trolling motor connection, the jumper connection to the 4th battery. At that spot or at the positiive battery connection of the 4th battery you will have the + terminal of the cranking battery.

Then, on the negative terminal of the 4th battery, you will have the single cranking battery connection.

If you run accessories off your cranking battery, you will also have your two heavy fuse block leads running to the 4th battery as well.

--
No, there is no need for a switch to disconnect anything.
No, there is really no issue about open or shorts that are at all different than any other battery.

For example - every 12 volt battery is composed of 6 cells. If you happen to have an open in one of these cells, the battery won't charge.
If you happen to have a short in one of these cells, you may overcharge the battery, before you finally realize that the battery is bad.

No difference in this setup - The only thing that is different, is that instead of having 6 cells in series, you have 24 2.2 volt cells in series.

One charger, one setting. Simple and easy. Two wires to charge the battery. A plus wire at the +48 and a minus wire at the ground connection of the 4th battery.


Take care
REW

[REW]

p.s.
If you start talking about having batteries hooked in parallel, you are talking a different animal.
Here is a case where shorts in batteries could cause damage to other batteries in the connection.

However, the series connection eliminates that problem.

Take care
REW

[boat nut]

No, there is no need for a switch to disconnect anything.
You need the switch to prevent electrical noise from the trolling motor from getting into the accessory circuit.


No, there is really no issue about open or shorts that are at all different than any other battery.
For example - every 12 volt battery is composed of 6 cells. If you happen to have an open in one of these cells, the battery won't charge.
Actually, you now have an open series circuit (24 cells) in which no current will flow, so no battery will charge

If you happen to have a short in one of these cells, you may overcharge the battery, before you finally realize that the battery is bad.
Actually, you now have a 48v charger connected to a 45.6v(ish) series circuit, and too much current will flow through all of the batteries, overheating all of them (and overcharging the good ones), so you won't know which one is defective until you check each battery separately.

[Lazy Ike]

With a 48v configuration you must be careful of both devices (-) being common with the boat. Either the (+) of the 36 string or the single 12 could be a short to ground via the negative of the opposite device. Not worth the risk.

A single 48 charger would not be my choice on a trip. 4 banks of 12 shouldn't leave you stranded. You have a back up charger unless lightning takes out both.