12V TM, charger and wiring help

[Oldsmotion]

Bought a used Lund, 17' with 3 batteries. One for starting the engine, two for the 12 volt trolling motor. All three are brand new. I would like to order an on board charger and the appropriate accessories to wire and charge all three batteries. I have read numerous threads and have mixed feelings on how to do this. I can handle the wiring, but which method is the issue.

Questions are:
- If I configure the TM batteries in parallel, do I need to install an inline switch to isolate each battery during charging? If so, what type of switch?
- My plan is to purchase a three bank 10 amp charger and wire each battery. Can this be done with the TM batteries wired in parallel?
- Would I be better off to wire the two TM batteries as two separate batteries, controlled via a switch (battery 1, 2, or Off setting) thus allowing the charger to "see" two batteries during the charging process? If so, how?
- What other items do I need to purchase to complete the setup? Plug? Switch?
- Suggestions on where to order / purchase the items I need?

Other: the Minn-Kota TM is 12 volt and does not allow for 24 operation. Maybe once I get used to this boat I'll upgrade but for now it is what it is.

This boat is new to me and the electronics were handed to me in a box. Everything is in new condition but not wired.

Thanks for any advice.

 

[Silvertip]

Re: 12V TM, charger and wiring help

There are several ways to wire the batteries but my recommendation would be to keep this as uncomplicated as possible. Battery #1 is the starting battery. leave it as it is -- for starting the engine and operating the instrument panel, locator and even the live well pumps. As for the troller batteries you have a couple of options. One option is to simply wire them in parallel, then string the pair of wires to a troller receptacle at the bow. The other method would be to install a dual battery switch. The COM terminal of the switch would have the red wire feeing the +12 volt terminal on the troller receptacle. The ground wire on the receptacle connects to the NEG terminal on either battery. The NEG terminals would also need to be interconnected. The POS terminals on the troller batteries goes to the BAT 1 and BAT 2 terminals on the switch. In operation you have the option to use BAT 1 untill it gets low and then switch to BAT 2. You could also switch to BOTH and run that way. Neither battery would charge from the engine nor should they unless you have a very high output alternator. As for the charger, you could get by with a two bank (one for the engine and the other connected to the COM terminal and ground on either battery). Charging would then be BOTH in the both position, or you could charger either one by setting the switch to the desired battery.

Here ya go. Just pretend the outboard is the troller.

 

[Oldsmotion]

Re: 12V TM, charger and wiring help

Silvertip,

I can't thank you enough for the information.

This is pretty close to what I was thinking with one exception. If I place the switch in the "Off" position, can I use a 3 bank charger which would charge each battery based on the desired need, or discharge state. Would this be a faster way to charge the two trolling batteries opposed to using a two bank?

After reading so many of your posts and looking at the numerous diagrams you have posted to aid people, it was nice to get a response with your expertise.

I assume a Perko switch is close to the Guest shown? Is there a preference?

Let me know your thoughts as I have not ordered the charger or other related items yet but would like to get this job complete prior to this weekend.

Have a good day and thanks again.

 

[Silvertip]

Re: 12V TM, charger and wiring help

Either switch is fine and yes you can use a three bank regardless whether the switch is in the OFF, BAT 1, BAT 2 or BOTH position. With the batteries paralleled, a siingle bank charger will charge the batteries no differently than a dual bank connected separately. The reason is that the charger monitors "system" voltage. The weakest battery will absorb the charge until the two batteries are equal which will happen long before the charger is even turned on since they are already in parallel. So suit yourself. A three bank charger with three 5 amp outputs connected in your system is no more effective than a two bank charger with two 10 amp outputs. Charge rates will be the same except the start battery would recover faster.

 

[Oldsmotion]

Re: 12V TM, charger and wiring help

Going with a 3 bank 10 amp. By the time the sale price and rebate is deducted, it's very close to the two bank cost. Also purchasing the switch as I like having the power setting options.

Can you suggest a front mounted plug that will allow the charger to be plugged directly into the rear without cutting the plug off the new charger cord? Some I have read about are poor quality and once I cut the hole for this I hope it'll last.

Thanks

 

[Oldsmotion]

Re: 12V TM, charger and wiring help

Forgot this, I assume this will work:

http://www.iboats.com/Marinco-On-Bo...62992705--**********.905315147--view_id.39080

 

[Silvertip]

Re: 12V TM, charger and wiring help

Can you suggest a front mounted plug that will allow the charger to be plugged directly into the rear without cutting the plug off the new charger cord? Some I have read about are poor quality and once I cut the hole for this I hope it'll last.

Thanks

Sorry but you have me confused with the question. What are you plugging in and where. You mention front mounted plug but then are plugging something into the rear of the boat.

What I suggest you do is buy a recessed 115 volt inlet like this one. You then cut the plug off the charger and wire it to the back of the inlet which gets mounted on a vertical surface somewhere within reach of the charger power cord. You then use an extension cord to connect to the inlet. The inlet on the left in the top row is generally avaialble at any RV dealer and generally comes with a rubber cover. There are may others like this so this one is just an example.

http://www.kussmaul.com/accessories index.html

 

[Oldsmotion]

Re: 12V TM, charger and wiring help

Yea the image included is NOT what I am going to do in terms of the rear of the boat. I would install something as you noted, but locate it in the bow area.

The only problem that might surface is if there is a warranty issue with the charger, cutting the plug off to hard wire voids the warranty on some chargers. Hence the reason I was looking for a plug that I could plug the male end of the charger into.

 

[Silvertip]

Re: 12V TM, charger and wiring help

It's called an extension cord. You can mount a household outlet, but you still need to get power into it. That means a male plug and cord feeding that outlet. You then plug the charger into the outlet. Makes no sense as you already have a plug -- why complicate things. Mount the charger in one of the compartments. Leave the compartment open when you plug the extension cord in. Nothing to add. Or, use the item I showed, and wire it to a household outlet that you can then plug the charger into. Again, it makes a need installation but adds stuff that is really not needed.

 

[Oldsmotion]

Re: 12V TM, charger and wiring help

Yea after I hit submit reply I figured this out. Not rocket science which was made very clear.

Thanks

 

[Oldsmotion]

Re: 12V TM, charger and wiring help

What gauge wire do you recommend for the above configuration? The engine shown will be a 12 volt trolling motor.

 

[Silvertip]

Re: 12V TM, charger and wiring help

The size wire you use depends on the size (thrust/current draw) of the trolling motor. A 30# thrust motor will draw about 30 amps max, 40# = 40 amps and 50 - 55# = 46 amps give or take a little. Use an "ampacity chart and the length of the run of cable (round trip) to determine wire gauge. 6 gauge wire would allow use of a 55# motor.