Charging trolling motor battery while boondocking

[cbird02]

I have a two-battery bank that is charged by a solar panel via the onboard Renogy controller. I have a trolling motor that is run by a 12v deep cycle 100ah battery. I have 2 similar deep cycle batteries in the bank. When I am off grid, I want to charge my trolling battery from the RV without using an inverter to plug in my normal AC-DC charger. What is the most efficient way to do this? Can I just hook up my trolling battery in parallel with the other two and the whole bank will then be charging? What if I want to make sure that my trolling motor is fully charged even if my coach batteries are not? Thx

Craig

[Yosemite_Sam1]

Grit dog wrote:
The bigger question is do you have enough charging capability to keep up the house batteries AND the boat battery.

Seems ok although I only have the voltmeter as my tool.

It's all fully charged by mid-day of fairly sunny day.

[Grit_dog]

The bigger question is do you have enough charging capability to keep up the house batteries AND the boat battery.

[CA_Traveler]

Yosemite Sam1 wrote:

cbird02 wrote:
"Charge Controller Safety
• NEVERconnect the solar panel array to the controller without a battery. Battery must be connected first. This may cause a dangerous occurrence where the controller would experience a high open circuit voltage at the terminals. "

From my manual

Thats a problem for me -- though not seen any breakdown yet.

So which pole should I put an off switch to the controller?

Electrically either one is OK. It's very common in most situations to switch the positive wire.

I also disconnect the panels first before the battery connection.

[Yosemite_Sam1]

mr_andyj wrote:
An A-B switch can be bought at any auto parts store. Switched to the left it connects circuit A, to the right it connects circuit B and in the middle is off for both, and there is no way it can connect both A and B at the same time, so you know you only charge one battery bank at a time.
Just get a high amp switch.
Put the switch on the positive wire out of the charge controller, and then on the other side of the switch you will have two wires go to the A and the B (camper or trolling motor batt). The negative wires can all be connected together.
Connect the trolling motor before switching.
The more solar panels you have the faster the charge will be.
If you connect the trolling batts to the camper batts then the initial charge will be faster as the troll batts will pull charge off the topped-off camper batts, then when they equalize it will be faster to have only the troll batts connected, but then the problem is your camper batts will be very low.

Thanks, I appreciate that.

[mr_andyj]

An A-B switch can be bought at any auto parts store. Switched to the left it connects circuit A, to the right it connects circuit B and in the middle is off for both, and there is no way it can connect both A and B at the same time, so you know you only charge one battery bank at a time.
Just get a high amp switch.
Put the switch on the positive wire out of the charge controller, and then on the other side of the switch you will have two wires go to the A and the B (camper or trolling motor batt). The negative wires can all be connected together.
Connect the trolling motor before switching.
The more solar panels you have the faster the charge will be.
If you connect the trolling batts to the camper batts then the initial charge will be faster as the troll batts will pull charge off the topped-off camper batts, then when they equalize it will be faster to have only the troll batts connected, but then the problem is your camper batts will be very low.

[Yosemite_Sam1]

cbird02 wrote:
"Charge Controller Safety
• NEVERconnect the solar panel array to the controller without a battery. Battery must be connected first. This may cause a dangerous occurrence where the controller would experience a high open circuit voltage at the terminals. "

From my manual

Thats a problem for me -- though not seen any breakdown yet.

So which pole should I put an off switch to the controller?

[cbird02]

"Charge Controller Safety
• NEVERconnect the solar panel array to the controller without a battery. Battery must be connected first. This may cause a dangerous occurrence where the controller would experience a high open circuit voltage at the terminals. "

From my manual

[cbird02]

time2roll wrote:

Yosemite Sam1 wrote:

Housted wrote:
A word of caution here:
Most if not all solar controllers do not want solar connected without battery connection first. Be very careful when switching between batteries on the output of solar controller. You might want to add a breaker/switch to the solar input to the controller. You can then disconnect the solar panels and do your battery reconfiguration to charge the TM battery.

What could possibly happen?

Because this is my situation every time I take out my solar panels out of it's box and RV storage.

The solar panels are pre-connected to the controller, gets exposed to the sun as I set it up -- and before it gets connected to the batteries, the last step of the connection processes.

Depends on the controller. Mine very specifically says to always have a battery connected before solar power is connected.

Yes, if the controller sense the voltage of the panels first, it could set charging to the wrong voltage. It needs to sense the battery voltage so that it matches the charging or there could be problems. If your panels match battery voltage - ok. If your controller is programmed to switch after you hook up the battery - ok.

[time2roll]

Yosemite Sam1 wrote:

Housted wrote:
A word of caution here:
Most if not all solar controllers do not want solar connected without battery connection first. Be very careful when switching between batteries on the output of solar controller. You might want to add a breaker/switch to the solar input to the controller. You can then disconnect the solar panels and do your battery reconfiguration to charge the TM battery.

What could possibly happen?

Because this is my situation every time I take out my solar panels out of it's box and RV storage.

The solar panels are pre-connected to the controller, gets exposed to the sun as I set it up -- and before it gets connected to the batteries, the last step of the connection processes.

Depends on the controller. Mine very specifically says to always have a battery connected before solar power is connected.

[Yosemite_Sam1]

Housted wrote:
A word of caution here:
Most if not all solar controllers do not want solar connected without battery connection first. Be very careful when switching between batteries on the output of solar controller. You might want to add a breaker/switch to the solar input to the controller. You can then disconnect the solar panels and do your battery reconfiguration to charge the TM battery.

Housted

What could possibly happen?

Because this is my situation every time I take out my solar panels out of it's box and RV storage.

The solar panels are pre-connected to the controller, gets exposed to the sun as I set it up -- and before it gets connected to the batteries, the last step of the connection processes.

[Housted]

A word of caution here:
Most if not all solar controllers do not want solar connected without battery connection first. Be very careful when switching between batteries on the output of solar controller. You might want to add a breaker/switch to the solar input to the controller. You can then disconnect the solar panels and do your battery reconfiguration to charge the TM battery.

Housted

[Yosemite_Sam1]

cbird02 wrote:

Yosemite Sam1 wrote:
I've been doing this without problem.

In fact, I have a permanent external connection to plug-and-play the batteries in parallel every time it's not in use. Serves as standby (booster) to my already dual-batteries in the RV.

But, of course, my Renogy solar has a controlle and everything goes through it..

Ok, so you have not had a problem adding a lower charge battery added to the parallel bank? I have a Renogy Adventurer 30A controller. What size wires do you use for the connection and runs to the battery?

I don’t know the gauge, but it’s the same wires supplied by Renogy for which I have excess of. My RV is solar ready.

[cbird02]

Yosemite Sam1 wrote:
I've been doing this without problem.

In fact, I have a permanent external connection to plug-and-play the batteries in parallel every time it's not in use. Serves as standby (booster) to my already dual-batteries in the RV.

But, of course, my Renogy solar has a controlle and everything goes through it..

Ok, so you have not had a problem adding a lower charge battery added to the parallel bank? I have a Renogy Adventurer 30A controller. What size wires do you use for the connection and runs to the battery?

[Yosemite_Sam1]

I've been doing this without problem.

In fact, I have a permanent external connection to plug-and-play the batteries in parallel every time it's not in use. Serves as standby (booster) to my already dual-batteries in the RV.

But, of course, my Renogy solar has a controlle and everything goes through it..