Quistion to T-Max Dual battery system users

[Desert Dino]

My perfect 12 year old dual battery system just died on me. It's a time to get a new one the Australian company that made it is out of business.
3 systems are on the radar
T-max
IBS
Blue Sea - the most robust, but doesn't have a battery monitor. I can install one from National Luna or other, but this will drain the battery or will have to install a relay to disconnect the minus when the key is in the off position. This is the most expensive, but the most robust

IBS is double the price of the T-Max and I read both documentation and it seems they are identical even the manuals are almost the same wording, the IBS documentation is in perfect English whereas the T M there are some sections that most probably a bad translation from Chinese.

The IBS as the option to disable the system by pressing the auto/link button for 6 seconds, it will unlink and sends the system to sleep mode

I couldn't find this option on the T-Max documentation

Is there no way to unlink the battery from the T-Max controller? (There is a guy that put a switch on the green control wire on this thread T-Max Dual Battery Install)

 

[Rwhat]

The T-max system does the same thing. If I remember correctly.

 

[Fosters]

I have had the max for several years...bonus points because it can be ordered from autozone/discount auto parts.
It’s pretty transparent...it’s rare I have ever had to use the link function...it uses a ford type solenoid...
Simple to install...

 

[chap79]

Not what you asked but I’m running the blue sea 7622 ACR. For the battery monitor I wired in a dual voltmeter monitor I got off Amazon. There’s a few different types, a carling switch sized one and a round mount. I’ve been using the rounds style one for a few years without any issue. I do have it wired to a relay and then directly to a leg on each battery. On the main battery I just ran a wire to the return side of the fusible link to monitor the voltage coming from the battery with an in-line fuse of course.

I really liked the Blue Sea system. It’s also the only one rated for 500 amps continuous use. So you can link the batteries and winch to your heart’s desire.

 

[Desert Dino]

The T-max system does the same thing. If I remember correctly.

@Rwhat can you confirm the possibility to unlink and disable the auto mode of the T-Max unit from the unit itself ?

 

[Desert Dino]

@chap79 I am considering blue sea 7622 ACR instead of T-Max

The T-Max is much more straight forward to install, I have read the 7622 installation instructions are not so simple

One question the controling switch has 3 options, auto, permanent unlink and permanent link has two Leds in it. This 2 leds work together do they indicate when the 7622 unit is linked and off when Unlinked?

 

[Desert Dino]

.

 

[Rwhat]

Just wondering why you would want it to unlink? I added a relay so my solenoid will not trigger closed when the either battery sees 12.4 volts. Basically it’s keyed off the ignition so if I use a battery tender or solar panel to charge the solenoid is not constantly linking and unlinking the batteries. Since it sees 13.5v then the charge splits to both batteries and drops below the threshold of the 12.4 volts. So keep the solenoid closed it draws over 1.3 amps.

The battery display has logic built in to control a couple features like manually linking the batter for like 15 minutes. I think you can hold the link button down for a certain about if seconds to manually unlink the batteries. (Don’t quote me on that)

You can always run the small wires that sense the 12.4 volt signal to the solenoid to a toggle inside the vehicle to keep them unlinked manually.

 

[Desert Dino]

Just wondering why you would want it to unlink? I added a relay so my solenoid will not trigger closed when the either battery sees 12.4 volts. Basically it’s keyed off the ignition so if I use a battery tender or solar panel to charge the solenoid is not constantly linking and unlinking the batteries. Since it sees 13.5v then the charge splits to both batteries and drops below the threshold of the 12.4 volts. So keep the solenoid closed it draws over 1.3 amps.

The battery display has logic built in to control a couple features like manually linking the batter for like 15 minutes. I think you can hold the link button down for a certain about if seconds to manually unlink the batteries. (Don’t quote me on that)

You can always run the small wires that sense the 12.4 volt signal to the solenoid to a toggle inside the vehicle to keep them unlinked manually.

@Rwhat I am using two different chemistries of batteries (lead Acid and AGM) this is not my daily driver and it stands long period on my property connected to 2 different chargers giving optimal charging and maintenance to each kind of battery. For that I need permanent unlink.

To force the T-max to unlink you can add a switch on the control green wire, but I don't want more switches and extra wires

The green wire of the solenoid needs to get minus (body) to link if you add a switch that cuts the connection between the T-Max and the solenoid it will unlink permanently never mind what the T-Max controller is doing if the switch connect the solenoid to body minus it will link permanently and if the switch connector solenoid to controller it will be controlled by the T-Max controller.

 

[Rwhat]

So if I understand you correctly you just want to be able to unlink them for charging when it’s sitting not being used?

Without looking at the schematics right now you can do what I mention. Use a relay to trigger the 12v keyed ignition signal to only link the batteries when the vehicle is running or ignition turned on. This will use the relay to send a 12v via the relay to the solenoid. Very simple.

The down side is you will be unable to MANUALLY link the batteries from the push button on the panel. I just left the wires attached with male female connectors at the solenoid so I can connect them together if I want to self jump start or have the DB system run normally.

Let me know and I can send you the diagram of my setup. I went though the same issues as the thread you posted. I decided not to add a switch.