Isolator, solar panel and battery the triangle of love ... (1 Viewer)

[Vulkyn]

So my FJ80 came with dual battery system, isolator and a whole bunch of cut out and buttons to disable / enable the aux battery.

At the moment, the main battery is connected to the alternator charging it when engine is on. Isolator then kicks in when the battery is stuffed and charges the Aux battery.

Now I do need guidance to avoid frying my electrics and better understanding what does what and when, using my amazing drawing skills I have tried to draw the current system which i want to make even more complex by adding a solar panel.

So what I want to know is as follows:

1. Does the isolator kick in for charging only ? or does it allow cross battery flow in case one battery is drained?
2. Would adding a solar panel with charge controller to Aux battery give me the same result as the main battery with alternator ? i.e at camp would the charge controler charge aux battery then move to main when fully charged?
3. If number 2 doesnt work, would fitting the charge controller to the main battery work in principle like alternator ?

My experience with panels is solely keeping my boat battery toped up when i leave it for extended time. I use a small 20W panel and just let it keep the battery ready for when i want.

 

[Basie]

Hi Vulkyn

There is a lot of info an chatter about dual battery systems

Just having the two batteries in parallel when the main one is charged ( your present lay out ) is not optimal and one of them will not reach full charge. The best solution is to replace the isolator with a DC to DC charger. There are quite a few on the market and some better than others. I have been using CTEK 250 and it also has inputs for a solar panel with MPPT. So it will solve that problem as well. It will only charge the aux battery with solar and serves as an isolator as well. Your main battery will not run down from the loads on the auxiliary battery and they will both charge optimally when the alternator is running

So in your case the isolator and charge controller will be replaced by the DC-DC which have inputs from the alternator and solar panel and outputs to the aux battery

You cannot charge the main with solar in this configuration and they will not cross charge each other. At camp the only charging will be from solar to aux and if, for some or other reason, your main battery runs down you will have to use jumper cables

Hope it helps

 

[Vulkyn]

Hi Vulkyn

There is a lot of info an chatter about dual battery systems

Just having the two batteries in parallel when the main one is charged ( your present lay out ) is not optimal and one of them will not reach full charge. The best solution is to replace the isolator with a DC to DC charger. There are quite a few on the market and some better than others. I have been using CTEK 250 and it also has inputs for a solar panel with MPPT. So it will solve that problem as well. It will only charge the aux battery with solar and serves as an isolator as well. Your main battery will not run down from the loads on the auxiliary battery and they will both charge optimally when the alternator is running

So in your case the isolator and charge controller will be replaced by the DC-DC which have inputs from the alternator and solar panel and outputs to the aux battery

You cannot charge the main with solar in this configuration and they will not cross charge each other. At camp the only charging will be from solar to aux and if, for some or other reason, your main battery runs down you will have to use jumper cables

Hope it helps

Hi Basie,

This helps a lot actually I was not aware of other choices such as DC to DC charger. Does this mean that the solar panel and alternator give the DC-DC first and it manages the 2 batteries ?
And this also means it replaces the charge controller or do I still need to buy one ?

Extremally great info thank you !

 

[Basie]

Hi Vulkyn

Sorry about very late reply

The DC-DC charger will only charge and manage the aux battery. It has inputs for the solar panel and the alternator ( from the original wiring ) and that is the only connection to your car's electrical system. It also acts as an isolator and you can happily run stuff off your auxiliary battery with no chance of draining the starting battery, but it will not charge the main battery Depending on which model you choose it can or cannot have a built in charge controller. I would definetely go for one with a built in controller The CTEK one has a MPPT controller

 

[Vulkyn]

Hi Vulkyn

Sorry about very late reply

The DC-DC charger will only charge and manage the aux battery. It has inputs for the solar panel and the alternator ( from the original wiring ) and that is the only connection to your car's electrical system. It also acts as an isolator and you can happily run stuff off your auxiliary battery with no chance of draining the starting battery, but it will not charge the main battery Depending on which model you choose it can or cannot have a built in charge controller. I would definetely go for one with a built in controller The CTEK one has a MPPT controller

No worries at all, truly appreciate you taking the time to assist

As it stands, the current aux battery is draining considerably low (meaning i'm damaging the anodes).
Cost wise its very expensive and I have quite a lot of todo before reaching this point, so I will do the following:

• Keep the system as is using an isolator (at the moment both batteries are charged from alternator)
• Get a solar panel + charge controller for Aux battery
• Replace (in the near future) the aux battery (which is a normal car battery) with a deep cycle / AGM battery.
• I do have cables in case my main runs flat i can always jump start myself ( that sounds so wrong)
• Even if i switch to AGM i should be able to charge the battery and start (although i need to check crank engine power for deep cycle batteries)