Looking do install dual batteries

Seena832271 · Post by **Seena832271** » 12 Dec 2019, 15:06

Hello everyone,

I'm looking to do some camping with my 2008 xc90 and would like to install a dual battery system.
The second battery will be a deep cell.
Is it an easy system to setup with that VSR isolator or have a DC to DC charger.
Wiring is not an issue, I just want to make sure I won't be damaging my charging system.

Also for the DC to DC charger I was thinking I could use a solar charge controller.
Any ideas in this?

Thanks in advance for all your help.

Post by **matthew1** » 12 Dec 2019, 15:23

Welcome to MVS, Seena.

Interesting. Following. Sorry I can't help.

Post by **RickHaleParker** » 12 Dec 2019, 16:02

Charging two batteries will not overload the charging system. Every alternator has overcurrent protection.

The Battery Isolator was invented in 1959, It is very mature technology.

Seena832271 · Post by **Seena832271** » 12 Dec 2019, 18:18

Thank you for the replies and I'm glad to be here.
Just wanted to make sure that the alternator could handle charging the aux battery once the isolator is on.

Post by **RickHaleParker** » 13 Dec 2019, 02:14

Seena832271 wrote: ↑12 Dec 2019, 18:18 Just wanted to make sure that the alternator could handle charging the aux battery once the isolator is on.

Based on what you wrote above. Your biggest concern would be mismatched battery capacity. You might want to look for a Charge Controller has a 12V generator input. That way the capacity mismatch will not be a problem.

Seena832271 · Post by **Seena832271** » 13 Dec 2019, 05:57

RickHaleParker wrote: ↑13 Dec 2019, 02:14
Seena832271 wrote: ↑12 Dec 2019, 18:18 Just wanted to make sure that the alternator could handle charging the aux battery once the isolator is on.
Based on what you wrote above. Your biggest concern would be mismatched battery capacity. You might want to look for a Charge Controller has a 12V generator input. That way the capacity mismatch will not be a problem.

Do you think a 60a 12v pwm charge controller will work? It's for charging with solar panels, should be the same 12v as the alternator, I think.

Post by **RickHaleParker** » 13 Dec 2019, 17:58

Seena832271 wrote: ↑13 Dec 2019, 05:57 Do you think a 60a 12v pwm charge controller will work? It's for charging with solar panels, should be the same 12v as the alternator, I think.

If it is a "12V" CC, the "12V' is the output not the input. The input range could be anything. You need to read the spec sheet.

60A is the maximum charging current. If you have a 100A alternator the CC will use a maximum of 60A of the 100A. This might be OK because some of the current will be needed for other things. A 60A CC will charge the battery but maybe not as fast as a higher current CC. In my option, 60A should be enough for a 1 - 2 battery bank.

However I can see why you are considering a 60A. The cost of a CC goes up exponentially as the current capacity goes up.

You would need to dig to find them but there are CC that have two or more inputs. One for the Solar panels anothers for generators, some have inputs for charging off the grid, which could be used to charge the battery at a camping spot with utilities.

It would be real helpful to both of us if you could clearly defined how you are going to use the CC. From that the capabilities could be defined.

A PWM is not as efficient as a MPPT but a PMW is designed for maximum battery life. That is the trade off, MPPT for maximum solar panel efficiency, PWM for maximum battery life.

When solar panels cost more then they do today, the argument for MPPT was a hands down winner. With Solar Panel prices falling and batteries costing as much as $200 each, the MPPT argument does not hold water like it use to.

Seena832271 · Post by **Seena832271** » 14 Dec 2019, 15:42

Well I am looking at the solar CC on Amazon,
Input is 12v and the output is 12v.
I was thinking that I could wire the input to my starter battery and wire the output to my aux battery.
The aux battery I'm planning on using is a 105amp marine deep cycle.

Thank you in advance for all your help.

https://www.amazon.ca/gp/aw/d/B07XXT2HY ... VTBV&psc=1

https://www.canadiantire.ca/en/pdp/moto ... p.html#srp

Post by **RickHaleParker** » 14 Dec 2019, 19:16

Seena832271 wrote: ↑14 Dec 2019, 15:42 I was thinking that I could wire the input to my starter battery and wire the output to my aux battery.

That would work. You could use a battery isolator, which is just a relay, to switch the CC input between the alternator and PV panels.
Engine running alternator connected to CC input. Engine not running PV panels connected to CC input.

You got to watch the Voltage Open Circuit (VOC) of the PV Panels. Make sure VOC is not higher the the maxium voltage of the CC input.

Seena832271 · Post by **Seena832271** » 14 Dec 2019, 19:19

Awesome, thank you.
Well dont plan on using an PV panels. I just want to use the cc for isolation and I feel that it will create less load on the alternator.