3x Solar panels - 2x Charge controllers - 1x battery

[Dodge]

Hi all!

First post as I've only just found this site,

I recently bought an LDV conversion on ebay, all ready to go, however have since stripped and started rebuilding.
Last week I took all the electrics out as it was a mess!

Now putting it back together I have 2x 120w panels going into the 20a charge controller and 1x 75w panel connected to the 10a charge controller (both MPPTs) - and underneath there are 4x 105aH leisure batteries

Can both the battery terminals from these charge controllers both link into main wires coming from the batteries?

Also, my inverter was connected directly from the batteries, should this instead come from the load on the charge controllers?

[PNPmacnab]

"charge controller (both MPPTs)" I very much doubt it.

[Dodge]

So would it be best to remove the 75w panel and 10a MPPT, and just use the other 2, and if i need more juice then upgrade the panels?

[littleharbor]

You can use two charge controllers on a single battery bank. Each controller should be connected directly to the battery though. What model charge controllers are you using? I'm assuming you are set up as a 12 volt system from your description. That being said you are way under paneled for that size battery @ 450 amp hours you would want no less than 25 amps and preferably 40 45 amps to properly charge that size bank. You have less than 15 amps.

[Dodge]

You can use two charge controllers on a single battery bank. Each controller should be connected directly to the battery though. What model charge controllers are you using? I'm assuming you are set up as a 12 volt system from your description. That being said you are way under paneled for that size battery @ 450 amp hours you would want no less than 25 amps and preferably 40 45 amps to properly charge that size bank. You have less than 15 amps.

Ah ok,
They are MPPT, but not sure on the brand, I will have to check,

Cheers for the info, might get rid of the 120's and get something bigger on,

[littleharbor]

What is the max Voc. for your controllers?

[SunEagle]

I also doubt that the 10A CC is really an MPPT type. I would not trust a product just because it may be labeled something when it really is not. Especially if it costs very little. That is a basic bate ans switch action to get people to purchase a product.

I would also not use the 75w panel on the same battery system even with a quality MPPT CC. There is always a chance of the two CC's fighting each other to charge the same battery with different charging amps.

I would use that 75w for a small portable system that can be dragged around to places that have not power. Just make sure you size the battery so it's Ah rating is no more than 10 x the Imp rating of that 75w panel.

Also please clarify what your battery system is rated. I know you have 4 x 105Ah but are they 6v wired to make a 12v 210Ah system or 12v wired to make a 12v 420Ah system. If it is the second then you do not have enough panel wattage or a big enough charge controller to keep them happy.

[littleharbor]

You can use two charge controllers on a single battery bank. Each controller should be connected directly to the battery though. What model charge controllers are you using? I'm assuming you are set up as a 12 volt system from your description. That being said you are way under paneled for that size battery @ 450 amp hours you would want no less than 25 amps and preferably 40 45 amps to properly charge that size bank. You have less than 15 amps.

My bad. I thought I read T-105 which is a 6 volt, 225 Ah battery, Your 105 Ah batteries are 12 volt aren't they? If so, and all four are paralleled 420 Ah. Four 12 volt batteries in a parallel configuration is another can of worms that could be done better with 6 volt batteries.

[Dodge]

Sounds good! I think I will just get rid of the 75w setup for now. Saves messing about!

They are wired to make a 12v 420ah system. which solar panels would be ideal for this?
I dont spend every day in the van, so it might not get used for a day or two,

[Dodge]

My bad. I thought I read T-105 which is a 6 volt, 225 Ah battery, Your 105 Ah batteries are 12 volt aren't they? If so, and all four are paralleled 420 Ah. Four 12 volt batteries in a parallel configuration is another can of worms that could be done better with 6 volt batteries.

How come it becomes a can of worms?

Sorry for all the questions, and i appreciate the answers, im not too shabby on electronics in some regards, but this is all quite new to me,

[SunEagle]

Sounds good! I think I will just get rid of the 75w setup for now. Saves messing about!

They are wired to make a 12v 420ah system. which solar panels would be ideal for this?
I dont spend every day in the van, so it might not get used for a day or two,

With a 420Ah battery system you need approximately 42amps of charging. That requires an MPPT type charger rated 45amps and about 500 watts of panels (12v x 42A = 504w).

So you will need to more than double that 240 watts you currently have as well as get a true quality MPPT type charger rated at least 45amps.

Your other choice would be disconnect 2 of those 105Ah batteries and only have a 210Ah 12volt system. That will match up to your CC and panel wattage. It will also get you out of the danger of having more than 2 batteries wired in parallel.

[SunEagle]

How come it becomes a can of worms?

Sorry for all the questions, and i appreciate the answers, im not too shabby on electronics in some regards, but this is all quite new to me,

Wiring batteries in parallel increases the chance of unequal charging and discharging due to different resistant paths in the circuit. What that does is make some of the batteries work harder and die quicker so soon all of your batteries die an early death.

[Dodge]

With a 420Ah battery system you need approximately 42amps of charging. That requires an MPPT type charger rated 45amps and about 500 watts of panels (12v x 42A = 504w).

So you will need to more than double that 240 watts you currently have as well as get a true quality MPPT type charger rated at least 45amps.

Your other choice would be disconnect 2 of those 105Ah batteries and only have a 210Ah 12volt system. That will match up to your CC and panel wattage. It will also get you out of the danger of having more than 2 batteries wired in parallel.

Ah ok, so whoever had it last just over compensated on the batteries

Cheers for the information,

[Dodge]

Wiring batteries in parallel increases the chance of unequal charging and discharging due to different resistant paths in the circuit. What that does is make some of the batteries work harder and die quicker so soon all of your batteries die an early death.

Ahh! Now that makes sense, I use lipo/li-ion batteries for my RC stuff, and they all need balancing as they charge!

I may keep 2 batteries in for the 240w panels, and one in for the 75w system. And use the smaller for things like lights etc and the bigger for powering the bigger things,

[SunEagle]

Ahh! Now that makes sense, I use lipo/li-ion batteries for my RC stuff, and they all need balancing as they charge!

I may keep 2 batteries in for the 240w panels, and one in for the 75w system. And use the smaller for things like lights etc and the bigger for powering the bigger things,

Sounds like a plan. I built a small portable system with an 80watt panel and a 65Ah battery. The panel is a little small to keep the battery happy but it is portable and has worked for me when I need a little power while I fly my RC stuff.