Solar / Split Charge System

IHateNewShoes · 11-03-2021 9:20pm #1

Hi guys, I would be very grateful if anyone could help me out.

I am converting a van and I am looking at 2 methods for charging the leisure battery, a split charge relay from the starter battery and also a 100 W solar panel.

My question is, do I hook both of these straight onto the leisure battery (after the charge controller) or is there something else I can get to put in before the battery so that it will charge off the starter battery when driving and the solar panel when parked?

Any advice would be greatly appreciated, thank you!

colm_mcm · 11-03-2021 10:33pm

The mppt and split charger are both connected to the leisure battery.

If your van has a smart alternator, you will need a battery-to-battery charger instead of a split charger.

Note that a 100w panel isn’t going to do a huge amount, bigger panels aren’t much more expensive and in the case of a big panel (1500*1000mm approx) they can be cheaper than a 100w panel, all depends on what you need it to do of course.

IHateNewShoes · 11-03-2021 10:44pm

Thanks Colm, found it very difficult to find that information anywhere.

I must look into the bigger solar panels, I only have a 100 amp hour battery so I was thinking between the starter and the 100W on the roof that it would charge it enough. Don't plan on being parked up for any extended periods of time.

Was then going to have a battery charger pack as a back up just in case.

colm_mcm · 11-03-2021 11:23pm

are ye going to be running a fridge or a diesel heater or anything like that?

IHateNewShoes · 12-03-2021 1:14am

A cool box that draws 3.5amps, hoping it will manage that?

colm_mcm · 13-03-2021 7:37pm

I guess between driving around and the solar panel you should be ok. If you have room for a second battery, it mightn’t be any harm fitting one.

Deseras · 13-03-2021 7:57pm

You can fit 2 300 watt solar panels on top of van
Then get 1 or 2 portable ones that you can take out when parked
There are a lot of good youtube videos for van solar

100 watts will not do much and ireland has a lot of overcast rainy days
You can buy a wind turbine from china on eBay
It says it does 1000 watts but it only does 300 watts it will last for 2 years but it will run at night or if there's no sun.then buy 2 deep cycle batteries

15-03-2021 7:28pm

300W solar panel "for house"= €100
150W solar panel "for van" = €200

spaceHopper · 16-03-2021 11:25am

A well insulated top loader cooler box should be fine if you pack it with cold packs or freeze juice boxes. Are you using it a weekend camper or for week at a time? If you a have a 100ah battery and a 100 w panel with a charge controller but only use the van at weekend you have the drive back and the drive there and 5 days charging it should easily be able to keep up. If you are on extended trips then you need to look at something bigger. Alternatively buy a good battery charger and run a cable out to it the make sure to charge the battery before you go.

Put effort into having proper fused heavy wiring that's where a lot of campers fall down.

IHateNewShoes · 16-03-2021 4:03pm

Sir Liamalot wrote: »

300W solar panel "for house"= €100
150W solar panel "for van" = €200

I’ve noticed this, presume it’s is purely marketing the difference?
Any reason why something like this would not be suitable?

https://mpe-online.ie/shop/pv-solar/pv-solar-panels/q-cell-monocrystalline-pv-solar-panel-300w/

17-03-2021 5:32am

Everything "for a van" is a rip off.
Gas hobs, fridges, ovens, solar, "leisure" batteries etc, etc...

....Something to do with people being willing to pay it.

The power output is a significant difference for the price as well as size and voltage. Most of which you can overcome with MPPT.

freddyuk · 17-03-2021 6:30am

Sir Liamalot wrote: »

Everything "for a van" is a rip off.
Gas hobs, fridges, ovens, solar, "leisure" batteries etc, etc...

....Something to do with people being willing to pay it.

Actually the main manufacturers do not like making the smaller modules as there profit is in the "house" market. Hence the 100w/150w are more expensive to buy in. Many modules are generic and then badged for each distributor so the origins may nor be clear to the buyer. The labels on the back are just stuck on so no guarantee they are correct. If it has an MCS certification then you should be buying an audited production facility and you can ask for the factory test results on each module. If you don't get this then maybe go elsewhere however in my experience buyers tend to go for the cheapest option without asking for info on something that should work for 40+ years!

The distributor should have this data but nobody ever asks.

17-03-2021 8:44am

Why is flexible solar double to 4 times the cost of rigid?
Given that it performs worse due to heat sinking and lack of cooling & degrades to unserviceable due to UV instability over the course of 4-6 years?

freddyuk · 18-03-2021 10:25am

Never used them for the reasons you point out. Boaters like them because you can walk over them but in any position on a yacht they are in shadow so ........
Of course couriers have found it very difficult to destroy the flexi panels unlike the rigids which they can shatter in seconds.
I imagine the manufacturing process is more complicated then rigid frames which are made in very high volumes.

markmoto · 19-03-2021 4:35pm

IHateNewShoes wrote: »

My question is, do I hook both of these straight onto the leisure battery (after the charge controller) or is there something else I can get to put in before the battery so that it will charge off the starter battery when driving and the solar panel when parked?

Any advice would be greatly appreciated, thank you!

After several trials and errors I finally choose victron, Orion for B2B and victron smart solar charger, 2 separate units that can talk to each other over local network and I have Bluetooth app on the phone to see all charging history data etc

19-03-2021 9:20pm

By trial and error you mean?

Neither of those are bi-directional split charging they're just chargers.

I don't fit B2Bs they're usually an expensive way to bottleneck a system. I've superceeded 120A B2B units by bypassing them.

markmoto · 19-03-2021 9:36pm

Sir Liamalot wrote: »

By trial and error you mean?

Neither of those are bi-directional split charging they're just chargers.

I don't fit B2Bs they're usually an expensive way to bottleneck a system. I've superceeded 120A B2B units by bypassing them.

Would you leisure battery be able to handle 120A ?

19-03-2021 10:02pm

Oh course. It's scalable.

I can pull 100A with a lead 200Ah battery.

My record is 250A with a 650Ah.
Three alternators, all pegged, I could get another 100A outta that system but no need.

I generally don't do less than 40A for alternator split charging and that disqualifies most of the products on the market for being too feeble.

IHateNewShoes · 29-03-2021 10:23am

I thought I had a decent handle on it all, but reading your guys back and forth has certainly humbled me!! :-)

Thanks for the help!!

29-03-2021 10:28am

IHateNewShoes · 29-03-2021 10:46am

Thanks Liam, can you spot any glaring mistakes in my sketch?

29-03-2021 10:54am

Solar charge controller sharing a fuse with the alternator.
Split charge relay probably not very good if it looks like this.

split-relay-02_2000x.jpg?v=1588282506

No SOC meter.
Cable gauges not specified.
You are far better off to Y from the alternator than put the Habitation battery downstream of the engine battery.
Better again is put the habitation battery between the alternator and engine battery but leave the starter motor feed from the engine battery.

29-03-2021 11:01am

Homework reading assignment.

IHateNewShoes · 29-03-2021 12:36pm

Sir Liamalot wrote: »

Solar charge controller sharing a fuse with the alternator.
Split charge relay probably not very good if it looks like this.

No SOC meter.
Cable gauges not specified.
You are far better off to Y from the alternator than put the Habitation battery downstream of the engine battery.
Better again is put the habitation battery between the alternator and engine battery but leave the starter motor feed from the engine battery.

Is it definitely needed to use the alternator to charge the leisure battery as opposed to the starter battery? Would be keen to avoid if possible as I am currently not running anything to the engine block. (Starter batteries are under the drivers seat)

29-03-2021 4:59pm

The alternator is the power source not the engine battery. If you daisy chain off the engine battery it'll probably be >5 times worse than if you go direct.

Standard practice is to use too long, small, and circuitous cables to undermine the potential of the system. Most motorhomes are pulling ~15A to 7A from >100A alternators. I call that pi$$ poor but it's quite normal.
Take the machine to a "professional" they deliver <10% of the system capability in performance and call it good.

Solar / Split Charge System

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