Solar Panel Isolation (1 Viewer)

[poppycamper]

Morning you knowledgeable Funsters.
Advise please.. Fitting battery isolation type switch to control the charge from panels to batteries as I don't want to trickle charge batteries when Sun is not at its best...
2x100w panels
Votronic 250 mppt duo charger
2x120ah lithium batteries
So do I fit switch between panel and controller or controller and batteries?

 

[Richard n Ann]

Between solar panel and controller ?

Got one of these on ours, they're good quality. The fuse would never trip of course but just used as a switch..

 

[andy63]

Isolate the panels... The controller nerds battery voltage connecting up first if it's to crackup properly..
The controller will just thinkits getting dark more often?? if the switch is in the panel side..
Andy

 

[poppycamper]

Thanks for prompt input.. those switches certainly look the biz and much neater than ones I was looking at...Again many thanks

 

[Minxy]

On previous campers I just put a fuse holder in the positive wire for each of my solar panels between the panel and the solar regulator, that way I could just pull the fuse when I wanted to isolate them from the system. Do NOT put one between the solar regulator and the vehicle's battery or electroblock (or equivalent) as it could cause serious damage to the solar regulator if there is nowhere for the 'input' power to go to.

^{_{Subscribers  do not see these advertisements}}

 

[poppycamper]

Thnx for input Minxy Girl

 

[Silver-Fox]

Between solar panel and controller ?

Got one of these on ours, they're good quality. The fuse would never trip of course but just used as a switch..

What size would be required for 300w of panel.

Also do these interrupt the supply from from the panels or do the allow 100% through

Ta ?

 

[DBK]

Why do you want a switch at all? The controller won't over charge the batteries and if there isn't much sun it won't do any charging. Seems an unnecessary complication to me.

 

[andy63]

. Do NOT put one between the solar regulator and the vehicle's battery

You lost me there Mel.. That's exactly where you do put a fuse on the solar system and the ones ive done the instructions tell you to fuse the output side of the controller..
The input or panel side is protected anyway and instructions don't generally ask for a fuse there... But as you have said it can be a handy way of isolating the panels?
Andy

 

[eddie]

On previous campers I just put a fuse holder in the positive wire for each of my solar panels between the panel and the solar regulator, that way I could just pull the fuse when I wanted to isolate them from the system. Do NOT put one between the solar regulator and the vehicle's battery or electroblock (or equivalent) as it could cause serious damage to the solar regulator if there is nowhere for the 'input' power to go to.

What input power? When the circuit is open there is no "power"

^{_{Subscribers  do not see these advertisements}}

 

[andy63]

Why do you want a switch at all? The controller won't over charge the batteries and if there isn't much sun it won't do any charging. Seems an unnecessary complication to me.

Think its the fact he doesn't want to be float charging his lithium batteries?
Andy

 

[eddie]

Think its the fact he doesn't want to be float charging his lithium batteries?
Andy

Use a Victron MPPT regulator with the Bluetooth option and download the App and use the Lithium Solar charging profile and he won't have to

 

[andy63]

Use a Victron MPPT regulator with the Bluetooth option and download the App and use the Lithium Solar charging profile and he won't have to

Sounds good? I might have a look at that ..I'm debating and looking into solars compatibility with lithium installs atm.

But I'm guessing my answer to john is the reason the op wants to be able to isolate his panel.??
andy

 

[poppycamper]

Change my votronic for victron!!! Hokw much will that cost me... more than £7.99 for a manual switch.. Yea spot on Andy.. want to isolate batteries when not using as motorhome to prevent full charge( not overcharge) and also float charge... Both i believe bad for lithiums

 

[andy63]

Both i believe bad for lithiums

Yea that's what I'm told.. But the standard solar controller can have different charging regimes for the various lead acid types..
Have you considered that on most of them the solar will never actually fully charge the lithium batteries.. The voltage is not high enough on most..
Like I said I'm looking into that myself and would be keen to know what others think.. Sure it will most probably enter a float charge mode but the lithium's won't be fully charged anyway ..is that still bad?
Andy

^{_{Subscribers  do not see these advertisements}}

 

[eddie]

Change my votronic for victron!!! Hokw much will that cost me... more than £7.99 for a manual switch.. Yea spot on Andy.. want to isolate batteries when not using as motorhome to prevent full charge( not overcharge) and also float charge... Both i believe bad for lithiums

Well if you don't want to use a regulator with the correct Lithium profile and are going to use a switch it would be better to use a "switch" rather than a circuit breaker that is designed for re-setting in the event of a problem not used daily

Cheaper too!

We install a lot of Lithium batteries, most with solar and don't fit a switch.

 

[eddie]

Yea that's what I'm told.. But the standard solar controller can have different charging regimes for the various lead acid types..
Have you considered that on most of them the solar will never actually fully charge the lithium batteries.. The voltage is not high enough on most..
Like I said I'm looking into that myself and would be keen to know what others think.. Sure it will most probably enter a float charge mode but the lithium's won't be fully charged anyway ..is that still bad?
Andy

If you have a solar regulator that has a Lithium profile it will not damage your Lithium batteries

 

[poppycamper]

Thanks for input... yes i have a solar panel controller with lithium settings (4 i believe). I have taken your comments on board and will hold fire with switch until i see how the panels react with batteries but i have not completely dismissed the idea. As matter of interest battery says 14.6v setting to charge and I have controller initially to 14.2.....time will tell

 

[andy63]

If you have a solar regulator that has a Lithium profile it will not damage your Lithium batteries

I sort of guessed that??
But I'm wanting to know what effect a conventional charge controller on one of the lead acid profiles will do if lithium are installed and you don't change your charge controller , certainly in the short term till they get round to it.. Is it likely to do any damage.
Andy

 

[eddie]

I sort of guessed that??
But I'm wanting to know what effect a conventional charge controller on one of the lead acid profiles will do if lithium are installed and you don't change your charge controller , certainly in the short term till they get round to it.. Is it likely to do any damage.
Andy

Without knowing which Lithium batteries its hard to say what will happen. But, the BMS should protect the Lithium from overcharging, but, some BMS have to be re-set which would shut down all the 12 volt operation until the BMS was reset meaning that you "could" be micro managing on a daily basis. Of course if your using the motorhome it could be that the upper voltages don't get reached, and of course it depends on the time of year and the Location!

More likely in the South of France in the Middle of June than the middle of December in the Highlands of Scotland !

^{_{Subscribers  do not see these advertisements}}

 

[poppycamper]

Andy.. when I did my research into this I gleaned 2 things are bad for lithiums. full charge and trickle charge... using conventional charger you won't get high enough voltage to fully charge so that is good. However once it thinks it is charged it will trickle charge battery which is BAD so you have to manually disconnect charger. For max life cycles lithiums should be used between 20 to 80% DID. However there is so much dis/information out there on this subject
Stevie

 

[eddie]

Andy.. when I did my research into this I gleaned 2 things are bad for lithiums. full charge and trickle charge... using conventional charger you won't get high enough voltage to fully charge so that is good. However once it thinks it is charged it will trickle charge battery which is BAD so you have to manually disconnect charger. For max life cycles lithiums should be used between 20 to 80% DID. However there is so much dis/information out there on this subject
Stevie

Or use the correct charger and you don't have to do any of that.

 

[andy63]

However once it thinks it is charged it will trickle charge battery which is BAD

But that's what I'm wondering.. Trickle charging a full battery is bad..but the lithium will be short of full charge.. So is that float or trickle still damaging.. If yo follow what I'm trying to say..
Andy

 

[poppycamper]

Can't be 100% Andy but my understanding is yes... even though not fully charged it is still bad to put such a small constant charge into battery.

 

[andy63]

Without knowing which Lithium batteries its hard to say what will happen. But, the BMS should protect the Lithium from overcharging, but, some BMS have to be re-set which would shut down all the 12 volt operation until the BMS was reset meaning that you "could" be micro managing on a daily basis. Of course if your using the motorhome it could be that the upper voltages don't get reached, and of course it depends on the time of year and the Location!

More likely in the South of France in the Middle of June than the middle of December in the Highlands of Scotland !

Again thanks Eddie.. All points I've considered... The lithium batteries in question are the lithium iron phosphate and different manufacturer s exist but they will be much of a muchness in terms of charging voltages I would have thought...
The BMS built into the batteries coming on stream now are just that..built in with no user settings.. And I imagine that's the way it will stay in the leisure market sector..
So with all that in mind I'm still wondering what effect a conventional solar controller will have
Andy

^{_{Subscribers  do not see these advertisements}}

 

[Lenny HB]

Well if you don't want to use a regulator with the correct Lithium profile

The Votronic does have the correct profile.

 

[Lenny HB]

Why can't you set your BMS so they don't get fully charged?

 

[andy63]

Can't be 100% Andy but my understanding is yes... even though not fully charged it is still bad to put such a small constant charge into battery.

Thanks.. That's what I've been wondering but I was sort of coming down on the side of it most probably won't be doing much harm..given that there may be small drains on the batteries anyway..like the controller its self..
Andy.

 

[andy63]

Why can't you set your BMS so they don't get fully charged?

That's a point I just made above... A lit of the batteries aimed at our market have built in protection and BMS that are not user adjustable.
Andy

 

[Reallyretired]

I dont have lithium but still have a circuit breaker between panels and controller. Makes it easy to disconnect the panels if I need to replace or otherwise disconnect the batteries. As the circuit breaker acts as both switch and fuse in one it simplifies matters.

^{_{Subscribers  do not see these advertisements}}