Bad idea? Portable Zamp Solar related question

[paddlesurf.net]

Greetings,

Here's my situation: I will soon be the owner of a new Hawk flatbed - it will come with the dual 12v battery option but I did not get the solar panels or controller installed (I wanted to explore the land of 24v, mppt systems and at the time FWC did not offer that as an option).

So 2 questions:

1. I already own a 160watt Zamp portable panel with PWM controller already on it.

I'd like to use that 160watt portable - it was expensive when I bought it two years ago.

So... can I hook the rear FWC solar wiring directly to the battery bank and use this 160watt portable while also having an MPPT controller installed inside the camper where it would use the FWC factory wiring connected to a 24volt system on the roof?

There is a zamp drawing that seems to show that you can hook the portable directly to the house battery - bypassing the "house" solar controller. Can I only do this if both controllers are PWM?

I'm sure this is a bad/foolish/stupid idea - please educate me.

2. Assume I scrap the 160watt portable zamp and I still have the 200 watts at 24volts upstairs - is there any way I could get a portable panel in 24volt configuration that I could control with the house MPPT controller that is not giant?

Does anybody with a 24 volt system have a portable 24volt panel(s)?

 

[longhorn1]

Our 2014 Grandby came with 100W Zamp and Zamp controller. We also had the rear plug. I bought an 80W portable Zamp, which doesn't have a controller, I did this without the controller due to the fact the rear wiring went directly to the Zamp Controller. In the winter with the camper covered, I plug in the portable for 3-4 hours to keep the batteries charged.

You don't want to wire through any controller. I'm not a solar guy so you will have to wait until others Chim in on what you should do.

Regards,. jd

 

[Squatch]

1st question: I take it you want to use 24v panels to take advantage of what an MPPT controller does best?

But your camper and the loads within will still be 12 volt correct.

So you will feed the controller with 24v nominal from panels but charge a 12 volt battery system and run a 12 volt system of lights, fridge ect?

If that is the case then yes you can add 12 volt from any source to your battery terminals. Be it separate chargers or the truck itself. The batteries don't care where the 12 volts comes from. My camper is set up to charge batteries from different sources. I assume the MPPT controllers use a shunt like my PWM does. I don't have experience with them. If so you just need to make sure that all 12 v charge sources go through the shunt so that the monitor sees the actual battery state no matter where the charge comes from.

The camper wiring is just that, wiring. Roof and back wall should be separate. Just make sure that everything is well labeled. You don't want 24v panels on a 12 volt input or vice versa.

12 volt and 24 volts should not meet at any point without electronics to separate them.

That's the issue without trying to get confusing. There are many ways to wire up a 24 volt system and still use 12 volts for the camper. The big question is where are you converting from 24 to 12 if at all. Seeing as how most fridges and stuff are 12 volt I'm assuming you'll be set up as my description above. 24 v from panel to controller. 12v from controller to batteries for a 12 volt system.

 

[paddlesurf.net]

Squatch that's very helpful - yes the whole camper is 12volt. I'd just be wiring roof panels in series to take advantage of the 24volt to the mppt controller which would then feed to 12volt battery bank.

I guess I don't know how the "shunt" section from the rear, portable panel would work. Maybe I should just suck it up and get a portable without a controller already on it?

If that panel didn't have a controller on it, I assume I'd just connect the factory rear wiring to the mppt controller along with the 24volt wiring from the roof panels. Right?

Jeez if anybody has a diagram that would be helpful.

 

[ckent323]

Paddlesuf,

I think I understand the situation so will try to give what I think is a reasonable way to think about this.

A battery does not care where it gets its 12 v from. It does care about its state of charge and how it is charged (i.e. Bulk, absorbance, float).

If you have two different panels with two different controllers it is my perspective that you can put a switch in to use one or the other but not both at the same time. I don't think it is a good idea to have two different controllers potentially competing to charge the battery at the same time.

In any event you need a controller between the panel and the battery (or battery bank) and not connect a panel directly to a barttery (or battery bank).

I do not know how the controller is integrated into the pane/controller combination you already have but if it is possible to bypass the integrated controller and then connect both panels to a single controller suitable for accommodating the combined panels I see no reason why you cannot or should not do that.

Hopefully one or more of Rando, ntsqd or Vic Harder will comment and add on or correct anything I may have gotten incorrect in my comment above.

Regards,
Craig

 

[paddlesurf.net]

Thanks everybody for all the help.

Ckent,

The controller on the 160 Zamp portable is set up in such a way that you can't unplug it from the charging wires - it's a bummer because it worked well for the battery bank in my old camping set up.

Understood about the need for a controller between panel and battery - watched some guys cook off their batteries in Baja, even after I told them I had a feeling they were doing something wrong (looking at my set up, looking at their setup, knew something wasn't right.. kinda funny actually). I was just hoping there was someway I could put that expensive piece of equipment to use.

It looks like I will have to find a set of portable panels that I can wire in series (to get 24v) that will then be connected to the mppt controller in my camper - which is also connected to the 24 volt roof panels of the camper.

Do I just crowd the portable's wiring into the appropriate terminals of the controller along with the roof's wiring.

Or do I splice like polarity wires together from roof and portable and then feed into the controller? Does it matter?

 

[Squatch]

Actually there is no competing. as long as the battery is full.

Hard to explain this without drawing pictures. The shunt has nothing to do with the panel or it's controller.

On my Bogart system a shunt (very precise resistor) is installed in line between everything and the battery. The solar charge controller takes measurements from both sides of this shunt to know if current is entering or leaving the battery. That's how the monitor can give precise readings on state of charge, voltage, amperage in or out.

So if you add another charge source add it with the shunt between any sources and the battery. The solar charge controller will adjust it's output by seeing that (the truck, another solar panel, plug in battery charger) is charging the battery. The solar charge controller is typically the smartest device. So it will let the dumber devices charge and stay out of the way unless needed.

This may be handled slightly differently by an MPPT solar charger. Because they are digital I know some probably have inputs for both your 24v series solar array and possible a 12 volt input for other sources as well. In that case ditch the integrated controller and just wire into the controller for both sources.

My system is not set up that way. The Trimetric monitor(controls the charge controller) watches as stated above. So I have 2 common binding posts in the battery cables. Both + and -. All loads and other sources wiring into these.The shunt and solar charge controller are between them and the battery.

If my batteries are low and I need to use a plug in battery charger to charge them I hook up to these posts. That way the Trimetric sees the charge and knows that I have charged the battery when solar could not.

If I use my 12v air compressor to fill my air bags. I hook it up to these posts and the Trimetric knows I'm drawing juice from the battery. The fuse box, fridge, and truck charging relay are hooked there as well.

Think of them as remote battery terminals with a measurement device between them and the battery. That's all they are. Anything hooked there will do what it does. draw power or add it. The solar charger will compensate.

1st thing you need to do is figure out which MPPT controller you will use. Then worry about the rest. it all comes down to the features of that charger and monitor and the method it uses to watch the charge and discharge of the batteries. if it's integral than you have to know if you have multiple inputs and outputs. If it uses a separate shunt the directions will tell you how that works. and you can use your portable as is.

One step at a time. We can help.

 

[paddlesurf.net]

Or maybe I just load all my stuff up into my new camper, drive to Solvang with a lot of beer and beg you (ckent) to wire it all up for me.

 

[paddlesurf.net]

Actually there is no competing. as long as the battery is full.

Hard to explain this without drawing pictures. The shunt has nothing to do with the panel or it's controller.

On my Bogart system a shunt (very precise resistor) is installed in line between everything and the battery. The solar charge controller takes measurements from both sides of this shunt to know if current is entering or leaving the battery. That's how the monitor can give precise readings on state of charge, voltage, amperage in or out.

So if you add another charge source add it with the shunt between any sources and the battery. The solar charge controller will adjust it's output by seeing that (the truck, another solar panel, plug in battery charger) is charging the battery. The solar charge controller is typically the smartest device. So it will let the dumber devices charge and stay out of the way unless needed.

This may be handled slightly differently by an MPPT solar charger. Because they are digital I know some probably have inputs for both your 24v series solar array and possible a 12 volt input for other sources as well. In that case ditch the integrated controller and just wire into the controller for both sources.

My system is not set up that way. The Trimetric watches as stated above. So I have 2 common binding posts in the battery cables. Both + and -. All loads and other sources wiring into these.The shunt and solar charge controller are between them and the battery.

If my batteries are low and I need to use a plug in battery charger to charge them I hook up to these posts. That way the trimetric sees the charge and knows that I have charged the battery when solar could not.

If I use my 12v air compressor to fill my air bags. I hook it up to these posts and the Trimetric knows I'm drawing juice from the battery. The fuse box, fridge, and truck charging relay are hooked there as well.

Think of them as remote battery terminals with a measurement device between them and the battery. That's all they are. Anything hooked there will do what it does. draw power or add it. The solar charger will compensate.

1st thing you need to do is figure out which MPPT controller you will use. Then worry about the rest. it all comes down to the features of that charger and monitor and the method it uses to watch the charge and discharge of the batteries. if it's integral than you have to know if you have multiple inputs and outputs. If it uses a separate shunt the directions will tell you how that works. and you can use your portable as is.

One step at a time. We can help.

Great explanation - thanks for that. And thanks for the word of encouragement. This stuff will make your head spin after awhile.

So lemme try for a shortcut - it sounds like an MPPT without the shunt (integral as you say) would be the easiest for me to set up- anybody out there have a suggestion for an MPPT controller brand and model for me? Would prefer easiest set up (for dumb guy).

I'm not averse to going with PWM controller but I've spent long periods off grid to know that I burn through energy fast so I'm seeking whatever advantages I can get in this new camper build.

 

[Squatch]

I'm not that up on MPPT controllers. But I feel the Bogart PWM stuff does a wonderful job and can handle most anything you would do with a small camper. There is a reason many of us use them. Cost is reasonable. They are not hard to install and are programmable to do a pretty precise job. To me the main advantage of MPPT comes when you get to a bigger system such as you would use on a home. I think on a small system under 300 watts or so the advantages of the MPPT are more on paper than real world. Not that there is anything bad about them. Just not sure our small systems really need them.

I'm sure others will have different opinions and can supply other links.

Start your homework reading here.
https://handybobsolar.wordpress.com/

This is the Bogart engineering site. Lots of info on how the stuff works here. This is PWM but is a far cry from cheap amazon and ebay stuff!
http://www.bogartengineering.com/

 

[ckent323]

I am a Victron advocate. Their MPPT controllers are reasonably and competitively priced (PKYS is a good source for these and they offer good service too).

Lots of info here: https://www.victronenergy.com/solar-charge-controllers

I still recommend not using two different controllers (unless perhaps they can both be programmed to have the same bulk, absorption and float charge settings). In fact I would ask the manufacturers for advice before using two different controllers.


Here is a link to my solar install:

http://www.wanderthewest.com/forum/topic/14892-adding-solar-to-a-2007-keystone/?hl=%2Bkeystone+%2Bsolar

I also recommend this one (but it is long and probably best to read from last page back to first:

http://www.wanderthewest.com/forum/topic/13230-i-need-more-power-scotty/?hl=%2Bscotty+%2Bpower


Craig

 

[Squatch]

That's why I say start with the controller. Always better to have one brain. Especially if that brain allows a variety of inputs.

X10 if this is not your THING so to speak. Kiss principle.

My system is very simple and versatile. But I have a good working knowledge of what I'm doing. Might not seem so simple to one who doesn't work with 12 volt all the time.


Same reason I tell people to have an electrician install a transfer switch in their house if they use a generator. Dummy proof. Plug in the genny, start it, throw the switches. Sure it's cheaper to back feed a breaker and I know many who do. But it's a good way for a novice to get hurt or hurt someone.

 

[ckent323]

I just noticed this comment in your post:

"It looks like I will have to find a set of portable panels that I can wire in series (to get 24v) that will then be connected to the mppt controller in my camper - which is also connected to the 24 volt roof panels of the camper."

Most of the MPPT controllers I am familiar with will accept either 12 V or 24 V panel input (actually what is called a 12 V panel puts out as much as about 18 v and what is called a 24 V panel puts out as much as around 36 V) However, I think you can mix "12 V" and "24 V " panels going into a Victron MPPT controller - I have not done that so best to read here:

https://www.victronenergy.com/blog/2014/03/28/matching-victron-energy-solar-modules-to-the-new-mppt-charge-regulators/


Craig

 

[paddlesurf.net]

Guys really - thanks for all your help.

I like keeping it simple. I did that for years with my portable 160w zamp and.... gasp.... just my starting battery.

I be off road in southern Baja running my arb (the only load I put on the battery) from the big group 30 I put under the hood. I could do three weeks with ice cold Tecates but it eventually killed that battery and I think the low cranking also took out my starter eventually. So - this is my chance to do it right.

I appreciate the input, I'm a bit closer to putting it together correctly.

I think.

 

[Vic Harder]

Your portable panel is likely TWO panels. Likely wired in parallel. Change that to series, and now you can use your MPPT controller as usual.

 

[rando]

There is no issue with running two charge controllers to the same battery. Run your roof panels through a Victron MPPT charge controller and run your existing portable panel through its built in charge controller. Each charge controller will switch on and switch off at different voltages, but that isn't really a problem.

Just to be clear, you don't want to put panels of different out put voltages in parallel or panels with different output currents in series. The lower voltage panels will pull the higher voltage panels down to their operating voltage, or depending on the diode configuration the lower voltage panels may not provide any power. In series, the panel with the lowest output current will limit the current out of the rest of the panels.

To generalize - if you are going to feed multiple panels into a single charge controller, they should all have the same specs. If you are going to use different types of panels, each different type of panel really should have its own charge controller.

Finally the discussion of a shunt is a red herring, charge controllers don't need a shunt. You can add one for a battery monitor (like the BMV-712) but that is independent of the charge controller.

 

[paddlesurf.net]

There is no issue with running two charge controllers to the same battery. Run your roof panels through a Victron MPPT charge controller and run your existing portable panel through its built in charge controller. Each charge controller will switch on and switch off at different voltages, but that isn't really a problem.

Just to be clear, you don't want to put panels of different out put voltages in parallel or panels with different output currents in series. The lower voltage panels will pull the higher voltage panels down to their operating voltage, or depending on the diode configuration the lower voltage panels may not provide any power. In series, the panel with the lowest output current will limit the current out of the rest of the panels.

To generalize - if you are going to feed multiple panels into a single charge controller, they should all have the same specs. If you are going to use different types of panels, each different type of panel really should have its own charge controller.

Finally the discussion of a shunt is a red herring, charge controllers don't need a shunt. You can add one for a battery monitor (like the BMV-712) but that is independent of the charge controller.

I like it.

Ok, so I'm going to connect rear FWC solar wiring directly to battery bank - it will receive 12v from my 160amp portable that already has a PWM controller on it.

I will also connect the leads from my MPPT controller (most likely Victron... seems to have a strong following) to the battery bank. The Victron will be controlling two matched panels - hooked in series for 24volts to the MPPT controller.

It sounds like I can run all of this (the portable and the MPPT) at once and there won't be any problem. Right?

BTW I heeded your advice, Rando, and upgraded my truck to an F350 for the flatbed camper.

 

[rando]

That all sounds good. The advantage of hooking the rear FWC outlet directly up to the battery is that you can also use it as a 12V power outlet if you ever wanted to. Definitely add a fuse on those wires close to the batteries,

What size roof panels will you be using? Assuming they are 100 - 150W, you may just want to put them in parallel. You don't gain much by the series arrangement at lower power levels, and it locks you into using an MPPT controller. If it ever were to die while you were traveling, you couldn't just jumper around it, or swap in a harbor freight pwm controller.

 

[paddlesurf.net]

That all sounds good. The advantage of hooking the rear FWC outlet directly up to the battery is that you can also use it as a 12V power outlet if you ever wanted to. Definitely add a fuse on those wires close to the batteries,

What size roof panels will you be using? Assuming they are 100 - 150W, you may just want to put them in parallel. You don't gain much by the series arrangement at lower power levels, and it locks you into using an MPPT controller. If it ever were to die while you were traveling, you couldn't just jumper around it, or swap in a harbor freight pwm controller.

Interesting. I'd read that 24volt through the "thinner" factory wiring was the way to go with an mppt controller. But maybe that's assuming really big arrays of panels? Yes, I was thinking 100 -150 watts each. Looking into the Victron BMV700 monitor (has a shunt) seems pretty straightforward install - does the negative side go like this: battery to shunt to ground?

 

[rando]

There is definitely a slight advantage to putting the panels in series w.r.t voltage drop in the wiring. But practically speaking the advantage is pretty small. I think the wires are about 12 gauge, so at full output of a 200w array (16V at 12A) and 30' of 12AWG you will loose around 3% of your available power . If you go to series (32v at 6A) you loose about 1%, so the advantage of going to series is about 2% more power.

The disadvantage of going with series wiring is also pretty small (limitations on charge controller) so it is a toss up whether to go with series of parallel.