Second Battery w/ PV panel

[Tigerstripe40]

In the quest to get a solar powered beer fridge, I got a 65 watt solar panel for my truck. I figure that I will use the panel to keep a battery charged, which in turn will power my on board 12v refrigerator (Coleman Stirling refrigerator, probably an ARB fridge later on down the road).

So I am going to put in a second battery. I am also going to put in a 6 circuit sub fuse panel. This aux panel will power some work lights, amateur radio, CB, and I'd also like to hitch the trucks stereo into it at some poitn so I can have tunes without worrying about killing the starting battery.

I know that I need a PV charge controller.
What I am wondering about is if there are second battery kits, like the one made by National Luna, that have a PV input provision.

If so, great. If not, how should I integrate the PV into the battery system?
Should I home brew the battery isolator and monitor setup? Should I just keep the second battery entirely separate from the rest of the electrical system?

 

[tag3]

I am using a batter isolator for my 2nd. battery, running a third battery charged by the solar panel completely separate from the alternator for the fridge. Buy a good quality controller not a cheapie for the stand alone system. Have had the fridge running for 7 months continuously with out a problem.

 

[ntsqd]

The solar controller will want direct access to the battery. Some have a low voltage disconnect, so if you want that functionality your load(s) need to run thru the solar controller rather than the other way around.
http://www.solarblvd.com/Charge-Controllers-PWM-Charge-Controllers/c6_48/index.html
http://www.solarblvd.com/Charge-Controllers-MPPT-Charge-Controllers/c6_46/index.html
http://www.solar-electric.com/chco.html

Any sort of radio beyond a CB will also want a direct battery tap for both the power and the ground. Do Not put it in a fuse panel with other power consumers. I've yet to see an amateur radio manual that didn't call for both power and ground connections to be directly at the battery. Some have done it differently, not a good plan.

Blue Seas and BEP Marine both offer "Add a battery" kits with a VSR/ACR and a marine battery bank switch.
http://www.bluesea.com/products/7649/Mini_Add-A-Battery_Kit_-_65A
http://www.bluesea.com/products/7650/Add-A-Battery_Kit_-_120A
http://www.bepmarine.com/home-mainm...dvs-high-current-remote-operated-vss-275-amps
http://www.bepmarine.com/home-mainmenu-8/product-714/digital-voltage-sensing-relay-dvsr

Unless the battery monitor has a shunt to monitor current in/out it's just an elaborate voltmeter and can only tell you approximations.

A real battery monitor:
http://www.bogartengineering.com/products/TriMetric

 

[jawjatek]

Harumph. I run my VHF/UHF off a Blue Sea 6-circuit fuse block mounted near the battery in my FJ60. It works perfectly. As does the high power sound system. As long as you avoid common-mode impedances in your power distribution it isn't a concern. A direct connection to the battery is not required if you know what you're doing. EE with over 30 years experience here, amateur extra HAM.

 

[ntsqd]

snip...
...A direct connection to the battery is not required if you know what you're doing. EE with over 30 years experience here, amateur extra HAM.

And what do you recommend for those who don't have that experience and education? Planning on holding their hand long distance when it doesn't work for them?

 

[RobRed]

Ample Ham radio power can be obtained via a remote fuse block implementation. Going directly to the battery is not a requirement.

I think u could interpret go direct to the battery as "dont connect to factory vehicle wiring"

 

[ntsqd]

It is not about enough power. It is about clean power. As jawjatek alluded to, some other power consumers should not be connected in parallel with a radio at any point downstream from the battery. If you wish to play lawyer with interpretations on your own rig I'm OK with that. If it does work then either your interpretation was correct or you got away with it. If it doesn't work....

Advising someone else to also play lawyer isn't helpful if they don't know what they might be getting into.

It really isn't that big of a deal to simply connect directly to the battery. Can still do a clean install, doesn't have to be a rat's nest at the terminals.

 

[RobRed]

It is not about enough power. It is about clean power. As jawjatek alluded to, some other power consumers should not be connected in parallel with a radio at any point downstream from the battery. If you wish to play lawyer with interpretations on your own rig I'm OK with that. If it does work then either your interpretation was correct or you got away with it. If it doesn't work.... Advising someone else to also play lawyer isn't helpful if they don't know what they might be getting into. It really isn't that big of a deal to simply connect directly to the battery. Can still do a clean install, doesn't have to be a rat's nest at the terminals.

Can you explain the difference between clean power and non clean (dirty) power? And specifically why going directly to the battery is cleaner than say running #4 stranded 5 feet to a fuse block containing say 7 circuits connecting parallel to that #4 lead?

 

[ntsqd]

Ever notice how some stereo amps (the cheap ones are best at this) will whine at a freq. directly related to engine RPM? One cause of that noise is a diode in the alt's rectifier about to fail and some would consider it already partly failed since it is "leaking" AC into a DC system.
The battery acts as a big filter for any noise in the system. Clean, noise-free power is important to some circuits and others, like incandescent lights, could care less.

Then there is this issue, which while not being an EE I have some understanding of what is being said, but no idea how to identify these things:

As long as you avoid common-mode impedances in your power distribution it isn't a concern.

Combating noise in a system can be a very frustrating thing to do. We went thru hell at my old work's Dyno trying to get noise out of our D/A system, and our MS-EE shouldered most of that work. I'm not about to attempt to do it remotely via some forum postings and I'd strongly advise that no one else try to do so either.

 

[george_tlc]

As ntsqd is explaining, the battery is VERY LOW impedance and essentially acts as a humongous capacitor. Wiring directly to the battery ensures that you are as close to that low impedance power source as possible.

Running wires to a fuse distribution panel that then has various loads attached means that those loads (depending on what they are and the frequency they pull power at - switching supplies, inverters etc etc) will introduce noise at the distribution point. That noise will be higher than right at the battery terminals. If you wire your radio at the fuse panel distribution point you will have higher injected noise versus the radio getting power right at the battery terminals.

This is all basic electronics and the same issue as PCB designs where you have a mix of analog and digital circuitry. You want to star connect the power for the two domains at the power entry point to ensure minimum injected noise into the analog circuitry.

Of course a radio may work just fine with its power coming from a fuse distribution point and the noise level may be lower than a strong signal (especially FM) and so all seems good. That isn't necessarily the case as you get lower and lower received signal and you need to adjust the squelch to pull in that weak signal, that's when extra noise can cause issues and be 'heard'.

So, what we're talking about isn't whether a) will work or b) will work. The issue is will a) provide better performance than b) when signal levels are low.

Clearly, connecting a radio directly to the battery will provide the lowest impedance connection and thus the lowest noise on the power feeds. Whether that is important to you or to others is something that only you can decide.

I wire all my rigs DIRECTLY to the battery and use the TWO fuses, ONE for the +12V and ONE for the GND connections.

cheers,
george.

 

[Tigerstripe40]

The radio i am going to be using is an Older Kenwood mobile station at 25 watt (its old enough it only does 2m and does not have a Tone generator, but one can be added).

I wanted to run this to the aux battery so as not to drain on the starting battery. If it's better to run it direct to the battery, then I will do so. I've got it fused on both the 12V Pos and 12V GRND cables. No biggie that way.

So far, I've got:

Blue Sea Systems 6 circuit panel

Morning Star Sun Saver 6 amp charge controller though I am thinking maybe the 10 amp version might be better?

LCD Digital Volt Meter


2x Scosche 100 amp fuse holders and fuses (1 positive, 1 negative)

The Panel is a Solartech 65 watt Polycrystaline panel

Right now, I have a flooded lead acid starting battery (I know), but that is more or less a place holder until I can get either a Diehard Platinum AGM, or better yet a custom LiFePO.

So far, the only load I am planning running continually is a Coleman Free Piston Stirling 'cooler' (it's actually a freezer/fridge). It pulls 48 watts in freezer-2 mode (I run it in Fridge-3 mode, which is MUCH less draw).

I also want to put in a USB port to be able to charge devices, like Cell phones, tablets, etc.

 

[RobRed]

So are you saying if you have several devices including a Ham radio connected to the battery terminal, of which some of these other devices may be the noisy variety, that the proximity of the connection point, in this case at the battery post, will mitigate the noise problem?

 

[george_tlc]

So are you saying if you have several devices including a Ham radio connected to the battery terminal, of which some of these other devices may be the noisy variety, that the proximity of the connection point, in this case at the battery post, will mitigate the noise problem?

Yes, because the impedance of the battery is very low. It basically acts as a large value capacitor with extremely low ESR and you are connecting the load(s) directly at that point.

cheers,
george.

 

[ntsqd]

Doubt that the radio will care what battery it is connected to. Mine don't.

65W panel will yield, at most, about 5.4 amps. Your 6 amp controller should be fine for just that panel. You'll only need a bigger amperage controller if you plan to add more panels.

I'd ditch the voltmeter and go with a "Watts Up" meter. It's a bit more $$, but will tell you a whole lot more about what the system is doing. I know of several of these being used in small mobile solar systems. The next step up in system monitors is considerably more $$ and I think is overkill for what you're needing to do: http://www.bogartengineering.com/products/TriMetric

Blue Seas/Marinco makes a dual USB outlet in the same form-factor as their locking power points. Simply put 12VDC to it's rear terminals. I have two of these, one in the camper and another in the cab of the truck. I ditched the 2 screw mounting plate in both cases.
http://www.amazon.com/Blue-Sea-Syst...id=1389625458&sr=1-3&keywords=12+VDC+USB+port

 

[LandCruiserPhil]

Morningstar Prostar ps-15m will controller, read panel output and load in one unit for around ~$120 Pictured is a 30A model but the 15A model looks the same

 

[e9999]

The radio i am going to be using is an Older Kenwood mobile station at 25 watt (its old enough it only does 2m and does not have a Tone generator, but one can be added).

I wanted to run this to the aux battery so as not to drain on the starting battery. If it's better to run it direct to the battery, then I will do so. I've got it fused on both the 12V Pos and 12V GRND cables. No biggie that way.

So far, I've got:

Blue Sea Systems 6 circuit panel

Morning Star Sun Saver 6 amp charge controller though I am thinking maybe the 10 amp version might be better?

LCD Digital Volt Meter


2x Scosche 100 amp fuse holders and fuses (1 positive, 1 negative)

The Panel is a Solartech 65 watt Polycrystaline panel

Right now, I have a flooded lead acid starting battery (I know), but that is more or less a place holder until I can get either a Diehard Platinum AGM, or better yet a custom LiFePO.

So far, the only load I am planning running continually is a Coleman Free Piston Stirling 'cooler' (it's actually a freezer/fridge). It pulls 48 watts in freezer-2 mode (I run it in Fridge-3 mode, which is MUCH less draw).

I also want to put in a USB port to be able to charge devices, like Cell phones, tablets, etc.

wow! A true Stirling engine fridge? A rare find indeed! when were those made? Must have been expensive.

 

[Tigerstripe40]

wow! A true Stirling engine fridge? A rare find indeed! when were those made? Must have been expensive.

They are (were) made by another company for coleman. I think between 2002 -2005. They didn't sell well, I assume, because they were 400 - 500 & most people thought they were the horribly inefficient thermocouple based coolers, and so were discontinued. I paid $400 for mine about 3 years ago. I found it from a film supply store that went out of business. I've been trying to find another one but so far not successfully.

 

[Tigerstripe40]

I sent the morning star back and got a Sunforce 10 amp controller instead.

I think that might not be ideal. It only has the lead from the PV and a lead to the battery. In this situation, can I run the leads that are for the battery to one of the fuses in the fuse block?

Also, any ideas on how to run the wire through the cab for the PV and the battery? The battery is currently in the bed (I don't want it gassing out hydrogen in an enclosed space). I was going to use a military style connector, but the spot I wanted to run the connector to (has a ding in the roof) is covered by the towers for the roof rack.

Here are some pics.

 

[ntsqd]

From what I've read on various solar forums Morningstar is one of the best brands available in the U.S.

 

[LandCruiserPhil]

I sent the morning star back and got a Sunforce 10 amp controller instead.

I think that might not be ideal. It only has the lead from the PV and a lead to the battery. In this situation, can I run the leads that are for the battery to one of the fuses in the fuse block?

Also, any ideas on how to run the wire through the cab for the PV and the battery? The battery is currently in the bed (I don't want it gassing out hydrogen in an enclosed space). I was going to use a military style connector, but the spot I wanted to run the connector to (has a ding in the roof) is covered by the towers for the roof rack.

Here are some pics.

Curious why you didnt stay with a Morningstar controller?
FWIW I have several installed systems using the same Sunforce-60031 without any issues.