300 W solar panel on truck roof for dual battery system

[TacticalDoc]

I haven't seen any talk on my search about larger panels on trucks. I want to put a 300W (24v) panel on my 5 ton roof (M923). Then run that to a charge controller (20 amp) to a second set of deep cycle batteries. Then have an isolator (200 amp relay/solenoid) between the 2 sets of batteries with a switch.

I want to run my accessory lights off one set of secondary batteries with the option of using them to start my truck if the primary batteries fail. Also I want the solar panel to keep the batteries charged up like a battery tender would.

Any thoughts?

 

[tim292stro]

This is what I selected for my CUCV project:

http://www.ecodirect.com/ProductDetails.asp?ProductCode=Blue-Sky-SB1524iX
details: http://www.blueskyenergyinc.com/products/details/solar_boost_1524ix

Small and simple, does 24V banks and should support your 300Watt panel idea.

For the isolator - are you using a Diode (avalanche, Schottky, or "ideal" [MOSFET]), or a relay? I personally prefer magnetic latching relays for high current isolation, no draw once the movement has happened (and essentially no voltage loss), and they can usually be actuated manually at that current level in a pinch - which would support your self-jump-start idea.

[Edit:] I should mention, the above controller has the ability to trickle charge a second battery bank as a diversion load - if you use this charge controller, you could charge your second pack from the panel normally and top off your main start batteries with the trickle.

For the relay thing, it's a bit spendy but this is available for marine use: http://sterling-power-usa.com/ProLatch-R-240amp12vor24v.aspx
[/Edit]

 

[TacticalDoc]

I was thinking of this charge controller
http://www.amazon.com/gp/product/B007NNJO6I/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A31H76PZNDKUUJ

this switch between batteries
http://www.amazon.com/gp/product/B000MMC914/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=A1UNWS4MSNTF2A

this relay 500 amp
http://www.amazon.com/gp/product/B001YIPXR2/ref=ox_sc_act_title_5?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

this circuit breaker between the secondary batteries and switch going to primary batt
http://www.amazon.com/gp/product/B0024JJIN0/ref=ox_sc_act_title_3?ie=UTF8&psc=1&smid=A1IBW2HULNJLEY


I added the amazon web site for prices
I think blue sea or blue sky is top quality but don't want to spend that much

 

[tim292stro]

I used a circuit breaker like that I my Toyota truck for the stereo, the 4/0 wire melted the jacket and nearly caught the truck on fire when the positive rubbed on the frame wrong (the contacts welded closed inside, so it couldn't "trip"). Now I don't run anything but type-T fuses for stereos (very fast blow over 1000Amps, and good current ratings).

One thing you might think about - if the wire between the two banks is of sufficient length, you might want a fuse/breaker at each pack since you have two power sources - if the fuse blows because one battery bank is providing a short to ground it doesn't stop the other bank...

Also, keep in mind that relay is going to suck power while it's connecting the batteries. Depending on how you're set up, it may not mean much, but the draw can be as high as a few amps on those. If you are self-jumping the truck, it'll suck you down faster. The price difference for the relay + switch you picked out is about $40 away from the device that I linked above that does both, doesn't draw power when connected, and self disconnects, so you don't have to figure out how to wire that in - plus it comes with the self-jump function pre-configured (even less for you to figure out).

For me, I like the three-stage charging and second trickle output on the Blue-Sea unit, to each their own - I don't knock saving money, so I'm sure as heck not going to do that when you save money .

At the end of the day, its your truck so do it your way - I like the solar charge idea, I like the self-jump idea, so much so I'm doing it too - we just differ slightly on the execution .