Battery and solar panels questions lx470 (1 Viewer)

[MastiffDad14]

Couple questions for people running solar panels and or 2nd batterys.

Planning on an X2Power 31m battery 105ah reserve capacity deep cycle, along with a 100 watt solar panel with an Mppt control. I think the solar should be good for 6ah charging on most sunny days.

My goal for the rig is the ability to run an ARB fridge seems like average is 2 amps some rack mounted lights for camping approximately 2 amps per light X4, will also be charging 2 cell phones at 2.1 amps each and would like the ability to run the stereo at low to moderate volumes say 5-7 amps.

Let's say it's night time and the lights on are, fridge is running, music is on and phones are charging that would be close to 20Ah drain on the battery with no solar to help offset the drain.

This is where my question comes into play if the battery has a 105ah capacity it would be fully depleted in as little as 5 hours with everything in use. I read somewhere to cut that capacity in half of your still expecting the battery to start the truck so that brings me down to 2 hours.

How much does the alternator help charge the battery at idle? Can I run the truck for say 30 minutes around the 2 hour mark and expect it to charge the battery up to a save voltage to be able to start the truck in the morning?

Am I way over analyzing this should I just wire up the lights on a separate switch for sides and rears and just bring a separate radio like a beats pill or similar so I'm not draining the battery so quickly. Would put me down to 4 amps for the lights, 2ah for the fridge and maybe 2ah for a phone,
8ah total. During the day the solar 100 watt panel would almost compensate for the total load.

My other option is to get a smaller 2nd battery and wire up the fridge some rear USB plugs for the cellphones and have the solar panel hooked up to that battery and just keep it in the rear cargo compartment.

Sorry for the long winded post but I'm just torn on what todo and hope some other that's been through this dilemma before can help.

 

[Tigerstripe40]

Get a second larger battery.

 

[LandCruiserPhil]

Know several that are running same type of set up without issue. I would recommend a back up jump box (<$100> for protection. Im running a 27F (90ah) only on our LX with a less efficient Edgestar and it will provides plenty of power for overnight use.

 

[chevurai]

Get a second larger battery.

Things to keep in mind: Cell phones will be charged up and then will no longer be a power draw, (unless constantly searching at that point they should be turned off), ARB Fridge has a battery power saving setting which will turn off the fridge to preserve starting power, LED lights are your friend. If you are cutting it that close, the battery draw and reserve voltage should be monitored closely with meters. Alternators are designed to top off the battery after starting, they take hours and hours of higher RPM road driving to bring them back if drained.
Camp with another vehicle and have jumper cables available for the morning jump.

 

[titanpat57]

Couple things...(as Phil said)

Seems you're using a lot of light to lite up camp....I'd find something that uses a lot less then that (once you're set up)

The music situation....get yourself a good quality rechargeable Bluetooth speaker.

Your fridge calculation seems light....I'd figure 3-4 amps...obviously there's lots of variables.

A good group 31 should work fine (I used a Northstar AGM in the new truck). I waived the second battery this time around for a Li-ion charge pack....hell of a lot less weight, and always there if I need it....plus you can charge up a myriad of other goodies.

 

[george_tlc]

Your phones at 2A charging rate are at *5V*. That's a lot less than 1A from 12.8V (DC : DC converters in the chargers).

2A per light and 4 of them - if those are LEDs then your camp must appear like a small city at night. Even 12W (1A) of LED lighting is a heck of a lot of light. Do you not want to see the stars and enjoy the camp fire at night?

Fridge will run 2A or less AVERAGE unless you are in 100F temps at night. 70-80F evenings it's probably more around 1 to 1.5A average.

So, the reality is you are likely only drawing an average of maybe 3 to 4A per hour and that's only while phones are in charge mode and you are in the city lighting mode (maybe 1 hour max to charge phones from 20 - 30% to 100%).

The smart thing would be to put a DC current clamp on your battery+ and see what you are actually drawing to get a better idea of reality.

Ditto on a reasonable bluetooth speaker - that's what I run when camped and not blaring loud. Stream from a phone/music collection. No need for key in ignition/acc.

cheers,
george.

 

[MastiffDad14]

Thanks for the advice everyone and George for setting me straight on the lighting.

The only reason I'd want the city lighting is for my mastiff so she can run around and I don't have to worry about her.

BTW what lights would make for good auxiliary for my cap lighting / back up lights? Rigid makes some nice looking small 2x2'' lights but they are quite pricy. I don't mind spending the money but if you guys think I can get some "decient" quality lights for less keep me posted.

 

[Tigerstripe40]

The only reason I'd want the city lighting is for my mastiff so she can run around and I don't have to worry about her.

I attach a keychain light to my dogs collar

Multicolor Feauxton LED Light Key Rings | All Products

Then I can see where he goes without needing to light up the area.

 

[george_tlc]

Dogs have good night vision - your city lights will blind her and yourself. Sometimes less is better

There's lots of inexpensive LED lights on ebay/amazon. They'll work good enough for camp lights. I have DIY lights for around camp and they are all dimmable so I have the light *I* need - saves on the AHs too.

cheers,
george.

 

[Cruiserdrew]

Yes, piles of LED camp lights for small $$. These are mine:

0.5 amps each @ 12 volts. Considering they run maybe 4 hours per night a trivial draw off the batteries and light the night enough to cook, repair trucks, whatever. LEDs are so efficient, you can almost ignore the power use.

 

[JCruse]

Nice truck!

Don't forget that the battery will climb back up a few tenths after you shut things off. Then by the time you get up the sun will likely be charging too. By the time you need to go somewhere the truck should have no trouble starting.

Just cut back wherever you can while still having fun. You only need one side of the truck lit, so that's two lights not four. Turn the tunes off for a little while in between. I have a rule that when the voltage gauge drops to 12.5 everything but the fridge and a small light goes off! Then it'll creep up to around 12.8 in a half hour or so and the party resumes! lol
I ran the same system for four years and the truck always started.

 

[jonshonda]

Ideally your two batteries should be of the same size, age, and brand. No need for a mppt controller, actually a waste as it requires power from your system to work correctly. Remember that a 105ah battery only has 52.5ah of capacity, as you never want to drain a battery past 50%.

 

[Cruiserdrew]

Ideally your two batteries should be of the same size, age, and brand. No need for a mppt controller, actually a waste as it requires power from your system to work correctly. Remember that a 105ah battery only has 52.5ah of capacity, as you never want to drain a battery past 50%.

Not true about the batteries. You are confusing the situation of batteries that are always tied together. Most systems and switches only tie the batteries when charging. In that case the batteries can be different. Where you for sure want them to be the same is when you have them tied together in a "bank" of batteries and discharging parallel into a load or even each other.

All charge controllers require some power to operate, MPPT or PWM. That's why with either type generally should plug into the battery first, to turn on the electronics and then hooked up to the panels for charging. It's undeniable that MPPT is SLIGHTLY more efficient and generates more power off the same panel, since it allows the panel to run at it's optimum voltage for power generation. With a PWM controller, the panel will always operate at the voltage of the battery. But at low power levels the increased efficiency isn't enough to justify the much higher price. So I agree that for a 2 battery system with a smallish 12 volt panel, PWM is sufficient. With higher voltage panels, or with a larger system it might be worth it to pay for the MPPT controller.

 

[Bogo]

Where you for sure want them to be the same is when you have them tied together in a "bank" of batteries and discharging parallel into a load or even each other.

Actually the only time they need to be the same type is when the charging or discharging rate is such that the voltage is between the resting voltages of the two batteries. This also obviously happens when not in use. What happens is the higher voltage battery will try to charge the lower voltage one.

A time when the MPPT controller really pays for it's self is when the panel can't output enough voltage. A good MPPT controller will boost the voltage to still allow charging. This is very important on flat mounted panels, or panels that are shaded some. It also allows charging to start and continue in much lower light levels.

 

[george_tlc]

^ Boost MPPT are NOT the same as Buck MPPT. The common MPPT is a Buck (step down) since most panels have higher voltage than the battery voltage. Buck MPPT is a big win if you run higher voltage panels (say two 12V panels in series) - this lowers the output current on the feed wires from the panels to the MPPT and battery (charge controller should always be near the battery end). Lower current and long feed wires (if you move panels away from the vehicle that may be in shade while camped).

cheers,
george.