16 replies to this topic

[Murban]

You have a couple of decision points here. One of them is upgrading to a LifePo4 battery, excellent choice and prices are coming down. Second should be to upgrade your solar panels and since you live in sunny CA, this is highly recommended (200w). Third is whether or not to do a DC-to-DC charger (which will eliminate the isolator you have now btw). The rest of it is just picking out the best components.

 

I did the whole shebang last year except the DC/DC charger.  The cost and complexity of DC/DC was a bit out of reach at the time. Instead I utilized the existing wiring so that if something went wrong with my LifePo4 battery I can easily disconnect it and connect the camper to the truck battery in a pinch. I can also charge the truck battery with the solar panels. So, I basically have a backup plan if something breaks in the LifePo4, which btw was what I thought was most likely. I live in sunny CO and most of my travel is in the sunbelt states so solar is king. If I lived in the PNW I would add DC/DC for sure.

 

Thanks BlueSky -

 

1, 200 W panel is what I was thinking of putting on the roof.  Brand/model recommendations welcomed.

 

I like the simplicity of bypassing the battery isolator all together but at some point I will want to have the capability of charging from the truck battery/alternator as an option.  I would like to be able to have it switched and not on the the ignition circuit at all.  That would give me peace of mind that I am protecting the alternator.  Not a high priority for me this year, next year possibly. 

 

I have the 100W Lifepo4 battery in a box ready to go.  Just need to get the other components and decide if I really want to try this myself or seek professional installation help.

 

Question - How do you charge the truck battery with the solar panel?

 

Thanks again,

 

Mike

 

 

[ski3pin]

Last fall I redid our camper's battery system and moved from my 9 year old AGM with CTEK dual charge controller to a 100 ah lithium battery. I installed a renogy dual charge controller meaning that it runs both DC from the alternator and from the solar panels through the same programmable charge controller. Once the camper battery is charged it moves over to charge the truck battery (your question above). I have a small camper so one issue was keeping small and simple. I ran 6 gauge wire from the truck to the camper battery and followed Will's instructions -

 

I have 2 100W panels on the roof. Our electrical needs are small (the other piece of the camper battery use puzzle). In practical use during travel, it is rare I even think about the system. It is simple and works.

[Murban]

Thank you sir -

My confidence is building.  

Mike U

 

[Vic Harder]

Mike, you have gotten some good advice here already.  Allow me to add a few bits.

1) Get the biggest solar panel you can fit/afford.  Avoid the flexible ones.  Yes, they are light, but also have issues with overheating.  Check out solar panels designed for home/commercial use.  I got a 330W 2 years ago, and if I could I'd get a 600W one today, but my supplier went out of biz.

2) For the rooftop connector, I agree the SAE unit looks flaky, but many folks have them.  I used a solar gland.  I cut the MC4 connectors off and used wire nuts inside the gland to connect to the wiring coming up from the camper.  Sealed it all with 3m 4200.  Dicor works too.

3) The Renogy dual charge controller that Ski uses is pretty slick.  I'm not fond of Renogy personally.  I like the Victron gear, but they don't have anything like that.  At present, I have no way for the solar setup to charge my truck battery.  Have not needed that yet.

4) I do have a Victron DCDC 30A charger.  You don't need the isolated version, those are designed for marine applications.  I use 2g welding cable to carry the charge from the alternator.  You want the DCDC unit to be in the camper, as close to the batteries as possible.  That way the DCDC can maximize the power going to the batteries. 

5) You will want a breaker (blue sea 285 series is what I used) close to your truck battery, and another close to the camper battery, on the positive cable you run from the truck to the camper.  It would be no fun if that cable shorted out without a breaker in there.

 

Keep the questions/ideas coming!

[BlueSky]

I have a Victron MPPT solar controller. Solar panels are wired to it, then one red wire goes from the controller output to the LifePo4 battery (with an inline fuse) and another red wire goes from the output to the truck battery (another in-line fuse). The Victron controller allows me to select LIfePo4 or regular lead acid battery using the app on my phone. Pull the fuse from one red wire and put it into the other red wire and program the controller with my phone for the battery type I am trying to charge. I do have an inline fuse between my solar panels and the controller. I have never actually had to charge the truck battery with solar, but one time I did something stupid and ran the LifePo4 battery down too far and had to switch to the truck battery to make my water pump work in the morning while the solar recharged the LifePo4. 

 

As far as solar panels, Vic will tell you the flexible ones get too hot and fail.  This is true, so you have to install them with this plastic corrugated sheet (home depot) under them to allow air flow. Don't tape down them all the way around (as the guy in the popular video does), leave the ends of the corrugated "tubes" open. The Sunpower ones are fine, but I cooked the first one and the second one never got the full 100w output. The ones I like are Topsolar (amazon) because they stronger/tougher. The tape you need is called Eternabond (amazon).

 

 

Question - How do you charge the truck battery with the solar panel?

 

Thanks again,

 

Mike

 

[Atlin]

I'll chime in on this.  I built my own battery from cells so I could mount it outside the camper and maximize storage inside (the battery is flat on the front of the ATC).  I used #6 wire from the truck battery to the camper, 50A fuse adjacent to the truck battery.  Mounted on the side of the ATC is a Redarc DC/DC converter that limits current going to the battery to ~40A if I remember correctly.  I also put a battery disconnect switch just inside the camper to turn off any parasitic loads (like the Victron battery monitor, which will suck the battery dry in a couple of weeks if left on).  I do not have solar at this point, but the Redarc comes set up for a solar input.

 

The only downside to my arrangement is the battery on the outside of the camper in cold weather, which means the battery will not charge if the temperature is too low.  It would work better for cold-weather camping if the battery was inside the camper and a bit warmer.

[Vic Harder]

 

I have a Victron MPPT solar controller. Solar panels are wired to it, then one red wire goes from the controller output to the LifePo4 battery (with an inline fuse) and another red wire goes from the output to the truck battery (another in-line fuse). The Victron controller allows me to select LIfePo4 or regular lead acid battery using the app on my phone. Pull the fuse from one red wire and put it into the other red wire and program the controller with my phone for the battery type I am trying to charge. 

 

That's a clever work around for charging the truck...