Pro-Rig V2.0 - Home Built Compact Composite Pop-up

Okay, the long awaited update on the lithium battery charging and use.

Alternator Charging:

The first key, in my case, was to disable the trucks (2010 Frontier) clever alternator management system. I'm not totally clear on what the alternator is doing, but it is supposedly optimizing battery charging and saving gas by not constantly keeping the alternator under load. I imagine other newer vehicles have similar systems these days and options for disabling may vary. For me, I pulled a 20A fuse under the hood labeled "Alternator/Horn". This lets the alternator behave in a good old fashioned dumb way - pushing current to anything that will take it (in this case the camper battery).

I believe there is still an alternator protection circuit built in to keep the alternator from overheating - not positive on this though.

My wiring is double 6ga for the positive from the truck battery (+) to the Victron Cyrix Li-ct battery combiner. (-) is 4ga to the body of the truck close to the camper. When I start the truck, the combiner closes (connects the batteries) as expected. Charging ramps up quickly to almost 70 amps. After about one minute, the charging rate slowly drops to about 40 amps at idle and about 50 amps at higher RPM. After a few more minutes it settles in between 30 and 40 amps. This slow drop may be the alternator protecting itself, not sure. Either way, this is great - I think my alternator is rated at 120 amps so much time at 70+ amps would likely fry it. I did one real deep discharge and the alternator put 90ah back in to the battery with no apparent problems.

To stop the charging from the alternator, I set the relay trigger on the Victron BMV-700 to 14.0v. The relay triggers the Cyrix Li-ct to disconnect the batteries and charging from the alternator stops. This gets the battery to about 96% state of charge (SOC) and doesn't flirt with damaging voltages. I could edge the voltage of the relay trigger a bit higher I think to get the battery topped off but I'm playing it safe for now.

The BMV-700 relay signals the combiner to combine again when the battery voltage reaches 13.3v, which is just below the resting voltage of a "full" battery. This means the alternator should never try to charge a full battery. The SOC drops to about 94% at 13.3v. Alternator quickly charges the camper battery up to 14.0v and then they are disconnected again. Works nicely!

Solar Charging:

Didn't do careful testing of the solar system - we were mainly on the move during the day. Here's what I know for now. The Victron charge controller is set to absorption at 14.0v. This seems to tell the controller to switch to float mode at 14.0v. Float voltage is set to 13.4v so the battery voltage drops slowly towards resting voltage and then small amounts of current flow to the battery (0.1v isn't much of a gradient to push current over so even with 200w of panels in full sun, it's pushing less than 2 amps when the battery is at 13.2x volts). This keeps the battery at around 95% SOC all day with the fridge and other small loads running.

Battery Performance:

Pretty impressive. Used the hot water heater off the battery a couple times. Took an hour to get up to 140F (manual says it should take 80 minutes). Battery maintained 13.0v with water heater, fridge and lights on (30+amps of draw). Battery was at 10% SOC by morning but fridge was still running and all accessories working well. Battery was full after about 2.5 hours of driving the next day. Not sure how much lead acid would be needed to accomplish this.

So, in a nutshell, I think this set up works. See post #40 in this thread for some more details -be aware that some of the numbers have changed from then to now.

I didn't test the low voltage protection (Victron Battery Protect set at 12.0v) or the BMS protection circuits (disconnects everything at 14.6v or 10.4v) but will get to that at some point.

Very curious to hear opinions of what I might be doing wrong or missing with this setup.

I might duplicate this post (more or less) in the "Power Systems" sub-forum to get some other eyes and opinions on the setup.

matt
 
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Hey Wikel,

Wasn't ignoring you, been a crazy couple weeks here...

The same night you posted this message we evacuated in the middle of the night due to the Thomas Fire. Left in a hurry without the camper (and hardly anything actually) but was hugely relieved to find our house was okay and ProRig intact (both just a little smokey). It's only thanks to some amazing firefighters that we have a house (and camper) still. Lots of homes lost in our neighborhood, including three of our four immediate neighbors.

View from our backyard on Tuesday morning the 5th:


Obviously feeling lucky these days...

...and looking forward to some camping :safari-rig:

matt
 

brian94ht

Chateau spotter
Hard to imagine what going through something like that is like.
Good to hear you and your family are alive and well. Thanks for posting. Camp on!
 
Thanks guys. It's been a crazy month!

Recent highlight for sure was getting out for a New Years Eve overnighter in the camper. Just an hour or so up the coast to Refugio State Beach but was great fun. Met some friends, shared some bbq, wine, etc. around the campfire and actually made it to (and past :sombrero:) midnight! Found that I am capable of setting up the bed in an, uh, altered state :friday:. I consider this very important research!!

The next "morning" we backed the camper up to the beach for lunch time breakfast burritos and enjoyed the sun and 70 degree temps.


Of course our record heat means not much snow yet in the mountains - hope the next update comes in the form of cold weather testing in the Sierras!

matt
 
Looking good! Speaking of cold, where did you purchase
the propex heater from? Also the through hull fitting; does the
exhaust tube get too hot for the panel?
Thanks
 
Looking good! Speaking of cold, where did you purchase
the propex heater from? Also the through hull fitting; does the
exhaust tube get too hot for the panel?
Thanks
Got the heater itself online from Westy Ventures. They might have been the only importer to the US back then, there are others now. The through hull and exhaust insulation came from Sure Marine (online).

This recent overnighter was the first time we ran the heater all night (thermostat was turning it on and off) so it hasn't gotten a real cold weather test yet where it would be running more continuously. That being said, it looks like the panels are holding up fine.

I made the hole in the panel for the through hull as large as I could to keep any heat as far away from the panel as possible. I made an oversized hole where the exhaust pipe passes through an interior wall and used an aluminum bracket to keep the pipe centered and away from the panel. The big thick insulation thingy that I got was kinda pricey but does the job of protecting other stuff in the compartments where the exhaust tube is running.

It's a nice little unit - runs real quiet, is super compact and provides a lot of flexibility in mounting location. Not cheap but I think it was a good choice.
 
Got the heater itself online from Westy Ventures. They might have been the only importer to the US back then, there are others now. The through hull and exhaust insulation came from Sure Marine (online).

This recent overnighter was the first time we ran the heater all night (thermostat was turning it on and off) so it hasn't gotten a real cold weather test yet where it would be running more continuously. That being said, it looks like the panels are holding up fine.

I made the hole in the panel for the through hull as large as I could to keep any heat as far away from the panel as possible. I made an oversized hole where the exhaust pipe passes through an interior wall and used an aluminum bracket to keep the pipe centered and away from the panel. The big thick insulation thingy that I got was kinda pricey but does the job of protecting other stuff in the compartments where the exhaust tube is running.

It's a nice little unit - runs real quiet, is super compact and provides a lot of flexibility in mounting location. Not cheap but I think it was a good choice.
Thanks. Been looking for one of these https://www.sheridanmarine.com/product/propex-marine-through-hull-fittings
but can't find one here in the US. Maybe I can make something similar.
 
Got the camper out last weekend for a couple nights along the coast.

First night at El Capitan State Beach.


I think this is the most I've ever paid for a camp site ($45!), but it is a nice spot. Ran the heater at night. Had it set to the mid point on the heat scale. Had to turn it down two or three notches after I woke up sweating.

Second night we stayed at San Simeon SB. We were up a hill and out of the trees and in the afternoon the wind really started to blow and it cooled off. Found that when set up facing in to the wind (35+ mph with stronger gusts), the downward pressure on the roof can overcome the gas struts. It would blow down to a point and then pop back up. With a strong enough gust though, if would blow down low enough that the struts lost the fight. Used a tripod leg to prop it up for the night. Thinking of a prop of some sort to have on hand for high winds or snow.

Also found that with the wind and a cold night, there is a considerable amount of cool air coming in around the seals between the bottom of the slide-up and the fixed lower walls. Need to improve the seal somehow.

Also, a while back I added these:


After lots of thought about different options for getting the back to ride better, went with airbags. I used the Daystar cradles to keep downward travel and hopefully prevent tearing bags while offroading. Still playing with pressures but so far I like them. Back is riding at the normal height and handling is much improved. Haven't been off road yet.