LiFePO4 Install

shade

Well-known member
Uh ... wow!

All that and still just one 100Ah LFP battery?

I'm going to pick a few things from your parts list for a much simpler setup. No toasters or Foreman grills for me. :)
 

dreadlocks

Well-known member
haha yeah, it started off simple.. but as I spent more and more time in the field testing it, I realized I greatly underestimated the capabilities of LFP combined w/Solar.

since they basically take full "bulk" power until completely charged w/no absorb or float stage, and they charge at such high rates.. You should double or triple the amount of solar per battery as you would with a lead bank.. for 100AH of Lead 200W is about sweet spot, for my 100AH of LFP, I've got 650W of Solar..

This means I only need to get ~2.5h per day of direct sunlight and I can pretty much drain the battery every night.. 2.5h of direct sunlight a day when overlanding is STUPID easy.. covers most all hops to the next stop, will make use of a few hours of sun peeking through a forest canopy.. and on overcast days I have enough panels to still be producing 100-200W of power, even w/out direct sunlight.. worst case, if solar is somehow not enough (and its been plenty since I installed it) I have the genset which can get me back full in a few hours.

Before I didn't want to run generator or drive but every 2 days at most.. so a 100AH battery, with 50AH usable capacity, gave me a 25AH a day diet and would require either ~6-8h of driving/ideal solar/generator usage every 48h or so.. I could never get full day of sun on panels in a forest, not without staying at camp and moving the panel every hour or two chasing the sun..

Now I can drain battery down 70AH a night (14h tops), and effortlessly refill it the next day.. and if solar is just really good, then I'm producing so much excess energy that running something like a crockpot all day long while we are hiking dont even use any battery.. few mins of a toaster, or microwave might hit the battery pretty hard, but it recovers just easy.. play music all day long w/out consequence.

Other than a family reunion in July where I had shore power and required the air conditioner desperately, my trailer has been entirely off the grid all season.. fridge and exhaust fan are always powered even in storage.. everything is running great, and I have no wants for more power.
 

luthj

Engineer In Residence
I would argue lithium needs less solar for the same power consumption. In your case you found you had abundant capacity, and conserved less (used more) power. Generally for the same loads, you need 20% less solar, and 20-50% less capacity than similar sized lead.

Of course with the cost of PV panels, there is good argument to max out your available roof real estate.
 

dreadlocks

Well-known member
yeah PV is cheaper than more LFP, and expected to last longer.. I freely admit I overdid solar, I'm good w/half of my capacity.. the fixed roof one still provides abundant power.

but I'm planning for a bit of future expansion still.. I want to work from boondocking camp indefinitely.. write some code out in the woods during the summer and just live a nomad.. Wife has to travel frequently enough for work we could end up anywhere if we tag along.. Running a nice giant monitor, cell phone repeater, and charging a laptop would take quite a bit of juice, and I need that times two for the wife who is a project manager.. and there's also the future potential of EV toys that could be on the table eventually, some electric dirt bikes would be sweet around here if I could charge em effortlessly w/the sun.. otherwise I'll stick w/Gas and never hope to see much wildlife on the trails.. I may consider a mountain bike w/Electric assist to help my old ass get up the mountain.

Also the excessive solar still produces very admirable output when the sun's not shining.. I can get in overcast what most here w/100AH of lead cant get in direct sunlight.
 

shade

Well-known member
yeah PV is cheaper than more LFP, and expected to last longer.. I freely admit I overdid solar, I'm good w/half of my capacity.. the fixed roof one still provides abundant power.
That's what I'm considering. For my needs, one 100Ah LFP battery & one of those panels should do everything well. I could easily add a second panel & controller, but I don't think it'd be necessary.
 

dreadlocks

Well-known member
yeah I setup mine for worst case scenario, very little sun or overcast, calculated base minimum needs as less than 10-15% of total solar, so even in pretty terrible conditions I should be able to scrape by still w/solar.. all siblings on both sides are in PNW, whats easy here in sunny colorado is hard there.. I've yet to take it up there yet, but based upon my testing so far I'm not really worried.. when its not worst case, I can burn power like a trust fund kid burns money.. It is sooo stupid nice to finally just not give a crap about power usage in the least lil bit, such a burden has been taken off me.

Even planning for worse, hooking this much solar up to a single lead battery of similar size would make no sense as you'd be wasting like 80%+ on good days, but the LFP can take it all if ideal laboratory conditions are ever seen (0.5C) and it'll fill its self up in a hot minute when it does.
 

Wyuna

Observer
I've only got 180 watts of solar connected to my 240ah lithium system, its amazing how quick the solar tops up the batteries.

The small amount of solar works for us, as we can't stay still in one spot, the DC-DC keeps it topped up, while we explore

It's funny, how i used to ensure that my AGMs were 100%, now i make an effort not to keep the lithiums at 100%.

My venting fans and fridge stay on all the time.

the problem i've found is that i've gone from being frugal with power to enjoying it, cooking with induction is great, so is not worrying about getting them fully charged.
 

shade

Well-known member
@dreadlocks - I know you're deep into Victron products. Setting price differences aside, do you see any significant advantages to using Victron batteries instead Battle Born when integrated with other Victron products?
 

dreadlocks

Well-known member
Victron has an open source API to their BMS.. I could read all internal sensor data, and decide my self when to enable charging or enable discharging.. so I could set up all sorts of extra saftey on em.
 

shade

Well-known member
Victron has an open source API to their BMS.. I could read all internal sensor data, and decide my self when to enable charging or enable discharging.. so I could set up all sorts of extra saftey on em.
I like the sound of that. I don't like being locked into a system, but I understand that there are times when the integration offered makes it worthwhile. Leaving the code open seems to be a good middle ground.
 
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Alloy

Well-known member
My $0.002 is the amount of solar is dependent on the expected conditions (shade/summer&winter sunshine) and power consumption.

The type of battery is depended on cost, enviroment and pysical conditions (space & added weight) of the trailer/RV.

For 4 months it didn't matter what type of batteries we had because the solar panels on our roof kept the batteries at 100%.

Yesterday with trees blocking the Southern sun until 3:00pm the roof top panels brought in 84Ah (1140Wh) and we consumed +/- 64Ah (884Wh) overnight.

The $1000 FLA bank I have were at 13.99V and normally hang around 14.01V-14.04V at the end of the day.

If conditions (less solar and temps above 32F) were always like this the $5000 Lithium bank I considered would be ideal.

Today I may play around with tilting the panels or bring out the portables.

Edit: With winter coming I decided to make sure the portable system is still working. The roof top is at 50w while the portables were at 640w until the system went into absorption.
 
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shade

Well-known member
I have the advantage of being able to tilt the roof of my camper while parked, so that should help when I can point the truck south. I may still end up with a side tilt capability in the mount, but I'll wait and see. I hope my small power budget won't require a fully detachable panel to keep up with my fridge while I'm away from the truck for days.

Now that I have a way to log consumption in hand, the weather has cooled off enough that I can't quite get an accurate read on consumption, but I'll see what I see over the weekend.
 
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