Struggling w/ The Cost To Upgrade Power System

[posplayr]

Originally Posted by N147JK

Just a data point from the other end of the spectrum.. I have a simple single flooded house battery. I added 200 watts solar, brackets, cabling, and controller. The total for the entire project was about $450.

I just bought 2 used 150 amp-hr (these are off-grid UPS batteries) AGM batteries (2x$100) plus two 245W Solar panels (2x$80) with $150 racking.

With the 30A/100V Victron charge controller at $120, it takes about 5 hours at 30 amps to recharge the bank from 50% down.

(Total $620 ) for 300 amp-hr-AGM/500 Watts solar. Even though these are used panels by 10:00am the panels are saturating the change controller at 30 amps. By 3:00 pm the two AGM are fully recharged at 150 amp-hrs of depletion.

I know people don't like to buy used but for the cost, it is hard to ignore. There is lots and lots of used solar equipment in Tuscon.

https://tucson.craigslist.org/ele/d/...694843725.html

https://tucson.craigslist.org/for/d/...702352367.html

[MrHenrietta]

Quick question on installing solar to my current system. Instead of connecting the panels directly to my AGM battery which is underneath my van, can I connect them in line on the battery cables coming into my van before they plug into the inverter/charger?

[posplayr]

Originally Posted by MrHenrietta

Quick question on installing solar to my current system. Instead of connecting the panels directly to my AGM battery which is underneath my van, can I connect them in line on the battery cables coming into my van before they plug into the inverter/charger?

The solar charge controller should be fairly close (3-4 feet) to the battery bank to avoid voltage drops (again you should calculate voltage drops (Solar charger to the battery) and keep it within 0.1V at max charging rate). The charge controller is operating off what the battery voltage says and if you run 20 feet of small gauge wire you will probably overcharge due to false readings (i.e. voltage drops).

Of course, this effect will diminish as the charge current tapers off but this would be my first instinct to get you started.

I'm assuming you could be pushing 30+ amps from the Solar charge controller.

[dhally]

We had a similar situation, with 200 amp hours of AGM. First I installed a battery monitor with shunt to see what was actually happening. After monitoring for a while and looking at all the lithium issues, we just got new agms. Next step will be a fast idle controller plus either dc to DC charger and/or aux alternator.

I don't like generators or idling either, but I really don't like complicated systems that require attention.

[Scalf77]

How long do you plan on keeping your van?

How old is your battery?

What is your current charging strategy? Do you leave plugged in at home? How to you know your battery is fully charged?

I only ask these questions because the majority of people undercharge their AGM batteries. Everybody worries about overcharging, but few pay attention to actually fully charging the battery. This results in decreased capacity of the battery.

Have you done a energy audit?

the answer is probably no, a good first step would be to add a good battery monitor. This way you can get a good idea to your daily usage. It will also help you come up with a charging plan.

If really thinking about Lithium list out what invert/charger you currently have. Two of the three SMB can be programed for Lithium, the other one is considered usable, but it would not be my recommendation.

As I think you realized Solar should be a go without in either case.

Rich Solar makes some nice 200 watt (24 Volt) version.. Two these would give you 400 watts , the Higher voltage would give would answer the turn on voltage question in series versus parallel. Running them in parallel with a aux port for a nice foldable setup would give you another 200 watts. Pair it with a Victron SmartSolar Charge Controllers MPPT 100/50 and you would be good to go.

Yes you can attach the solar charger to the same battery cables that go to your inverter. As stated as close as possible to that point. The Inverter cables are most likely large thus somewhat minimizing the voltage drop from that point to the battery. Use the largest available size to that point.

Sorry to drop Victron in the equation, but they do make goo products. Feel free to reach out if you would like.

I also have a Morningstar TS MPPT- 60 in my garage. This is used, and it has been collecting dust for a while. It is a great controller. I have used it on both AGM and Lithium.

[kbeefy]

Originally Posted by MrHenrietta

My goal is to not have to run the generator or drive the van to charge the batteries because my single 4D doesn’t cut it off grid for more than a day with fridge, heater and kids charging devices.

Thats a really light load and easily met with less than a 4d. Before upgrading everything maybe you just need a new/better battery.

[kbeefy]

I don't know your heater load so maybe I'm speaking out of place....

[1der]

Originally Posted by kbeefy

Thats a really light load and easily met with less than a 4d. Before upgrading everything maybe you just need a new/better battery.

Draw down for his usage profile will be close to 80 amps per day. Fridge alone is 50ish. Easy for everything else to add another 20 to 30 per 24hrs. That would require 200AH in an AGM bank to get through 28hrs before dropping below 50% state of charge.

Adding 200w of solar input would harvest around 40 to 60 amps during daylight hours to put back in the battery during the day. Still at a deficit at the end of day 2.

For a use profile of stationary for three days would have me looking at 300AH Lith battery bank 200 to 300 watts on roof, and a 200 watt portable solar array to supplement main roof panels.

[Big_ern_101]

Originally Posted by 1der

Draw down for his usage profile will be close to 80 amps per day. Fridge alone is 50ish. Easy for everything else to add another 20 to 30 per 24hrs. That would require 200AH in an AGM bank to get through 28hrs before dropping below 50% state of charge.

50AH for a fridge seems real heavy or maybe just an inefficient fridge? My ARB Elements (62L?) will run for 3 full days in 80-90°F off a 1000 watt Hour Goal Zero and thats only 83AH.

Even on heavy beer drinking events (cooling down 2-3 30 racks from warm to 34°F and in and out at least a few times an hour) I can get a full Friday PM to Sunday AM out of that same 83AH with a few phone and light charges in there too.

[1der]

Your fridge is using 83 amps in about 36 hours? When it is running it is likely drawing a current close to 5 amps. This would imply you are drawing about 2.3 amps per hour with the fridge running a duty cycle of 40-50%. That is about right.

2 amps per hour over 24 hours= 48 amps per day.