Solar project thoughts.

[work2much]

Hi guys. Midway through installing. I have the panels mounted and working through wiring. Looking for thoughtful comments.



Here are a couple pics of install to date.

[work2much]

Mello Mike wrote:
Beautiful! A very impressive install. Congrats.

Thanks Mike. We are heading to AZ after the holidays.

[Mello_Mike]

Beautiful! A very impressive install. Congrats.

[Wankel7]

work2much wrote:

Wankel7 wrote:
Wow, what a setup! Solar powered AC in a truck camper 🙂

I have been pondering solar powered AC and was looking into these batteries.

https://hsrmotors.com/hsr/products/battery_module_85

I was reading a blog about these....A RVer with a sprinter used two and modified a mini split ac with heat pump.

http://www.imgins.org/ourlibertyvan?next_max_id=1637871861235122955_5687793474

There are some using electric car batteries in RV applications. Youtuber "beginning from this morning" is doing a nissan leaf install into a bus. Pretty impressive.

Mini split is an excellent way to go if you able. They seem to be more efficient.

As far as solar powered AC the challenge for a TC is the limited panel real estate on the roof. My system can run the AC for over 5 hours with 100% compressor duty and no solar. With solar charging and compressor cycling the range is much longer. Still though the panels don't charge at night and practical day to day use will require a charging strategy that will limit use to account for sun and recharging time.

What is interesting is he is running a 240V mini split....the only way to get a heat pump.

I will look for that Youtuber....thanks for the info!

[work2much]

Wankel7 wrote:
Wow, what a setup! Solar powered AC in a truck camper 🙂

I have been pondering solar powered AC and was looking into these batteries.

https://hsrmotors.com/hsr/products/battery_module_85

I was reading a blog about these....A RVer with a sprinter used two and modified a mini split ac with heat pump.

http://www.imgins.org/ourlibertyvan?next_max_id=1637871861235122955_5687793474

There are some using electric car batteries in RV applications. Youtuber "beginning from this morning" is doing a nissan leaf install into a bus. Pretty impressive.

Mini split is an excellent way to go if you able. They seem to be more efficient.

As far as solar powered AC the challenge for a TC is the limited panel real estate on the roof. My system can run the AC for over 5 hours with 100% compressor duty and no solar. With solar charging and compressor cycling the range is much longer. Still though the panels don't charge at night and practical day to day use will require a charging strategy that will limit use to account for sun and recharging time.

[Wankel7]

Wow, what a setup! Solar powered AC in a truck camper 🙂

I have been pondering solar powered AC and was looking into these batteries.

https://hsrmotors.com/hsr/products/battery_module_85

I was reading a blog about these....A RVer with a sprinter used two and modified a mini split ac with heat pump.

http://www.imgins.org/ourlibertyvan?next_max_id=1637871861235122955_5687793474

[Itinerant1]

work2much wrote:

Itinerant1 wrote:
Congrats on the finished install and welcome to the lithium side of life. Nice power to weight or lack of battery weight.
Once you get feel for the system and and it becomes something just running in the background you'll forget that you're running off batteries. Plus the added bonus of not worrying about topping the batteries off and still having power without the voltage drop.

Enjoy :C

Thanks, yes quite different discharge curve and characteristics. Big loads barely sag the voltage and it seems to run forever in the voltage sweet spot.

Yes, quite different. I've had mine on the morning of the 3rd day down at 28% (140ah) make a 12 cup pot of coffee, use the microwave for 5 minutes making breakfast, inverting at 12.4. Then watch the sun finally comeout and charge the bank back to a 55-60% and think a couple more days of sun like that and the bank will be back near full again. No worries.

[work2much]

Itinerant1 wrote:
Congrats on the finished install and welcome to the lithium side of life. Nice power to weight or lack of battery weight.
Once you get feel for the system and and it becomes something just running in the background you'll forget that you're running off batteries. Plus the added bonus of not worrying about topping the batteries off and still having power without the voltage drop.

Enjoy :C

Thanks, yes quite different discharge curve and characteristics. Big loads barely sag the voltage and it seems to run forever in the voltage sweet spot.

[Itinerant1]

Congrats on the finished install and welcome to the lithium side of life. Nice power to weight or lack of battery weight.
Once you get feel for the system and and it becomes something just running in the background you'll forget that you're running off batteries. Plus the added bonus of not worrying about topping the batteries off and still having power without the voltage drop.

Enjoy :C

[work2much]

Thanks guys!

[Dirtpig]

Looks like a very very nice install! Great job and thanks for sharing.

[jefe_4x4]

Work2,
Beautiful! Good thing we've had lots of sun lately on the west slope. Give a progress report down the road once you have a trip or 2 under your belt.
We have so many 100 foot trees on the property it's difficult to find a sunny winter spot for more than a couple hours per day. This eats into our charge time. Our tinky, by comparison, 200w array has only 2 things going for it: it's lightweight and has few distracting gauges and dials to worry about.
Again, nice job on the install.
jefe

[work2much]

The project is complete!

The bank has been assembled in the generator compartment. 24 CALB 3.2v/100AH cells producing a combined 600AH @12v



I have been testing the last few days. Everything has been working properly. Yesterday was the first test of actual available stored AH. The battery monitor tracks amps used. Solar panels not engaged.

Among things tested through inverter:

Air Conditioner uses just under 100AH
Fridge on AC mode uses about 30AH
Hot water heater on AC mode uses 135 AH

I played around with each for a while and ended up plugging in a 900 watt space heater and leaving the fridge and lights on as well for almost 4 hours to finish test before dark (which it didn't)

I installed a microair soft start on the air conditioning unit. As described in their literature the inrush starting amps dropped with each use as the unit programmed. The unit starts easily with a 2800 watt inverter.

Results were impressive. Charging the battery bank to a very conservative 13.6V and discharging to a safe 12v the 600AH bank produced right at 600AH before the inverter shut down to programed LVCO. This was more than I expected given the charging voltage I selected.I could get more with a higher charging voltage but without BMS this is where I feel safe. I could also get more with a slower rate of discharge or discharging farther although the added benefit is slim and not warranted IMO.

As a practical matter I don't anticipate using the battery this far down often, but does give a nice range in the event of multiple cloudy days or camping in the woods for a while where shading cuts solar production.



We are planning a trip south for the winter and I'm sure I will have more to learn as we start using it daily.

[work2much]

HMS Beagle wrote:
I understand you will not be using a BMS routinely. How often do you think you will need to check the cell voltage, and how often rebalance?

I will check often at first. From what I have read from people using these batteries for some time now I can't find anyone yet that has needed to rebalance unless they are adding cells to their system. Like any battery with multiple cells no two cells will be exactly "balanced" or equal. The important factor is that no cell is outside it's safe usage zone on both the high and low ends. Other than that concern lies with a cell failing and as it dies dragging other cells along with it. On this issue again I haven't found anyone who has experienced this. One long time electric car conversion company who uses these stated they have never seen a cell fail.

When assembled in P/S configuration the voltage in the parallel wired cells are balanced or maybe a better term averaged along the parallel stings. So having 2 batteries configured 3p/4s I will simply be checking the 3 in parallel 4 times per battery to see if the grouped cells voltage is similar to the others. This is all a BMS would be doing as far as monitoring. To monitor cells at an individual level they need to be run in series and a separate BMS required for each string in series. I would need 6 BMS to achieve complete cell level monitoring/balancing. In the configuration I am running the BMS would be monitoring/balancing each parallel string in series, so I would need 2 BMS.

A problem with BMS systems I have seen is their fairly limited shunting capacity. One I studied maxed to 1 amp shunting ability per "cell". Not sure how that would help control a cell being charged at 2-3x that amount, not to mention 3 cells in parallel.

At least for now my solution is to keep charging and discharging levels far away from the cause of all failures I can find to date, over and under voltages. Fortunately some quality chargers and inverters are fully programmable to control charging and discharging cut-offs with exact voltage levels.

There has been much interesting reading chasing this project for a while. The only thing I am sure about is there is much more to learn.

[HMS_Beagle]

I understand you will not be using a BMS routinely. How often do you think you will need to check the cell voltage, and how often rebalance?