New Zealand based camper - first project

[ianganderton]

Evening from a locked-down New Zealand.

We travelled from Sydney just before the lockdown started and had to self isolate for 14 days, we did that in my sister-in-law's campervan. The problem is they have stuffed their 12V lead-acid battery by not looking after it. I'm thinking I'll sort this out for them as a thank you for letting us use the camper.

This would be my first project. I've got a camper van plan of my own so I've been reading and watching lots of stuff for a while now. This smaller project would be a great to plan and action while the crazy world is doing its thing.

The camper is used by a family of 4. It's pretty old so I don't want to invest loads, just enough to do the job.

Please bear with me, I have a lot of question and I'm excited to learn

I've been doing some calculations



Do any flaws in these calculations leap out at you?

So I'm thinking 300W solar and 100Ah Lifepo4 battery

I read today that 300W panels are readily available and cost-effective because they are used so much in bigger arrays. But then I also read the series vs parallel post on Explorist.life today and that talks about the advantage of having a higher voltage created by more panels so I'm thinking 3 x 100W would be a lot more effective, is this correct?

What metrics should I be using to evaluate the quality of a panel? e.g. THIS ONE

I want to build a simple and robust system for my in-laws. What's the best way to get recommendations on products to use?

LifePo4 Calb style cells
BMS
MPPT Solar Controler
240V Charger
Battery & power monitors

I really want this to be as much about the learning for me so I'm also interested in measuring devices so I can really understand what is going on

Also, what do people use to create these neat wiring diagrams I see everywhere?

All help gratefully received, thanks

Ian

 

[ianganderton]

OK so I'm looking around and have now seen Will's DIY Solar Blueprints and the 400 Watt Solar Package w/ Alternator Charging version gives me a good starting point

The Renolgy DCC50S 12V 50A DC-DC On-Board Battery Charger with MPPT looks like a great solution as it deals with the alternator charging too. Interesting its max solar input voltage is quite low at 25V. My 3 x 100W or 1 x 300W question becomes irrelevant and 1 big panel the only correct answer

 

[Dhowman]

Under "Battery Power" 50% of 100Ah is 50Ah usable, 80% is 80Ah (LiFePO4). If you're going LFP and (.63 X 300W) of usable charging in a 12V system, the time it takes panels to replace that 80Ah is 80Ah/[(.63 x 300W)/12V] = 5.1 hours assuming no loads during that time. But if your daily consumption is 69.4Ah per day and your starting your day at 100% SOC (80Ah), if you get 69.4Ah/[(.63 x 300W)/12V] = 4.4 hours of sun, your batteries will still be at 100% SOC (80Ah) at the end of the day. I've found it's easier to just do all this budgeting entirely in Watts (vs Amps). Don't need to mess with system and appliance voltages.

 

[ghostwriter66]

agree with @Dhowman 100% ... I hate dealing with amps when calculating power-budget usage ...

Is the caravan going to be stationary or do they move it around?? If stationary i would do the 300W -- if moving I would do the 100 x 3

As Dhowman states your battery usage calculations are a little whack ... 100 * 50% is 50aH ... 100*80% = 80aH

 

[ianganderton]

Under "Battery Power" 50% of 100Ah is 50Ah usable, 80% is 80Ah (LiFePO4). If you're going LFP and (.63 X 300W) of usable charging in a 12V system, the time it takes panels to replace that 80Ah is 80Ah/[(.63 x 300W)/12V] = 5.1 hours assuming no loads during that time. But if your daily consumption is 69.4Ah per day and your starting your day at 100% SOC (80Ah), if you get 69.4Ah/[(.63 x 300W)/12V] = 4.4 hours of sun, your batteries will still be at 100% SOC (80Ah) at the end of the day. I've found it's easier to just do all this budgeting entirely in Watts (vs Amps). Don't need to mess with system and appliance voltages.

Because I created the spreadsheet for me it probably doesn't communicate some things very well to others.


The 100Ah in bold is the required Ah with the available energy in Watts calculated using 12V. It then calculates the battery requirement for that power need. So I've used 80% for LifePo4 125 x 80% = 100

Throughout the spreadsheet its the watts that are used for the calculations I have just converted these into different units so I can see the workings and compare them like for like in some instances.

Just reviewing the calculation

100Ah @ 12V = 1200W

Daily average power generation from 300W solar is between 1237W summer and 768W winter

Calculated power usage per day is 832W

So if the weather was really bad the van would be fine 1.44 days

In summer the power generation is greater than the usage but in winter its not. The different scenarios on the bottom of the sheet are me calculating worst case scenarios and how long it would take the van to recover with no other power input

I hope that makes sense

agree with @Dhowman
Is the caravan going to be stationary or do they move it around?? If stationary I would do the 300W -- if moving I would do the 100 x 3

It will move. Interested to know why you would do something different for the different scenarios

 

[ianganderton]

So this is my current thinking

100 to 125Ah 12V 1 pack of 4 cells Calb type LifePo4 battery - unsourced
BMS - unsourced
Charge controller - Renolgy DCC50S 12V 50A DC-DC On-Board Battery Charger with MPPT (includes alternator charging)
300W solar panel - unsourced but probably locally
Battery and power monitors - unsourced

I've been thinking about a 240V charger but currently think the van won't need one. If it's hooked up to shore power the fridge will automatically switch to that removing more than half of the 12V load plus with alternator charging there is just no need.

I'm not going to include an inverter at this point.

 

[ghostwriter66]

Because I created the spreadsheet for me it probably doesn't communicate some things very well to others.

View attachment 10835
The 100Ah in bold is the required Ah with the available energy in Watts calculated using 12V. It then calculates the battery requirement for that power need. So I've used 80% for LifePo4 125 x 80% = 100

Throughout the spreadsheet its the watts that are used for the calculations I have just converted these into different units so I can see the workings and compare them like for like in some instances.

Just reviewing the calculation

100Ah @ 12V = 1200W

Daily average power generation from 300W solar is between 1237W summer and 768W winter

Calculated power usage per day is 832W

So if the weather was really bad the van would be fine 1.44 days

In summer the power generation is greater than the usage but in winter its not. The different scenarios on the bottom of the sheet are me calculating worst case scenarios and how long it would take the van to recover with no other power input

I hope that makes sense


It will move. Interested to know why you would do something different for the different scenarios

Depending on the real estate on your roof - a 300 Watt panel is a pretty good size panel and takes up allot of real estate -- 3 x 100 theorectically takes up the same real estate but can be moved around to fit various knucs-n-crannies ... so if the RV is moving I would do 3 x 100 for space and aerodynamics .... if NOT then I would mount the 300 about a foot above the roof just slightly above A/C height and create an entire platform of them cheek to cheek ...

 

[ianganderton]

Depending on the real estate on your roof - a 300 Watt panel is a pretty good size panel and takes up allot of real estate -- 3 x 100 theorectically takes up the same real estate but can be moved around to fit various knucs-n-crannies ... so if the RV is moving I would do 3 x 100 for space and aerodynamics .... if NOT then I would mount the 300 about a foot above the roof just slightly above A/C height and create an entire platform of them cheek to cheek ...

Cool, understand. Haven't checked actual dimensions of the space available yet but pretty sure there is a good flat area up there. Fortunately, no AC to work around

Edit - looks like there is easily enough space for a 300w panel, roof is over 2m wide and there is a clear flat section just over 1.2m long, super happy about that.

 

[ianganderton]

Been getting my head around the wiring

 

[Dhowman]

So this is my current thinking

100 to 125Ah 12V 1 pack of 4 cells Calb type LifePo4 battery - unsourced
BMS - unsourced
Charge controller - Renolgy DCC50S 12V 50A DC-DC On-Board Battery Charger with MPPT (includes alternator charging)
300W solar panel - unsourced but probably locally
Battery and power monitors - unsourced

I've been thinking about a 240V charger but currently think the van won't need one. If it's hooked up to shore power the fridge will automatically switch to that removing more than half of the 12V load plus with alternator charging there is just no need.

I'm not going to include an inverter at this point.

Calbs are excellent and have really beefy terminals, especially good for mobile applications. Originally intended to go with their 180Ah cells but then found 150Ah Higee's (from BLS) that take up MUCH less space (higher energy density) and weigh about 100lbs for 300Ah worth (vs 200 for 360Ah of Calb cells). The terminals aren't nearly as robust, but the M6 studs and bus bars they come with are close enough to the Calbs and will likely be fine in my off-road rig once I get 'em all nice and snugged up in a box. We'll see.

Will P. did a review on that Renogy and seemed quite impressed. On the other side of the spectrum, might want to check out this guy's experience.

If you're space-limited, like I am, you might be interested in Electrodacus (see my sig). All SCC'g, cell balancing, monitoring, controlling covered by 2 pieces of kit that take up the space of a coffee cup (plus a couple of external shunts).

if NOT then I would mount the 300 about a foot above the roof just slightly above A/C height and create an entire platform of them cheek to cheek ...

Or, you might even be able to get 2 300 W panels up up there. These are 2 Renogy 300W (24V) panels I have on roof of my camper. And your roof's probably bigger than mine.

Nice rig btw!

 

[ianganderton]

More finding my way around

Raw LiFePO4 Cells

LiFePO4 BMS can be found by clicking here

www.mobile-solarpower.com

100 to 125Ah 12V 1 pack of 4 cells Calb type LifePo4 battery - CALB link on page
BMS - DYKB smart BMS 4S 12V 60A LifePo4 Lithium Protection Board balance High Current Bluetooth APP software GPRS Aliexpress link on page
Charge controller - Renolgy DCC50S 12V 50A DC-DC On-Board Battery Charger with MPPT (includes alternator charging)
300W solar panel - unsourced but probably locally
Battery and power monitors - unsourced



Spent a few hours putting this diagram together.

Because there is already a system in place a lot of the wiring is already there:

• Everything on the house side of the isolation switch
  • There are some other items that side I've not yet included in the diagram. These include the step, waterpump & TV
• Cabling from the engine bay to the area under a seat where all the electrics are

I need to get my head around the cable and fuse sizing next

 

[ghostwriter66]

Calbs are excellent and have really beefy terminals, especially good for mobile applications. Originally intended to go with their 180Ah cells but then found 150Ah Higee's (from BLS) that take up MUCH less space (higher energy density) and weigh about 100lbs for 300Ah worth (vs 200 for 360Ah of Calb cells). The terminals aren't nearly as robust, but the M6 studs and bus bars they come with are close enough to the Calbs and will likely be fine in my off-road rig once I get 'em all nice and snugged up in a box. We'll see.

Will P. did a review on that Renogy and seemed quite impressed. On the other side of the spectrum, might want to check out this guy's experience.

If you're space-limited, like I am, you might be interested in Electrodacus (see my sig). All SCC'g, cell balancing, monitoring, controlling covered by 2 pieces of kit that take up the space of a coffee cup (plus a couple of external shunts).

Or, you might even be able to get 2 300 W panels up up there. These are 2 Renogy 300W (24V) panels I have on roof of my camper. And your roof's probably bigger than mine.
View attachment 10877
Nice rig btw!

Thats sort of how I do it .. I look at all the space I have -- and then get various panels to fit that space .. we have a 310W across the very back of the work RV trailers -- and then 210s running up the side butt to butt .... and then on the front we have 120s squeezed between the A/C and antenna and stuff .. we just fill in every square inch we can with various things that will fit

 

[ianganderton]

Calbs are excellent and have really beefy terminals, especially good for mobile applications. Originally intended to go with their 180Ah cells but then found 150Ah Higee's (from BLS) that take up MUCH less space (higher energy density) and weigh about 100lbs for 300Ah worth (vs 200 for 360Ah of Calb cells). The terminals aren't nearly as robust, but the M6 studs and bus bars they come with are close enough to the Calbs and will likely be fine in my off-road rig once I get 'em all nice and snugged up in a box. We'll see.

Will P. did a review on that Renogy and seemed quite impressed. On the other side of the spectrum, might want to check out this guy's experience.

If you're space-limited, like I am, you might be interested in Electrodacus (see my sig). All SCC'g, cell balancing, monitoring, controlling covered by 2 pieces of kit that take up the space of a coffee cup (plus a couple of external shunts).

Or, you might even be able to get 2 300 W panels up up there. These are 2 Renogy 300W (24V) panels I have on roof of my camper. And your roof's probably bigger than mine.
View attachment 10877
Nice rig btw!

Thanks for the replies and all the info, I really appreciate it.

Good info on the Calb cells, good to know.

Hmmmm, that guy has definitely made me wonder about the Renogy unit. Because this is going to be looked after by someone else I'm keen on something simple and reliable. Having to disconnect everything definitely sits outside on that requirement

The other issues around balancing solar and alternator aren't so much of an issue for this install but I will check the numbers to make sure it will charge the batteries enough via solar on a day to day basis.

I'm not really space limited but I'm keen to look at interesting things. Key is simple, reliable and cost-effective.

I'll have a look at the Electrodactus. Does it have low-temperature charge cut off?

There would be loads of room for a big array but I'm going to stick with a single, simple 300ishW panel. It will be plenty for the way this van gets used

 

[ianganderton]

Last wiring diagram of the day. This includes the fuse and cable sizing for the components I need to source/purchase



Pretty pleased with this diagram Looks pretty ha ha

Tomorrow I have 2 things on my to-do list

1 - Work out how the various monitors work and what I want to be able to see. Off the top of my head I'm thinking

• Battery level as a %
• Power currently being consumed
• Power being generated (both solar and alternator)

2 - Create a costed shopping list

 

[ianganderton]

This looks interesting, just dropping the link here so I can find it again https://www.ringautomotive.com/en/product/RSCDC30

 

[Dhowman]

The other issues around balancing solar and alternator aren't so much of an issue for this install but I will check the numbers to make sure it will charge the batteries enough via solar on a day to day basis.

I'm not really space limited but I'm keen to look at interesting things. Key is simple, reliable and cost-effective.

Yeah, that sounds like the way to go with folks who might not be able to troubleshoot an issues that might arise. Alternator charging may add a level of complexity you just don't want to have to deal with if it can be avoided. An all-in-one system might be best for them for this reason, but those are more expensive than going DIY. If DIY, simpler is better-er. And usually you can build one that can scale better should you need to down the road.

I'll have a look at the Electrodactus. Does it have low-temperature charge cut off?

It does. See the temp probe on the bank in the diagram on my sig.

Last wiring diagram of the day. This includes the fuse and cable sizing for the components I need to source/purchase

View attachment 10900

Pretty pleased with this diagram Looks pretty ha ha

Tomorrow I have 2 things on my to-do list

1 - Work out how the various monitors work and what I want to be able to see. Off the top of my head I'm thinking

• Battery level as a %
• Power currently being consumed
• Power being generated (both solar and alternator)

2 - Create a costed shopping list

Don't really know too much about the Renogy bit on this diagram but only thing that pops out is that you may need something bigger than #4AWG from the alternator if you're fusing it at 75A and it's a long run. This is a nice resource for spec'g wire for figuring that out.

 

[Dhowman]

This looks interesting, just dropping the link here so I can find it again https://www.ringautomotive.com/en/product/RSCDC30

It does, but no built in LFP battery profile. Looks like there's some valuable tips/feedback in the comments on this vid.

 

[dashdrum]

I'm not going to include an inverter at this point.

Good for you! In my rig my only 120v appliances are the fridge and microwave. Next time I'll be sure to include a fridge with a 12V option (and dump the microwave)

 

[ianganderton]

Jut reading the thread about the review of the DCC50S and this post caught my eye https://diysolarforum.com/threads/renogy-dc-dc-charger-w-mppt.1406/post-45090

I sent an email to Renogy asking if a lithium battery disconnects itself due to low temperature what impact having solar panels connected will have, here is their reply:

Thank you for contacting Renogy. There can be an issue with leaving the panels connected without a battery connected as well. Your panels will continue to send power to the dcc and without any place for the unit to send the power it is receiving, can overheat and melt over time. Please let me know if you have any additional questions.

So I guess this means if you have a low temp disconnect on your charging circuit you also need to disconnect the solar panels.

I need to check the compatibility of the BMS and its low temp charge protection with the DCC50S

 

[Dhowman]

Sorry but that response from Renogy does not inspire a whole lot of confidence. Sounds like a design flaw and serious safety issue. Unless that's clearly stated in the manual (or better yet, ON THE PRODUCT) I'd steer clear of the whole thing.