How to Build a Battery Pack

[Anthony Sinn]

I have a 440 sq ft shack. Weekend use. Propane heated. No electricity. No well.

I will end up getting a Honda EU2200i for powering tools but do not want the noise of a gas machine for the other 99% of the time.

The battery pack is for evening use. Portable to take home and recharge during the week. I'm wiring the shack this spring and the battery pack will be the power source.
Later on I may add solar panels and a controller.

To power 3 LED lights, a 12V 3 gallon/minute water pump twice a day for a quick rinse or pump grey water from a sink, charge cell phones.

Question
Not looking for the cheapest and also not a cadillac.

What do I need?:

1 - 100Amp hr LiFePO battery such as the Battleborn
1 - Battery Management System
1 - Modified Sine Wave Inverter
1 - Charger
Assorted wires, connectors, plywood, wheels

Suggestions, links, questions and comments would be great.

I had originally thought of a Dewalt 1800 Watt Portable Power Station and four 20V MAX XR Lithium-Ion Premium Battery Pack 6.0Ah which would cost $1100 cdn +HST

How far or close am I?
Should I build a battery pack. It would cost more. Fair enough or use the Dewalt?

[Ralph Day]

Hi Anthony

Ottawa? You're as close as you can get to some really excellent advice and sourcing of parts. The host of the forum, Rob Beckers is also the owner of Solacity. I've sourced almost all of my latest equipment from him. It's worth the 2 hour drive for me. Check out the Contact Us link at the bottom.

[Rob Beckers]

Hi Anthony,

So just 3 LED bulbs, a pump for a few minutes a day, and cell phone chargers? If that's all, your largest load (by far) will be the inverter; depending on the size those use about 0.3 - 0.5 kWh/day, just to power the inverter, excluding any loads. The total of your loads should be no more than around 0.25 - 0.3 kWh/day. That makes for a rough estimate of about 0.6 - 0.7 kWh/day in energy use (includes the inverter). A single 100Ah 12V battery stores 1.2 kWh in energy, so that would till you over for about 2 days.

Regular 12V lithium-ion batteries already have a BMS build into them. That makes it nearly impossible to destroy the battery, the BMS will simply cut you off if you try. Keep in mind that the chemistry of lithium-ion batteries doesn't allow for charging below freezing, and all the BMS's will block this.

We have Battleborn in stock at this time (which is rare, they tend to sell out before we can get more). A cheaper alternative is Enerwatt's WPL31, see https://www.solacity.com/product/enerwatt-wpl31/

For inverters we don't really sell modified sinewave any more. It's a crap-shoot what works and what doesn't work in modified sine, until you try. Regular pure-sinewave inverters have become cheaper as well, so 99.9% of inverters we sell nowadays is pure sine. For something decent and cost-effective look at Samlex's PST-series, https://www.solacity.com/?s=samlex+pst&post_type=product

There are inverter-chargers, but if you want a separate small charger, see Victron: https://www.solacity.com/product-category/charge-controllers/charge-controllers-ac/?swoof=1&pa_brand=victron&really_curr_tax=72-product_cat

You're going to have to get your own wheels... :cool:

-RoB-

[Anthony Sinn]

That is exactly the information I need.
It's spring and the work is just beginning.

I did find this forum through a link on Solar City website. I know K-Town well and lived out near Pirates Cove.

There are sooo many Youtube videos and most are geared to how to do cheap fair enough but with the myriad of cheap electronics there are the ones that are truley cheap and crap out vs tried and tested.

I will maintain the post and when this project is under way I'll keep posting.

[Anthony Sinn]

So here's what i have done and what I will do next.

I bought a single Hanwha Solar Q.PEAK DUO BLK ML-G10+ 395 and mounted on the roof. PV number two is mentioned below.
There is lots of shade. That is sort of okay. I won't cut down adult or sub adult trees.
I have a Bluetti AC300Max which is enough power to run lights a, 5.1 stereo system with a small old flat screen and 12 volt Sureflo water pump. I can easily get an entire weekend which is one movie at night, from a full charge. I'll have at least 50% left. The rest of the week the PV charges the solar generator. The TV uses just over 100 watts/hr.

But I will add another PV this spring. The Ac300max will charge up to 900watts and I want to take advantage of the window of sun and the used PV #2 is crappy. Should have bought new. I have them wired in series and didn't see any energy gain.

Next project this year is refrigeration. I have an ICECO VL45 12V that will use a maximum of 10 watts /hr. I have a 100Ah LifePo4 battery and a Victron 100/30. This will be a separate PV and circuit. The old pv will be used for that circuit but it may not produce enough wattage to keep the battery charged and run the cooler at 2C for the three seasons. I will likely end up replacing the old and buying another PV. (from Solacity)
The goal is to build a DIY system. I want to see. This circuit will be for the cooler and water pump only.
Question. What type of fuses? Are 2 60 amp fuses, one at the battery and one before the MPPT to much? There will be a maximum of 20' of 10AWG wire from the PV to the battery.
I'm proposing A Blue Sea 5191 fuse block at the battery and a Blue Sea 7721 after the MPPT with 60A fuses?

[Rob Beckers]

Anthony, cool setup! :cool:

If you're connecting just one solar panel (or one string) to the charge controller you don't really need a fuse in there. Solar panels are in themselves current-limited (even code doesn't require a fuse in this case). If you really want a fuse there, then 15A would be all it takes.

The battery is a more important place to fuse since those things can generate large currents. You could either fuse it for the wire size you use; so 10 AWG wire is rated at 30 Amp, hence a 30 Amp fuse, or, you could fuse for the anticipated load(s) such as an inverter. The latter could draw much more (1kW inverter would be 90 Amp continuous, so a 150 Amp fuse would be used in that case), and you'd need much thicker wiring as well.

For small fuse values all you need are ATO (automotive) fuses. They're dirt cheap, and there are both inline fuse holders and little fuse blocks with a few fuses on them.

-RoB-

[Anthony Sinn]

Thank for that. Confirms what I was thinking. I do have a 700W Renogy inverter. I may or may not use it. When I run a toaster at breakfast this spring I'd use the commercial solar generator.
The cabin is wired with one circuit with seven out lets.

The project in it's entirety has gone really well. It was a lot of work. I know the buzz word is off grid but I don't believe anything we do is off grid. Everything we do is connected right down to to the manufacture of a single nail for example. Let alone a modern PV and electricity storage system. Nothing could be done with out a complex human and natural network. An electrical system not on the main hydro grid is still dependent on other networks that are also dependent on multitudes of networks. Fun stuff.

I'll fuse the battery and use automotive fuses for the wires to the appliances and add at least one more PV this spring.

I also constructed a rainwater catchment system. There is an outdoor shower with an instant hot water system. Plus a sink and drain to a grey water pit. Done to spec according to the local conservation authority. There is one more thing to complete the project and close the permit. Hand rails. I'll find out this summer. Keeping it simple but pretty.