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travellerw
Member
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# Posted: 21 Jun 2025 11:42am
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I took a quick look at the manuals for your devices. Based on the manuals it looks like the Inverter and MPPT controller would work with LFP batteries.
The MPPT controller has fully adjustable voltages in "User" mode.
The inverter has a wide enough voltage range to work! However, the low voltage shutoff may not work. That not a huge deal as the BMS on the batteries will protect them.
The battery charger is the problem. It could still be used if you monitored it closely. I wouldn't trust it in automatic mode though. I also would not let it float the batteries. If you added a Victron BMV-700 to the system then you could use that while using the charger. The BMV-700 will tell you the state of charge so you can shut the charger down long before you get to %100 and voltages that aren't good for LFP. Not an ideal solution but it can work (I did a similar thing on one of my systems for 3 years).
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gcrank1
Member
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# Posted: 21 Jun 2025 11:51am
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As a back-up charge plan (which I have yet to use) Id run the gen 1/2 to 1 hr of a morning to power the ac charger and top up from overnight usage. At that I dont think Id have to keep much of an eye on it.
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MtnDon
Member
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# Posted: 21 Jun 2025 11:51am - Edited by: MtnDon
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We used GC-2 golf cart batteries from Sam's Club when we built our first system. They lasted 9 years with gentle use. Much better pricing than Trojans at the time.
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FishHog
Member
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# Posted: 21 Jun 2025 02:44pm
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Even trojan batteries will die fast if your undercharging them daily. If your going to do something to get by for a year, go with the cheapest deepcycle batteries you can find. Or spend the time, make sure your batteries and charging system are the proper size for your needs and spend the money once.
All your usage items will have a power spec. Do an energy audit based on that and your best guess at use. Its not that hard and then you will know if you have the right size and just a bad batteries or if your under sized and killing your batteries.
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groingo
Member
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# Posted: 21 Jun 2025 06:36pm
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Best advice, keep it simple, looks like you already have the tools, inverter, charge controller, I would do an energy consumption test to see what is using how much juice then double the result and build around that. For cooking I would go with Propane or wood, refrigeration...try to avoid go with canned food or freeze dried, vacuum cleaner....oh hell no, get a good broom! Like I have learned, "Electricity is NOT your friend, find work arounds wherever you can, that is half the fun!
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Brettny
Member
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# Posted: 21 Jun 2025 06:42pm
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My system is built with Sam's club GC2 batteries..and two other brand ones i added a year later. For the WH that your paying for lithium is the way to go. Lead acid batteries really need to be 50% the cost of lithium to even break even and there definitely not that cheap. Lithium can take alot of amps until there nearly full. Lead acid need a longer slower charge, this really sucks in winter.
You may find that just getting the same WH lithium battery will suit your needs. And if not add another, if still not add another.
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