Lithium batteries

[Docwagner]

Are there big differences in the quality of Lithium batteries to justify the big difference in cost? Comparing 100AH Li with 10 year warranties ranging from $400 to $950. Is the $950 battery worth 2 of the less expensive batteries?

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Originally Posted by Docwagner

Are there big differences in the quality of Lithium batteries to justify the big difference in cost? Comparing 100AH Li with 10 year warranties ranging from $400 to $950. Is the $950 battery worth 2 of the less expensive batteries?

One of the MOST important things to know about an LFP battery before you purchase it.....does it have built in protection to keep it from trying to charge the battery(s) if the air temperature is 32° F or lower. In other words, a low temperature cutoff. Many of them do have that protection, but some of the cheaper made batteries do not. Trying to charge a LFP battery in 32° F or lower will damage the cells inside the battery and there is likely no going back.

I have never really looked too much at the plug and play LFP batteries because I'm building a battery out of 4 cells and making sure I have protections for it in case of cold weather. I'm sure others will be along to offer more advice, or maybe recommend a specific brand for you.

[BandT]

I looked long and hard at the available LifePo4 (lithium iron phosphate) batteries. Of the available storage batteries, most of them are made in china. They maybe assembled elsewhere. The BMS (battery management system) is what controls the battery limits. This is where the low temperature charging comes in. So as long as you are aware of that, you can make up for it in different ways. Keeping the batteries from freezing and having “smart charging components” that don’t charge below freezing. I do both. So no problem for me, with low temperature charging. I think there are a lot more problems with people getting the correct charging profile for their particular battery manufacturer. Yes I bought one of the cheaper battery brands, and I am very happy with my choice.

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Originally Posted by BandT

I looked long and hard at the available LifePo4 (lithium iron phosphate) batteries. Of the available storage batteries, most of them are made in china. They maybe assembled elsewhere. The BMS (battery management system) is what controls the battery limits. This is where the low temperature charging comes in. So as long as you are aware of that, you can make up for it in different ways. Keeping the batteries from freezing and having “smart charging components” that don’t charge below freezing. I do both. So no problem for me, with low temperature charging. I think there are a lot more problems with people getting the correct charging profile for their particular battery manufacturer. Yes I bought one of the cheaper battery brands, and I am very happy with my choice.

Almost all the LFP batteries will have cells in them that come from China...my DIY battery cells included. I did do a lot of research, mostly on the DIYsolarforums.com website and found a vendor that sells Grade A cells and you can get them from China (2-3 months for arrival) or pay a little more and get them from their Houston, TX warehouse. Since I live in an area that does get below freezing in the winter months, I am in the process of building an insulated/heated battery box with 28W of heat being controlled by a digital heat controller. They are 12v heaters, and they will draw their power from either the battery itself, or the converter if I'm plugged in and the temperature is low enough to cause the heaters to come on. On top of that protection, the BMS will also be set to cut off charging at whatever temperature I select.

[KJLarson]

Do your research first. Some BMS systems in the cheaper batteries do not have a low temperature cutoff. Also, consider what you want to run off the battery bank. I'm installing a 300ah rather than three 100ah, cost is about the same-around $1000. We charge off of 1Kw of solar on the TT. FYI it's the amperage that is important when charging so make sure your system is sized right.