LiFePO4 Capacity Testing | Does ambient temperature really make much difference?

[@DADvinci]

Retested Cell 10 (shown in this video) in a warmer spot and capacity went from 299.90Ah to 309.50Ah, so again almost 10Ah increase (similar to Cell 15). These EVE 280Ah cells from Docan are looking very good so far!

[@annscullamus]

Hi, I am looking for some advice and help ! I don’t really have any knowledge in terms of your extensive experience! I had a small solar array and battery and storage fitted by a North East company in August. I have been really pleased and as a low user up until the last month it was doing very well and my bills were low. Since the cold snap has happened my battery has started to draw from the grid when its temp goes below 10 degrees…..it is not on force charge from the grid. I looked at the Foxess community group and clearly other people are having the same problem ! The battery temp rose from 8.7 ( both battery and inverter are in my loft - nowhere else to put them) to now reading 11 as I opened the loft hatch for a few hours. Do you have any advice upon how I can insulate the battery for the cold months, bearing in mind I am a very sprightly 70 yr old female but I cannot access the loft myself ! It means getting someone in to do something- I just don’t know what exactly ! I am a subscriber to your channel and thought you were my best bet for help !! Thank you !

[@DADvinci]

@annscullamus Hey Ann! Thanks for reaching out and being part of our community👍😃. Ironically, this has been a hot topic across the growing battery owner communities in the UK. There have been a number of suggestions from other forums along the lines of building a box that sits over the top of the batteries which has some form of insulation. Something like a wood frame with walls made of Celotex or Kingspan insulation and even adding a small 40W tube heater (e.g. Dimplex) like those used in airing cupboards or greenhouses. Some have suggested wiring up temp sensors to control the heater so it keeps the 'insulated box' at the right temp without burning too much power. The box would be removable for when things warm up enough. Other suggestions include using hot water cylinder or cold-water tank thermal jackets, but I'm not sure that would make much difference without active heating inside. The process of charging should provide some internal heat for the batteries, but it's keeping it in, so insulation is probably the best way to go. May I ask what Fox ESS battery and inverter models you have? All the best, Adrian

[@annscullamus]

@@DADvinci Dear Adrian, Thank you so much for your reply and help ! My inverter seems to be an H1-3.7-E does that make sense ? I don’t really know how to find the battery type…hang on I just found it ! FoxESS Mira-HV25 HS5. I thought about the tubular heater but I am unable to get up to switch it on and off in the loft, which is rather too high up. Would you suggest an insulated box ? I could get a carpenter to make one and then my handyman could put it on and then take it off in spring ? Is there an official space needed around the battery and does the inverter also need insulation ? Sorry to be a pain !! Many thanks Ann

[@DADvinci]

@annscullamus Hey Ann! No problem at all. Thanks for the info, very useful. I found the datasheet for your battery and it had this note "*2, Charge derating will occur between 0°C and +15°C." So, it would seem it's limited when it gets under 15C, which does seem very conservative. Here's the datasheet link if you need it www.fox-ess.com/wp-content/uploads/2022/12/Mira-HV25-Battery-Datasheet-3.22.pdf It should only be the batteries that need insulating. As for space around the batteries, I can't find any reference to that, but from what I've seen on other forums (pictures), it's a box to keep the heat in nothing specific (I’ve not built one myself). I did find something on a FoxESS community about exactly what I've been seeing on a different version of Fox battery (HV2600), so it could be a question you ask on that forum (how big is the box, etc). The first couple of posts in this thread seem to highlight what's needed to improve temps on the HV2600 - foxesscommunity.com/viewtopic.php?t=215 In terms of the tube heater, you could always get a smart plug that you can switch on and off remotely if the temp sensor (automated) approach is not the route to take. I think your idea to get someone to measure up and make is spot on, with someone to remove when you see outside and battery temps start to rise to better levels. I hope this helps. Cheers, Adrian

[@annscullamus]

Dear Adrian, Thank you so much for the great advice ! My handyman is coming today so I will get him to go up into the loft and see what can be done re an insulated box, and if there is a plug for a tube heater. I am so grateful for the advice and knowledge ! I am thrilled with my little array but this deep cold caught me unawares and made me worry when I saw it drawing from the grid in large quantities ! Kind regards Ann

[@DADvinci]

@annscullamus It's a pleasure Ann😃. Fingers crossed that he can come up with something to cover the battery and see you through the rest of this winter and beyond. I'd love to know how you get on too. Completely agree on the solar power front, it's become addictive for me and turned into a passion without me realising. Stay warm and enjoy what sun turns up. Take care, Adrian