Adding a battery to my system.

[Markw]

So I have an Ampere Time 12v 100ah Lifepo4 battery that I have been using for roughly 6-8 months (though I have owned the battery for almost a year but wasn't on the road and was only able to afford the rest of the bits and bobs for the system 6-8 months ago). The battery is hooked up to an Epever 30amp controller, which is, in turn, connected to three 100 watt solar panels. From the battery I have a 1200 watt pure sine inverter, a 12v fuse block which in turn is running the USB and power port (which runs the fridge, charges my phone etc).

Plugged into the inverter is a laptop and tomorrow I will pick up the instapot I ordered.

So far I have had no issues running everything for however long I want to, however I also haven't really run into a string of bad solar days.

Now that the setup is out of the way, on to the reason for this post. I am wanting to add a 2nd 100ah battery...but in the interim between puchasing my current battery and now as everyone knows Amere Time has changed to LiTime. I doubt there will be any issues, but I still consider myself somewhat of a newbie and know I don't know as much as many here on the forum.

So my question is twofold. Will this present any immediate issues and what would be the best procedure for adding the 2nd battery?

Having issues a few years down the road doesn't concern me as much as eventually I will likely swap them out for a couple of 200ah batteries when I can afford it...but just can't afford that swap right now and will have to save up for it.

 

[alcook62]

So I have an Ampere Time 12v 100ah Lifepo4 battery that I have been using for roughly 6-8 months (though I have owned the battery for almost a year but wasn't on the road and was only able to afford the rest of the bits and bobs for the system 6-8 months ago). The battery is hooked up to an Epever 30amp controller, which is, in turn, connected to three 100 watt solar panels. From the battery I have a 1200 watt pure sine inverter, a 12v fuse block which in turn is running the USB and power port (which runs the fridge, charges my phone etc).

Plugged into the inverter is a laptop and tomorrow I will pick up the instapot I ordered.

So far I have had no issues running everything for however long I want to, however I also haven't really run into a string of bad solar days.

Now that the setup is out of the way, on to the reason for this post. I am wanting to add a 2nd 100ah battery...but in the interim between puchasing my current battery and now as everyone knows Amere Time has changed to LiTime. I doubt there will be any issues, but I still consider myself somewhat of a newbie and know I don't know as much as many here on the forum.

So my question is twofold. Will this present any immediate issues and what would be the best procedure for adding the 2nd battery?

Having issues a few years down the road doesn't concern me as much as eventually I will likely swap them out for a couple of 200ah batteries when I can afford it...but just can't afford that swap right now and will have to save up for it.

The only issue I could possibly see is to make sure that both batteries state that they can be paralleled. Not all of these ready-made batteries have a BMS that is parallel compatible.

 

[Markw]

The only issue I could possibly see is to make sure that both batteries state that they can be paralleled. Not all of these ready-made batteries have a BMS that is parallel compatible.

My intention is for the second battery to be a LiTime (which is the same brand as my current battery, really, just with a different name). As far as I know, all LiTime 100ah LifePo4 batteries are 4p4s compatible, though I will make sure to further research this before making a purchase.

 

[alcook62]

My intention is for the second battery to be a LiTime (which is the same brand as my current battery, really, just with a different name). As far as I know, all LiTime 100ah LifePo4 batteries are 4p4s compatible, though I will make sure to further research this before making a purchase.

They probably are but it doesn't hurt to check. Adding a second battery is a straightforward, simple process. I did the same thing earlier this year. Make sure to match the SOC between the batteries prior to paralleling to avoid a large current transfer/inrush/spark.

 

[GXMnow]

Make sure to match the SOC between the batteries prior to paralleling to avoid a large current transfer/inrush/spark.

Yes, this is very important. It would be best to fully top up both batteries to 100% SoC and then connect them together when they measure the same voltage. The very flat voltage curve of LiFePO4 batteries is great for many things, but it makes balancing them difficult. They could both measure exactly 13.4 volts on a decent meter, while one is at 70% charge, and the other is at just 40% charge. To be truly balanced, you need to run them up into the top knee, and then hold them at the same voltage for a while so the current falls to near zero. Holding them both over 14 volts should do the trick.

 

[joeExotic]

Should be fine. Go big on batteries especially if they LFP get as much as you can. I have three 120ah LFP batteries and getting one cloudy day will pretty much drain them down to zero. Plus the shorter days in the winter means my batteries do not get topped off and I have 600w array so should get more than that. Hope this helps