diy solar

diy solar

Adding battery capacity over time

Leboy001

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Joined
Sep 25, 2021
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Hi Leroy here and I'm new to the forum.

I planning on building a 12 solar generator for camping. And maybe back lighting if the power goes out at home. I want to build a lifepo4 battery but as you all know these are costly.

There is a local seller of Prismatic cells here in NZ that are well priced with 3.2v and 50AH cells. 50Ah is enough for this summer but ideally I would like 100-150AH. But having at buy a the other parts of the set up as well is expensive.

Is it a dumb idea to start with a 50AH battery this year then next year but some more cells and add them in parallel to the existing batteries? Or are they like bricks and you are better off using cells all from the same batch to avoid balancing issues?

Thanks for your help
 
You can add later. There’s members on the forum that have paralleled like sized and slightly mismatched Lithium batteries at later dates.

Another good thing about starting out with one small bank is if you decide to do something totally different, you won’t be left with a a 50 ah bank instead of 150 ah.
 
Thanks. If it was for my house I would definitely save up for decent sized batteries, but as it's only for 3 or 4 weeks of the year I also might also find a 50ah battery is enough
 
Hey, new here. This is actually why I jumped into this forum. So, in my case. I was going to start with a 100ah battery and consider adding another later. Does this degrade or cause more issues on the old or the new battery? Or is it just fine. Currently considering a 12v all in one inverter. My thought is to be able to use it for vehicle (my van), or normal home power down situations (versatility). Still working on what I will land on, but that is my thoughts. With that batteries are expensive, so what can I do to keep the project less expensive to dive into. Thanks,
 
Mixing batteries sometimes is a problem. First, the age of the different batteries will make a difference. Second different manufactures of batteries make a difference. Different sizes of batteries make a difference. And of course never mix flooded cells with LP04 batteries. Everything charges at different rates. Best thing is get one of the batteries you will buy in then future. When you expand, try to by the same or as close as possible the batteries that you have. Flooded batteries is the easiest to mix and match, LP04 is the hardest.
 
That makes sense... so my thought is, stick with the brand, type, and likely even size... I am hoping the age is a mild sacrifice. So, if double my capacity in a few months, hopefully that won't be too bad. I don't plan on using it a lot, more set it up as a battery backup for my main freezer. So only variable is age, does that seem to be a decent compromise, or should I really just wait and get all the battery at once? Thanks for the quick response!
 
That makes sense... so my thought is, stick with the brand, type, and likely even size... I am hoping the age is a mild sacrifice. So, if double my capacity in a few months, hopefully that won't be too bad. I don't plan on using it a lot, more set it up as a battery backup for my main freezer. So only variable is age, does that seem to be a decent compromise, or should I really just wait and get all the battery at once? Thanks for the quick response!
I used to think that the answer was to get all the lead acid batteries at once and if you upgrade, replace the entire pack.

That is an expensive decision, and if you do get new batteries, what do you do with the old ones.

For my two battery truck, I replace batteries one at at time as they die. Usuallya waranty thing With it only paying for one battery, not both.

For my solar build, I replaced my entire pack with lithium batteries I assembled from cells. Lithiums wth their lower internal resistance cn be added to later on without the issues of lead acid.
 
That makes sense... so my thought is, stick with the brand, type, and likely even size... I am hoping the age is a mild sacrifice. So, if double my capacity in a few months, hopefully that won't be too bad. I don't plan on using it a lot, more set it up as a battery backup for my main freezer. So only variable is age, does that seem to be a decent compromise, or should I really just wait and get all the battery at once? Thanks for the quick response!
You are on the right track. I actually made 12 battery purchases withing a year and a half but i bought the exact same Lithium batteries. Took a while to keep them all balanced as i added them but it all worked out.
 
You are on the right track. I actually made 12 battery purchases withing a year and a half but i bought the exact same Lithium batteries. Took a while to keep them all balanced as i added them but it all worked out.
Cool, thanks for the feedback!
 
I used to think that the answer was to get all the lead acid batteries at once and if you upgrade, replace the entire pack.

That is an expensive decision, and if you do get new batteries, what do you do with the old ones.

For my two battery truck, I replace batteries one at at time as they die. Usuallya waranty thing With it only paying for one battery, not both.

For my solar build, I replaced my entire pack with lithium batteries I assembled from cells. Lithiums wth their lower internal resistance cn be added to later on without the issues of lead acid.
Thanks for the help as I start to piece together a plan... :)
 
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