Adding to Battery Bank

[Bodo]

Howdy gang.

I keep hearing that enlarging a battery bank at a later date is a 'bad idea. Battery capacity degrades over time and when you add to a bank the new batteries are forced to perform at the state of the old ones.

My question is why does it matter? Let's say I buy 8 batteries now (48v bank) and in a year they degraded 10% and they're at 90% performance. Then I add 8 more batteries and so the entire bank is at 90% performance since the new will match the old. Versus buying all 16 now and they degrade 10% over the next year and the whole bank is at 90%. Aren't I still at the same place a year from now?

What am I missing?

[Bodo]

Hmm, why is the rest of my post not showing up?

Turns out if you use an alt- code everything after it doesn't post. Very strange.

[PNW_Steve]

Hmm, why is the rest of my post not showing up?

Turns out if you use an alt- code everything after it doesn't post. Very strange.

This is a know "feature" around here.

Regarding your battery question, I am waiting for the answer as well.

[inetdog]

Hmm, why is the rest of my post not showing up?

Turns out if you use an alt- code everything after it doesn't post. Very strange.

Only those codes for which the muliti-byte UTF-8 representation contains a 0x00 byte will cause this problem.

[Bodo]

Only those codes for which the muliti-byte UTF-8 representation contains a 0x00 byte will cause this problem.

*breaks out geek-to-english translator* Umm, got it. I think. Thanks!

[Ampster]

It is not a problem for Lithium packs because Lithium batteries can be paired at the cell level. That is true as long as you use batteries of same chemistry and capacity. Sorry for the digression, I know your question related to Lead Acid batteries which consist of 3 or 6 cells in series.

[SunEagle]

Howdy gang.

I keep hearing that enlarging a battery bank at a later date is a 'bad idea. Battery capacity degrades over time and when you add to a bank the new batteries are forced to perform at the state of the old ones.

My question is why does it matter? Let's say I buy 8 batteries now (48v bank) and in a year they degraded 10% and they're at 90% performance. Then I add 8 more batteries and so the entire bank is at 90% performance since the new will match the old. Versus buying all 16 now and they degrade 10% over the next year and the whole bank is at 90%. Aren't I still at the same place a year from now?

What am I missing?

Well first you are guessing that you will only lose 10% of the existing batteries. Chances are if they are wire in parallel in any way, one or more may lose much more than 10%.

So you take the chance of bringing down the life of your new batteries to the worst one of the existing bunch.

If needing to go purchase new batteries sooner then you figured but you can afford that then no sweat. But if you are on a fixed budget and you now want to replace all 16 batteries you might expect to need a loan to spend that much money.

All we are saying is that adding new batteries to an old set will end up with a shortened life for all of the batteries. The decision is yours to make.

[Bodo]

All we are saying is that adding new batteries to an old set will end up with a shortened life for all of the batteries. The decision is yours to make.

I appreciate that.
The plan is to add in the next year. If the budget improves, we'll probably change out the whole bank. Just depends. We'll go easy on this set and see how it goes.