After much deliberation and questions, I'll likely be purchasing the 48v Lithium battery pack instead of 4-12v. I liked the idea of 12v batteries for weight and ease of handling, but the possible cell-balancing issues are a deal-breaker. Looks like the 48v pack will be around 130lb. I'll just have to find a couple guys to get it in there. Once in, it shouldn't ever have to come out... at least not in my lifetime. According to the techs at Relion, cell balancing issues can occur if discharged below 80%. And if I only went with 100a of total capacity, that's a possibility. Relion company is redesigning their 48v 150ah pack (which I think would be more than sufficient), so I'll be waiting to see what they come up with.

2oldman,Was the issue due to connecting 4 12's in series? I don't understand why that would make any difference if the cell count is the same.

No first hand information on Relion battery packs but here are a couple of quick items in general about Lithium Ion battery pack.Ingeneral, there are 2 types of Lithium Ion batterieslithium cobalt oxide, LiCoO2Lithium iron phosphate LiFePO4LiFePO4 are "safer" but require different charging techniquesFor best performance, Li-Ion packs should be balanced, but this requires batteries to have extra leads as well as skeptical chargesThese should last a LONG time !

Is there a reason to avoid four 12 volt lithium in series?Or do the individual batteries get out of balance?

pianotuna wrote:2oldman,Was the issue due to connecting 4 12's in series? I don't understand why that would make any difference if the cell count is the same.It doesn't make sense to me either, but for now, I have to trust the expertise of the techs.I've been cautioned about this from two techs, that using 4 individual 12v batteries in series will result in cell imbalances which can essentially shut down the entire series string..especially if you drag them down to 80% DOD. In my case that's quite possible.This is also evident in the "48v" chargers I've seen, which are really 4 separate connections to each of 4 -12v batteries. So.. there must be something to this.

pianotuna wrote:2oldman,Was the issue due to connecting 4 12's in series? I don't understand why that would make any difference if the cell count is the same.And I have to ask:What is it that you have that actually requires 48 volts ??I hope you are happy with your decision but MOST folks settle on AGMs as the best bang for the buck. Long life plus MUCH less expensive than any variety of Li ones. And generally much easier maintenance too.....as in virtually none.

Li batteries at 48vdc | Good Sam Community

342 Replies

pianotuna
Nomad III
Jan 23, 2017
I can understand if it were parallel. But series each cell is "alone". Perhaps their system doesn't have sensors on each cell for doing the balancing?
time2roll
Nomad
Jan 23, 2017
OK I figured if they were used in parallel they would periodically be at exactly the same voltage.
I am not excited about the large heavy metal containers.
2oldman
Explorer II
Jan 23, 2017
time2roll wrote:
Apparently parallel is better than series if using separate batteries.
From Relion tech:

All of our batteries have balancing internal to each battery. When you connect multiple batteries in series or parallel they cannot balance as a “group”. The 24V will give you the same possible balancing issues.

Looks like problems either way.
2oldman
Explorer II
Jan 23, 2017
time2roll wrote:
Yes I see. Not going to work with 48v solar as the primary charge.
Appears so, which is why I was asking (in another thread) about running separate wires to the 4 batteries from the Solar controller. Somehow that doesn't seem like a great idea.
time2roll
Nomad
Jan 23, 2017
Yes I see. Not going to work with 48v solar as the primary charge.
Apparently parallel is better than series if using separate batteries.
Sam_Spade
Explorer
Jan 23, 2017
pianotuna wrote:
2oldman,

Was the issue due to connecting 4 12's in series? I don't understand why that would make any difference if the cell count is the same.

And I have to ask:
What is it that you have that actually requires 48 volts ??

I hope you are happy with your decision but MOST folks settle on AGMs as the best bang for the buck. Long life plus MUCH less expensive than any variety of Li ones. And generally much easier maintenance too.....as in virtually none.
2oldman
Explorer II
Jan 23, 2017
pianotuna wrote:
2oldman,

Was the issue due to connecting 4 12's in series? I don't understand why that would make any difference if the cell count is the same.
It doesn't make sense to me either, but for now, I have to trust the expertise of the techs.

I've been cautioned about this from two techs, that using 4 individual 12v batteries in series will result in cell imbalances which can essentially shut down the entire series string..especially if you drag them down to 80% DOD. In my case that's quite possible.

This is also evident in the "48v" chargers I've seen, which are really 4 separate connections to each of 4 -12v batteries. So.. there must be something to this.
time2roll
Nomad
Jan 23, 2017
Is there a reason to avoid four 12 volt lithium in series?
Or do the individual batteries get out of balance?
theoldwizard1
Explorer II
Jan 23, 2017
No first hand information on Relion battery packs but here are a couple of quick items in general about Lithium Ion battery pack.

Ingeneral, there are 2 types of Lithium Ion batteries
lithium cobalt oxide, LiCoO2
Lithium iron phosphate LiFePO4
LiFePO4 are "safer" but require different charging techniques
For best performance, Li-Ion packs should be balanced, but this requires batteries to have extra leads as well as skeptical charges

These should last a LONG time !
pianotuna
Nomad III
Jan 23, 2017
2oldman,

Was the issue due to connecting 4 12's in series? I don't understand why that would make any difference if the cell count is the same.

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Li batteries at 48vdc

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