Running 2nd life Revov Batteries with other 48V Batteries

[Disco4]

Hi Gents,

I got myself 2 x sets of Revov 2nd life batteries with the BMS systems. My current setup is 48V(4 x 100ah batteries), can I run them together on the same system, looks like my current 48V system draws power from the Revov system, almost like getting charged. If any one can help please.

Edited May 20, 2020 by Disco4

[___]

15 minutes ago, Disco4 said:

can I run them together

No. Well, yes... it will actually work, but you're going to destroy the lead acids in the long run.

First things first, it depends on how many cells in the LFP pack. If it's a 15 cell pack, then all bets are off. A 15-cell pack will disconnect itself if you go over 3.6V per cell, or 54V. 54V is too low for the lead acids and they will be damaged due to not being charged properly. A 16-cell pack would be more suitable.

The LFP battery will also grab most of the charge current and the lead acids will only start charging once they are full, further impacting their proper charging. The LFP will tend to do most of the work most of the time, it will charge first, and discharge first.

The worst thing, however, is that if anything bad happens to your lead acids (like an internal short), then the full discharge capability of the LFP might be let loose on the lead acids, which may be a safety concern. So at the very least you'd have to individually fuse them.

Finally, you may be voiding warranties if you do that. Pretty much every LFP battery I've seen has instructions telling you not do to this

Edited May 20, 2020 by plonkster

[Disco4]

Hi Plonkster,

Sorry my bad, my current system is LFP. 3 x Li - ion tech and 1 x Natlon. 

[___]

1 hour ago, Disco4 said:

Sorry my bad, my current system is LFP. 3 x Li - ion tech and 1 x Natlon. 

Oh, you have two different Lithium banks you want to parallel? That makes it a bit more difficult. In theory it should not be a problem, if the number of cells and the chemistry is the same. In practice there might be some obstacles... eg one BMS wants you to stop charging, or one BMS disconnects and not the other, things like that. I can't really say...

[Disco4]

The 2 systems seems to work against one another, I just took out my old system. Might have to sell it, I  don’t wamt to take any chances with the Revov system. 

[shanghailoz]

I won't say I'm doing exactly this (Revov + 48v Dead Acid), but I like to live dangerously.

At least till summer pops its head around.

I REALLY need to wire things up correctly one of these days...

 

[AhmedDoc]

Good day, I am in the process of buying a revov 5.12kw 2nd life, and just wondering how have they performed thus far? Also how has their service been, if you happened to contact them?

[phidz]

3 hours ago, AhmedDoc said:

Good day, I am in the process of buying a revov 5.12kw 2nd life, and just wondering how have they performed thus far? Also how has their service been, if you happened to contact them?

What made you settle for the 2nd life battery? Is it significantly cheaper than other new ones?

[AhmedDoc]

33 minutes ago, phidz said:

What made you settle for the 2nd life battery? Is it significantly cheaper than other new ones?

Hi, I wouldn't say significant but I understand it is cheaper eg. I have been quoted R24k for the R100 5.12kw and seems to have the same performance and warranty as the other options. Is there something else you would suggest? The invertor I'm considering is the mecer 5kw MKS 2.

[Gnome]

1 hour ago, phidz said:

What made you settle for the 2nd life battery? Is it significantly cheaper than other new ones?

I bought 2nd life cells.  Which is costing me R13k for 18s.  Whereas a 16s 100Ah would cost R20k+ (and almost certainly use a much worse BMS than I'm running).

So I think the cost difference is significant.  The question is how it will perform long term, but at ~R8k saving, I'm willing to give it a go

[phidz]

7 hours ago, AhmedDoc said:

Hi, I wouldn't say significant but I understand it is cheaper eg. I have been quoted R24k for the R100 5.12kw and seems to have the same performance and warranty as the other options. Is there something else you would suggest? The invertor I'm considering is the mecer 5kw MKS 2.

I use this one and it's about R2k cheaper than the Revov one. I'm not sure if it will work well with the inverter you want. It's working well with my Sunsynk.

[phidz]

6 hours ago, Gnome said:

I bought 2nd life cells.  Which is costing me R13k for 18s.  Whereas a 16s 100Ah would cost R20k+ (and almost certainly use a much worse BMS than I'm running).

So I think the cost difference is significant.  The question is how it will perform long term, but at ~R8k saving, I'm willing to give it a go

This is a significant saving. I was referring to the Revov 2nd life battery

[BritishRacingGreen]

8 hours ago, Gnome said:

I bought 2nd life cells.  Which is costing me R13k for 18s.  Whereas a 16s 100Ah would cost R20k+ (and almost certainly use a much worse BMS than I'm running).

So I think the cost difference is significant.  The question is how it will perform long term, but at ~R8k saving, I'm willing to give it a go

Just love the courage you have of your conviction.

Just read the IEEE engineer journal on meaning of second life batts.  Long story short it's taking automotive grade specs , that has been degraded , and re-purpose it to storage grade specs.  You may not have the original instantaneous power demand , but the long term lower power storage  is still there, which is exactly what we okes are interested in.!

So , this is by far better than new Lead Acid ,actually by country mile.

Good luck with your setup, and we will be watching you to feedback your experience over time.

Cheers.

 

[AhmedDoc]

Thanks for the feedback all. Any recommended installers for the Durban area?

[Gnome]

9 hours ago, 87 Dream said:

Keep us updated on the performance of these cells and also your 18s config. It's very intriguing & when you mentioned it the other day it was the first time I had heard of someone building in this 18s arrangement. 

I think you have a winner in that config & one of the many reasons I hate the 15s batteries, so by deduction this is better than my 16s. Will cost more $$ with 2 extra cells in the pack but I guess at the scrum it will definitely count in its favour.

87

Yep will keep the updates coming + pics.  I went with 18s just for the lower current consumption and my inverter seems to be ok up to that voltage.  Since the inverter is always running in boost mode, lower voltage should equal a slight efficiency improvement.  Time will tell

3 hours ago, phidz said:

This is a significant saving. I was referring to the Revov 2nd life battery

Aah ok.  I actually thought most of the cells you buy don't say what their source is, so for all you know other kits are also using 2nd life.  They are guaranteeing the kit, not what kind of cells they are using.

1 hour ago, dropkick said:

Just love the courage you have of your conviction.

Just read the IEEE engineer journal on meaning of second life batts.  Long story short it's taking automotive grade specs , that has been degraded , and re-purpose it to storage grade specs.  You may not have the original instantaneous power demand , but the long term lower power storage  is still there, which is exactly what we okes are interested in.!

So , this is by far better than new Lead Acid ,actually by country mile.

Good luck with your setup, and we will be watching you to feedback your experience over time.

Cheers.

 

Wow thanks, guess I was more frustrated than anything with the lead acid cells.  And recently built some other lithium batteries that have performed really, really well which kind of made it a no brainer for me.

I got my cells today:

But unfortunately my BMS hasn't even shipped (AliExpress).  So I'll likely still need to wait some time before I can give any feedback on progress

[Gnome]

1 hour ago, AhmedDoc said:

Thanks for the feedback all. Any recommended installers for the Durban area?

Inverter or battery?  Or both?

[AhmedDoc]

Both 

[phidz]

5 hours ago, Gnome said:

Yep will keep the updates coming + pics.  I went with 18s just for the lower current consumption and my inverter seems to be ok up to that voltage.  Since the inverter is always running in boost mode, lower voltage should equal a slight efficiency improvement.  Time will tell

Aah ok.  I actually thought most of the cells you buy don't say what their source is, so for all you know other kits are also using 2nd life.  They are guaranteeing the kit, not what kind of cells they are using.

Wow thanks, guess I was more frustrated than anything with the lead acid cells.  And recently built some other lithium batteries that have performed really, really well which kind of made it a no brainer for me.

I got my cells today:

But unfortunately my BMS hasn't even shipped (AliExpress).  So I'll likely still need to wait some time before I can give any feedback on progress

Where did you get these from?

[Gnome]

54 minutes ago, phidz said:

Where did you get these from?

Batteries: https://lithiumbatteriessa.co.za/

BMS: https://www.aliexpress.com/item/1005003092762026.html <- Still waiting on delivery, if this is anything like my usual AliExpress experience, I'll probably wait a month.

For the bus bar between cells I got a piece copper flat bar from a local metal seller in Cape Town.  I'll just drill the holes with my drill and then screw them down.

I'm using my existing disconnector (voltage rating is too low on this disconnector, so I'll have to create an anti-spark configuration).  Using existing fuse and fuse holder I already had from my current setup.

I do a lot of electronics, so I have a bench power supply.  I'm busy getting each of the cells individually up to the exact same voltage (3.220 volts).  When they go in series, they should all be pretty much at the same potential and the BMS shouldn't have too hard a time keeping it that way.  Probably overkill to do that but on my eBike I didn't bother doing that and it took a long while for the BMS to bring them all to within 0.01v of each other.

Edited November 5, 2021 by Gnome