First PB Deep-Cycle pack advice appreciated.

amerrigan

amerrigan

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Sep 26, 2019
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Hey all,
I know 18650's are the preffered storage (I'm still harvesting these) but have sufficient Lead-Acid deepcycle batteries (from unused UPS replacement packs) to at least utilise the 100W (18v) panel and crappy cheap 10a PWM controller I have sitting idle.

So for now I've got:
4xRBC55 18AH (12v)
12xRBC43 5.5AH (12v)

Any suggestions on how to string the batteries together (still have all the 100amp fuses and Anderson connectors etc from the UPS) or what else I need to get up and running?

Initally I'll be looking at powering the shed, mainly to charge up tools or RC batteries as and when needed; pretty sure I've got an invertor somewhere...

Cheers
 
You didn't say what voltage you were designing for. Just because the solar panel is 18V, doesn't mean that's your design build as charge controllers can boost that up to 48V nominal.

I would match 3x 5.5Ah with each 1x 18Ah.
 
Korishan said:
You didn't say what voltage you were designing for. Just because the solar panel is 18V, doesn't mean that's your design build as charge controllers can boost that up to 48V nominal.

I would match 3x 5.5Ah with each 1x 18Ah.
Click to expand...

Thanks for answering so quickly.

I'm thinking 24v as I'll be able to charge my RC stuff straight off the grid without a step-down.

So assumably (6x5.5ah and 2x18ah) in Series?
Would I need a way of balancing these (same way I would with Li-lithium packs)?
 
Sounds like something similar to my setup for RC charging.

I am using lithium battries which are charged off solar in a "24 volts" configuration. In the photo I have a series cable which allows me to quickly change to "48 volts" I can use if I need to charge at higher rates. Most of the time I leave it at 24 for convenience and because my solar setup wont charge at the 48v pack voltage.


image_kzlpho.jpg
 
>So assumably (6x5.5ah and 2x18ah) in Series?
Do you mean
1) 6x5.5ah in parallel (12v@33ah) and then 2x18ah in parallel (12v@36ah) and then put these in series for 24v@34.5ah and then do a 2nd one in parallel for 24v@69ah?
Or
2) parallize 6x5.5ah with 2x18ah for a total of 12v@69ah and then put those in series for 24v@69

I would go with #2. As far as BMS... I don't have experience with LA BMS except to observe that in #1 you would have 4 'cells' to manage (with BMS) and in #2 you would have 2 'cells' to manage.
 
OffGridInTheCity said:
I would go with #2. As far as BMS... I don't have experience with LA BMS except to observe that in #1 you would have 4 'cells' to manage (with BMS) and in #2 you would have 2 'cells' to manage.
Click to expand...

You don't really need a BMS for LA.

I would however connect everything in parallel first for a couple days and allow everything to equalize before making the series connections.

Most commercial products like a APC UPS wont have any "cell" monitoring. They only look at total pack voltage and perhaps apply a low voltage disconnect at most.
 
If you go 24V, then I'd go with 2x 18Ah with 6x 5.5Ah all in parallel, then series the 2 sets. This will give you equal capacities in both parallel packs. A total of ~69Ah.

The other option is to have 2 strings. Pair up your 2 18Ah batteries for 1 string, then parallel 6x 5.5Ah *2 to give you the second string. Then parallel both strings together.

Either option will work. First option is electrically 1 battery bank. The second option is electrically 2 battery banks and allows for disconnection of one bank while the other one is still connected. This means 0 interruption in your power delivery as long as you aren't consuming too much current at the time.
 
Korishan said:
If you go 24V, then I'd go with 2x 18Ah with 6x 5.5Ah all in parallel, then series the 2 sets. This will give you equal capacities in both parallel packs. A total of ~69Ah.

The other option is to have 2 strings. Pair up your 2 18Ah batteries for 1 string, then parallel 6x 5.5Ah *2 to give you the second string. Then parallel both strings together.

Either option will work. First option is electrically 1 battery bank. The second option is electrically 2 battery banks and allows for disconnection of one bank while the other one is still connected. This means 0 interruption in your power delivery as long as you aren't consuming too much current at the time.
Click to expand...

Awesome, thanks for your help -I'll take some photos assuming the British weather holds out over the weekend for the install.
 
amerrigan said:
Realised I'd probably need 2 panels to charge a 24v bank with the crappy Chinese/Generic PWM... Will setup as 12V for now to get the cells charged up,.

Options for a MPPT?
Click to expand...

MOST solar charge controllers are BUCK controller, meaning the PV input has to be higher than the battery voltage.

They are a handful of BOOST controllers... less common, but they do exist. The most popular crappy Chinese one is the MPT-7210A, which I have mixed feelings about. It's not that great, but it does work... I actually use it more as a DC-DC boost charger in my car to charge a 24v pack from a 12v alternator.

Companies like Genasun makes awesome compact charge controllers, and they have a boost models as well. I have a few of their controllers and they are great.

If you can add more panels, I would do that and use a buck controller as its a lot more common. I know ur going cheap, but those Victron SmartSolar units are great.
 
Unfortunately it looks like all the 12x RBC43 5.5AH (12v) have all been discharged (they have never been used as far as I know) to 6-7V each.
Guessing these are useless now, or can they be revived (or even worth doing)?

Plan B is some 36v 30AH LifePo4 I've been offered.
 
You can try reviving them... hopefully they are not too sulfated internally. Its a pretty easy process... just hook it up to low current charger, trickle charger, bench top DC power supply, or RC charger (my recommendation) on a low settings.

I recommend doing a capacity test like we typically do on 18650 cells. That would give you a much better idea of the general health, along with an internal resistance measurement.

I do this a lot with recovered APC / UPS batteries... sometimes you get lucky, sometimes you get crap.

Unfortunately all of the ones I got below, were VERY low capacity even though the held a reasonable surface charge voltage.Pretty disappointing. Point being, the voltage doesn't always tell the whole story.


image_pkyjts.jpg



image_uqrhpx.jpg



image_pyvuzh.jpg
 
Cheers!
That's somewhat reassuring as these had been sitting unused in my server room well over a year in their box (some tit ordered the wrong ones for a client) before making their way home with me.

Will stick them on my ISDT q6+ on PB trickle mode tonight, then run a cap test.
 
I have 8 brand new 5Ah SLA batteries that recently made its way home with me I ordered them to refurbish an APC unit only to find out the unit itself was dead. Too lazy to return it, so now I have 40Ah worth of SLA I need to use somehow.

As much as I love lithium, these types of batteries really are great, easy, and safe. Great for small projects without the complexity of BMS modules and stuff. Plus I already have a bunch of really high quality lead MPPT solar charge controllers.

You already have a capable charger so just use that for testing.
 
CrimpDaddy said:
You can try reviving them... hopefully they are not too sulfated internally. Its a pretty easy process... just hook it up to low current charger, trickle charger, bench top DC power supply, or RC charger (my recommendation) on a low settings.

I recommend doing a capacity test like we typically do on 18650 cells. That would give you a much better idea of the general health, along with an internal resistance measurement.

I do this a lot with recovered APC / UPS batteries... sometimes you get lucky, sometimes you get crap.

Unfortunately all of the ones I got below, were VERY low capacity even though the held a reasonable surface charge voltage.Pretty disappointing. Point being, the voltage doesn't always tell the whole story.
Click to expand...

Have you ever had to top them up with distilled water?
 
amerrigan said:
CrimpDaddy said:
You can try reviving them... hopefully they are not too sulfated internally. Its a pretty easy process... just hook it up to low current charger, trickle charger, bench top DC power supply, or RC charger (my recommendation) on a low settings.

I recommend doing a capacity test like we typically do on 18650 cells. That would give you a much better idea of the general health, along with an internal resistance measurement.

I do this a lot with recovered APC / UPS batteries... sometimes you get lucky, sometimes you get crap.

Unfortunately all of the ones I got below, were VERY low capacity even though the held a reasonable surface charge voltage.Pretty disappointing. Point being, the voltage doesn't always tell the whole story.
Click to expand...

Have you ever had to top them up with distilled water?
Click to expand...

No, I haven't bothered to go out of my way to refurbish in that manner.

At this point batteries are more of an unnecessary addiction. I have more than I need or could care to use so I dont really go out of my way to save them.

The lead acid stuff is only because I come across a lot of server room UPS units and I just have a habit of wanting to take it home to see if they are any good. More often than not I take them to recycling centerfor the scrap lead value if they are end of life.
 
CrimpDaddy said:
I have 8 brand new 5Ah SLA batteries that recently made its way home with me I ordered them to refurbish an APC unit only to find out the unit itself was dead. Too lazy to return it, so now I have 40Ah worth of SLA I need to use somehow.

As much as I love lithium, these types of batteries really are great, easy, and safe. Great for small projects without the complexity of BMS modules and stuff. Plus I already have a bunch of really high quality lead MPPT solar charge controllers.

You already have a capable charger so just use that for testing.
Click to expand...

I'm a electronics engineer(in a past life) and IT manager nowadays; alsoa keen"drone" racer so I've got plenty of bits and bobs that suit this "new hobby" (/addiction) in the shed. Honestly see this getting out of hand at some point.

The Q6+ is a good bit of kit in the field, I reckon I could probably use that to charge the PB bank straight from the solar panel better than the crappy PWM I got currently. It's trying to bring the battery up to min voltage @0.1A (set to 1A) in pulse mode and seems to be holding at 6.8V (up from 5.2v on this cell)
 
Ive been into this stuff for about 15 years by now it all started with RC cars, helicopters, and flashlights which started my battery addiction.

Let me know when it get out of hand I think I hit that limit when I bought 33kwh worth of EV modules.


image_uchsrt.jpg
 
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