New system, first timer, battery setup question (Sam's 6V golf cart batts)

FL_dok

New Member
Joined
Jan 13, 2021
Messages
2
Haven't set anything up yet. Amazon has most of the gear out for delivery today (3 100w renogy panels) and the controller (Rich Solar 40amp MPPT). I purchased two Duracell GC2 6v golf cart batteries that will be running in series for 12v.

Question 1: How concerned should I be about off gassing/venting. Can I set the batteries up in my office? It's a decent size 16x20 so not super cramped. Is this a go, no-go, or *go-but-ensure-I-do/consider.....?

Question 2 is a complex question around expanding the battery bank (eventually) as funds permit to add more battery and panels. (I would like to eventually add two more golf cart batteries.) I understand running in parallel is a no-go and absolutely last resort, so I'm wondering if there's a turn key gadget out there that would allow me to setup two independent banks off the same controller/inverter? E.g. able to switch which bank the controller is charging, which bank the inverter is using (independent of each other). From what I've been reading I'm not seeing anything like that. May be easier to just sell the 12v inverter and buy a 24v once I'm ready to expand. What do you guys think?

Requirements for the current 2 battery setup is minimal: low draw items like laptop, rechargeable batteries, small fans. I'd like to eventually expand to two more golf cart batteries (4 total) to add a small chest freezer.
 

snoobler

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Welcome to the forum.

1) If properly configured and maintained, very little. I sit next to an indoor 11kWh bank that I abuse. There are times when I equalize it, so I have to be a little more mindful of ventilation then.

2) "running in parallel is a no-go" = wrong unless you're thinking something silly. Your resulting idea based on your belief that there's a "no-go" is pretty horrifying. Please don't.

2 6V in series is fine.

2 6V in series in parallel with another 2 6V in series is fine.

See "Wiring" in link #2 in my signature.

Consider that you are buying cheap batteries. They're cheap for a reason - they're not fantastic. They're not bad, but you get what you pay for. Don't expect them to last. Don't discharge them more than 50%.

Do your design before you buy bits.

Good luck!
 

FL_dok

New Member
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Jan 13, 2021
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Wow, sorry to horrify you. There's lots of concern and caution on the internet and forums around parallel connections. I've got plenty of time to come up with something. Thanks for the feedback snoobler.
 

snoobler

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Where?

Just put them in parallel. Battery manufacturers literally recommend it.

The aforementioned 11kWh bank is comprised of 2S2P Rolls Surrette S-605 6V batteries.

No need for a Rube-Goldberg contraption.
 

12VoltInstalls

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Jan 18, 2021
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Wow, sorry to horrify you. There's lots of concern and caution on the internet and forums around parallel connections. I've got plenty of time to come up with something. Thanks for the feedback snoobler.
Checking to see how it’s going for you.

good advice aka snoobler is practical.

The people that snoot on parallel batteries are being uppity or ignorant. There’s a sound chemical/electrical reason against big parallel banks- most usually barely discernible in a lab. In most practical uses especially for your smallish setup if you don’t discharge deeply the single digit or fractional percent of theoretical ’less life’ over years will be indiscernible

I run lead acid- conscious of alternatives. Long before I heard that deep cycles don’t last I was getting well above average life out of lead acid batteries. I still do. If you treat those batteries well and make sure they get fed distilled water when needed I wouldn’t be surprised if you got 5+ years out of them. I might not be surprised if you got 10+ years out of them- but I wouldn’t be surprised if you didn’t, either.
 

NMNeil

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Mar 14, 2020
Messages
388
I have 8 of the Sam's club 6V batteries in series for a 48 volt system. Two are from 2017 which are starting to get suphated plates, the others are from 2019 and are hanging in there. I check the water levels every Saturday and most times they need a slight top up. Gassing doesn't seem to be an issue with the MPP all in one unit.
I'm abusing the batteries and have taken them down to 30% capacity, but I have little choice in the matter due to the long wait times for the replacement LiFePo4 cells. My local Sam's Club is no longer stocking golf cart batteries so my excursion into solar power may be coming to an end, and I'm gradually rewiring my house back to grid power again :mad:
 

12VoltInstalls

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Jan 18, 2021
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^^
I have 8 of the Sam's club 6V batteries in series for a 48 volt system. Two are from 2017 which are starting to get suphated plates, the others are from 2019 and are hanging in there. I check the water levels every Saturday and most times they need a slight top up. Gassing doesn't seem to be an issue with the MPP all in one unit.
I'm abusing the batteries and have taken them down to 30% capacity, but I have little choice in the matter due to the long wait times for the replacement LiFePo4 cells. My local Sam's Club is no longer stocking golf cart batteries so my excursion into solar power may be coming to an end, and I'm gradually rewiring my house back to grid power again :mad:
^^^you can get LiFePo, and other places sell golf cart batteries. Or my method that’s worked out well: multiple 27 deep cycle batteries. Inexpensive, light weight… just have more battery than you need do you don’t go deep, but not so many that the charge controller can’t belt them hard enough regularly to mitigate sulfation issues
 
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