Would you buy these batteries?

[unicutie]

https://dallas.craigslist.org/ndf/for/d/vmax-slr125-solar-batteries/6471362597.html


I was planning on buying  2 new 6v golf cart batteries, duracell from batteries plus for about the same price.
I will have 200w of renogy solar plus alternator.

I'm wary of buying used batteries unless it's worth it. I'm not sure. Can you battery experts give me your thoughts? He says they are not used but who knows how long they have been sitting in his garage...

 

[unicutie]

To add to this, what's the story on charging  agm batteries from an alternator, especially if i am charging up all 3 in parallel

 

[jimindenver]

Ok the questions are 1. age of batteries. 2. how are they kept charged, 3. how often are they charged. 4. What is the resting voltage right now.

IF I am satisfied with those answers I would run some simple test. How does the voltage hold up under a decent load for the amp hours they are listed for and how fast does the voltage climb back up when they are recharged. Too fast for either and I would not touch them.

A $50 savings over new is hardly worth not getting a warranty and old batteries that have been sitting uncharged.

 

[frater secessus]

I vote for the new Duracells.

 

[unicutie]

Yea I've been thinking about it and I'm gonna go with golf cart batteries since I have the alternator setup, i read that it is a good idea to have the batteries all with similar charging profiles. They do kinda have that "been sitting in the garage all summer" kind of look to them... Thanks

 

[RepublicOfTXPatriot]

My vote is for the new batteries. "More Sparking For Parking"

 

[unicutie]

Lol! I love it

 

[John61CT]

I would only consider secondhand batteries if the savings were 70%+ off the new price, or thousands of dollars, as I recently did with 40+ big LFP cells.

For batts that go for $200 a pair new, would have to be $50 *and* verified good with a load test.

So, no, buy new.

 

[John61CT]

To add to this, what's the story on charging  agm batteries from an alternator, especially if i am charging up all 3 in parallel

Stock alt setups vary so widely.

Assuming all the paralleled members are identical model and age

Get each batt at 50% SoC and measure and notate alt input at "high idle",

both volts and amps with an ammeter

every five minutes until voltage plateaus

then every fifteen minutes as amps start to drop.

Don't bother going more than an hour and a half, fully charging is likely 4-5 hours more, but at ever lower currents once the batt gets past 85% SoC.

 

[EnduroRdr]

Agreed, unless you’re saving 75% not worth the risk on used.

I was tempted by this one:
But too risky for me.

Moderator Note: Link removed per 'New posters must have 10 substantive posts before using links'


Sent from my iPhone using Tapatalk

 

[DLTooley]

Date of manufacture should be on the battery and is the easiest place to start. Those sound like they've been sitting around for awhile. A connected trickle charger in that photo would almost be a necessity.

 

[unicutie]

I got everything set up! It's awesome, I'm so stoked x.x my old truck battery I was using for my house must have been down to less than ten amp hours, closer to five probably. I killed it so many times.

I have my two panels mounted flat up top in series, my batteries are fully wired into the alternator and the charge controller, and I charged them up fully today. All of my electronics are small enough load that I can run them off of the load terminals on my charge controller and see my amps usage. I'm using less than 1Ah/hr at night. When I ran my laptop earlier I peak out around 4 amps.

This morning I drove for 30 minutes at sun up and by noon I was already on float. Right now I'm sitting at 12.55V and I feel rich by this time a few nights ago I would be down to probably 12.1 or less! It was sweet seeing my meter go to 12.7 and just hang there ? summer is gonna be awesome energy wise.

That's all just wanted to gush a little XD

 

[John61CT]

Fantastic! What batt(s) did you buy?

 

[unicutie]

Duracell gc110 batteries from batteries plus bulbs. It took an obnoxious amount of searching to determine that they are actually deka gc10 's.

It cost $215 after the core refund from my truck battery

 

[John61CT]

Duracell gc110 batteries from batteries plus bulbs. It took an obnoxious amount of searching to determine that they are actually deka gc10 's.

It cost $215 after the core refund from my truck battery

Excellent! Should've just asked here

The gray EGC2 at 230Ah is Deka Pro-Master GC15.

Yours are black?

GC2 at 215Ah is Deka Pro-Master GC10

Not all outlets stock both.

For those with a Sam's Club nearby, they're usually a bit cheaper, and there are ways to get around paying the membership.

 

[frater secessus]

This morning I drove for 30 minutes at sun up and by noon I was already on float. Right now I'm sitting at 12.55V and I feel rich by this time a few nights ago I would be down to probably 12.1 or less! It was sweet seeing my meter go to 12.7 and just hang there ?

That's straight up awesome.   I'll file it under "things house dwellers won't understand"

 

[unicutie]

Ha yea i guess I should have known one of you gurus would know about the duracell s. Yea they're black so I got gc10 s, it actually says gc10 on the label but no manufacturer information. B+b actually has both of those sizes as well as a larger size iirc, gc25 maybe. I saw it on the deka flyer.

Yea i thought about doing Sam's club but I did the math and it was pretty close to the same price as far as I could tell. Given that there's a +10% at sam's, vs a 10% discount at b+b if you order online and pick up in store.

I'm pleased. just need a refractometer and I'm all set to take care of my new pet batteries hopefully they are less needy than the pup

 

[unicutie]

Also: do any of you know what voltages I should set for float and absorb on my controller? I haven't found that info anywhere, it's on the default settings right now.

 

[John61CT]

The recommendations from East Penn, for that battery, in a cycling / off-grid application are. (Note: floats are higher in off-grid than typical golf cart use). 

At 12V:

Max Charge Current = 30% or less of Ah capacity (20 hour)

Absorption Voltage = 14.4V - 14.7V

Absorption End Point = Current change over 1 hour period of less than 0.1A

Max Absorption Time = 12 Hours

Float Voltage = 13.8V - 14.1V

Float End Time = No Limit

Equalization = 15.0V to 15.3V 

Equalization End Point = Current change over 1 hour period of less than 0.1A

Max Equalization Time = 12 Hours

Temp Compensation = -.018V for every degree °C rise above 25C

Note: 

For storage you may want to compensate float down to 13.4V to 13.6V the guidance above is for off-grid or deep cycling applications where the batteries are cycled daily. 

Stick to the 14.7V end of the absorption range and the batteries will do much better when they are being cycled .