battery comparison question

[drcii]

Hi guys...

I've been looking at batteries lately and ran up on a question...

I have a question about two batteries:
1) 6volt 232amphour (@20amp rate) Interstate Batteries deep cycle golf cart batteries. These batteries have a total capacity of 1392 watthours.
2) 12volt 114amphour (@1amp rate) Walmart premium deep cycle "EverStart" battery. These batteries have a total capacity of 1368 watthours.

I understand that the walmart battery amphours number is deceptive due to the 1amp rate parameter of the measurement. I have two questions about the above...

1) Is there any way to know what the amphours of the walmart battery is in a 20amp discharge situation with the given data?

2) I only have a 120 watt solar panel setup and if I get two of the interstate batteries to build a 12 volt battery bank I am afraid that my solar setup is under powered for the batteries and would ultimately allow the batteries to be damaged.

3) I guess I have one more question.. If I do setup up the 12 volt bank with the two 6volt batteries do I need to systematically swap the position of the two batteries in regard to who is the first and second battery so they both are used similarly?

thanks for your assitance.
david

[Wy_White_Wolf]

Hi guys...

I've been looking at batteries lately and ran up on a question...

I have a question about two batteries:
1) 6volt 232amphour (@20amp rate) Interstate Batteries deep cycle golf cart batteries. These batteries have a total capacity of 1392 watthours.
2) 12volt 114amphour (@1amp rate) Walmart premium deep cycle "EverStart" battery. These batteries have a total capacity of 1368 watthours.

I understand that the walmart battery amphours number is deceptive due to the 1amp rate parameter of the measurement. I have two questions about the above...

1) Is there any way to know what the amphours of the walmart battery is in a 20amp discharge situation with the given data? Not from the data given but I can tell you it's 75Ah from looking at them for others. They are also a hybrid battery instead of a true deep cycle so there life is limited when used with solar.

2) I only have a 120 watt solar panel setup and if I get two of the interstate batteries to build a 12 volt battery bank I am afraid that my solar setup is under powered for the batteries and would ultimately allow the batteries to be damaged. Yes, you would be undersized. You can limit that by using a generator to give them a monthly or so equalizing charge.

3) I guess I have one more question.. If I do setup up the 12 volt bank with the two 6volt batteries do I need to systematically swap the position of the two batteries in regard to who is the first and second battery so they both are used similarly? No

thanks for your assitance.
david

See above

WWW

[SunEagle]

The only other point I can add beside the good ones that WWW gave you is that I purchased a couple of those 6v 232Ah interstate batteries for my RV.

They work great but it is not a solar installation so I can't tell you how well they will work on a daily discharge/recharge cycle. But I will say they probably will do better then those Wallyworld batteries.

[drcii]

Wy White Wolf,
Thank you for the straight forward response. Could you either expound a little on the "using a generator to give them a monthly or so equalizing charge." comment or give me a vector to an article that explains it?


Sun Eagle,
Thank you for the response. I thought this would be the case but just wanted to get the feedback. I will be going with the Interstate Batteries.

thank you both,
david

[Living Large]

1) Is there any way to know what the amphours of the walmart battery is in a 20amp discharge situation with the given data?

Not with the given data. Someone on the Wallyworld comments section ran a test at 5% capacity (5+ amps) and came up with 71AH, and said someone looking for 114AH would be disappointed. But that's one anonymous report on the internet, with incomplete data.

[paulcheung]

Hi guys...

I've been looking at batteries lately and ran up on a question...

I have a question about two batteries:
1) 6volt 232amphour (@20amp rate) Interstate Batteries deep cycle golf cart batteries. These batteries have a total capacity of 1392 watthours.
2) 12volt 114amphour (@1amp rate) Walmart premium deep cycle "EverStart" battery. These batteries have a total capacity of 1368 watthours.

I understand that the walmart battery amphours number is deceptive due to the 1amp rate parameter of the measurement. I have two questions about the above...

1) Is there any way to know what the amphours of the walmart battery is in a 20amp discharge situation with the given data?

2) I only have a 120 watt solar panel setup and if I get two of the interstate batteries to build a 12 volt battery bank I am afraid that my solar setup is under powered for the batteries and would ultimately allow the batteries to be damaged.

3) I guess I have one more question.. If I do setup up the 12 volt bank with the two 6volt batteries do I need to systematically swap the position of the two batteries in regard to who is the first and second battery so they both are used similarly?

thanks for your assitance.
david

If you don't plan to get more panel soon, better you get the 12 volt 114ah battery as it is a better fit with the panels.

[SunEagle]

Wy White Wolf,
Thank you for the straight forward response. Could you either expound a little on the "using a generator to give them a monthly or so equalizing charge." comment or give me a vector to an article that explains it?


Sun Eagle,
Thank you for the response. I thought this would be the case but just wanted to get the feedback. I will be going with the Interstate Batteries.

thank you both,
david

If you plan on using those interstate 232Ah batteries with solar you will need to increase the panel wattage so that you can generate 20 to 24 amps.

That comes to about 4 x 100watt battery panels and a 30 amp PWM CC or about 300 watts with a 30 amp MPPT CC.

[drcii]

Well the truth is that I've kind of run the gambit over the past few weeks thinking about what I want to do as my first setup. I "prematurely" purchased two 24volt 180watt panels about a month ago for $100 each. It was a good deal "IF" they were the right panels for my system... Fact is, I didn't have a system... and i thought i would build my system around those two panels. After a little education on here and then just digging around a bit on my own it turned out that the right system for those two panels would have been something like the following:

1) 2 existing panels - 380watts ($200)
2) 1 additional panel - 195 watts ($85)
3) Solar Odyssey 50Amp MPPT 700w12v / 1400w24v charge controller ($200)(I am sure that this is not a "great" charger, but it is all I would want to spend.. that's a problem)
4) 2 6v 232ah batteries ($270)
5) Sunforce 650watt pure sinewave inverter ($150)
6) Miscellaneous cables, connectors, fuses, etc... ($100 - and this is probably low)

At this point I had a total of about $1000....

The problem then became my use case.. It's not intended that I set this up right now and just use it all the time.. It's intended for an emergency kind of situation.. So the problem was "how to keep the batteries from degrading if they weren't being used and recharged." I found several AC chargers that I could run off the grid to "tend" to them, but the more I read the less certain I was about what I really needed in regard to this AC powered "tending or float" charger...

so.. I kind of backed off my 24volt panel and started thinking from scratch again...

After several more attempts at looking at individual 12volt panels and other ideas I ended up with just a turnkey Renogy, Eco_Worthy, or Anpowe folding panel with charger being the best solution for my bare minimum needs.. Luckily I'm an engineer and I work with a lot of other guys that would be interested in the panels that I already had. I've already got them sold for what I had in them...

So now, I'm thinking one of the above "folding panel" kits with attached charger, a battery setup, and a small AC charger like this one "Genuine SKYRC iMAX B6AC V2 Dual Power (6Amps, 50Watts)"... and running most everything that I care about straight off +12v.

I'm trying to decide which folding panel kit to purchase... I want at least 100watts but I see them (in my price range) from $235 (120watts - Eco-Worthy) to $344 (160watts - Anpowe). The Renogy units look nice but are more expensive per watt... and I don't think any of these are top of the line kinds of units... but again, that's not really what I'm trying to achieve.. with that said, I don't want something that is just going to not work when I need it to work.

so.. back to batteries.. It looks if I go with the 120watt Eco-Worthy setup I'm at somewhere between 800watts - 1kwatt a day through the year..... which really does line up with the Walmart battery pretty well given what WWW said was the real amhour number for the battery. (75ah) --> (900wh)

At the same time I would really like to have better batteries but I understand everything needs to be in balance and I would need to increase my costs considerably to support the two 6v232ah batteries (2.78kwhrs)

any comments are welcome..

thanks,
david

[SunEagle]

Well the truth is that I've kind of run the gambit over the past few weeks thinking about what I want to do as my first setup. I "prematurely" purchased two 24volt 180watt panels about a month ago for $100 each. It was a good deal "IF" they were the right panels for my system... Fact is, I didn't have a system... and i thought i would build my system around those two panels. After a little education on here and then just digging around a bit on my own it turned out that the right system for those two panels would have been something like the following:

1) 2 existing panels - 380watts ($200)
2) 1 additional panel - 195 watts ($85)
3) Solar Odyssey 50Amp MPPT 700w12v / 1400w24v charge controller ($200)(I am sure that this is not a "great" charger, but it is all I would want to spend.. that's a problem)
4) 2 6v 232ah batteries ($270)
5) Sunforce 650watt pure sinewave inverter ($150)
6) Miscellaneous cables, connectors, fuses, etc... ($100 - and this is probably low)

At this point I had a total of about $1000....

The problem then became my use case.. It's not intended that I set this up right now and just use it all the time.. It's intended for an emergency kind of situation.. So the problem was "how to keep the batteries from degrading if they weren't being used and recharged." I found several AC chargers that I could run off the grid to "tend" to them, but the more I read the less certain I was about what I really needed in regard to this AC powered "tending or float" charger...

so.. I kind of backed off my 24volt panel and started thinking from scratch again...

After several more attempts at looking at individual 12volt panels and other ideas I ended up with just a turnkey Renogy, Eco_Worthy, or Anpowe folding panel with charger being the best solution for my bare minimum needs.. Luckily I'm an engineer and I work with a lot of other guys that would be interested in the panels that I already had. I've already got them sold for what I had in them...

So now, I'm thinking one of the above "folding panel" kits with attached charger, a battery setup, and a small AC charger like this one "Genuine SKYRC iMAX B6AC V2 Dual Power (6Amps, 50Watts)"... and running most everything that I care about straight off +12v.

I'm trying to decide which folding panel kit to purchase... I want at least 100watts but I see them (in my price range) from $235 (120watts - Eco-Worthy) to $344 (160watts - Anpowe). The Renogy units look nice but are more expensive per watt... and I don't think any of these are top of the line kinds of units... but again, that's not really what I'm trying to achieve.. with that said, I don't want something that is just going to not work when I need it to work.

so.. back to batteries.. It looks if I go with the 120watt Eco-Worthy setup I'm at somewhere between 800watts - 1kwatt a day through the year..... which really does line up with the Walmart battery pretty well given what WWW said was the real amhour number for the battery. (75ah) --> (900wh)

At the same time I would really like to have better batteries but I understand everything needs to be in balance and I would need to increase my costs considerably to support the two 6v232ah batteries (2.78kwhrs)

any comments are welcome..

thanks,
david

Well whatever way you decide to go just remember that an FLA battery will live longer if you only discharge it 1/5 or 20% per day. Using it more per day will shorten it's life. So size your battery based on your daily watt hour usage x 5. Then make sure you have enough panel wattage that generates around 1/10th of the Ah rating of your battery system and can put back 120% of watt hours per day that you take out.

I can also tell you that I have built two solar / battery systems. The first is a small one that has an Eco-Worthy 80watt folding panel and 65Ah battery (not enough panel wattage for that battery) which was to be used for my RC flying in the boonies battery charger. Total cost was ~$550.

The second system is composed of 5 x 80 - 90 watt panels(should have used 2 x 200watt panels), 30Amp PWM CC(should have gotten an MPPT type), 4 x 12v 50Ah AGM batteries (should have gone with 2 x 6v 232Ah instead) and a 600watt Xantrex pure sine wave interver. This system was supposed to be for an emergency power source after a hurricane to run an oxygen machine. Total cost was ~$2500. I used the wrong batteries, panels and CC and over spent by $1000. Worst issue is that this one will only generate about 500 - 600watt hours a day and the Oxygen machine requires close to 1000wh for an 8 hour usage.

In the end I have spent a lot of money learning about solar / battery systems and have come to conclusion that while the first one has many uses and is easy to move around the second one was just about a waste of money. I could have gotten a 2000 watt inverter style generator for ~$1000 which would power that oxygen machine plus small frig and a couple of other loads and the cost of gas to use it would be no where near $500.

So keep reading, ask questions, design your system on your watt hour needs and then purchase your equipment.

[drcii]

this is a very useful post to me...
thank you.
david