Which battery is better?

cephlon · May 2016

I'm in Hawaii and building our house off grid. Mainly because there is no power run down my street yet.

I have limited choice for batteries, but this is what I am looking at.

Dekka l16 type - 390ah flooded
L16 agm
Outback nc200

According to the specs on all these batteries the outback nc200 is by far the best, claiming the most cycles. 5000 cycles at 30%.

Dekka are the cheapest, but the specs give me 1000 cycles at best.

With the amount of amps being equal, it seems the outback the obvious choice. But I can't find much recommendation for them online. Anyone have experience with these?

vtmaps · May 2016

Welcome to the forum.

The usual advice we give to the newly off-grid is: buy the cheapest batteries possible.   There is a learning curve to off-grid living and the usual victim of beginner mistakes is the battery.

The lead-acid batteries you mentioned are not all the same... usually batteries are recommended based on your needs (your loads).   (Tell us more about your loads)

For example, the capacity of a battery is largely a function of how much lead and electrolyte it contains, but a given amount of lead could be in the form of a few thick plates, or many thin plates.   The thicker plates will last longer, but having less surface area, the thick plate battery will have higher internal resistance.   This can really matter if you are trying to run a microwave on some flooded L-16 batteries.

By the way, what voltage will your battery bank be configured? Are you planning to have parallel strings of batteries?

--vtMaps

Photowhit · May 2016

As vtMaps has pointed out, I would worry that the lower capacity to voltage would require multiple strings of the outback batterys.

Dave Angelini · May 2016

The Outback batteries are the "smart carbon". It is the same thing Trojan did. It sounds real nice. It does not do much.
Why are your choices so limited? We ship to the islands easily these days!

cephlon · May 2016

Thanks for the comments. I am not really new to being off-grid. I have lived off-grid before (just me alone though, not my family). Plus my business is involved in solar powered communication towers. I have a lot of experience with Flooded Lead Acid batteries.

The Outbacks are 200amps at 12v, so about the same as an L16. So either way I would probably do 2 or 3 strings at 48v.

Loads will be standard loads of a household of 4. All heating is gas. So main loads are fridge, hair dryer for my wife, washer and dryer, dish washer, TV and computers. All lights are LED.

I also have a well pump, but I have a separate battery/inverter system for that.

Mainly I am just wondering if Outback's claims are correct. Can you really go 7000 cycles on their NC200 batteries? The outbacks are only $200 more then the Deka, but will last 5x longer?

Dave Angelini · May 2016

L16's are usually 400 AH @ 20 hour rate or 1,100 AH for the 2V cells BTW. I never use parallel strings of batteries.

They can and do last 10 years if you take care of them.

I have not looked at Outback because they are relatively new at supplying batteries. I would read exactly what their claim is and how they warranty it. Go on their forum and read what the user's say. This may be hard because they are new at the battery supply business. Also, they do not manufacture the batteries they sell.

Photowhit · May 2016

cephlon said:

Thanks for the comments. I am not really new to being off-grid. I have lived off-grid before (just me alone though, not my family). Plus my business is involved in solar powered communication towers. I have a lot of experience with Flooded Lead Acid batteries.

The Outbacks are 200amps at 12v, so about the same as an L16. So either way I would probably do 2 or 3 strings at 48v.

Loads will be standard loads of a household of 4. All heating is gas. So main loads are fridge, hair dryer for my wife, washer and dryer, dish washer, TV and computers. All lights are LED.

I also have a well pump, but I have a separate battery/inverter system for that.

Mainly I am just wondering if Outback's claims are correct. Can you really go 7000 cycles on their NC200 batteries? The outbacks are only $200 more then the Deka, but will last 5x longer?

I don't like the term "cycle" tell me what a "cycle" is and I will try to answer your question.

Is a "cycle" every time you switch from charging to discharging? I might go through a 100 "cycles" when I run my water heater, a 900watt load, on a partly cloudy day.

Is a "cycle" every time you fully charge your battery? So it's good to leave your battery partly charged. I do understand that they claim these are better at resisting sulfating at partial charges but would you recommend not fully charging once a week? And how much extra battery capacity do you want if you'll only fully charge once a week? Do you think the battery bank will last 7000 ÷ 52 = 134 years? ...if fully charge once a week? They are claiming if you "cycle" the battery once a day it will last 19 years, that would be very impressive. "Cycles" do represent how we use batteries in an Off grid situation. They are great if you want to figure costs of a forklift battery that will be used to 50-80% of capacity each shift and recharged once a day, but we charge when we can, we must have additional capacity for those times when we can't recharge.

Having "200amps at 12v, so about the same as an L16" This is only true in Kwh capacity. Having 3 strings is like having a 1000lb weight over your head held up by a single rope that is held by 3 bolts each can only hold 350 lbs. If one fails, it all fails. This may seem like an incorrect assessment, but they don't just fail, they fade, a single cell has problems and the other strings try to help it out. The other strings become compromised, if not caught early, and you are left with 2/3rds of a system that has already been overly stressed.

vtmaps · May 2016

cephlon said:

So either way I would probably do 2 or 3 strings at 48v.

That is a less than optimal design... Putting batteries in parallel results in a bank with a shorter lifespan than a single string. And there will be the hassle of monitoring the current flow in each string. And then when you find the strings diverging, there's usually not much you can do... maybe remove the offending string and have a bank with reduced capacity and greater cycle depth.

Don't forget that each string in a parallel bank must have its own fuse or circuit breaker.

You should be looking at 2 volt batteries. Beware of Trojan's 2 volt L-16re battery... each battery is three 2 volt cells in parallel. Trojan does make a true single cell battery in their industrial line.

--vtMaps

cephlon · May 2016

I would love to get 2 volt batteries, but I can not find them on island. I know one person that has them, but he had to get his own container to ship them from California. Cost him over $20,000 to get them here. I looked for forklift batteries also, but have yet to find any.

I know going parallel is not ideal, but I don't really have any other option if I want to increase my available amps.

Vic · May 2016

Hi cephion,

Most of the issues have already been covered in earlier Posts ... errrr, Comments.

Those OB batteries appear to have a Rated 20-hour Capacity of 178 Ah.
http://www.solar-electric.com/lib/wind-sun/energycellnc_specsheet.pdf

Parallel strings are generally a bad design for daily cyclic-use, especially if they are AGM batteries, as are the OB batteries. With AGMs, current balance differences are often more extreme, and with relatively short charge times, using PVs or other RE power sources, the lagging parallel batteries do not get a chance to attain a full charge before the next discharge cycle.

The stated 7,000 cycle battery life seems crazy to me.

As you know, at least with Flooded batteries, one can actually measure the SOC, and know how well the battery bank, and individual cells are being charged, and so on.

Flooded batteries are relatively inexpensive, and are generally forgiving. Just pay attention to any battery.

IMO, there is no general "best" battery, as each application tends to be at least a bit different than the next ... just buy the best batteries that you can afford, monitor them carefully, maintain them, keep them cool (generally treat them like they are a valued member of your family, which is often the case), and they should reward you with good long-term performance, IMO.

FWIW, Vic

TURNEROFFROAD · August 2016

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Which battery is better?

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