Pros and Cons of different battery types?

DrySide · February 2020

Hi there, I'm new to the board. We're replacing our old ghetto 200 Watt solar + Lead-Acid battery DC-only system, with a beefy 4000W solar + something line an Outback Radian inverter for an off-grid application. My big question at this point is what type of battery to use.

Our location can get sub 0 Fahrenheit, maybe -10 or -15, and we are often away for long periods during winter. Our old lead-acid batteries were able to survive that without any special care. We don't plan to maintain a heated space when we're away. I haven't kept up on battery technologies since way back...... is there a battery comparison you could point me to that would help inform my decision on battery type for our new installation? What other considerations should I be taking into account?

Thanks!

mcgivor · February 2020

Lead acid, despite their shortcomings when compared to more modern technologies, definitely has its advantages when cold is a factor, they are able to tolerate extreme low temperatures if fully charged. Since you've had good results with LA there would be no reason to consider anything else, particularly if left unattended without auxillary heating.

BB. · February 2020

That is a huge system upgrade... Have you worked out the daily energy usage, battery size (voltage and Amp*Hours), solar panels, backup genset (if needed), etc.?

Flooded cell Lead Acid are relatively cheap and forgiving... AGM (a version of lead acid) are sealed cells--So are much cleaner/no adding distilled water, more efficient than FLA batteries. However, AGMs are more expensive and may have slightly less life vs FLA (much depends on how well the battery bank is maintained, charged, etc.).

Will this be a full time system, summer, or weekend system?

LiFePO4 batteries (lithium/iron battery) are getting there, but not cheap. Does usually require a battery management system and charger/inverter setup to support Li Ion. But again as Migivor says, they do not cycle at freezing or below... Storage down to 0F (and some discharge current support) is possible. As always check the specifications.

Build some paper models of your system options (lead acid, AGM, etc.) and see what they cost out too, and if they will meet your needs.

A suggestion is always to build the "first battery bank or two" out of cheap FLA batteries, get some experience, then buy your "dream" battery bank later. Many (most?) people end up murdering their first battery bank or two. Better to do this with "less expensive training batteries".

In general, whatever battery bank you choose, look at maximizing your solar array Wattage... Most batteries do much better with lots of charging current (and backup genset, if needed). Under charging/over discharging has always been a good way of killing batteries.

Another question is system security... A "cheap genset" plus a small(er) battery bank and solar array (for night/off peak/silent time power power usage) can leave less expensive hardware exposed to theft. Or some of it can even be taken home at the end of the season. Can make more sense for a weekend/4 weeks in summer cabin. A "full" solar system make more sense for a full time, or near full time usage (like 9+ months a year).

Anyways--Just suggestions, energy usage and power systems are a highly personal set of choices and we just want to make sure the system you design/install works for you.

-Bill

DrySide · February 2020

Thank you both for your comments. I hear what you're saying about murdering an expensive battery set. FLA worked before.... why not now. That said, if I can reduce maintenance that would be nice.

Do you have any experience or comments about dry cell (Discover) batteries in this application? They are called hybrid-AGM. Can I just consider these to have all the attributes of AGM or are they different in some practical way?

BB. · February 2020

They appear to be Lead/Calscium/Tin batteries... More or less tubular AGM (or similar) battery type?:

https://discoverbattery.com/en/products/ev-traction-batteries
https://discoverbattery.com/assets/box/Dry%20Cell%20Traction%20Brochure.pdf?dl=1

-Bill

petertearai · February 2020

What about lead carbon . I put in set a year ago , no issues yet, but of course there shouldn't be . My last set were surette , lasted 8 years .

Pros and Cons of different battery types?

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