Time for new batteries...looking for suggestions

caleb · March 2020

I’ve had some issues keeping my system charged this winter and it’s been especially cold. As a result, I had one of my batteries drop too much, freeze, and split. So now I need to replace them.

I currently have a FlexPower One FXR system with the VFXR3524A inverter, so 24v. My whole setup is as follows:
• 6 x 265 Watt panels
• 4 x Surrette 428 Ah Batteries (S-550)
• VFXR3524A Inverter/Charger
• Mate 3 HUB
• FLEXmax 80

This is for use in a cabin that is used on average two weekends a month in the summer (usually every other weekend) and three or four times total in the winter. The system has zero issues keeping up in the summer. Due to the location and the lack of use in the winter, the panels spend most of the winter covered in snow. My current daily power use when at the cabin is around 1000-1200Wh. That’s on the high side, all appliances are propane, so my electrical needs are lights (all LED), a water pump that’s not used much, and a new power efficient LED TV that we will watch a movie on once a weekend generally.

I would like to replace my batteries with Lithium-ion to allow for a deeper discharge and to minimize maintenance. I am aware that lithium do worse than FLA in the cold. However, I’m thinking that if the battery(ies) are smaller, I may just remove them entirely for the winter and put them on a charger/maintainer at home and just use generator power for my Winter use. So I’m looking for two things, first, recommendation on batteries to replace my existing batteries. I think 3 days worth of reserve should be plenty given this is a weekend only cabin. I've seen a lot of good things about the SimpliPhi batteries, not sure if that's true or that's just their marketing? Second, is my plan to remove them in the winter a terrible idea?

In addition to this, I'm going to be buying a new generator so that I can take advantage of the AGS feature on my setup. Deciding on which generator is another topic

softdown · March 2020

How many years did you get out of the Surrette's? I'm guessing they got awfully dead in order to freeze and split. FWIW we generally find lithium to perform very poorly below ~32F.

One could disconnect the battery bank and leave it there. Good batteries are fine for months when stored cold.

BB. · March 2020

Just to be clear, Softdown is typing "approximatly" (~) 32F. (looks like a - minus sign if you are not looking closely).

Li Ion batteries (rechargeable type) are not usable below freezing.

-Bill

caleb · March 2020

This was only my third season on the Surrettes.

I had them die last winter too due to me accidentally leaving the inverter on so it drained them dead (so previous damage was certainly done already). They were fine enough all summer. When I got up to my cabin recently and found the bank low (and the one cell frozen), they were measuring 22.5V with a voltmeter, it may have been lower at some point as when I got there, the panels were mostly clear of snow so some charging was likely happening. It was also around -20* F the night before and had been colder the previous nights.

This is why I'm thinking of disconnecting and removing them but it's good to know that just disconnecting a healthy battery would likely be ok as well.

caleb · March 2020

Yep, I understand Lithium isn't good for cold environments. This is why I'm thinking just disconnecting them and not even trying to use battery power during the winter months. I shut off water and winterize pipes before it freezes so disconnecting batteries could just be one more thing I do and it wouldn't be that big of a deal. Really, the risk of ruining yet another expensive battery bank isn't worth it to me, I would rather just remove them (hope that makes sense)

softdown · March 2020

I have ten old cars and trucks plus four solar systems - two of which are tiny. I play around with battery maintenance a lot. Discharge rates in cold weather are minimal for sure.

Change of subject/off topic:
I'm not recommending this as it is a recent experiment and a change of subject. I'm currently trying a regimen of driving each vehicle at least once/month. Hoping this maintains the battery and lowers the frequency of unused equipment electing "early retirement" (quit working). Lubricating seals and gaskets via usage is useful. The question is - will ~1/2 hour, or more, of driving every month really maintain the batteries? Time will tell.

caleb · March 2020

Funny you mention the vehicle thing. I have a similar problem with my vehicles but my issue is I drive so little (when I go in to my office, I drive ~5 min to the train station) that it never really gets to properly charge. So one of my vehicles (it's a 2016, so not really that old) is showing the battery is weak. When I drive to our cabin, about 1.5 hours away, the battery then starts to show/check fine and is good for a couple months. 30 mins every month would probably be fine if the battery is otherwise healthy.

BB. · March 2020

I went the route of a good quality (in my case, 120 VAC on an extension cord) charge controller for cars that are not driven much. BatteryMinder and Battery Tender are two well known brands.

Costco is selling a (Duracell?) smallish battery float (capable) charger--Now on sale at my Costco for ~$40--That seems to be "battery friendly".

Many of the "standard" 12 volt car battery chargers do not have a good float mode--And tend to overcharge the battery and you may need to add water every 2-6 months. The BatterMinders I use (not cheap

), but have worked very well. Batteries stay charged, and do not use water. Also covers for when the in-laws forgot to close the trunk (trunk light discharged battery). And one car that the computer would occasionally use extra power and kill the battery in under a month (my 2002 Honda Van, when I left the sliding door open & interior lights off).

I had bought a small 1 amp "battery float charge" (the plastic cube from a local auto parts store)--And it over charged and caused the batteries to lose water, and even overheated/split the case when put on a near dead battery that needed charging.

If you do not have 120 VAC power to the vehicles, I would look at a solar panel on the roof/hood, or behind a south facing windshield). I don't know the brands below, but a 6 watt panel is commonly used on cars shipped from Europe to the USA:

https://www.amazon.com/s?k=solar+panel+battery+charger

For any float/trickle charger, I suggest that after the unit has been plugged into the battery for a couple days, go out with a volt meter and change the charging voltage... You probably want around 13.2-13.6 volts or so, if you see >13.6 volts, that will cause unwanted battery gassing/loss of water. (I will go out a bit later with a DMM, and see what my Batteryminders hold for the battery float voltage).

-Bill

caleb · March 2020

I use a Battery Tender Jr. (IIRC) for my dirtbike batteries. Dirtbikes aren't great at charging batteries anyways and then throw in a long period over winter of no use and you can kill a battery pretty quick. The tender works great.

BB. · March 2020

Just went and checked, 55F in insulated garage, battery floating at 13.55 volts with a BatteryMinder... We don't drive the van much for the last couple of years, and the battery has been lasting very well. So, 13.2 to 13.6 VDC looks good for me (moderate climate).

Of course, the other details matter too... Have a "simple" 1998 Ford pickup (no gps, no On-Star, just simple alarm and clock radio). I would let it sit for 6 months at a time (around here typically 50-70F most of the year), without much issue.

In-laws have a newer/nicer car with many of the bells and whistles--I would not not it go more than 1 month (~60F garage) without charging (for best battery life). It is also on a Batteryminder when not driven, and has done well too. It would go 2+ months OK too--But I really like to float charge for longer than 1 month.

-Bill

706jim · March 2020

My 1979 Camaro devoured several batteries while awaiting spring. (Never drove it in the snow)
The only drain was the clock on the stereo and that was enough to drain the battery. The last time I changed the battery I disconnected the ground and all was well 6 months later. As for the drain from the stereo radio , I never bothered to measure it, but it couldn't have been very much.

BB. · March 2020

Just out of curiosity... 80 AH car battery... Assume 25% discharge over 2 months due to loads in car:

80 AH * 0.25 = 20 AH available for loads between charges:
20 AH * 1/24 hours per day * 1/30 Days per month = 0.028 amps = 2.8 milliamps (1 month between charges)
20 AH * 1/24 hours per day * 1/60 days per 2x months = 0.014 amps = 1.4 milliamps (2 months between charges)

That ain't much load (0.028 amps * 12 volts = 0.336 Watts).

-Bill

softdown · March 2020

Aftermarket lights and stereos are rather famous for placing additional phantom loads on car systems - FWIW.

Time for new batteries...looking for suggestions

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