Battery Storage in Hot Weather

[jfaulkner]

I will not be using my Fiver this summer. It will be stored outside in Yuma, AZ where the temps will reach 120. I have a solar system with 4 Siemens 75 watt panels, controlled by a Blue Sky Energy Solar Boost 50, feeding 4 Sam's Club deep cycle batteries. Would it be better to leave the batteries in place in the fiver, or, move the batteries to my garage and place them on a trickle charge with a Battery Minder? Temps are going to reach above 120 in both the fiver and the garage, probable around 130-140 in the garage. I will not be able to check on the batteries for at least four months. I am worried about battery water levels in either situation. I think it would be less of a worry with the Battery Minder. Should any precautions be taken with the panels themselves?

Jer

 

[oldjohnt]

I would sure rather have my batteries at home at a more reasonable temperature and environment where they can be kept at or near 100% SOC (even if solar and controller might do the same if left running which I don't like for so long unattended) and I can insure the electrolyte levels are maintained. Sure its more work and a slight expense, but for a $400 battery investment it may well be worth it. Id just give the panels a good cleaning before leaving, shut down the charge controller and not have the panel energy feed into the controller.

 I'm NOT a solar expert, just a too long retired and rusty electrical engineer and this is only my opinion, so if the experts differ do as they suggest.

 John T

[Kirk W]

A lot depends upon just how long you will be away. I have many times stored a wet-cell battery by making sure it is fully charged and then just open circuit it. (remove the battery cables) I left our golf cart with the negative cable removed for almost 5 months and came back to find it charged enough to operate for a couple of hours before I put it back on the charger. If you are concerned about evaporation, you could safely increase the electrolyte levels a bit higher than normal before you leave if it isn't on any charger. 

[jfaulkner]

As noted in the posting, I will not be able to check the batteries for at least four months.

Jer

[Yarome]

Considering the temps.. I would do neither. Fully charge your batteries, shut down your solar as John described, physically disconnect them and either leave them in place (providing there is adequate ventilation), or move them to a shaded and well ventilated area (possibly elevated off the ground and covered under your 5er?). The garage would be a "no go" for me. It will retain the days heat much longer and you really want them to be able to cool over night.

Considering their self dischare rate (~10-15%/30days. Likely less in those temps) you should be more than fine for 4 months. Upon return, I would put them on a shore powered charger (to ensure a consistent charge rate) until full, then reconnect and go about your business. 

In your case... keeping them on charge at 100% SOC will do more harm than good.

[oldjohnt]

13 hours ago, Yarome said:

In your case... keeping them on charge at 100% SOC will do more harm than good.

 Yo Yarome, I read somewhere (Trojan perhaps ?) once 100% SOC is achieved its good to let a battery come to complete rest and stabilize for some time NOT connected to any charging source THAT TRUE OR DID I JUST DREAM THAT LOL

 One reason for asking is when considering a so called "smart" chargers algorithm, I chose one that after 100% SOC FLOATS at 13.2 volts WHICH I CONSIDER TO BE PLENTY HIGH. Some brands FLOAT at 13.4 to 13.6 which I think IS TOO HIGH. "Some" of the so called "trickle" charges I've seen don't produce enough energy to power a rubber chicken, maybe an amp or so, how would those (if low energy maybe one amp) "do more harm then good" assuming electrolyte level was maintained ??????????

 If I were the OP and brought my batteries home I still would NOT leave them on a trickle charge for four months 24/7. I leave my golf cart and other vehicle batteries unattended five months at a time and never had a problem, but they aren't sitting outside at high temps and aren't any single $400 investment either and I'm just darn particular about my RV house batteries!!! 

Lay some smarts on me my friend

John T

 

  

[bobsallyh]

Being in Yuma for 6- 7 months, I usually get the job of helping folks shut down their RVs that stays there for the summer. And since we are usually the first back I usually open them up before the owners have returned. We turn off all solar if equipped. With or with out solar we disconnect all batteries and make sure they are topped off with of course, distilled water. When getting back in the fall in over ten years there never has been a problem. The water levels are just where we left them. Just think of all the battery powered golf carts left in the parks, etc., if the same thing above is done, they are also good to go.  

[jfaulkner]

What about my truck batteries? I have had them on a trickle charge since last October. Should I leave them on the trickle charge or remove the charger and let them set until I return in October? 

Jer

[Yarome]

4 hours ago, oldjohnt said:

  ...which I think IS TOO HIGH.   

This.. coming from a pal that still owes me 4.25ah's for my portable ice maker from LAST summer (it's the vig that's gonna get you)!?

You weren't dreaming. Any deep cycle wet cell, in any form (AGM's) are meant to be "exercised" to maintain optimal health. Float charges are going to vary. 13.2 is a bit high for something like a sams/costco GC2 battery, but not out of line for a T105/RE. Something like a lifeline/full river AGM... 13.6 isn't out of line either, but not over extended periods of time.

Stricly from my experience, calculating self discharge and letting them sit as is (in general) a better option than a battery minder... in MOST cases. It's really no different than day to day usage. You don't want to discharge below 50% SOC, but it's perfectly fine to let them discharge within that range.

Where a battery minder comes in to play is for those folks when their ventures are undetermined. 2, 4 or 10 months in between. "Out of sight out of mind" and "low maintanence".

In the case of the OP... with temps like those... it's highly likely that he would burn off his batteries, and a $400 investment is no joke.... in anyones world. That's steak and lobster for 4..... 

As a rule of thumb, expect 10-15%/30 self discharge on standard wet cells and 1.5-3%/30 on AGM's.

I'm not really a proponent of "battery minders". It might be an inconvience to have to plan ahead and charge your batteries before a trip, but you're really not doing your batteries any favors keeping them at 100% over extended periods of time (following... that you don't allow them to drop below 50% SOC)

[Kirk W]

8 hours ago, oldjohnt said:

I read somewhere (Trojan perhaps ?) once 100% SOC is achieved its good to let a battery come to complete rest and stabilize for some time

The best of the float maintenance devices do just that. They monitor the voltage and the float charge cycles on and off. I have a Battery Minder ® product that I used on the chassis battery of our motorhome while we were fulltime. I parked at volunteer positions for anywhere from one to four months at a time, two or three times per year and I had mine connected to the battery permanently, powered up by 120V power as soon as I connected to shore power. I began using it after our first chassis battery failed and then kept that same battery for 8 years with it still in service when I sold the motorhome. 

[oldjohnt]

15 hours ago, Kirk Wood said:

The best of the float maintenance devices do just that.

  Thanks for the info Kirk, I'm never too old to learn I HOPE lol

 

19 hours ago, jfaulkner said:

What about my truck batteries? I have had them on a trickle charge since last October. Should I leave them on the trickle charge or remove the charger and let them set until I return in October? 

 

 jfaulkner, good question. I guess I'm more a fan of battery minders then others, but hey it would be a darn boring world if we all had the SAME opinions now lol HERES MY TAKE:

   IMHO Its unhealthy for a battery to sit in a fairly high level of discharge state for long periods (talkin Sulfation). They only have x number of rated Life Cycles and a discharge then having to recharge uses one up even though only one don't hurt much. If I had my choice between letting  one sit long term fairly discharged versus sitting long tem under a quality battery minder ID OPT FOR THE CHARGED ONE. I cant envision a quality small trickle charge (ESPECIALLY IF ONE LIKE KIRK MENTIONED) of maybe only 1 or even 2 amps hurting a battery, let alone hurting it MORE then it sitting in some degree of discharge !!!!!!!!!!!!! BUT NO WARRANTY IVE BEEN WRONG BEFORE YA KNOW

 So you have 2 choices, let them sit in Yuma and self discharge some amount (unhooked and solar all shut down)  ORRRRRRRR bring them home and place on a quality battery tender like Kirk spoke of. If the tender didn't auto shut down I would manually disconnect it now n then to let them sit a few days. If left sitting in Yuma  have them full charged and topped off of course, but you already know that.

OBVIOUSLY we have all left vehicles sit for long term and never had any major problem nor would you if you leave them sit in Yuma 4 months WELL DUH. Id bring them home and hook to a tender myself, but I'm an over cautious old engineer who errs on the side of quality and longevity and is a real stickler when it comes to my baby my RV and may go the extra mile (regardless if warranted or not) to extend battery life.  

 That's my story n by golly  Ima stickin to it EVEN THOUGH IM NO EXPERT

 

John T

[bobsallyh]

jfaulkner, there is a 1997 Buick sitting on our RV lot in Yuma. Belongs to a friend of ours. I disconnected the battery April 20 and it will remain that way until the first week of October with no charger, minder etc. I'll bet when I re-hook the cable up, the old girl will fire right up. Most folks I know just unhook the battery cables and are good to go.