[RE-wrenches] Winter Battery Maintenance

Sun May 1 09:54:33 PDT 2016

Seasonal use is a very frequent application that we design for in Mexico and Canada. Usually the seasonal residence sets for 6 months or longer. We have tried several methods of preserving flooded battery life including water-miser caps, short absorb times, no absorb time, 2 stage charge with the CV below gassing point and battery additives.  Even so, more than half of our Mexico customers ruin batteries in 3-5 years due to prolonged periods without maintenance. The northern customers fair much better. 

AGM’s perform much better than flooded but Lithium batteries are the best for long term non-use. You can simply discharge the battery to 50% then turn off the battery and walk away. When you return in 6-7 months, you will find it at the same SoC as when you left. For long term seasonal storage, that is all I recommend anymore.    

Larry Crutcher
Starlight Solar Power Systems

On Apr 30, 2016, at 12:54 PM, Dana <dana at solarwork.com> wrote:

I have yet to see any FLA battery that can go 4-5 months without service. Typically a FLA needs an increased voltage to attain the same full charge rating at low temps, but you still require watering. I have clients with shut down houses and no load situations, we back off the Absorb set point voltage, & time at full & they still require watering.
This thread started with “? I don't think the friend will be savvy enough to disconnect/connect them every year and I don't feel like having to go out there every season for them.”

Based on this statement would you still recommend FAL batteries? I have clients with AGMS that are partial year residents & their AGMS are at 8-10 years and still doing the job. That said some clients even full time occupants cannot water & test the SG on a FLA to save their life (or sustain the batteries life).

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Dana Orzel
Great Solar Works, Inc -  NABCEP # 051112-136
E - dana at solarwork.com  - Web - solarwork.com
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"Responsible Technologies for Responsible People since 1988" 
P Please consider the environment before printing this email.

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Starlight Solar Power Systems
Sent: Saturday, April 30, 2016 1:28 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Winter Battery Maintenance

I agree with Todd and Bob, leave the PV solar on, EQ off. 

I also instruct my customers to reduce the absorb timer to 0.1 hours. Since the battery is staying full, there is no need to spend time above cell gassing point which will increase water loss.

Larry

On Apr 30, 2016, at 10:28 AM, RE Ellison <reellison at gmail.com <mailto:reellison at gmail.com>> wrote:

Everything mentioned so far works well however, if you're using a charge controller with an auto equalize function.

Turn it off!

I had a friend who has left his system over the winter for years with no issues and he shut his inverters off one year got back to the batteries being boiled dry

After a lot of looking I figured out that it had gone into auto equalize and since the available sunshine per day was so low that it just kept trying all winter long to equalize the batteries

There was a battery replacement in his future relatively quickly!

It was an expensive lesson and I have since gone to all of the systems similar to that that I have installed over the years and shut off the auto equalize

It's not an issue if somebody's around but they were gone for like five months and it was not a good outcome

This particular system had three charge controllers,
A combination of MX 60 and FM 60s I believe

Just my thoughts,
Bob ellison

On Apr 30, 2016, at 12:43 PM, toddcory at finestplanet.com <mailto:toddcory at finestplanet.com> wrote:

> i built a system for a friend's seasonal (summer) off-grid residence in alaska.
>  
> my instructions were simple:
> leave the pv input & cc output breakers "on" and the load breakers (inverter, dc sunfrost etc) "off".
>  
> there was never a problem with winter freezing (even at -40f) until one year when he accidently left the inverter's breaker on. even with no load, the inverter's idle current drained the batteries and they froze. he only made that mistake once.
>  
> todd
>  
>  
>  
>  
>  
> On Saturday, April 30, 2016 8:13am, "Solar" <dahlsolar at gmail.com <mailto:dahlsolar at gmail.com>> said:
> 
> > I do systems like this every year. (-45F winter temps). Use quick connects and
> > train the customer on the batteries and their maintenance. Find bats with freeze
> > points that match your area. I typically mount the modules at 90degree so snow
> > never covers the array/module.
> > 
> > I always recommend removal. I've thought about temp controlled incandescent lamp
> > with a timer in a battery box for really cold nights.... Haven't got around to
> > working through that design.
> > 
> > I'm interested in the real seasoned off-grid installers thoughts about this.
> > 
> > Jesse Dahl
> > 
> > NABCEP PV Installation Professional
> > IBEW Local 292 - Electrician
> > Electrical/Solar PV Instructor - HCC
> > 
> > Sent from my iPhone
> > 
> > > On Apr 30, 2016, at 9:07 AM, AE Solar <autonomousenergies at gmail.com <mailto:autonomousenergies at gmail.com>>
> > wrote:
> > >
> > > Hey Wrenchers,
> > >
> > > A friend wants a very small battery set up at hunting cabin (like under 1kW).
> > It will only be used in the warmer months. I'm wondering what you all recommend
> > for the batteries over the winter. I assume the ideal situation would be that they
> > would be disconnected and brought somewhere warm for the winter (the cabin will be
> > subject to below freezing temps)??
> > >
> > > So long as they go into the colder months with a full charge is it alright to
> > leave them hooked up? I don't think the friend will be savvy enough to
> > disconnect/connect them every year and I don't feel like having to go out there
> > every season for them.
> > >
> > > Thanks for any thoughts.
> > > Adam
> > >
> > > Adam Katzman
> > > Autonomous Energies
> > >

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