The (old) battery storage question
After searching deep cycle battery storage questions, it seems my dilemma is a little different.
I can "store" 4 deep cycle batteries (12V, ~150 ahrs) as spares for my golf cart in a vented box inside my "solar shed". Connections are set up to parallel these "spares" with my in-situ cart batteries. The combined energy is enough to run certain ceiling fans, lights and a TV during the night in an emergency use case - and all is set up to do so quickly if an emergency (hurricane) happens by. I bought the "spares" over a year ago (maybe 2) thinking it must be close to time of failure of the golf cart set (almost 6 years of torture by my Grandkids). I recently put the "spares" in operation and trying to:
1. Decide when to buy a new "spare" set - would like to have them available IF the second set ever fails - not easy to get (good) new ones at this remote cabin.
2. Decide on how best to maintain them in a South Texas (hot) shed. Note that I've managed to use ventilation and reflective insulation board to essentially keep the interior of the shed approx same as outside - but still gets to 100 +oF a few days every summer. No freeze problems!
3. Bite the bullet and consider Li tech batteries at some point - $$$'s?
Any suggestions appreciated.
I can "store" 4 deep cycle batteries (12V, ~150 ahrs) as spares for my golf cart in a vented box inside my "solar shed". Connections are set up to parallel these "spares" with my in-situ cart batteries. The combined energy is enough to run certain ceiling fans, lights and a TV during the night in an emergency use case - and all is set up to do so quickly if an emergency (hurricane) happens by. I bought the "spares" over a year ago (maybe 2) thinking it must be close to time of failure of the golf cart set (almost 6 years of torture by my Grandkids). I recently put the "spares" in operation and trying to:
1. Decide when to buy a new "spare" set - would like to have them available IF the second set ever fails - not easy to get (good) new ones at this remote cabin.
2. Decide on how best to maintain them in a South Texas (hot) shed. Note that I've managed to use ventilation and reflective insulation board to essentially keep the interior of the shed approx same as outside - but still gets to 100 +oF a few days every summer. No freeze problems!
3. Bite the bullet and consider Li tech batteries at some point - $$$'s?
Any suggestions appreciated.
3850 watts - 14 - 275SW SolarWorld Panels, 4000 TL-US SMA Sunny Boy Grid tied inverter. 2760 Watts - 8 - 345XL Solar World Panels, 3000 TL-US SMA Sunny Boy GT inverter. 3000 watts SMA/SPS power. PV "switchable" to MidNite Classic 250ks based charging of Golf cart + spare battery array of 8 - 155 AH 12V Trojans with an APC SMT3000 - 48 volt DC=>120 Volt AC inverter for emergency off-grid. Also, "PriUPS" backup generator with APC SURT6000/SURT003 => 192 volt DC/240 volt split phase AC inverter.
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|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
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Many li-ion batteries monitor with their electronics the temperatures they are charged at and log this for warranty.
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> 1. Decide when to buy a new "spare" set - would like to have them available IF the second set ever fails - not easy to get (good) new ones at this remote cabin.
6yrs is pretty good for used/abused batteries. The second set WILL fail, the question is how (sudden death or slow loss of capacity), and when.
> 2. Decide on how best to maintain them in a South Texas (hot) shed. Note that I've managed to use ventilation and reflective insulation board to essentially keep the interior of the shed approx same as outside - but still gets to 100 +oF a few days every summer. No freeze problems!
I'd dig a hole in the shed deep enough to moderate the temp of the "stored" batteries, and charge them every 3mos or so. Put the reflective board on top (but well above battery posts!).
> 3. Bite the bullet and consider Li tech batteries at some point - $$$'s?
Maybe if the power to weight ratio would give you a hot-rod golf cart, otherwise I don't really see the point
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
The one good thing is that the shed has a silver galvalume roof and often gets quite cool by morning (emissive cooling?). The averaged temps during the summer are likely to be more like 85-90 oF. I also have 4 "trickle" chargers - batteryMinder Plus that claim "desulphating" action. Should I keep those on each battery continuously or for a few days every month or so? In the "spare" set kept in storage, I discharged them (lightly) with my 48 VDC system every few months and recharged them with my 15 amp auto style to periodically mix the electrolyte. They seem to be holding up OK in the cart, but its only been a few months.
Discharging them slightly with a 48 volt system seems like a bit of a project.
The board members often tend to feel that stored batteries are toast by the "time you finish coffee." I live in a cool environment and have been able to store batteries for significant periods. One must keep them charged of course. That is much easier in a cool environ.
I still have a number of 8D's built in 2011 in service. Worth no more than scrap value to anybody else I supplement my existing bank with them. But my electrical demands are not very noteworthy. Below average in all likelihood.
In higher temps, self-discharge will be higher, so charging more frequently (eg bi-weekly or monthly) at lower voltage (temp corrected, if possible) may be best. Others may disagree, but I wouldn't bother discharging beyond self-consumption. De-sulfation will likely be some sort of equalization at higher voltage and low current for some period after absorb and before float. Probably worth doing periodically.
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
I thought stratification was an issue with NOT discharging and bulk charging with FLAs - if left stored too long**? Also, that minimal charge levels of .1C are needed. These are why I "exercised" the spare set periodically. Note that the spare set seems in great shape - time will tell!
**However, I do hear "gassing" when charging even with the 48 volt 50 watt charger.
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
Going to watch forecasts - if things change and we get into the "cone of certainty