Dielectric grease and battery temp Q's

garynappi

I've cross posted this elsewhere so if I ran afoul of forum rules mea culpa and this can be deleted. 



My four lead acid deep cycle batteries (currently 12V going to 24v soon) are outdoors, well protected from the weather and sun, have forced air ventilation and all new 1/0 battery cables and I do not live anywhere near salt water.

I'm looking at using dielectric grease on my battery terminals but CRC makes two types (premium or technician grade) and I wondered if there's a large difference?

Is grease a good idea?

Next my batteries are running at outdoor shaded Florida summer ambient temperatures due to them being well covered and having forced air cooling, and my loads are so far minimal and I'm not drawing them down much but I have some planned expansion. So, I wonder about battery degradation from my real world temperatures.

At my last job we had a large air conditioned room housing dozens of batteries for an industrial UPS with minimal loading (only when we had a blackout) that stayed at what I considered a comfy 80 degrees or so and battery life was several years..

Then a vendor of AC units stated that the room was too hot and we installed a hugely expensive commercial AC unit which kept the room at ~74 degrees.

I thought this was overkill but it's the reason I ask about my batteries running outdoors and battery life.

PS: the "at" temperature statement is due to the forced air fan is drawing air from a very cool brick structure which houses a reservoir for a 12 volt water feature which is powered by a 12 volt panel not connected to my main system

BB.

Grease, battery terminal "paint", etc. all seem to help. Just keep the connections clean and tight. Ventilating, especially during charging/EQ charging helps keep the electrolyte "mist" from the terminals and wiring--Probably where most of the corrosion issues start. And there are battery caps designed to reduce misting and electrolyte losses:

https://www.flowsystemsusa.com/

I lived near the coast for years, and salt fog was a killer for anything metal/electrical--Phone lines were poor, electrical panels rusted quickly.

The standard engineering rule of thumb for "life" (of almost anything) vs temperature is--For every 10C (18F) rise over "room temperature" (25C/77F "typical") is "the thing" will age 2x faster. For 20C over (45F), the "thing" will age 4x faster.

Conversely, for every 10C drop, the thing will age at 1/2 as fast or last 2x longer.

This rule of thumb also applies to storage--Say you have a standard deep cycle battery that needs charging every 30 days (if not kept on float charger). If stored at 95F, they need recharging every 15 days. Similar for AGM batteries which need recharging every 6 months of storage, but need recharging every 3 months at 95% storage.

Need thing with this rule of thumb... You can compare the cost of A/C (installation, power, maintenance) vs the cost of battery bank replacement if operated at 77F vs 95F (I.e., 1/2 life of bank).

Obviously there are lots of variables that affect battery life (cycle life, charging and depth of discharge, temperature, using plain water vs distilled, battery design and construction, etc.) too.

Batteries used for UPS systems are generally designed for "float service" (kept charged, rarely discharge). They will last many years with proper servicing. Cycle them deeply (such as 85% state of charge, or deeper), and they will usually need replacement "soon".

Deep Cycle batteries (I am only talking about lead acid) are designed to discharge to below 50% SoC. And Deep Cycle batteries--Some folks will discharge them below 75% SoC once and recharge or twice a year to help extend their "float life".

Try to never take almost any rechargeable battery dead, and avoid reverse charging--Where some cell voltages go "negative".

Monitoring Specific Gravity levels (for Flooded Cell Lead Acid or FLA batteries), keeping cells "balanced" with Equalize Charging (as needed, some are once a month EQ recommended), don't over charge/over heat batteries, etc. all can help.

And there are times when Battery Mfg's screw up and turn out a Lot of batteries that just fail early. Or truckers mishandle pallets and dump out electrolyte/expose plates to air. Batteries sit on the warehouse floor for months without charging and sulfate, etc... Lots of possible mistakes out there.

-Bill

mike_s

I use NOCO NCP2 on battery terminals. Works great.