Ohio Winter Battery Box

[Svencool]

Where on this site has this topic been covered? Ohio Winters can be pretty cold sometimes 5 below zero days. Looking for idea's on how others built a insulated battery box. Or how they have kept there flooded batteries warm durning those cold months.....

[organic farmer]

WE normally see -20F every winter. We keep our batteries indoors.

[Svencool]

WE normally see -20F every winter. We keep our batteries indoors.

What type of batteries? Flooded? Inside your living quarters?

[J.P.M.]

Given the inherent thermal mass of FLA batteries, if the climate was reasonably sunny, it would be fairly straightforward to design what amounts to a superinsulated, passively heated solar battery house, but aux. backup heat would still be necessary for occasional use and insurance.

If it was me, I'd consider simply superinsulating the battery containment and heat the inlet air required for venting on a thermostat using resistance heat supplied by the batteries and increase the battery capacity accordingly. If insulated well enough, most of the aux. energy required would be heating the incoming ventilation air to required temps. for proper battery operation/maint.

Disclosure: I'm ignorant of how local codes and battery containment requirements, primarily as related to safety concerns and mandates would impact the design.

[Wy_White_Wolf]

A non working chest freezer works for a battery box. Small hole to vent in the lid if you're worried about hydrogen buildup.

WWW

[J.P.M.]

A non working chest freezer works for a battery box. Small hole to vent in the lid if you're worried about hydrogen buildup.

WWW

Good thought, but how about heat ? Unless the batteries generate heat (?), a well insulated containment will still get cold. Winter's are long.

[Svencool]

A non working chest freezer works for a battery box. Small hole to vent in the lid if you're worried about hydrogen buildup.

WWW

Could you use this chest freezer in a living space? Such as 1000sq ft cabin?

[BackwoodsEE]

Consider the other time of year before getting carried away with insulation ideas. A lead-acid battery's life is halved when you increase the temperature from around room temperature to, I think, around 90 F. If you are putting 48V and 50A into a battery to charge it, say with with 90% efficiency, 240W is being dissipated as heat inside it. That's a lot of heat, and it has to go somewhere or the temperature will rise until it does.

In power electronics, the concept of thermal resistance is very helpful. A power MOSFET with a TO-220 package has a thermal resistance from semiconductor junction to free air of around 60 degrees K per watt. That means you can only dissipate around 2.5 watts in such a device without a heatsink, even if its power rating (with ample cooling) is a hundred watts or more.

A battery inside a chest freezer is likely to be a very hot and short-lived one indeed, unless maybe you turn the freezer compressor on when the temperature gets too high.

[Wy_White_Wolf]

Good thought, but how about heat ? Unless the batteries generate heat (?), a well insulated containment will still get cold. Winter's are long.

The charging process generates heat that the insulation of the freezer keeps in. If one wanted they could turn one side of the freezer into a solar collector like they do when they get converted to stock troughs.

WWW

[Wy_White_Wolf]

Could you use this chest freezer in a living space? Such as 1000sq ft cabin?

Don't see why not as long as you vent it outside. I do know of a couple in garages.

WWW

[J.P.M.]

The charging process generates heat that the insulation of the freezer keeps in. If one wanted they could turn one side of the freezer into a solar collector like they do when they get converted to stock troughs.

WWW

Yea, I thought of that. For design, some info on charging (in)efficiency that turns to heat might be needed, as well as some quantitative idea of the heat transfer to/from the box. I guess maybe one good/necessary HVAC feature for a battery box, if used indoors or out, might be a (differential) thermostatically controlled fan on an inlet w/ a heating element for cold weather, all controlled by something like an HVAC thermostat, and a vented outlet w/ maybe some flapper arrangement, etc.

This is getting complicated and I'm mostly unfamiliar with what's available or what's practical, and specific other design requirements for battery containment besides those that may be required or similar to HVAC requirements for a dwelling for human occupancy, or at least along those likes.

[neweclipse]

So many thoughts...

Forget outside.

Use AGM batteries, maybe?? Less gassing.

AGMs stacked on shelves against cabin inside wall and then encased in plexiglass acrylic panels would contain and control their small amount of gases. No need of adding water allows to stack above lower batteries all the way up, unlike FLAs which require ample top access to each cell for regular water checks etc.

Plexiglass encasement whether be for AGM or FLA keeps exposed voltage sources protected while still having easy visibility to things.

Some inverter/chargers are able to operate a relay to start a muffin fan during high charge rate times with FLAs in order to push air exchange in in order to push H2 gases outside. For during light to moderate charge times the H2 easily disapates to a non confining open space. However, if encased you may then run the muffin fan all you want if it gives you more joy.

BTW:
I am in Ohio myself...near to Youngstown in NE Ohio.
What part are you near?

[solarix]

My thinking is to avoid anything made of metal or wood as the battery acid and gasses just make a mess out of those. My solution is to go to a "big box" store and buy a big box. The home stores have nice patio boxes that are double wall construction with a hinged lid, strong enough to sit on, and are low cost - and look good. A 120gal size will hold eight L16s very nicely. Put it indoors in the garage and vent the box through an outside wall.

[J.P.M.]

My thinking is to avoid anything made of metal or wood as the battery acid and gasses just make a mess out of those. My solution is to go to a "big box" store and buy a big box. The home stores have nice patio boxes that are double wall construction with a hinged lid, strong enough to sit on, and are low cost - and look good. A 120gal size will hold eight L16s very nicely. Put it indoors in the garage and vent the box through an outside wall.

Perhaps, and the tops of such devices may vet well support 2 bodies sitting on them, but will the floor of such a container support the weight of batteries ?

Also, how about venting ? I bet such boxes are not tight enough to float for long (if empty), but are they loose enough for adequate venting ?

And what type of insulation might be needed in a cold environment if waste heat from battery charging was less than the heat loss rate and also somewhat intermittent, if say, not much charging was needed for a few days for whatever reason(s) ? Back to the HVAC requirements ?

[solarix]

The "deck box" floors are strong and can handle battery weight, the lids are not air tight but we use a hole saw to plumb in a vent and also for the cables. There is enough space to put in foam insulation if you want.