Batteries and Inverter next to each other, bad idea?

rp3703

I am planning to build a stepped battery box that will house 12 FLA batteries. I would like to place my inverter inside this box as well. Is this a bad idea due to the possibility of the inverter becoming an ignition source for battery gases?

BB.

And, flooded cell lead acid batteries do vent a bit of electrolyte (sulfuric acid+water+hydrogen+oxygen) when charging/equalizing. Not great for the long term life of electronics.

Plus you want good ventilation for the inverter to keep it from getting too hot (and you don't want to warm the battery bank either--Unless in subfreezing weather).

-Bill

rp3703

I guess I should mention that this will be in Northern Ontario so temps will get up to 80's F but also down to -20 C. I just want to keep inverter as close as possible to batteries plus the inverter hums under load so would rather not have to hear that.

mcgivor

The double edged sword question, it's always best to keep the distance between the batteries and inverter as short as possible. This reduces voltage drop etcetera etcetera, but the corrosive gasses cam harm the electronics, so mounting in the same box is not a good idea, in fact many manufacturers specifically state this caution. The ignition possibly is a secondary concern but also valid, if something were to go wrong with the inverter such as a short circuit, in my opinion keep them separately  but as close as possible. There are many ways to achieve this such as mounting the inverter inside of an external wall, with the batteries outside, close but completely different environments.

706jim

The Trace manual specifically states to not put the batteries and inverter in the same spot. I would be mainly concerned about the effect of corrosive gases from the batteries degrading the inverter electronics over time.

Estragon

I put my batteries and gear in an insulated crawlspace, with the batteries in a plywood box, and gear mounted on a partial wall behind the box facing away from the box. It keeps the batteries separated, but cabling short. Being in the crawlspace also means moderated temperatures. It got into the 80s a week ago, and the batteries etc stayed around 50°F. In winter at -40°, batteries don't get much below ~10°F.

In the cabin, I don't hear any normal operating noise, but can hear any alarms (eg if small inverter gets overloaded).

rp3703

With batteries in crawlspace, are you not worried about risk of fire directly under your floor? 

rp3703

As always seems to happen when I post on this forum, I was concerned about one thing and you guys pointed out a much more important totally different concern which I had not even considered. Thanks for all the help and the super quick response time.

mcgivor

Generally lead acid batteries are not a fire risk unless maintenance is disregarded, the most dangerous aspect is the accumulation of hydrogen gas, which doesn't burn but explodes, given the right fuel air ratio. Hydrogen is lighter than air so tends to accumulate in confined spaces above batteries, the best ventilation method would be a push fan with a high exhaust, this would reduce the possibility if ignition, brushless fans would be an obvious choice.

Estragon

Hopefully with properly sized breakers and regular monitoring and maintenance, the fire risk is minimized. Maybe I'm wrong, but I worry more about propane. Ideally, I would have dug a separate vault, but it's pretty rocky around here.

mcgivor

Propane is heavier than air, so creeps to the lower extremities, the opposite to hydrogen but equally hazardous, especially in boats, where that starter motor is itching to ruin your day.

Photowhit

I built a battery box with a power center to house the charge controllers and inverter on a cantileavered 4x4' panel on the other side. It worked out well for me for about 7 years and I haven't heard about problems from the new owner in the last 5 (I'm still talk with them from time to time.) Only difference I would make is to create some sort of shingled cover for the hinged lid, it rarely dropped more than a few drops of rain through, less than may careless filling of battery cells, but I always seemed to worry.


I made it out of scraps from building my cabin, The reason for 2 different types of siding...

rp3703 said:

I guess I should mention that this will be in Northern Ontario so temps will get up to 80's F but also down to -20 C. 

Is that as cold as it gets? I live in Missouri and get below -20c (-4f) pretty much every year.