question

Hi all,

There's technically nothing wrong with installation of these units on a horizontal surface, but they will be more prone to overheating since the passive convective cooling system can't function as designed. When installed on a vertical surface, the unit's heatsink expels hot air out the top and as it does so, of course cool air is pulled in through the bottom, through the fins of the heatsink, cooling the unit as it flows upward and warms; technically speaking, the warmer the heatsink gets, the better this design works.

Installation on a horizontal surface largely defeats this mechanism, since now the fins of the heatsink are no longer oriented vertically; the heatsink gets hot and air rises upward from underneath the device in all directions, and to an extent of course is replaced by cooler air, but you lose that directional convective cooling offered by an installation on a vertical surface.

So, the cooling mechanism having been discussed: first, the units themselves can handle the overheating: it's not a concern of damage to the units, but rather that when they get too hot they will derate until they cool off, during which period of time of course you're suffering from decreased if not entirely interrupted charging. I will mention that it's important to update all units to the latest FW version, as it includes better logic for handling this circumstance than the original FW version included with the earlier units in particular.

To minimize this overheating and subsequent derating when installed on a horizontal surface, then, there are a few things that can be done: It would help a bit if they were elevated off the surface, as this will more efficiently allow cool air to enter the space underneath as the hot air from the heatsink rises. I would also suggest, if possible, using aluminum or copper material to fabricate the elevation platform, as this will help dissipate heat through direct transfer from the heatsink.

It's also worth looking into the addition of one or more small fans, like computer case fans, to the installation; these could be controlled via a thermostatic relay so that they're not running all the time but only turn on when the heatsinks reach a predetermined temperature (say, 120F or so). This would not only keep them off, and thus keep them from draining the battery, except when needed, but would also sort of ensure that they're only running when the chargers are running, since the heatsinks shouldn't be reaching that temperature unless the charger -and, thus, the engine- is operating.

We don't actually stock this sort of thing, so I unfortunately can't offer much insight as to the reliability of the options out there; computer case fans in 12v are plentiful, of course, and I'd advise sticking with known brands like CoolerMaster or ThermalTake just because they have a long history and proven reliability. The thermostatic relay is where it gets tricky; we have some experience with controllers that either are, or are very similar to, these: https://www.ebay.com/itm/DC-12V-F-Fahrenheit-Temperature-Controller-Thermostat-Control-1-Relay-NTC-Sensor/141777090187?epid=595237246&hash=item210292b68b:g:lOgAAOSwQPlV-i0Y

Reliability is always the question with those latter items, though... It's one of those where you order 5, assuming that 1 of them probably won't work.

Alternatively, you can use programmable fan controllers (again, for computer cases) like this one: https://www.amazon.com/Thermaltake-Commander-Channel-Controller-AC-010-B51NAN-A1/dp/B00V80IQTS/ref=psdc_11036291_t5_B08FBTC2BR

As a final option, though this would be for the less price-sensitive customers, AC Infinity offers some self-contained options that are absolutely fantastic. I've used their components -in 120vAC- for numerous high-end home audio installs in the past, and they also have a range of DC cooling systems. Expensive, but super slick, aesthetically appealing, and reliable: https://www.acinfinity.com/

What you will often notice, if you look at the tech specs of various units is that many of their AC/home cooling systems are actually powered by 12vDC and just come with an adapter; in the case of a mobile installation (assuming 12v) then you could probably just not use the adapter.

Of course, as with everything, please confirm your intended usage with the manufacturer before ordering anything just in case what seems like it will work from the tech specs isn't actually the way it would work, but... definitely some options there for premium clients! And for the more price-sensitive clients, the individual computer fans and a $15 thermostatic relay/controller is a viable option too.