Why not a RoadPro heater?

[justoneman]

I know 12v heaters generally do not output much. I also know that 12v cigarette lighter connections are bad connection points that restrict the output of a heater. I have read here not such good reports on how a RoadPro heater heats. I bought one today to check it out. I connected it directly to my van's battery and on a cool morning fired it up in the driveway to get an idea of it. It very quickly heated up the minivan inside. I was surprised how well it actually worked.

So my thought is to put a deep cycle battery in a battery box in the hatch area with the heater hard wired to it. I am also considering a solar panel to place on the roof of the car while parked at work. This way the main heater will not reduce the winter range of the primary I-miev battery pack because this heater along with the heated seat should generally work for heating I think.

So my main questions are:

How long with a fully charged separate battery run the RoadPro heater?

Can a 45 watt solar panel charge back up this battery on an average 8 hour winter day?

 

[Don]

Welcome to the forum!! Glad you found us!

The Road Pro is a 25 amp, 12 volt 'heater' which equates to only 300 watts - Not a lot of heat. By comparison, a 120 volt AC household heater provides 750 watts on low and around 1500 watts on high. On a cold morning, 300 watts isn't going to do a great deal. Their advertising suggests "Kindly be aware these heaters are not a substitute for your original car heater. These heaters can ONLY work AS warmers, along with your factory installed heaters."

At any rate, a 50 AH battery (a standard sized car starting battery) would safely run that heater for about an hour without doing the battery any harm (50% discharge) so it could supplement your heat for a fairly long drive. As for recharging it with a 45 watt solar panel, you would need good sun, with the little panel pointed directly at the sun for 7 or 8 hours to put the 25 amps you took out of the battery back in. On a winter day, with the sun low in the sky and the panel flat on the roof of the car, you *might* get it halfway recharged in 8 hours. Even if you didn't get it fully recharged, you could top it off at home with a dedicated battery charger

Give it a try this winter and let us know how it does on cold days - There may be enough heat there to keep the windshield defrosted and if it only did that much, it might be worth the time, trouble and $$$

Don

 

[justoneman]

Thank you for that thoughtful response. It is exactly what I wanted to hear. Yes I realize on a very cold day this heater would not warm the car much. What I thought I would do this winter was have a household AC heater in the garage and when I got up I would place it in the car and warm the car up inside very hot. You know, while I took a shower getting ready for work. Then when under way I would switch on this auxillary system to maintain the heat of the car as best as it can. Even if the heater slowly loses the heat of the cabin it would be that much less I would need to run the cars heating system. If as you say a 50a battery will discharge half way on my ride to work then that would be great! Sounds like my plan with a small solar panel will top it up enough to maintain the battery enough so that it runs on my way home fine and then I can charge it up fully when I get home. I luckily have an employer that is allowing me to charge at work and so far I only need to charge for a couple of hours to make my ride home not stressful, so I anticipate in the Winter it should work out fine. I may even be able to charge this separate heater battery at work as well.

 

[Don]

If you can plug in at work, I would forget the solar panel and just get a little 6 amp battery charger and go with that. For sure there will be days when you'd get little or nothing from solar, but with a battery charger plugged in you would always start with a full battery at both ends of your trip

I tried a little 10 amp, 12 volt heater one winter aimed at the windshield and it didn't provide much if any heat, but it did make a dent in defrosting the windshield. I 'mounted' my heater on the top of a Coke can and placed the can in the passenger side cup holder, aimed at the windshield. I would say that little heater was a better defroster than a heater and your 25 amp Road Pro would almost certainly keep the windshield clear, as well as adding a little heat. It will definitely give you more winter range as with the heater and the heated seats and preheating the car at home, you should be able to make the trip without using the car heater at all. You may not be toasty warm by the time you get to work, but with a jacket on and clean windows, you should be fine

Don

 

[justoneman]

I have, in the past felt the meager heat from a little 12v car heater plugged into a cigarette lighter. It did not produce hardly any heat. Its why I was surprised by the RoadPro. It was significantly better.

I thought I would make a wooden base with a bean bag bottom. This so I could both place it on the dash and have it generally stay put and on the passenger seat or floor, without worrying about it tipping over. I'll report back later on, to give my actual results.

 

[justoneman]

The only place I see a secondary battery fitting is in the cabin rear hatch area. This poses a bit of a problem. I have some concerns about gasification especially during charging. If I am charging a battery in the hatch area I would have a power cord coming out of the vehicle so I suppose the simple thing and the minimal thing to do is simply crack the hatch open a bit during charging.

 

[Don]

For use in a space where humans are breathing the same air, I would buy a sealed AGM battery, no question - I wouldn't even look at anything else

For charging, you could plug the EVSE into the car, put the brick in the back along with the little 6 amp battery charger and plug both into an extension cord. Plug in the extension at work and close the rear hatch on both cables

Don

 

[jray3]

The only place I see a secondary battery fitting is in the cabin rear hatch area. This poses a bit of a problem. I have some concerns about gasification especially during charging. If I am charging a battery in the hatch area I would have a power cord coming out of the vehicle so I suppose the simple thing and the minimal thing to do is simply crack the hatch open a bit during charging.

With due respect to Don, I am daily driving a lead sled with 720 lbs of flooded lead acid batteries in the passenger compartment, and have done the same with flooded nicads. The off-gassing is very easy to deal with, as hydrogen is the lightest gas we'll ever encounter, and nontoxic to breathe (though you'd asphyxiate at very high concentrations). The explosion-proof muffin fan that ventilated my battery box failed many recharges ago (and got scarily hot in the act of failing), but the simple act of opening and closing a door brings hydrogen concentrations waay down, even if you forgot to crack a window during recharge. My converted RX-7 EVen has an open -frame contactor inches from the front six batteries, but passive underhood ventilation has sufficed to prevent explosions for the past 25 years of electric operation. The lower explosive limit for hydrogen is 41,000 parts per million, compared to 50,000 for Natural Gas, which lingers much longer than hydrogen... Here's a nice article on how they evaluated the hydrogen hazard on electric submarines.
https://www.nap.edu/read/12032/chapter/9#153

That being said, I do have one acquaintance who experienced a hydrogen incident. His converted compact pickup truck had an open frame contactor above the battery pack, both of which were under the bed. On a windless morning after a full recharge, the contactor's spark lit off the hydrogen and actually caused the bed of his pickup to bulge noticeably upward, though no other damage...

I conducted experiments with hydrogen during college, and became pretty proficient at making incendiary balloons via electrolysis without blowing the dormitory's breakers (or my room). It's a great party trick, maybe worth a reprise at an EV car show! :twisted:

 

[Don]

My comment was based on the fact that the Coast Guard forbids mounting flooded batteries of any type in any passenger space on a boat - They usually don't make such rules without good reason

I'm sure you could probably breathe the fumes in low concentrations without any harm, but the very thought of explosive gas in any concentration in a small compartment where someone or something might produce a spark to set things off (he will be powering a DC motor with that battery and just feet from it) would at least make me think twice about the wisdom of doing that - Especially when there are so many non-gassing battery choices to be had

Don

 

[Aerowhatt]

My comment was based on the fact that the Coast Guard forbids mounting flooded batteries of any type in any passenger space on a boat - They usually don't make such rules without good reason

The same rules apply to RV's. It is a hazard for those who know not what they are dealing with. For those who do, it's another matter. For the interior of the "i" my biggest concern would be that domed ceiling in the car. That's a great place to collect hydrogen. It want's to rise so much that it would be difficult to clear out especially since the roof liner would help it stay put.

My bigger concern would be in a fender bender or more severe collision. Even a close shave with radical maneuvers could be a hazard. Spill acid on many plastics or carpet and all manner of noxious products result. I recommend an AGM which mostly solves a couple of problems at once. The initial price is high perhaps. But one of good quality, properly cared for, will last longer than a flooded (up to 2X) and thereby cost about the same overall.

Aerowhatt

 

[justoneman]

For use in a space where humans are breathing the same air, I would buy a sealed AGM battery, no question - I wouldn't even look at anything else

For charging, you could plug the EVSE into the car, put the brick in the back along with the little 6 amp battery charger and plug both into an extension cord. Plug in the extension at work and close the rear hatch on both cables

Don

I managed to find my RoadPro used but unused for $20 on Craigslist. In keeping with my "cheapskate" nature I will look for a used AGM battery as well. After all its Spring and I will not need an auxiliary heater till Autumn, so I can keep my eyes peeled. I like the idea of not having to worry about spills or gasification issues.

 

[justoneman]

For use in a space where humans are breathing the same air, I would buy a sealed AGM battery, no question - I wouldn't even look at anything else

For charging, you could plug the EVSE into the car, put the brick in the back along with the little 6 amp battery charger and plug both into an extension cord. Plug in the extension at work and close the rear hatch on both cables

Don

I picked up an AGM deep cycle battery this evening. I also bought a battery box. I think I will look for some sort of black plastic tray that I could mount along side the battery box, to fill the rear storage area. I pick up a fair bit of debris when placing the charging cable in the vehicle. It would be nice to have a plastic container for the power cable to be dumped in. Tomorrow I will pick up some wire management coil to clean up the wire leads to the heater from the box.

 

[Aerowhatt]

Would be a great idea to secure the battery box to the cargo area using the Child seat anchor under the cargo carpet. Just in case!

Aerowhatt

 

[justoneman]

Would be a great idea to secure the battery box to the cargo area using the Child seat anchor under the cargo carpet. Just in case!

Aerowhatt

Yes I am working on that. I have a cluster of items in the back now that has the box wedged in. Here is the unit on the floor of my house:

 

[justoneman]

Here is the battery box and a plastic tray I bought that wedges the battery box in and the tray holds my dirty charging cable. You can see the freezing rain snow mixture coming down in the photo. 39 degrees today. A perfect day to test the heater which I did. I enjoyed having the heater on the driver floor pointing forward. Heated up my feet which was nice.
It is putting out a pretty nice amount of heat. Its not a lot but does heat up the driver foot area or if you put it on the passenger seat it heats the body and if you place it on the dash it de-fogs the windshield. It does heat up the cabin a bit in general but it is not a zero degree day so...

 

[justoneman]

RoadPro placed on the driver floor:

 

[justoneman]

I am not sure how or if I will make some sort of mount system. I like that it is a box and can place it places. It however does not work on the dash that way as of course it is not secured. Still thinking about it.

 

[Don]

I for sure wouldn't place anything on the driver side floor - That's an invitation to all sorts of problems

If you can find the inlet for recirculated air for the HVAC system, mount it near there and duct the hear in there you could use the OEM blower to move the warm air to where you need it - Defrost, dash vents or floor

Don

 

[justoneman]

I for sure wouldn't place anything on the driver side floor - That's an invitation to all sorts of problems

If you can find the inlet for recirculated air for the HVAC system, mount it near there and duct the hear in there you could use the OEM blower to move the warm air to where you need it - Defrost, dash vents or floor

Don

The inlet? That sounds like a major bit of work. What I have now is simple. I am not drilling out or altering anything of the car as it is now. I am sure where the inlet is, is inaccessible or outside of the cabin behind a filter or some such.

 

[Don]

The HVAC system has two air inlets - One gets you outside air and there's another inlet which recirculates inside air within the cabin. If you could position your heater near that inside air inlet and then run the HVAC on fan only, it would suck the heat into the HVAC system (with the car's heater off) and you could then blow that warm air where ever you need it - Up against the windshield by selecting the defrost setting on your dash controls most likely. It may be as simple as mounting the heater to a board so it stays put where you need it

Don