Charging batteries AND running the DC fridge on the road: a DC-input battery charger - Page 3

ThePair · 01-18-2011, 01:31 PM

So Dave, any feedback from this system/setup?

I've also noticed that it can function as a battery isolator as well. This would mean less paranoia about turning of the refer every single stinking time I shut off the engine, since I do not have an isolator in my TV charge circuit.

Anyway, just wondering how it's been working out for you, if you've had a chance to really utilize it.

Thanks.
Marc

**ShrimpBurrito** · 01-18-2011, 11:12 PM

Marc - So far, so good, although I unfortunately haven't done any further testing to fine tune things. But for one, I no longer ever arrive at camp the first night out with a negative battery meter. But that is to be expected, at the very least.

On longer trips between camps, such as our 7,000+ mile trip this past summer, it makes a significant difference. Unfortunately, I have not yet taken any precise notes on charging rates, but if we get a 6A bulk charging current over and above the 9A consumed by the fridge, a 6-hr drive tops the battery off with about ~33 Ah (assuming a 90% charge efficiency). With our new LED lights, that's probably 4-6 days of camping during the summer, and 2 more days of winter camping (assuming a modest furnace use).

So while I am mostly satisfied, I was hoping for better performance out of the box.

The max charge rate on the charger is rated at 20A, but the manufacturer says most units can actually output 22A. I haven't gotten near that, as I noted in my original post, but I haven't had time to mess with it any more to find out why. It may be that the wire resistance in the TV and TM is rearing its head again as I eluded to in the second post of this thread - the manufacturer said I should be getting better performance. I need to measure the wire resistance from the TV battery to the charger input....they said ideal operating conditions require <30 mOhm. This unit is designed to operate under the hood, next to the alternator and the spare battery it charges, so that typically isn't a problem. But based on some preliminary measurements I took earlier for another project, my guess is I have much more than that. I could also plug a 12v power supply directly into the unit, and see if that increases the current. That would eliminate any variables with the wiring, and verify the capabilities of the unit. But I don't have a 30A power supply, so I need to find someone who does.

If I were to get a 22A output on the charger, that's a 13A charge current considering the fridge draw, and a 6-hr drive now restores 70 Ah -- twice what I'm getting now.

Dave

ThePair · 01-19-2011, 10:15 AM

Good feedback, thanks!

Obviously our situations are different: I drive under 4 hours when we camp -- the rest of the family dictates that. Usually under 3 when we can help it. I also only have one battery to use/worry over.

That being said, I'm starting to think that, if I really wanted to go this route, I'd definitely upgrade the bulbs (at least some key ones) to LED. Since our trips are routinely 4d/3n type jaunts, it seems like it would be doable...but for the family's insistence on certain luxuries. :P

Certainly this will make non-electric camping a possibility for me, so that's exciting! As to whether or not we actually try it, that's another matter entirely

**ShrimpBurrito** · 01-19-2011, 10:27 AM

Quote:

Originally Posted by ThePair

That being said, I'm starting to think that, if I really wanted to go this route, I'd definitely upgrade the bulbs (at least some key ones) to LED. Since our trips are routinely 4d/3n type jaunts, it seems like it would be doable...but for the family's insistence on certain luxuries. :P

I think the single thing you can do that gives you the biggest bang for your buck, aside from conservation, is getting LEDs. It's also the cheapest and easiest option. Frankly, I would expect TM to make them standard very soon. They already use them in the marking lights. With a Group 24 battery, or whatever TMs come with now, camping for a week on a single charge would not be a problem, even when using the lights as you do at home. I think it even eliminates the need for solar panels and generators for alot of folks. For every incandescent light we have on in the TM, we could have 6 LED lights on and have the same amount of light and and like appearance. It's incredible.

LEDs average $20 each. Try 3-4 and try them out.

Dave

ThePair · 01-19-2011, 11:26 AM

I can do lights. I can do battery-powered entertainment for the kiddies (iPad can potentially replace TV/DVD for them, as they don't care if something is OTA or pre-recorded).

The three things that I currently have that would be hold-outs are (in no order): microwave, AC, coffee pot (for the DW, I use an aeropress

). I know that the last one is available in 12V, but I'd hate to have to buy 2 pots for her use, on the off chance we decide to go non-electric. AC...well, the family does like their AC on a 90+ degree summer day. Perhaps springtime when it's not so hot in the midwest... As to micro, we'd adapt to using the stove/oven, so that's not the end of the world, for sure.

Hmm, hmm, hmm. It probably will come down to campsite availability more than anything else. But, I do intend to look into the LED bulbs as the weather turns warmer...

**ShrimpBurrito** · 01-19-2011, 11:51 AM

Marc - Well, if you're dependent on all those power-hungry appliances, camping off the grid will be a little more challenging. As an alternative to your coffee pot, I know they make propane fired drop coffee makers (saw one in the store), or you could simply use a percolator or French press.

Dave

T and C · 01-19-2011, 12:47 PM

Quote:

Originally Posted by ThePair

I can do lights. I can do battery-powered entertainment for the kiddies (iPad can potentially replace TV/DVD for them, as they don't care if something is OTA or pre-recorded).

The three things that I currently have that would be hold-outs are (in no order): microwave, AC, coffee pot (for the DW, I use an aeropress

). I know that the last one is available in 12V, but I'd hate to have to buy 2 pots for her use, on the off chance we decide to go non-electric. AC...well, the family does like their AC on a 90+ degree summer day. Perhaps springtime when it's not so hot in the midwest... As to micro, we'd adapt to using the stove/oven, so that's not the end of the world, for sure.

Hmm, hmm, hmm. It probably will come down to campsite availability more than anything else. But, I do intend to look into the LED bulbs as the weather turns warmer...

I learned to drink coffee when I was in the USAF. As a result, I almost never encounter coffee that I don't enjoy drinking. You have seen these flavoring syrups at places like Starbucks that you add to coffee for that special flavor you like. If they had one called "cheap scouring powder" it would taste like Air Force mess hall coffee, and I could drink it.

As a result, I just carry a good brand of instant coffee with me in the TM. I just put the tea kettle on the stove and make my coffee in a hot cup. Electricty use 0.

Works for me.

Tom

T and C · 01-19-2011, 12:49 PM

Folks,

A question: When you convert your TM bulbs to LED lights, do you have to place an adapter in the socket, or do the LED's just plug into the same sockets?

Tom

**ShrimpBurrito** · 01-19-2011, 01:24 PM

Quote:

Originally Posted by T and C

When you convert your TM bulbs to LED lights, do you have to place an adapter in the socket, or do the LED's just plug into the same sockets?

There are both types out there. I prefer plugging into the socket directly (less to go wrong), but for my LEDs, that wasn't an option, so I use an adapter. Not a big deal.

Dave

ThePair · 01-19-2011, 01:54 PM

Quote:

Originally Posted by ShrimpBurrito

Marc - Well, if you're dependent on all those power-hungry appliances, camping off the grid will be a little more challenging. As an alternative to your coffee pot, I know they make propane fired drop coffee makers (saw one in the store), or you could simply use a percolator or French press.

Dave

It's more the DW and 4 y.o. twins, and the doggie

I think it's doable, especially in the earlier spring months when the AC is used as a heater (or not at all). I know there are some good rechargeable/battery fans, too. Humidity in the midwest is terrible in the heat of the summer, tho, so it'd be unlikely then.

Like I said, it's more a matter of finding the need to do so (campsite/campground availability) rather than seeking it out actively. For where we live, it's not like out west where some of the truly inspirational sites are associated with boondocking. But, I always like to think about these things extensively, because, you never, ever know

Of course, there is the alternative: put in this charger as well as an inverter, and recharge the battery either after or during inverter use. That could potentially work as well.

I know you stated you installed yours inside the back compartment with the battery, but I know it can get fairly hot during use, and I keep that compartment fairly full, I'd have to mount it on the roof of the compartment if I did that. Would that be a reasonable place, or should I consider someplace else? The "else" I was thinking was maybe in the bumper under the compartment, since you said it should be weatherproof there wouldn't be a moisture issue. Since it wouldn't need to be accessed but for troubleshooting purposes anyway, seems like it might work there?