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Charger for house batteries


rdickinson

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The plan is to put a Pro sign isolator on the truck alternator to charge the house batteries when underway. The fridge sucks the batteries down over 8 hrs or so and when parked the Magnum 2812 wants to take over a whole circuit to bring the batteries back up. I can turn the charge rated own to 10% or even off.

 

The truck charger would eliminate that need.

 

So it has been suggested we use Anderson plugs for both ends. One end could be fastened to the truck in the area of the hitch well / cutout and the other could be on the end of a cord similar to the 7 pin RV cord

.http://www.ebay.com/itm/2pcs-Battery-Gray-Quick-Connect-Disconnect-Plug-CAPS-175A-1-0AWG-RV-Connector-/222089254798?hash=item33b58d178e:g:sAgAAOxy69JTGnXe&vxp=mtr

 

 

 

All connections would be soldered and heat shrink with glue used. In order to keep the connections clean we would clip the other end on when not in use.

 

Cable could be marine/tin coated or not.

 

 

Batteries charge up to 12.75v with the Magnum 2812.

 

Any thoughts? Does this seem right?

 

Thanks

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Roger,

 

If you were going to do anything to link the batteries together (other than a relay connection that's turned on only when the truck is on), I'd use a relay-type battery separator. SurePower's 1315-200 would be more than plenty (and it looks like Bussman markets the same thing under their own name cheaper here). That way, if either battery system is being charged, both get taken care of, and if the charging isn't keeping up, they're separated. If you're able to leave them connected, the trailers charger will take care of maintaining the truck batteries when you're parked, and vice-versa when you're driving.

 

If you aren't in a hurry, I could probably give you mine once I fully remove the 12V house batteries.

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The online price is about 60$ The one here is between 3 and 500$. Are we talking about the same thing? The Prosign will act as a separator and will fill each battery bank as needed. Truck is 12v and trailer is 6v.

 

When will it be available please?

 

Thanks

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A diode based battery separator will drop about 1/2 volt for anything passing through it, that will impact your charging rate.

 

When charging the truck and fiver batteries (isolator or not) the truck battery will be the one getting most of the charge and as it rises to full charge the alternator will be putting out less power, leaving the fiver batteries less charged than the truck batteries. This setup will keep the fiver batteries a bit recharged and may meet your needs but even with large power and ground wires, heavy connectors and big fuses at both ends of the hot lead it won't be optimal.

 

A far slicker installation is to install an inverter in the truck if it doesn't already have one and use that to provide AC power to your converter in the fiver. That leaves you dealing with far smaller wire and connectors, makes the double fuse problem go away and if you have a decent converter it gets you a far superior charge too.

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A Trail Charger mounted in your trailer is what is used for this nowadays. It can use the tractor 7-way aux and solves the problem that Stan mentions above. It is temp compensated like your inverter too. But it is only 20A so you'd have to do the math on your average DOD when you pack up and leave and figure if you drive enough hours in a day to to recharge again. It might not work out. They do make a 50A unit but it ain't cheap at all either.

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Scrap,

 

One of my ideas (and it hasn't even made it onto the back burner yet) is to use a small boost converter on the truck, and a buck converter in the trailer to step up to somewhere in the 24-48V range so more power can be carried over the existing wiring. Since a boost converter will have an adjustable current limit, you could limit how much it takes from the truck too.

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Heh last time I went to check on your battery project you were sidetracked on pumping sewage with a garbage disposal! ;) The trailer link would make a neat wiring project though, hopefully it'll make it on the list.

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Stan, you are 100% correct about the voltage drop across the PN junction of a diode. The most commonly used value is .6 volt for each junction when actually conducting with a load. I put a diode in each of the 12V lines to the LED's in my fiver so that the 14.4 volt desulfation cycle from the converter does not damage the LED's that do not have an internal regulator.

 

But, the thing is with an alternator cranking out 14 volts you will still get a full charge on both your house and truck batteries when using a solid state diode isolator - that loss of .6 volts only marginally slows the recharge time. Still, I do prefer to use continuous duty marine solenoids for isolation.

 

Roger, I have #2 AGW cable running to Anderson connectors between the truck and trailer for charging my fiver batteries and powering my second electric fridge/freezer and ice maker by using solenoids to isolate them from the truck batteries. The cables I used were made for a 10K pound electric winch and made up with the connectors. It was actually less expensive than buying the wire and connectors individually. But, I also use the second bank of AGM's in the truck for the fiver when not running so I do need the #2 cables for that purpose - along with 300 watts of solar if the sun shines. The solar panels work and provide up to 10 amps of charge power even when moving (as long as you are not in a tunnel <_<. On a good day that will keep your batteries ahead of the fridge drain.

 

As for wire, connections, etc. always use marine grade cable when possible, and yes the adhesive heat shrink tubing is the best for exposure. Solder? Not always - a good crimp tool can make a more reliable connection than getting a copper cable too hot (or not hot enough). Solder sounds good but unless done right can be a problem. FWIW - the NEC does not allow soldering on grounding wires since a cold solder joint or the wrong flux can turn it into a resistor - they only allow mechanical connections. Same can go for other wire connections in our environment - good mechanical is better. I also like the idea of putting an inverter (for the fridge) closer in to the truck battery's and running 120 VAC back to the fiver - but this does add the possibility of contact with lethal voltages from the truck to the fridge if a cable is cut or chaffed at some point. You would need to use at least #12 AWG sunlight resistant SOOJ wire that is well protected with a water tight twist lock connector between the truck and fiver. Since my generator is under the passenger side of the Volvo that is what I have done on my rig to put 120 VAC to the fiver.

 

Another thought for the fridge is a small inverter generator - like a 1600 watt Champion or Honda 2000. Yes, it is another fuel but they don't use enough to make it a big deal and you divorce yourself completely from the truck electrical system. I bet you have an empty compartment you could ventilate to put one in :). I have a remote electric start 3100 watt inverter generator in the Volvo with a 3.5 gallon gas tank. When my 2000 watt truck inverter puked I ran the gas inverter generator all the way from the panhandle of FL to Central VA for AC power to the truck fridge as well as the camper fridge, etc. to keep things cold and never had to add fuel to the genny tank. In fact it is still 1/2 full. I think you saw this set-up when we were together in Melbourne February.

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Monday, I'll head down to the location that sells these chargers and let them read the replies. If modifications are needed they will be done. The truck fridge is never used. I want this charging circuit so the Magnum 2812 doesn't try to take a whole circuit to charge the batteries at the end of a day of driving. The residential in the trailer pulls down the batteries. Yes I know the charge rate can be turned down. This is more of a factor when boondocking enroute and using the generator. #4 cable has been recommended as it is still handleable.

 

Thanks

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  • 2 weeks later...

Roger,

 

If you were going to do anything to link the batteries together (other than a relay connection that's turned on only when the truck is on), I'd use a relay-type battery separator. SurePower's 1315-200 would be more than plenty (and it looks like Bussman markets the same thing under their own name cheaper here). That way, if either battery system is being charged, both get taken care of, and if the charging isn't keeping up, they're separated. If you're able to leave them connected, the trailers charger will take care of maintaining the truck batteries when you're parked, and vice-versa when you're driving.

 

If you aren't in a hurry, I could probably give you mine once I fully remove the 12V house batteries.

Getting going on the wiring for this system. Any idea when or if the 1315-200 is closer to being available please? The wiring could be done and it could be installed when I'm in the US on the Rally. EZConnector has a firm in Boise who could do it. It is frustrating when given the same information different firms here draw widely different conclusions and non of them the same or close.

 

Is 100 amps adequate s the alternator puts out 135. Or is this based on the assumption that 80% of max charge is all I'm going to get. Also EZ Connector has a 2 wire plug that will take 100 amps. Would that be an option instead of the Anderson Connector?

 

Also these local guys have no clue about the HID headlight upgrade. Seems the first guy to install them made some errors and the second firm is worse wanting to wire in relays for the old stock high beam. I put a hold on the project before something gets wrecked.

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Hi Roger,

 

I'm showing the link above as available next day for $45--is it a Canadian issue perhaps?

 

I would think you'd be fine with 100A, but last time I looked there really wasn't a price difference between the 100 and 200A versions.

 

Give me a call/e-mail on the lights. You really shouldn't be trying to hack in to the factory wiring, and shouldn't need to.

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My trailer power solution is 120 VAC. 2000 watt sine wave in the truck -- runs house loads MW etc. there -- and a 120 plug going back to the trailer. In the trailer, it goes to the normal house loads, but none of the following. A/C, hot water, refrig (usual culprits). Fed through the trailer inverter / charger. It does feed to the deep freeze though.

 

I limit the current to 50 amp DC with the load shed feature in the trailer. That still gives me 85 amps of headroom of the truck alternator.

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