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noteven

Turtle Island

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Joined: 02/13/2011

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Posted: 02/21/21 05:17am Link  |  Quote  |  Print  |  Notify Moderator

I’m thinking of using a 3 pole electric trolling motor connector to make the connection between truck and camper. One pole for the ignition on wire that turns the charger on and the other two for size large cable to carry the charge current. I will disconnect the “charge wire” in the camper 7 way plug.

BFL13

Victoria, BC

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Posted: 02/21/21 06:15am Link  |  Quote  |  Print  |  Notify Moderator

That's an idea. I will see how many amps I get and check voltages before thinking of using different wiring instead of the 7-pin's.

I wonder if the "ignition" wire has to be at the same voltage as the input. Using any old 12v to turn the unit on would work, but would it confuse its little brain if it was a different voltage?

I can jumper the pos input and ignition terminals and put the switch in the jumper wire I think.


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StirCrazy

Kamloops, BC, Canada

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Posted: 02/21/21 06:47am Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

That's an idea. I will see how many amps I get and check voltages before thinking of using different wiring instead of the 7-pin's.

I wonder if the "ignition" wire has to be at the same voltage as the input. Using any old 12v to turn the unit on would work, but would it confuse its little brain if it was a different voltage?

I can jumper the pos input and ignition terminals and put the switch in the jumper wire I think.


any switched 12V supply will work. and no it wont put the batteries in parralel, it is a one way charger that only turnes on when the truck is running if you hook that triger wire to a ignition switched source. I wouldnt put it through a fuse block if you dont have to I would just run a nice cable off the batterys to the charger.

I see you are mounting it in the camper? is there a reason for this? I am going to put one in my truck but was thinking of mounting it in the engine bay so I can take advantage of it for both the camper and the 5th wheel.

Steve


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BFL13

Victoria, BC

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Posted: 02/21/21 07:14am Link  |  Quote  |  Print  |  Notify Moderator

Is everyone getting one of these things? [emoticon]

It says to put the unit as close to the house batteries as possible. Makes it tricky for using with a trailer or truck camper and have fat wiring to the truck.

Not clear to me, but they want to reduce voltage drop between unit and starter batt, but want the unit closer to the house batts. So longer wires will be from unit to starter batt, but they will need to carry the higher input amps. Maybe putting the unit closer to the starter batt makes more sense? Guess it depends on your set-up and what your voltmeter tells you once you try it out.

I was looking at making it portable with quick connects of some sort, but I don't need it in the Class C.
---------
EDIT--engine bay gets really hot! I tried an inverter above the battery with the hood open when idling, and it got too hot and shut down. Had to hang the inverter out over the fender away from the heat.

They say to install it where it gets some cooling air flow, more like with a solar controller. Don't know if the engine bay gets cool enough when driving down the road compared with parked and idling with hood up.

All this wiring in truck or MH seems to be about getting the wires past the firewall. That is a PITA when I looked at doing that before.
--------

Did you read the manual near the end on how to set it up for LFPs? Do you agree with their approach?

The main worry seems to be how the input will draw steady high amps from the alternator, which might not be up to that for a long drive. No worries with the 20 amper pulling 30 amps, but choosing a higher amp version of the DC-DC has to match what your alternator can handle.

But then choosing a lower amp unit might be useless for not enough charging amps to the house batts to make it all worthwhile--as in my Class C.

* This post was edited 02/21/21 08:26am by BFL13 *

pianotuna

Regina, SK, Canada

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Posted: 02/21/21 08:44am Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

The main worry seems to be how the input will draw steady high amps from the alternator, which might not be up to that for a long drive. No worries with the 20 amper pulling 30 amps, but choosing a higher amp version of the DC-DC has to match what your alternator can handle


That is not an issue. Drawing power when idling IS an issue. I believe there are pulleys that have an "extra" fan available?


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, soon to have SiO2 batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

noteven

Turtle Island

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Posted: 02/21/21 08:46am Link  |  Quote  |  Print  |  Notify Moderator

I ran 2 x 6v golf car batteries and charged them through a diode isolator in our camper outfit in the 2000's. Dodge diesel with 160amp alternator. I connected with an Anderson plug and used big cables. "Charge wire" disconnected in the 7way camper cord.

Never did get around to doing a solar spend on that camper - we didn't sit for much more that 3 or 4 days, temps at just below freezing or above, no inverter/AC loads, outside doing stuff all the time, never ran out of DC power. If batteries got a bit low in cold weather I would start the 300hp Cummins generator. We weren't full time but trips lasted 7 to 30 days a couple times a year.

The DCDC charger is a more sophistimicated version of what I had before, adjustable for different batteries, controlled output. Near as I can figure.

I think it is important not to have a second connection between the house batteries and the truck via the 7 way plug.

When sizing wiring and connectors for the Renogy "40 amp" unit I have, I think the literature states input current is 1.3 times what output is so 40amp output will be running 60amp on the input side. I see Marinco trolling motor connectors rated at 70amp.

* This post was edited 02/21/21 08:52am by noteven *

deltabravo

Spokane, WA

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Posted: 02/21/21 09:05am Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

You convinced me to get one, too! Thanks for finding what, for me, is the right size for the right price.


I bought the Renogy unit and found the size to be quite enormous. Too big for my mounting space so i returned it.

I already have heavy gauge wiring in place as shown here

I'm working on installing a Victron DC to DC Charger.


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pianotuna

Regina, SK, Canada

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Posted: 02/21/21 09:07am Link  |  Quote  |  Print  |  Notify Moderator

Hi noteven,

I think BFL13 got the 20 amp unit--that is what I chose, too.

BFL13

Victoria, BC

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Posted: 02/21/21 10:04am Link  |  Quote  |  Print  |  Notify Moderator

"I think it is important not to have a second connection between the house batteries and the truck via the 7 way plug."

It would not matter IMO. The 7-pin would be at lower voltage than from the Renogy so the battery would just ignore it.

I expect when using the Renogy to have solar and Renogy in parallel at the same voltage so they add their amps (but the main reason to have the Renogy is for when not enough solar with overcast skies.)

On shore power I could have the adjustable voltage converter on too, so that's three chargers at once all set to the same voltage.

I will not have any problem running this thing when parked idling the 2003 Chev truck. I did that before when I was doing the inverter trick. It made no diff idling at higher revs either.

Truck voltage fell off with too much inverter load so you have to watch for that. The dash voltmeter quivers pointing up at 14v, then collapses down to the left when you add more load. You can keep doing it until you see that happen. That tells you what your loading limit is. I could run the 35 amp charger but not the 55 amper off the inverter so somewhere between that is my limit. (Also turn off the auto climate etc.)

I imagine it would be the same trying to run a higher amp Renogy than what your limit is in your truck.

The manual does say something about working the alternator too hard, so it is up to the individual to figure out what applies to his own truck.

Gdetrailer

PA

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Posted: 02/21/21 10:46am Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

Better to do a solenoid than a diode. Why? because a diode introduces voltage drop--about 0.7 iirc.

The device you ordered has a sense wire so it will only be active when the truck is running. If that is so, then there is no need for a diode or a solenoid.


Schottky diodes do not drop .7V..

They do drop some voltage but they typically have about .3V-.4V drop unlike Silicone diodes which typically drop .6V-.7V.

However, consider this, adding a diode in front of a DC-DC converter, that small .3V-.4V drop no longer is of any issue since the DC-DC converter will boost the voltage, overcoming any voltage loss on the input side.

The only downside with DC to DC conversion is the input current will go up some to compensate for the voltage loss..

Although personally since OP has a GM, they really NEED to add a relay to the charge line so the charge line is ONLY active with the ignition on.. A $2.00 40A "Bosch style" cube relay is all it takes. A relay in the charge line eliminates the possibility of accidentally discharging the vehicle battery when the vehicle ignition is off.. Shame on GM for being such cheapskates (a TWO DOLLAR RELAY FOR GOODNESS SAKES), Ford and Ram are way ahead of GM for this feature.

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