battery questions

[babock]

Originally Posted by cl733

I dont think they even make a fridge that runs off of 12v any more,

Actually, new 12VDC compressor fridges are being used a lot. It will be my replacement fridge.

[chriscowles]

Originally Posted by TitanMike

I would run the largest wire that fits the terminals on your converter. THAT will depend on the brand. ...

At this point it's the stock WFCO WF-8955, so whatever fits in that. I am willing to replace it with a PD but only after I determine if the WFCO does not bulk charge as it should. I don't think I can make that determination without an adequately-sized conductor.

My first step will be to combine the stock charging wire with the pre-wired solar wire in parallel, then measure the voltage at each end. If the voltage drop is unacceptable I'll spring for the 2 AWG cable and drop the underbelly to install it; if the drop is minimal but the WFCO isn't going into bulk charge when the battery is discharged, I'll invest in a replacement converter. I guess either way I'll eventually put a bigger conductor in.

All of that is a longer term project. It has to be road-ready for a short trip next weekend. I don't expect to rely on the battery for awhile except while working on the trailer in storage. In the meantime I'll just plug my charger into the generator and connect it directly to the battery to get a full charge.

[BOO-BOO-IS-IN-CAMP]

heres what i did i boondocks alllllll the time from early spring to late fall when the snow is falling then when you think it all don there's hunting season ..
wair i go we get 6 to 12" at times...
any way

i have never ran my frig in transit so not realy suppose to do that !!!
i use 110 i have 2 100 watt renogly panels & windy nation 1500 was pure sign
i ran a 14 ga extenchion cord to the back of my fridg from 1500 watt pure sign.
my truck is a dodge diesel i have 2 deep cycle 1000 m c a
my truck i have hard wired the camper charge cable with it's own ground and power cables... 8 ga.
my trailer has 2 deep cycle 1000 M C A batt's
all 4 batt's i bought at wall mart all new all at once
only time i have to run my gen is on a week straight rain but i still have batt power out the ying yang even then it's just to run the A.C
that my take it works for me

[TitanMike]

Originally Posted by BOO-BOO-IS-IN-CAMP

heres what i did i boondocks alllllll the time from early spring to late fall when the snow is falling then when you think it all don there's hunting season ..
wair i go we get 6 to 12" at times...
any way

i have never ran my frig in transit so not realy suppose to do that !!!
i use 110 i have 2 100 watt renogly panels & windy nation 1500 was pure sign
i ran a 14 ga extenchion cord to the back of my fridg from 1500 watt pure sign.
my truck is a dodge diesel i have 2 deep cycle 1000 m c a
my truck i have hard wired the camper charge cable with it's own ground and power cables... 8 ga.
my trailer has 2 deep cycle 1000 M C A batt's
all 4 batt's i bought at wall mart all new all at once
only time i have to run my gen is on a week straight rain but i still have batt power out the ying yang even then it's just to run the A.C
that my take it works for me

And I have never NOT run my refrigerator in transit. Been doing so since the early 70's.

What exactly is different between sitting still while parked and driving down the road other than the motion?

I recall reading in one of my OLD owner's manuals for the refrigerator that the motion while traveling down the road was one of the reasons the refrigerator didn't need to be perfectly level. The motion prevented liquid coolant from blocking normal circulation in the coils.

As for shutting it off when refueling, no big deal. Refer is right on the way to the bathroom and that's where I usually head first thing when stopping.

[chriscowles]

I just measured voltage at the converter and at the battery with the stock conductor to the battery. I got 14.3V at the converter and 13.2V at the battery. Seems like the conductor is inadequate.

I'm not in a position to relocate the solar conductor to the converter yet but will do that after I return from our trip next weekend. We'll have power there so recharging isn't important.

If there is no voltage drop with the solar kit conductor connected in parallel, does that mean there is also no current loss?

[TitanMike]

Originally Posted by chriscowles

I just measured voltage at the converter and at the battery with the stock conductor to the battery. I got 14.3V at the converter and 13.2V at the battery. Seems like the conductor is inadequate.

I'm not in a position to relocate the solar conductor to the converter yet but will do that after I return from our trip next weekend. We'll have power there so recharging isn't important.

If there is no voltage drop with the solar kit conductor connected in parallel, does that mean there is also no current loss?

Voltage drop is a function of resistance and current. If you are reading the same voltage at the battery as you are at the solar controller output there is no loss of current. Bear in mind that you may also have a very low current output from the solar system which will show low voltage drop. Voltage drop increases as current does even on real large conductors. It just doesn't increase as much on large conductors that have low resistance.


The voltage drop you measured definitely indicated your wire size is inadequate. Over three times the desired max percent drop.

[chriscowles]

Originally Posted by TitanMike

Voltage drop is a function of resistance and current. If you are reading the same voltage at the battery as you are at the solar controller output there is no loss of current. Bear in mind that you may also have a very low current output from the solar system which will show low voltage drop. Voltage drop increases as current does even on real large conductors. It just doesn't increase as much on large conductors that have low resistance.

The voltage drop you measured definitely indicated your wire size is inadequate. Over three times the desired max percent drop.

My reference to the "solar kit conductor" may be confusing the situation. I don't have a solar system. I paid for the solar pre-wire option on the trailer but have not installed a panel or charge controller.

Reference to the solar kit conductor is to the wires installed at the factory. The factory rep told me it's 8 AWG from the area under the refrigerator, where the factory intends for the charge controller to be mounted, and where the WFCO converter/charger is, to the battery. That's separate from the wire from the WFCO converter/charger. I have no idea what AWG FR uses for the WFCO conductor to the battery.

I plan to make use of the solar pre-wire conductor by combining it with the standard charge wire. That's the easiest way for me to increase the wire capacity available to the WFCO charger. I'll probably put a short stub of 2 AWG to connect directly to the charger, then connect the other end of that to the two conductors going to the battery, in the space behind the power center. Maybe use some kind of bus bar, well insulated?

[TitanMike]

Originally Posted by chriscowles

My reference to the "solar kit conductor" may be confusing the situation. I don't have a solar system. I paid for the solar pre-wire option on the trailer but have not installed a panel or charge controller.

Reference to the solar kit conductor is to the wires installed at the factory. The factory rep told me it's 8 AWG from the area under the refrigerator, where the factory intends for the charge controller to be mounted, and where the WFCO converter/charger is, to the battery. That's separate from the wire from the WFCO converter/charger. I have no idea what AWG FR uses for the WFCO conductor to the battery.

I plan to make use of the solar pre-wire conductor by combining it with the standard charge wire. That's the easiest way for me to increase the wire capacity available to the WFCO charger. I'll probably put a short stub of 2 AWG to connect directly to the charger, then connect the other end of that to the two conductors going to the battery, in the space behind the power center. Maybe use some kind of bus bar, well insulated?

Most factory installed "main" wire from battery to power distribution panel and converter that I've seen is #8.

IF your solar pre-wire is also #8 and you pair them it is the equivalent of a #5 awg wire. This puts it just under the "minimum" size (55 amp @ 13.8 volts in a 20 foot run) for a 2% drop. Just guessing but based on calculators you will lose a tenth of a volt or so from the #4.

You will definitely see an increase in charge current and reduced charge times but not as good as if you went to a larger gauge wire. Better, not best.

[chriscowles]

Originally Posted by TitanMike

Most factory installed "main" wire from battery to power distribution panel and converter that I've seen is #8.

IF your solar pre-wire is also #8 and you pair them it is the equivalent of a #5 awg wire. This puts it just under the "minimum" size (55 amp @ 13.8 volts in a 20 foot run) for a 2% drop. Just guessing but based on calculators you will lose a tenth of a volt or so from the #4.

You will definitely see an increase in charge current and reduced charge times but not as good as if you went to a larger gauge wire. Better, not best.

Thanks for validating my plans. If I see a significant improvement, ideally including the WFCO charger going into bulk charge mode when appropriate, I'll probably stop there for now. To do more requires paying $1.00-$1.50 per foot for adequate cable and, more importantly, dropping the underbelly to route the wire.

I do plan to add solar capability at some point but it's not my highest priority right now.

Edit: BTW, I have a 2507S, the Rockwood equivalent of your 25BDS. You're familiar with the factory wiring on them, I'm sure.

[TitanMike]

Originally Posted by chriscowles

Thanks for validating my plans. If I see a significant improvement, ideally including the WFCO charger going into bulk charge mode when appropriate, I'll probably stop there for now. To do more requires paying $1.00-$1.50 per foot for adequate cable and, more importantly, dropping the underbelly to route the wire.

I do plan to add solar capability at some point but it's not my highest priority right now.

Edit: BTW, I have a 2507S, the Rockwood equivalent of your 25BDS. You're familiar with the factory wiring on them, I'm sure.

Intimately.


If you ever decide to run a larger wire I ran my #4 awg along the frame below the floor. I didn't drop the entire belly cover, just made access at the portion under the converter and again under a front compartment I converted to a battery compartment with inverter, bus bars, new disconnect switch, large fuse, and a DC-DC charger for charging lithium batteries from tow vehicle while underway.

I merely fished the wire through the cross strut holes and rather than try to get in above the axles to secure the wire with zip ties I merely ran the wire through a piece of high pressure air hose so there was extra chafe guard on the welding cable I used. I then secured it on both ends with zip ties to keep it from moving as much as possible.

Where I connected the grounds to the frame I used a couple of single panel lugs, secured to the frame with machine bolts. Ground paint off frame and used some No-Ox-Id grease between lug and frame to prevent any corrosion from degrading the connection over time.

Factory merely uses a ring type crimp connector with a self drill/tap screw through the frame without removing any paint.

If you do just pair the two existing wires it might be a good idea to upgrade the ground connections to a larger gauge wire. Merely cutting an access flap in the belly cover to accomplish the task at the converter end isn't that big a deal. Use the old wire to pull the new wire though by connecting end to end.

On the battery end it's easier as the connection to the frame is only a foot or two from the battery box.

If I were doing it I'd make the ground connections the largest that will fit into the termanal at the converter. IF you ever upgrade the main wire this part will then be done. Until that time the larger ground wires will just have the effect of lessening the effective overall length of your wire as the grounds are part of the circuit as well. The frame has huge current carrying capability
and other than poor connections is rarely part of the voltage drop issue.

[chriscowles]

I do plan to upgrade the grounds at both ends, improving the connection to the frame in the process, as you describe.

For pairing the existing 8 ga wires at the converter, I'll use a short stub of 2 ga, connecting one end at the converter and the other end to this:

ZOOKOTO 0/2/4 Gauge in 4/8/10 Gauge Out Amp Power Distribution Block Audio Splitter
https://www.amazon.com/dp/B07K436945..._8i-2Eb0W2XFTF

If I can't get a 2 ga wire into the converter lug, I'll use 4 ga.

[babock]

If you want to go to a larger gauge that what fits in the converter, just mount transition posts like these and make the last foot of wire the size that fits your converter.


https://smile.amazon.com/Blue-Sea-Sy...s%2C222&sr=8-2
or
https://smile.amazon.com/Blue-Sea-Sy...s%2C222&sr=8-1

[chriscowles]

Considering the required wire size further, 4 ga should suffice as grounds, since the distance to the frame is relatively short, no? And, since the combined 8's are equivalent only to 5 ga, and the length of the positive stub from converter to the splitter also is short, should 4 ga not serve there, too? (This assumes using the existing 8 ga conductors for the positive line.)

Edit:

Originally Posted by TitanMike

... If I were doing it I'd make the ground connections the largest that will fit into the terminal at the converter. ...

I skipped over that advice but will heed it.

[chriscowles]

Originally Posted by TitanMike

... If you ever decide to run a larger wire I ran my #4 awg along the frame below the floor. I didn't drop the entire belly cover, just made access at the portion under the converter and again under a front compartment I converted to a battery compartment with inverter, bus bars, new disconnect switch, large fuse, and a DC-DC charger for charging lithium batteries from tow vehicle while underway. ...

Which compartment did you adapt for that use? Front street side? Can you post a pic?

Assuming they're not in the standard battery location, where did you put your Li's?

[chriscowles]

Originally Posted by babock

If you want to go to a larger gauge that what fits in the converter, just mount transition posts like these and make the last foot of wire the size that fits your converter.

https://smile.amazon.com/Blue-Sea-Sy...s%2C222&sr=8-2
or
https://smile.amazon.com/Blue-Sea-Sy...s%2C222&sr=8-1

The audio power splitter I posted is cheaper, and suitable for this specific purpose.

[TitanMike]

Originally Posted by chriscowles

Which compartment did you adapt for that use? Front street side? Can you post a pic?

Assuming they're not in the standard battery location, where did you put your Li's?

Forward compartment curb side.

Here's pic

The meter on back wall is volt/ammeter that shows current flowing into lithiums from tow vehicle. Just a cheapo from Amazon. Necessary? Maybe no but for less than the price of lunch i just felt like tossing it in[emoji16]

Battery mount is a floor mount that holds two grp 27's and rather than the usual j-hooks a nylon strap holds them down.

I now have a light aluminum storage box on tongue wher batteries used to be that i store chocks and the like when underway and spring bars when setup.

[chriscowles]

Originally Posted by TitanMike

Forward compartment curb side.

Here's pic

The meter on back wall is volt/ammeter that shows current flowing into lithiums from tow vehicle. Just a cheapo from Amazon. Necessary? Maybe no but for less than the price of lunch i just felt like tossing it in[emoji16]

Battery mount is a floor mount that holds two grp 27's and rather than the usual j-hooks a nylon strap holds them down.Attachment 230883

I now have a light aluminum storage box on tongue wher batteries used to be that i store chocks and the like when underway and spring bars when setup.

Nice setup. I'd have to relocate the stuff I keep there now, such as chocks and bars, as you did. I'll buy a locking hitch pin and store my 3P stinger in the back accessory hitch to get it out of that space, as well.

Since you're charging from your vehicle, did you supplement the wiring there, too?

[babock]

Originally Posted by chriscowles

The audio power splitter I posted is cheaper, and suitable for this specific purpose.

So are power posts. Done in industrial applications ALL the time. I would never use anything that didn't use ring connectors.


I used a couple power posts in my build to transition wire sizes.

[chriscowles]

Originally Posted by babock

So are power posts. Done in industrial applications ALL the time. I would never use anything that didn't use ring connectors.

I used a couple power posts in my build to transition wire sizes.

My use of the splitter indicated is a stop-gap measure utiliziing existing wires to increase the capacity of the charging conductor. Whatever type of connector I use will be an improvement. When I can give it my attention, I'll do it with properly sized and connected cables.

Edit: BTW, I surmise that the panel in the picture is hinged on the bottom. Nice design.

[babock]

Originally Posted by chriscowles

My use of the splitter indicated is a stop-gap measure utiliziing existing wires to increase the capacity of the charging conductor. Whatever type of connector I use will be an improvement. When I can give it my attention, I'll do it with properly sized and connected cables.

Edit: BTW, I surmise that the panel in the picture is hinged on the bottom. Nice design.

Yes...hinged at the bottom.


This is what it looks like when tilted up.





It was my first electrical engineering job after I retired from EE.