Top up batteries faster with plug-in charger in-parallel?

Can somebody splain why the effing WFCO has to stay exactly where it is? Because looking at this I see $10 worth of additional wiring and maybe twenty minutes of work to move it and orient it exactly to suit. You could even hang it from the cross members.

Keeping the WFCO going saves you two-three hundred dollars otherwise spent on a proper charging system. And I would not spend a dime to backstop the WFCO with additional boost capacity, either it's good enough alone or it gets tossed in favor of anything else, which would be by definition better.

I just TORTURED my WifCo 55-amp power supply. I have several 600-watt DC to DC boosters. So this morning I hauled the sobbing burping WFCO down to the mechanics shop, and connected the converter and the booster to 4-8-D's that are in a discharged state in an electrical service truck.

The WFCO maxxed out. The booster maxxed out. I checked 10-minutes ago, the gizmos are at 14.5 volts and the converter is still at 55-amps. A strong 120 ac fan is blowing across them both. When it reaches 14.8 volts they both get a cool-down.

Tinker Tinker Cheapskate...

A pair of 140 watt solar panels will solve your problem.

One problem that you might not be thinking of is that the RV uses 35 AH daily to just run the CO meter, propane detector and refrigerator. This load is about what one 120 watt panel will produce in 24 hours. By installing a pair of 140 watt panels, you will make more power than you consume most of the time, and if you ever did need to run the generator, running it for a few minutes in the morning will provide a great start to a full charge, and the solar can finish charging over the next 7 or 8 hours.

I have a 400 watt solar system and 4 batteries. With more panels, you do not need to save as much for overnight, as you will be recharging each morning pretty early. This saves weight too!

SunElec.com had some 140 watt panels on sale for $229 rated at 12 volt nominal output and have frames to mount them to the roof mounts.

I made my roof mounts from 6" long aluminum angle 2" wide. Three holes 3/16" into the roof with #10 screws and plenty of rubber roof sealant, and a 5/16" hole for a 1/4-20 bolt into the panel frame on each corner. This way you will also be able to circulate air under the panels, cooler produces more amperage.

A PWM controller is only about $20 for a 20 amp version. The MPPT controller does not provide enough 'extra' power to justify it's cost anymore.

Yes you can plug in the external charger, but it will also make the built in charger think the battery is 'full' and at 14 volts, so it will stop the bulk charging sooner, and prevent the 100 amp charger from working at full capacity, so it might actually charge slower than without the external charger. You would need a DC clam on amp meter to know if that is correct or not. .

Better to go with solar, and then you will have full batteries at the start of each campout! And the solar will make up for most of the loads used during the day too, with the battery only being drawn down a little bit at night....

Charging a battery has been described well by comparing it to a frog jumping towards the end of a log. The first couple of leaps are pretty big, but as it gets closer to the end of the log, each jump is very small, until it finally takes the last couple of steps to get to the end.

Same thing with the battery bank. If it is at 11 volts, then your 100 amp charger can put out 90 amps for a short time, and then slowly will slow charging as internal resistance and built up voltage on the plates reaches 13 volts. Amperage will slow as it gets closer to 70% full, and really slow down in the 70-80 % full mark. That last 15% can take all night to get in 40 amp hours, while in the first hour, you can usually get 40 - 60 amps per hour when the battery is really low.



Good luck,

Fred.

Yes, you just have to decide who is running your place--you, or the person who installed that converter so you can't get at its button! :(

That vertical black PVC pipe goes straight up to the main bathroom sink.



Maybe drilling a hole in the base of the cabinet and pushing the bulk button with a stick is not so far fetched!

I don't know what needs to be where for the space you took the picture from just outside that compartment, but there is enough slack in the converter's DC output wires to take it off that wall and put it just outside that panel (when back in place).

The DC wires would go through a hole you make in that covering panel.(DC end of converter being towards the panel)

Now the red front end is out in the open, there is ? lots of ventilation for the converter, and it won't get plogged up with dirt and dust from whatever usually goes on there, and you can get at it?

Actually you could put the converter on a stand so it is above the floor there to the height the wires will allow. Or just hang the converter on the outside of that panel as its new wall.

Some of these inverters and converters want you to mount them horizontally so their internal heat does not rise through them and make the fan work harder. You would know by the way that unit works in its vertical mounting, whether it needs to be horizontal instead.

egad. I think I would open the box and see if I could attach a momentary switch in parallel.

smkettner wrote:
Push the boost button to get four hours at FULL THROTTLE.

Maybe I can drill a hole in the floor and poke the button with a stick.

Can you poke it with a stick? What it the button hiding behind? I would drill a hole if possible.

BFL13 wrote:
If you have the 68100, it has a button on the front to select bulk

I do have that one and would use the bulk button if I could reach it.

Wonder if it's possible to rig up a remote for that button?