Disconnect/Shut off converter when inverter is on

[storyarc]

I recently got 600W of solar, two 12V 100ah gel batteries, 40amp charge controller, and 2500W inverter installed on my travel trailer. The guy who installed the system disabled charging via the converter so it wouldn’t create a loop when my inverter is on. He did this because there was no switch to physically turn off the charger when I want to turn on the inverter.

The problem is that I’m currently in Oregon and solar input is seriously low. We’re at a campground and our batteries are almost dead because there’s very little sunlight and charging via the 30 amp shore power is disabled.

1) How do I add a breaker/switch for the charger to my electrical panel so I can charge my batteries with shore power when my inverter is off?

2) I have a 35 amp converter charger. Can I just get a 35 amp breaker and have it installed?

[BFL13]

So C/20 on two 100s is 40 amps? (NOPE!!!) Forget the 75 amper unless you get two more.

EDIT- C/20 is the 20 hr rate, so that is only 5 amps per 100AH!
_______________________



Looks like bite the bullet on the Gels. Toss them and get four AGMs or Flooded.

Note the DC amp draw for 120 is divide by 10, so:

Microwave- 1400w (input is higher than the watts name for output watts) so that is 140 amps. You only do that for a few minutes even with four batts.

Toaster- 900w pulls 90 amps.

TV/DVD 100w is 10 amps but then furnace comes on 10 more and you have 10 amps worth of lights on-- draw is now 30 amps so you can do that with the two Gels. But you left the laptop on! Now at 40 amps.

[storyarc]

CA Traveler wrote:
Buy a automotive charger with a gel setting and use it when you've got shore or gen power.

Would this charger work?

[pianotuna]

Here is the skinny on Gel's:

"Gelled Electrolyte

Gelled batteries, or "Gel Cells" contain acid that has been "gelled" by the addition of Silica Gel, turning the acid into a solid mass that looks like gooey Jell-O. The advantage of these batteries is that it is impossible to spill acid even if they are broken. However, there are several disadvantages. One is that they must be charged at a slower rate (C/20) to prevent excess gas from damaging the cells. They cannot be fast charged on a conventional automotive charger or they may be permanently damaged. This is not usually a problem with solar electric systems, but if an auxiliary generator or inverter bulk charger is used, current must be limited to the manufacturers specifications. Most better inverters commonly used in solar electric systems can be set to limit charging current to the batteries.

Some other disadvantages of gel cells is that they must be charged at a lower voltage (2/10th's less) than flooded or AGM batteries. If overcharged, voids can develop in the gel which will never heal, causing a loss in battery capacity. In hot climates, water loss can be enough over 2-4 years to cause premature battery death. It is for this and other reasons that we no longer sell any of the gelled cells except for replacement use. The newer AGM (absorbed glass mat) batteries have all the advantages (and then some) of gelled, with none of the disadvantages."

From: https://www.solar-electric.com/learning-center/deep-cycle-battery-faq.html/#Gelled%20Electrolyte

[BFL13]

pianotuna wrote:
Hi,

Gel batteries are extremely finicky about charging and discharging rates. Contact the maker on the wobbly wide web for the best charging protocols.

I suspect the bank has already been compromised. Unfortunately there is no method for ameliorating the damage.

The installer has done you no favors.

Could be. So adding two more new ones in parallel with those might not be a good idea. Needs to get those first two tested ( however you test Gels )

[2oldman]

wa8yxm wrote:
What is the make and model of the inverter?

Many are "Inverter/Converters" ..

Wouldn't that be a hoot. OP isn't responding.

[pianotuna]

Hi,

Gel batteries are extremely finicky about charging and discharging rates. Contact the maker on the wobbly wide web for the best charging protocols.

I suspect the bank has already been compromised. Unfortunately there is no method for ameliorating the damage.

The installer has done you no favors.

[time2roll]

storyarc wrote:

time2roll wrote:
Yes just get a 15 amp breaker at the local hardware and connect your converter.
Use the breaker as a switch to power it up only as needed.

Could rewire to make this seamless and automatic but the breaker as a switch is fine for now.

Thanks! I was thinking of using a contactor to automatically shutoff the converter when the inverter turns on. Is that a safe option?

Not what I would do. But I am not familiar on how that would be wired.

[BFL13]

I don't know how it works with Gel batts, but with chargers that have an AGM setting, it is often just a little below what the Flooded setting is. That may or may not be the spec voltage for the AGMs you have. AGMs specs are all over the map for charging voltages.

Perhaps Gels are all the same, don't know. My Tracer solar controller has settings for Gel, AGM, and Flooded at 14.2, 14.4, 14.6.

The OP's solar controller should also be set to Gel of course.

My Vector portable charger also has settings for Gel, AGM, and Flooded. I don't know what the voltage is for Gel on that. AGM is lower than for Flooded. I have AGMs that specify charging voltage at 14.5-14.9 at 80F, which goes higher at lower temps. Not all chargers have temperature compensation. So 14.4 is too low for them, but would be ok for Lifelines, which have lower charging voltages

[CA_Traveler]

Buy a automotive charger with a gel setting and use it when you've got shore or gen power.

[BFL13]

This also has the circuit breakers you can order for it scroll down

http://www.bestconverter.com/WFCO-8935-ANP-35-Amp-_p_51.html#.XjWS1knsZpw

The WFCO 35 amper is ok for running the rig's 12v while on shore power, but you don't do much of that.

It is unsuitable for charging gel batteries which need particular voltages (see their charging specs!) plus 35 amps is too slow to recharge the bank if on generator.

You will need to get two more gels to make the four- battery bank intended, keeping your batts all the same. You need a better battery charger as others have also said.

You don't mention a generator, but you do need one for off-grid and not enough sun. Even on sunny days you can still need to do a shot of generator high amp charging in the morning and then go on solar for the rest of the day to get the batts as high as possible.

You need to have a generator that has enough watts (VA really) to run the charger's amps, so you have to pick the size of charger in amps to "match" what the portable gen can do.

Four batts can take 100 amps easily but that requires a 3000w gen, so if you are getting a 2200w gen, (today's popular size) look at a 75 amp charger, eg. If you need air conditioning you will need shore power, but perhaps not in the PNW.

Where gels are so fussy about charging voltage, IMO you want an adjustable voltage charger. You can get a deck mount converter and cut the end of a set of jumper cables to make it into a portable charger. Here is one example of a 75 amper with adjustable voltage that will run off a 2200w gen.

https://www.boatandrvaccessories.com/products/powermax-pm3-75lk-75-amp-12-volt-power-supply-with-led...

[wildtoad]

If you’re going to be flipping the converter on and off a lot, I’d opt for a switch. CB’s aren’t really designed to be flipped repeatedly.

Can’t you install a device that automatically switches between two input sources? If it senses input on input A (converter) it uses it otherwise it use input B (solar). I forget what it’s called just know they exist, as I have one on my MH that switches which source powers the tv receptacle.

[wa8yxm]

What is the make and model of the inverter?

Many are "Inverter/Converters" with power pass throug on these if you have shore power they auto switch to "Converter" mode and generally a good 3+stage converter

Some are DC to AC only.. but sans a make and model I have nothing to google at.

[2112]

Is the WFCO WF-8935AN charging profile a good match for your batteries?

Maybe a better approach would be to get a standalone battery charger better suited for your batteries and just plug it in when you need it.

[storyarc]

time2roll wrote:
Yes just get a 15 amp breaker at the local hardware and connect your converter.
Use the breaker as a switch to power it up only as needed.

Could rewire to make this seamless and automatic but the breaker as a switch is fine for now.

Thanks! I was thinking of using a contactor to automatically shutoff the converter when the inverter turns on. Is that a safe option?

[time2roll]

Yes just get a 15 amp breaker at the local hardware and connect your converter.
Use the breaker as a switch to power it up only as needed.

Could rewire to make this seamless and automatic but the breaker as a switch is fine for now.