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wmcrinc · 10-14-2021, 11:09 AM

Hey all, I've been looking into upgrading my converter to a staged converter charger. I've come to realize that when dry camping I'm using more battery resources than my generator can pump through my existing converter without running it all hours except after bedtime.
So I'm seeing that these smart converters produce maybe as much as 15 volts during the charging cycle which means all my 12 volt stuff is getting 15 volts as well. Is that ok? Are there voltage regulators that are needed to limit the house 12 volt systems to no more than 13 volts? Or isn't that necessary?

Thx, Kevin

96 Wideglide · 10-14-2021, 11:18 AM

The vast majority of 12v appliances have no issue with 15v.

Persistent · 10-14-2021, 11:33 AM

Lead acid batteries have a charging voltage profile. Raising the voltage to push more current through does not increase charging. It produces hydrogen gas.

The best you can do is to have a charger with high enough capacity to satisfy deeply discharged batteries. If the charger produces 13.6 volts at the battery terminals, you cannot do much better. Battery absorption limits rate of charge.

Flooded cell lead acid batteries vent the gas and often a mist of sulfuric acid. AGM batteries reabsorb the hydrogen gas and convert it back to water. AGM batteries have a limited ability to reabsorb hydrogen. Higher voltages vent the excess. That causes permanent loss of storage capacity.

Charging voltage profile:

14.4 volts for deeply discharged lead acid batteries. High current will flow. The bigger the battery bank and the deeper the discharge, the higher the current. A 200 amp hour battery bank may draw 50 to 60 amps.

13.6 volts after 4 to 6 hours. Lead acid batteries absorb less as charging progresses. Voltage is lowered to reduce hydro gas emission.

Current continues to decrease as charge progresses. A 200 amp hour battery bank may draw 5 amps or less at 90% state of charge.

13.2 volts is ideal for fully charged batteries in storage. It reduces hydrogen emission and grid corrosion.

15 volts is occasionally used to cause flooded cell batteries to "boil" and mix the electrolyte. It also may remove crystalize sulfate from plates of abused batteries. It should never be used for long periods. Very rarely does an AGM battery manufacture recommend 15 volts. Most prohibit it.

Battery University https://batteryuniversity.com/articles

How does the Lead Acid Battery Work?
https://batteryuniversity.com/articl...d-battery-work

How do battery chargers work
https://batteryuniversity.com/articl...-chargers-work

How to Charge and When to Charge?
https://batteryuniversity.com/articl...when-to-charge

Old-Biscuit · 10-14-2021, 11:40 AM

Thanks Paul!!!!!

Nailed it...........

*my fingers are tired

Persistent · 10-14-2021, 11:45 AM

I've been looking into upgrading my converter to a staged converter charger. I've come to realize that when dry camping I'm using more battery resources than my generator can pump through my existing converter without running it all hours except after bedtime.

A larger battery bank plus a higher current capacity charger would work. A 15 volt charger will not help.

Lead acid batteries require 14 to 18 hours for a full clean charge. This is the nature of the chemistry. The battery chemistry limits how fast they can absorb power.

Deeply discharged lead acid batteries may reach 80% state of charge in 4 hours using a high enough capacity charger. The last 10% of charge may take 8 hours more.

Deep draw AGM batteries tend to charge a little faster than deep draw flooded cell batteries.

Lithium batteries tend to charge much faster than lead acid batteries. They can use higher capacity chargers. A constant 14.4 volts is optimum.

A larger battery bank will absorb more power fast. It will still require 14 to 18 hours for a full clean charge. It would need a higher capacity charger.

shootist · 10-14-2021, 01:29 PM

You get that information from the battery manufacturer. Lead acids also need a temp. Compensation. More voltage when colder, less when hotter.

twinboat · 10-14-2021, 04:46 PM

Get yourself a 3 or 4 stage 55 amp smart converter/charger.

Check the converter/chargers length and gauge of the wires to the batteries. If to light, there will be charging amps lost.

Better to place the converter close to the batteries. Extend the 120 volt line.

Power Max makes a 55 amp 4 stage converter. Been using one 7 years.

wmcrinc · 10-14-2021, 05:43 PM

Thanks for the responses. I think I have the battery needs down ok but what I was actually wondering about is knowing that for a period of time the charger will produce more than 14 or even 15 volts. The batteries will be fine but it's the other stuff. Refrigerator circuit, furnace circuit board. Then there's the stuff you bring along like cell phone chargers, laptop, small or micro inverters. All this stuff could be plugged in and running when that charge voltage is higher than normal. Does anyone have such a staged converter charger and experience using these add on 12v devices?

Persistent · 10-15-2021, 06:46 AM

I was actually wondering about is knowing that for a period of time the charger will produce more than 14 or even 15 volts.

14.4 volts is the top voltage high quality staged chargers are programed for. My WFCO charger will produce 14.4 volts when the batteries are deeply discharged.

The WFCO has a timer. It will only produce 14.4 volts for a maximum of 4 hours. Some staged chargers drop the voltage when current slows down. These chargers spend most of the time providing 13.6 volts.

The batteries will be fine but it's the other stuff. Refrigerator circuit, furnace circuit board. Then there's the stuff you bring along like cell phone chargers, laptop, small or micro inverters. All this stuff could be plugged in and running when that charge voltage is higher than normal. Does anyone have such a staged converter charger and experience using these add on 12v devices?

As a previous post said. Nominal 12 volt devices for automotive use are all designed to work with 15 volts input. That includes computers, cell phones, inverters and other things.

Some 12 volt appliances require a special cord. The instructions for these things usually require such use and caution against direct connection. For instance, my wife's previous CPAP machine ran on 12 volts. It required a special cord with a filter and a fuse in it.

cletesingler · 10-18-2021, 06:41 PM

I do NOT understand most of my hearing that I should place the converter as close as possible to the batteries! The main purpose of the converter is to provide DC power to DC equipment on the power panel when on shore power, and then also to charge the battery. If you have large DC loads listed on the power panel, larger than the battery, then the converter should be close to the power panel and not the battery! Thus my 75 amp converted is right near the power panel, and some distance from the battery, with appropriate gauge cables to the panel and battery.

Persistent · 10-19-2021, 08:19 AM

Quote:

Originally Posted by cletesingler

I do NOT understand most of my hearing that I should place the converter as close as possible to the batteries! The main purpose of the converter is to provide DC power to DC equipment on the power panel when on shore power, and then also to charge the battery. If you have large DC loads listed on the power panel, larger than the battery, then the converter should be close to the power panel and not the battery! Thus my 75 amp converted is right near the power panel, and some distance from the battery, with appropriate gauge cables to the panel and battery.

There are requirements for where and how to mount a converter/charger. See the installation manual for the device.

As long as you meet those requirements it is OK to run a long heavy output cable.

Battery charging is more sensitive to line loss than most other appliances. For efficient battery charging, short heavy cables work better. Many people use 1 or 2 size larger size wires for battery charging. Running those large cables long distance can be difficult and costly.

Large inverters are also sensitive to line loss. They draw high current and shut down if voltage drops too low. People often mount both the inverter and the converter/charger near the battery, but not in the battery compartment.

Most other appliances run well over relatively smaller wire. See wiring tables for size required for distance and current. Smaller wires need smaller fuses.

My small travel trailer came with a single 70 amp hour battery on the tongue. It had a 6 AWG gauge wire from the battery to the converter/charger in the back, 18 feet away.

I installed a pair of 100 amp hour batteries in the back near the converter/charger. To charge the 200 amp hour battery bank, I used 2 AWG gauge wire two feet long.

I built a battery box for the new batteries that was vented to the outside and added a 100 amp circuit breaker for the inverter I also added near by.

In my case the main distribution fuse panel was also near by. It could have been further away for efficient use.

The appliance branch circuits on the fuse panel were mostly 15 amps. The 15 amp rating is to protect the 14 gauge wires. It is not how much each branch appliance actually uses.

14 gauge wire is cheap, small, and flexible. It is easy to pull through walls and commonly available at hardware stores. The appliances connected to them use much less current. Three amps would be a lot. Also, they are not as sensitive to voltage loss.