Need real life experience! Deep charging batteries

[homeless]

I am not an electrical genius. Here is my question. I have heard of surface charge and deep charge. I am on my first long time boon docking adventure. I am running the generator four hours a day. Two hours at night and two in morning. I am noticing that my house batteries are showing low voltage after I turn off the generator. The meter shows generator is at 13.6 or there about when running. Now if I run down the road and then turn off engine the batteries or at 12.6 or 7. But after a few days of the generator after each event I am not seeing only 12.2 or 3!

Is my issue that I am not running the generator long enough and if so how long do I need to run the generator to get the batteries up each day?

[powercat_ras]

It looks like you have a 2000 Itasca Suncruiser. Some of my answers assume that.

Something called lead sulfate can form on battery plates and degrades the performance of batteries reducing their ability to hold voltage during discharge. In particular this can effect use of your inverter. Standard RV battery converter chargers tend to allow this to form gradually, as they don't ever provide what is called an equalization charge, which is a slight over-charge that causes the lead sulfate to leave the plates.

I added a Battery Minder OBD-12 battery desolator that desulfates the batteries whenever it senses a battery charging voltage applied across the batteries. I would buy when or before you buy next batteries. It is an install and forget item. Just works. Well under $ 100.

I assume your RV has two 12 volt coach batteries, suggest you replace them with two 6 Volt Costco Golf Cart Batteries connected in series when you replace batteries. Well under $ 200.

Consider upgrading your RV's existing OEM 120 volt to 12 VDC, 45 Amp Max Output, converter charger to a larger unit so that when you run your generator you charge your batteries 2X faster, during the phase where are being charged to the 80% point. I suggest the PowerMax PM3-100 Converter Charger 100 Amp Max Output, $ 160.

Finally, make sure that when traveling, that the RV is connecting the Chassis 12 volt system to the Coach 12 volt system and putting charge on the Coach batteries. You can confirm with the monitor panel , in particular if you have 2 or 3 battery status lights and it goes to 4 lights with Chassis Engine running. I don't know if Winnebago was using an intelligent Coach / Chassis battery manager in 2000 that should be doing this. Current Winnebagos do and you can retrofit if not for under $ 200.

[vanmark]

Running the generator for two hours of an evening and two in the morning is correct. When you are doing this you are only putting back about 80% of the charge. That is why you cannot get as much out of batteries each time when you have a partial charge of 80%. I have found that it is best to put a full charge in the batteries about every five days, as this will bring them up where it prevents damage to the batteries and make them last longer and it will bring them back where you get the most amps from them otherwise you will see decreasing volts and amps that you can take out. I lived on a boat off the grid for six months at a time with only a generator and alternator and I found that running a generator for several hours to get a full charge about every five days worked.

[Morich]

I did telephone work for quite some time and it involved a lot of work on batteries. One big thing is that they are not as simple as we often think. A point that I found was it may take a long time, like a couple weeks for a battery to fully cover after a long period of discharge. Each cell in each battery will work just slightly different, so in a long string of cells which totalled to 48 volts, we monitored, checked and maintained each cell monthly and that allowed the company to use batteries which were often more than twenty years old! I might guess that no RV person does that and we really could not as we can't access each cell separately. But we can check each cell and be sure that it has the correct amount of water and that we are using distilled water to avoid adding minerals we don't want.
From there, a good long charge to a full 14 volt charge will make the battery last longer.
But since most all of this takes extra time and effort, most of us will settle for checking the water one or twice and just replace the battery when it dies!
It gets down to how you take your poison. You can do the extra money, time and worry now or you can replace the batteries a bit earlier.
For me, it gets down to how retired or tired I want to be at any given time.

[homeless]

Thank you for the incite.

One more question. With only the generator is it possible to run the batteries up to 100% and if so how long would that run time be? Or do I have to fully charge it on shore power or alternator?

[creativepart]

Are the batteries old? Have you been running them down to 12.2 and lower frequently over the years? Do you ever get a chance to fully charge them to 13.7v or so? If so is it rarely or is it routinely?

Does your RV have an 18 year old converter charger or has it been updated since new?

All of these answers will be an indication of the condition of your batteries and your ability to charge them completely and effeciently.

It sounds like old worn out batteries that have been run too low too many times and if that's the case the best fix is new batteries. If you're going to be Boondocking a lot - get really good (expensive) batteries and also look at getting a more up to date converter/charger to keep them in good shape longer.

It might be a good excuse to get an pure sine wave inverter/charger to replace the converter/charger and enjoy both an AC power source and state of the art battery charging, too.

[creativepart]

Originally Posted by homeless

Thank you for the incite.

One more question. With only the generator is it possible to run the batteries up to 100% and if so how long would that run time be? Or do I have to fully charge it on shore power or alternator?

You'd want shore power - it could take 24 hours or more to fully charge the batteries. And, if the batteries have been run too low too many times once fully charged they could lose a full charge really quickly.

[homeless]

Thank you all

[Morich]

Originally Posted by homeless

Thank you for the incite.

One more question. With only the generator is it possible to run the batteries up to 100% and if so how long would that run time be? Or do I have to fully charge it on shore power or alternator?

Shore power is likely to be better as it does take some time. How much time will depend on the battery and condition. We kept batteries on full time change at 52.08 for a "48" volt supply and that was something that we would check almost constantly. After a long period of discharge like during a storm outage, we could see some cells pop back into good shape in a day while other cells in the same rack and same age might take a couple weeks before getting back. It was not something that could be laid out all nice and neat but as it was an area that was prone to thunderstorms putting AC power out, so the deal was that if a power plant went down, you might be able to wait till the next morning to call somebody out but if it happened again the next week, you better get somebody much quicker as the batteries would be a bit more shaky and not last as long.
But that was also before telephones were deregulated and service was fully expected to stay up. Not the current wait a few days and call back to see if I care!

[BobC]

And, from what I've read, a good, automotive battery charger is likely to do a better job than your converter.

[vanmark]

Originally Posted by homeless

Thank you for the incite.

One more question. With only the generator is it possible to run the batteries up to 100% and if so how long would that run time be? Or do I have to fully charge it on shore power or alternator?

You can do it with the generator ok and it may take 5 hours depending on the size of the converter or charger. Shore power is the easiest way, but boondocking it may be just the generator. In the morning instead of running for two hours, run the generator for maybe 5 hours. The best way to know the charge of the batteries is to have a battery computer that shows the amps taken out and the amps put back in. They don't cost that much and they are easy to install.

[powercat_ras]

The trouble is that RV converter chargers do three stages, and once they fall out of stage 1 they are no longer generating the conditions required to de-sulfate the batteries. And once they fall out of stage one they amount of charge they push per unit time also goes way down. Why? Because they make a engineering choice to charge in such a way that minimizes the need to add distilled water to the RV coach batteries.

1. Maximum current bulk charge mode when they sense batteries are below 80% charged. Voltage across the battery terminals will be less than 15 volts, generally 14.4 or whatever is enough to reach the maximum current output of the converter charger.

2. Topping charge mode where they put out a fixed voltage and current tapers down until the converter charger senses they around 95% charged. Generally will be well below 14 volts, 13.4 is common.

3. Float charge mode where they apply around 13 volts which trickle charges and eventually gets the batteries to 100% plus it allows the converter charger to provide the current to any loads rather than the batteries draining and providing it.

If you have two 80 amp-hour when new 12 volt batteries (typical OEM), Then say they are 75% of what they were then they were new, or 120 amp hours now.

at 12.2 volts resting voltage say you are at 50% state of charge. You need to push 60 amp-hours into the batteries to get back to 100%. Assuming your stock converter can push 35 amps into your batteries (typical OEM):

50% to 80% = 60 -> 96 amp hours, or about 1 hour
80% to 95% = 96 -> 114 amp hours, about another hour
95% to 100% = 114 -> 120 amp hours, about another 2 hours.

Considering that your generator uses at least a gallon per hour fuel even under light load it's just not very cost effective to go past 2 hours. Get the BatteryMinder OBD12 its more cost effective than running generator 4 hours every week just to maintain your batteries.

[homeless]

Ok I want to thank all you guys for the information and tell you its giving me a good understanding of what Im looking at.

I have one more question if you have the time.
I'm considering an emergency run home and might have to leave my rig in storage for a couple weeks. I'm thinking with a fully charged set of house batteries that the Norcold will have plenty of power to maintain itself for several weeks????

[creativepart]

Perhaps I don't know the exact circumstances - but I take it you're thinking of parking your rig for "several weeks" with the fridge on and running on propane/battery.

Perhaps I'm wrong. But, I can only envision returning to the RV to find it uninhabitable due to the rotten food in the fridge. And, a completely ruined fridge.

[powercat_ras]

Originally Posted by homeless

I'm considering an emergency run home and might have to leave my rig in storage for a couple weeks. I'm thinking with a fully charged set of house batteries that the Norcold will have plenty of power to maintain itself for several weeks????

For several weeks, I would toss anything perishable and just shut off the refrigerator with the doors blocked open. I would operate the battery disconnect switch or disconnect the battery/batteries if you don't have a disconnect switch. That's your zero risk option.

If you want to take risk, then if you start out with charged batteries, AND you can make sure that the ONLY DC load in the RV is the refrigerator, you likely could go 4 weeks. There are other things known as "vampire" loads that draw from the coach batteries that you will need to kill - hopefully by pulling fuses in the 12 volt fuse box ... if you don't kill them you will come back to dead batteries and nasty mess in refrigerator if you left perishable food in it

note they may not be labeled with these exact names so you may have to use trial and error.

Make sure the refrigerator door light still comes on that you still have power to the refrigerator as you pull fuses.

Fuse for propane detector
Fuse for dash radio
Fuse for entertainment radio
Fuse for audio/video gadgets like IR repeaters, Video converters, etc.

[Morich]

The theory of letting the frig alone run "might" work as the controls take very little but the problem comes in as you leave the coach batteries connected and there are other things using the same batteries. May do it or may not, depending on how much the total draw is compared to the charge and condition of the batteries, so it gets into a bit of gamble. The price of being wrong is enough for me to say I would not want to do it.
Any chance of getting a temporary home for the frig stuff, would seem better to me.

[BobC]

I wouldn't risk it.

[AndyAk]

You don't say where you plan to leave it. If you're here in Anchorage, there's a good chance it could go for weeks with no problem, if it's just the fridge, but if it's somewhere warm....no so much. Some RV fridges can draw over 10 amps, and in warm weather they're "on" a lot.
You don't mention if you're running your fridge on propane or DC current, but if you're running on DC, you're pulling your batteries down a LOT when your generator isn't running. Batteries can only be recharged so fast.....the voltage will rise quickly at first and that brings the charging rate down. Adding charging capacity only increases the internal heat in the battery and can destroy it. The max you want to have for charging capacity is about 15 amps per "car size" battery unless it's made to be charged at a high rate, as the golf cart batteries are.
If you leave the fridge on batteries I suspect you only get a few days of cool before the batteries are dead. You'll be able to revive them (if it's warm there) but it takes a bit of life off of them.

[CheriRandy]

Hello Powercat. I learned a lot from your reply, in this thread. I've never owned a golf cart, so wondering why you recommend the 6volt golf card batteries. Do they hold a charge longer, are they more powerful? I'm inclined to go this route, next time I need batteries (MicroMinnie 2106FBS), but just wanting more detail about why.

Originally Posted by powercat_ras

I assume your RV has two 12 volt coach batteries, suggest you replace them with two 6 Volt Costco Golf Cart Batteries connected in series when you replace batteries. Well under $ 200.

Consider upgrading your RV's existing OEM 120 volt to 12 VDC, 45 Amp Max Output, converter charger to a larger unit so that when you run your generator you charge your batteries 2X faster, during the phase where are being charged to the 80% point. I suggest the PowerMax PM3-100 Converter Charger 100 Amp Max Output, $ 160.

Finally, make sure that when traveling, that the RV is connecting the Chassis 12 volt system to the Coach 12 volt system and putting charge on the Coach batteries. You can confirm with the monitor panel , in particular if you have 2 or 3 battery status lights and it goes to 4 lights with Chassis Engine running. I don't know if Winnebago was using an intelligent Coach / Chassis battery manager in 2000 that should be doing this. Current Winnebagos do and you can retrofit if not for under $ 200.

[BobC]

Originally Posted by CheriRandy

Hello Powercat. I learned a lot from your reply, in this thread. I've never owned a golf cart, so wondering why you recommend the 6volt golf card batteries. Do they hold a charge longer, are they more powerful? I'm inclined to go this route, next time I need batteries (MicroMinnie 2106FBS), but just wanting more detail about why.

Here's some information on this subject:

https://deepcyclebatterystore.com/co...s-dry-camping/