12V Wet Cell Deep Cycle Batteries

[Ramona]

No story, just questions:

1a. Does being plugged into 120 shore power all the time in order to maintain charge actually shorten battery life?

1b. Does being plugged into 120 shore power all the time cause water to need to be added more frequently?
2. How do I know if the battery is being overcharged?

3. Once a battery boils and dries out a cell, is it for sure now a bad battery? My digital tester says they are still good.

[richard5933]

Originally Posted by Ramona

No story, just questions:

1a. Does being plugged into 120 shore power all the time in order to maintain charge actually shorten battery life?

1b. Does being plugged into 120 shore power all the time cause water to need to be added more frequently?
2. How do I know if the battery is being overcharged?

3. Once a battery boils and dries out a cell, is it for sure now a bad battery? My digital tester says they are still good.

1a. No. Not if done properly.
1b. No. Not if done properly.
2. Voltage meter.
3. Usually. Take it to an auto parts store and ask them to load test it.

A good battery charger will be multi-stage. It will start at a higher voltage for up to a few hours - this is commonly called bulk mode. On my charger this is about 14.4 volts. Then comes the middle stage, called absorption stage on mine and at about 13.6 volts. This lasts for a few more hours, depending on the state of the batteries. The final stage on my charger is called float mode and is about 13.2 volts.

Every charger company calls these slightly different names. The final stage may be called storage mode. They voltage settings themselves can be adjusted on many chargers, and you can get the recommended voltage levels from your battery manufacturer.

Once the battery has charged and enters the float/storage mode at 13.2 volts, there is very little to no out-gassing. You will still need to monitor, but if your charger is keeping things at the proper voltage levels you should not have to refill constantly and the battery should not boil dry unless you ignore them. I had mine connected in storage mode all winter and only had to add water twice.

Download the instructions for your batteries. Get and learn how to use a voltage meter. Make sure your charger is charging at the proper voltage levels. And top off the water monthly. That should cover it.

[Ramona]

Originally Posted by richard5933

A good battery charger will be multi-stage...

This is a brand new, fancy coach. I assume that it has multi-stage charging for when using 30 amp shore or the gen or while driving...
?

[FatChance]

Get the manual for your inverter/charger. It should have the information you need.

[Ramona]

Originally Posted by FatChance

Get the manual for your inverter/charger. It should have the information you need.

It's a ProWatt 1000W SW sine wave inverter. and it's turned off while being stored and traveling. Is it supposed to be turned on while plugged in?

Inverter turns DC into AC so what's the inverter have to do with charging or over charging the 12v batteries?

[bucks2]

Prowatt 1000 sw is ONLY an inverter, not a charger. Your original question is about charging and appears to have nothing to do with inverting. Yes, you probably want the inverter off while the rig is is storage.

Now, back to your charger question. Find the manual for it. (online or in the box of manuals that came with the rig) Look to see if it's a 3 stage or better yet a 4 stage. Don't assume it's a high quality, look and check. If you have a good charger with a float mode that only charges when needed, your water levels will stay constant for a long time. Check the batteries every month until you KNOW how much water they use, then check them a month before you expect them to need water. (my qualifications to give that advice? I care for a total of 23 wet cell batteries in my 5 cars/trucks, motorhome and boat. My boat deep cycle batteries were last replaced at 10 years, my motorhome batteries are in their 6th year, and I'll tell you about 2 of my car batteries in the next paragraph)

Being plugged in all the time on a GOOD charger extends the life of the battery by not letting it get completely discharged or otherwise abused. Real life story, I put new batteries in 2 of my cars this year, cars that sit for 6-7 months each year while I'm travelling. Each is put on a Battery Tender brand automatic battery charger. I replaced them this year as they were 8 years and 2 months old and I didn't want to push my luck any longer. They still worked fine, absolutely no sign of going bad, but I wanted to choose when I replaced them. One is a fairly obscure battery size and not available just anywhere. I believe the Battery Tender makes a big difference by keeping the batteries charged but not overcharged. I would not, NOT, use a cheap "trickle charger" or "battery minder".

Look at your particular charger and make sure it does what you want it to, that is a true float charge that only charges after the battery is slightly discharged.

[Ramona]

Originally Posted by bucks2

Now, back to your charger question. Find the manual for it. (online or in the box of manuals that came with the rig) Look to see if it's a 3 stage or better yet a 4 stage. Don't assume it's a high quality, look and check...

The satchel of manuals did not include one for the converter. I only know, from the brochure, that it is a 45 Amp converter. Not sure how to get more info on the converter.

[Ramona]

On a related topic: The RV is plugged into a 120 GFCI outlet when stored. Is the GFCI good enough or do I need a surge protector also? Recommendations?

[garyre]

What kind of bad experience have you had with a battery minder charger?

[richard5933]

Originally Posted by Ramona

This is a brand new, fancy coach. I assume that it has multi-stage charging for when using 30 amp shore or the gen or while driving...
?

You'd be surprised how many threads I've seen where someone spent half a million on a new motor home, only to bring it home and think that using a $15 charger from Walmart was better than just plugging in the onboard power.

Originally Posted by Ramona

The satchel of manuals did not include one for the converter. I only know, from the brochure, that it is a 45 Amp converter. Not sure how to get more info on the converter.

Manual should be available on the manufacturer's website. If not, call them and ask for them to send one the old fashioned way.

Originally Posted by garyre

What kind of bad experience have you had with a battery minder charger?

Why trust an expensive coach to a cheap battery minder instead of letting the onboard multistage do the job. These little battery minders do fail, and I've read threads of them failing by providing a charge at too high a voltage level. When charging batteries, the voltage is more important than the amps with regard to keeping your batteries protected.

Everyone thinks that a little 2 amp or 3 amp charger can't do any damage and leave them connected all winter, only to find out that that 2 amps was coming through at 16 volts (or something else which was too high.) Sure, it will charge, but it will also boil your batteries to an early death.

[153stars]

I think he is promoting battery tender brand. Some of those only keep up fully charged batt. There are some good boat charge maintainers.
Many other no name and name brand are poor , aka green light on not charging or unplugged and green light and actually draining the batt.
Premanantly mounted and draining batt. when not plugged in.Besides overcharging under charging.
Many use mineral oil on top of the acid to conserve water, they make battery watering systems as well as water conserving caps. Caps with float indicators.

[bucks2]

"The satchel of manuals did not include one for the converter. I only know, from the brochure, that it is a 45 Amp converter. Not sure how to get more info on the converter."

Find the converter itself. Get a brand/model. Search online. You may or may not get the correct information from the dealer, he might be guessing. Find it in your rig.

The converter is probably very close to the batteries. Probably next to the inverter. Check the next compartment over.

[bucks2]

I guess I've not fully explained myself. Richard 5933 and 153stars have both assumed things that I didn't explain. So, let me explain a little more.

My vehicles in storage do indeed get Battery Tender brand chargers applied to them. I do endorse that specific brand. (I have no financial interest in the company) Those specific chargers are true 4 stage (initialization, Bulk Charge, Absorption Mode, Float Mode) chargers. They are not designed for recharging heavily discharged batteries, but for maintaining batteries. Float status applies NO CHARGE to the battery until it self discharges (or more typically a parasitic drain discharges the battery below a certain point. In an RV, a CO detector, along with some engine and transmission brain boxes are typical parasitic drains) below a set point. When the battery reaches that point, then the charger adds an appropriate amount of voltage and amperage (electrical pressure and volume) to recharge the battery to full, then goes back to float mode and puts no more charge in until the cycle repeats.

Compare the Battery Tender (BT) to the cheaper chargers found elsewhere. Often these are marketed as "trickle" chargers or the generic battery minder. Trickle chargers put out a small amount of charge all the time to keep a battery charged. This tends to use water and allow batteries to sulphate, as a small amount of charge is continually applied whether the battery needs it or not.

It also seems that some might believe I was promoting using a BT instead of the built in charger/inverter/converter (use the words you like). That couldn't be further from my intent. I fully trust and believe in my Magnum MS2812 inverter/charger. (the terms I prefer) It goes into float mode as described above. It maintains my MH batteries perfectly. The same is true for the house and starting banks on my boat. The inverter/charger uses float mode to maintain the batteries. On the boat I also have a separate battery which starts the generator and a separate battery which runs the windlass for the dingy winch. The windlass would require a long run of heavy cable so a separate battery and BT on it works more efficiently. The generator has a separate battery and BT for redundancy, ensuring that I can start the genset to charge the main batteries even if someone let both main banks run down. Again, the windlass and genset BT's use float mode for longer battery life and efficiency.

The OP does not have a sophisticated inverter/charger in his rig. He has a separate 1000 watt inverter and a separate 45 amp charger. He doesn't know if his charger has a float mode or if it only goes to trickle mode. This is why I am encouraging him to look at his particular charger and find the manual and its specs.

If you have a good charger/inverter system in your RV, with a float charge setting, then you should certainly use it, I do and it works well. If you don't, or if you don't know what you have, investigate and then invest in one that will treat your batteries properly for long life and good service.

Now for absolute clarity this is the charger I use. (Battery Tender® Plus 12V, 1.25A Battery Charger) (I use the 75 amp booster/charger on the dinghy winch battery because is does draw a lot during use) It is available for less money than the list price from the factory. Amazon often has a good price.

I've NEVER heard of a Battery Tender charger failing. If you have, I'd love to hear the particulars. If you just know of a brother of a friend whose dad had on that quit, don't bother, but if you've seen first hand of one ever failing it'll be the first I've heard. And yes, I did a search for BT brand failures. I found one, it was a corvette that the fellow left for 2 years and failed to check water level in the battery. When he did it was dry. That's not a BT failure, that's an owner failure.

[NXR]

Originally Posted by Ramona

On a related topic: The RV is plugged into a 120 GFCI outlet when stored. Is the GFCI good enough or do I need a surge protector also? Recommendations?

They do two completely different things. The GFCI protects against a defective "thing" plugged into the outlet that could result in a shock to people. That's it.

A "surge protector" in and of itself simply protects against momentary massively high voltage spikes on the incoming power. They effectively "short out" for a very small fraction of a second to keep the spike from proceeding and then then "reset". It's all electronic so it's astonishingly quick. I have a whole house surge protector on our home because of the hot tub motors.

A plain old "surge protector" does not protect against high voltage conditions, low voltage conditions, defective pedestal wiring, etc. Those usually are the more common dangers seen in campgrounds.

I use the hard-wired Progressive Industries EMS-HW50C https://www.progressiveindustries.net/ems-hw50c because it provides all protections in one package. I think they also have the portable one if you do not want to hard-wire it.

The portable ones that plug directly into the pedestal usually cannot protect you against a failure in your own power cord, though. If the neutral wire opens up due to a defective plug or similar you can fry your RV.

So short answer: Both, at least.

HTH,

Ray