RE: Battery on Trickle Charger - Removed from RV

[dward51]

Originally Posted by Wolverine 1945

Is it safe to connect a trickle charger to a set of battery's still connected to a TT
In cold weather ??? Or is it better to leave TT connect to house power ???

As long as the trickle charger can keep up with the phantom loads and still have some "trickle" left to maintain the batteries, yes.

If you have a trailer disconnect, just flip it to off and you should be good. I recall reading some posts that indicate the LP and CO detectors are often not disconnected with a battery disconnect so that phantom load may still remain.

But if you have 1 amp of phantom loads and a 3/4 amp trickle charger, you will never charge and it will eventually discharge the battery as you are still pulling out more than can be put in. Physically disconnecting the negative wire from the battery (or battery bank) will let the trickle charger work on just the batteries, but you can physically leave them in the battery box of the trailer/RV.

Also it depends on which converter you have. For example, the Progressive units have a true trickle mode and will do periodic equalization on a timed cycle. For those, if connected to shore power in storage, you don't need a supplemental trickle charger as you already have one in the converter. Some are better than others at how this is implemented, so check the brand/model you have and the specs.

[KEN9XL]

Originally Posted by Flybob

I prefer an intelligent charger that will change charge voltage based on state of charge vs a constant current trickle charger. Two that have have worked well for most members are "Battery Tender" and "CTEK" The CTEK models offer a higher max charge rate and a lithium compatible version. I prefer to not use the onboard convertor as we have lots of line voltage variations due to falling trees. UOTE=Wolverine 1945;2215489]Is it safe to connect a trickle charger to a set of battery's still connected to a TT
In cold weather ??? Or is it better to leave TT connect to house power ???

[/QUOTE]



FlyBob ... Thanks for the advice on those two battery chargers / trickle charger. I guess for the time being, I will work with what I have since, but certainly put this information to the side for future research and possible purchase.

Wolverine ... Batteries are disconnected from TT and placed in a heated basement, so not too concerned about any rapid discharge.
As for power variation and cold weather, I'd rather not leave batteries outside connected to shore power while still on TT.
I live in New England (southern Massachusetts). Weather in winters can never be predictable, especially snowfall or extreme cold.
FYI ... My TT is stored outside at home in the elements of the weather.

[Wolverine 1945]

Our TT is stored in A RV Port, out of the weather, but not out of Temps we get here in the GREAT LAKES !!! I would agree the best way to store batters is to have them fully charged and place on some heave wood in a heated or non heated Basement !!!
I am just looking for the best way to not have to remove and place in the Basement,,,
As I said I left our MH plugged into shore power last winter, but I planed to replace the battery's in the spring anyway, because I was not sure if they were any good ???

Battery Tender or Shore Power with Surge Protector ???
Roger & Sharon

[KEN9XL]

Originally Posted by Wolverine 1945

Our TT is stored in A RV Port, out of the weather, but not out of Temps we get here in the GREAT LAKES !!! I would agree the best way to store batters is to have them fully charged and place on some heave wood in a heated or non heated Basement !!!
I am just looking for the best way to not have to remove and place in the Basement,,,
As I said I left our MH plugged into shore power last winter, but I planed to replace the battery's in the spring anyway, because I was not sure if they were any good ???

Battery Tender or Shore Power with Surge Protector ???
Roger & Sharon

Gotcha! I just replaced my batteries this spring. The new ones were more expensive than the stock, so I want to take care of them and make em last.

I think if my TT was stored indoors, like a garage or storage shed, I'd do the same thing as you, plug into shore power rather than remove them.

I definitely agree with surge protector if on shore power, no matter where.

[camaraderie]

Originally Posted by Wolverine 1945

Our TT is stored in A RV Port, out of the weather, but not out of Temps we get here in the GREAT LAKES !!! I would agree the best way to store batters is to have them fully charged and place on some heave wood in a heated or non heated Basement !!!
I am just looking for the best way to not have to remove and place in the Basement,,,
As I said I left our MH plugged into shore power last winter, but I planed to replace the battery's in the spring anyway, because I was not sure if they were any good ???

Battery Tender or Shore Power with Surge Protector ???
Roger & Sharon

1. Wood in the basement has not been needed since batts went to polypropelene cases from rubber. It is now officially and old wives tale!
2. A FULLY CHARGED battery will not freeze or go bad down to minus 92 degrees. Even at 60% charged it will not freeze till 16 below. A disconnected battery will last months (more than five)...from fully charge to 60% charged in freezing temperature.
3. This means that if you fully charge your batteries in the camper...THEN disconnect the negative battery wire...you don't need to do ANYTHING else including bringing them inside. If you check them after 3 months with a volt meter and they are 12.3V or below...then plug in with your regular charger again overnite to fully charge them and then disconnect the black wire again.
You should not need to do this at all in cold climates...and not more than once a winter in temperate climates.

[Wolverine 1945]

Originally Posted by camaraderie

1. Wood in the basement has not been needed since batts went to polypropelene cases from rubber. It is now officially and old wives tale!
2. A FULLY CHARGED battery will not freeze or go bad down to minus 92 degrees. Even at 60% charged it will not freeze till 16 below. A disconnected battery will last months (more than five)...from fully charge to 60% charged in freezing temperature.
3. This means that if you fully charge your batteries in the camper...THEN disconnect the negative battery wire...you don't need to do ANYTHING else including bringing them inside. If you check them after 3 months with a volt meter and they are 12.3V or below...then plug in with your regular charger again overnite to fully charge them and then disconnect the black wire again.
You should not need to do this at all in cold climates...and not more than once a winter in temperate climates.

I knew the first reply would mention the use of wood, I still do it anyway !!!
Thank You for the advice !!!

[DanandMary]

Do you need to charge batteries if the RV is plugged in?

[Sarahcat]

We removed our two batteries, put them in the insulated garage and connected a small battery tender on each. Best practice is to individually float charge each battery. Harbor Freight offered a coupon to buy the battery tenders for $5 each. Even at the regular price of $9.95, it’s still economical to use separate battery tenders.

With regard to connecting one side of a charger to the terminals of one battery of a parallel connected pair is electrically equivalent. If it’s not, then your connection is not properly parallel. I.e., any physical terminal of each bus (+ or -) should be electrically equivalent and if not, that can cause circulating current in the battery array. That’s a good case for not paralleling 12 volt batteries, rather than two 6 volt batteries in series. I lost the battle to have my dealer install two 6 volt batteries in lieu of the 12 volt batteries in parallel, particularly without separate current limiting (fuses) on each battery.

[babock]

I don' take the batteries out of anything unless they are in a storage lot. I have 2 of my pontoon boat batteries sitting straight on the concrete floor. Since it is warm here, I charge them up once a month.

[The Evil Twin]

Originally Posted by Sarahcat

With regard to connecting one side of a charger to the terminals of one battery of a parallel connected pair is electrically equivalent. If it’s not, then your connection is not properly parallel. I.e., any physical terminal of each bus (+ or -) should be electrically equivalent and if not, that can cause circulating current in the battery array.

Connecting the charger to opposite batteries (+ on batt 1, - on batt 2) balances the cells.

[bikendan]

Originally Posted by DanandMary

Do you need to charge batteries if the RV is plugged in?

You shouldn't have to. The RV's converter should do that.

[AlaskaRed]

Ken,
Last year on recommendation from our RV mechanic, we pulled our AGM batteries from our Dynamax REV 24CB for the winter here in Alaska and put them in our heated garage. (Mechanic had several clients whose batteries had frozen and broke the cases while keeping them in their RVs outside, even with heat pads and trickle chargers.)

When we separated the batteries, I put a moderately powerful jumper/charger/trickle unit on one battery. It took nearly a week to fully charge the battery, even when set on the proper settings, then it maintained charge without much input. The other battery had the same timetable, even though both were fully charged upon removal. I had waited about a month researching which charger to buy, and they lost about a third of their charge in the meantime.

When reinstalled into the the MH this past spring, everything fired up just fine, but I still suspect I need to have the ghost loads located to stem the power losses. This fall we pulled the batteries, and will put on the chargers in about a month to check their loss rate.

[Sarahcat]

Originally Posted by The Evil Twin

Connecting the charger to opposite batteries (+ on batt 1, - on batt 2) balances the cells.

Actually, no. If the batteries are connected in parallel, there is no electrical difference. The cells in each battery are internally connected in series (there is no access to the individual cells in each battery) and the terminals of each battery in a parallel connection are connected to the positive and negative nodes of the array, so there is no significant voltage difference between the two batteries. If there is a difference, then the theoretical parallel connection has too much resistance in the paralleled busses. That most likely means that the connections are made with conductors (wire or bus bar) of too small a gauge.

My dealer installed battery array was installed like this, with #2 AWG wire to the inverter/charger, but were bussed together with single 8 AWG wires. I lost my argument with the service department, so I replaced the #8 bus wires with #2. The physical location of the connections to the inverter/charger are distributed along with direct battery connections to the solar cells, however was most convenient for wiring management.

[Sarahcat]

Originally Posted by babock

I don' take the batteries out of anything unless they are in a storage lot. I have 2 of my pontoon boat batteries sitting straight on the concrete floor. Since it is warm here, I charge them up once a month.

We removed the batteries from our travel trailer after winterizing the plumbing and because it is stored in a storage facility for the season. It is not warm here in the winter and we don’t have a source of power to charge the batteries, when the trailer is in storage.

[The Evil Twin]

Originally Posted by Sarahcat

Actually, no. If the batteries are connected in parallel, there is no electrical difference. The cells in each battery are internally connected in series (there is no access to the individual cells in each battery) and the terminals of each battery in a parallel connection are connected to the positive and negative nodes of the array, so there is no significant voltage difference between the two batteries. If there is a difference, then the theoretical parallel connection has too much resistance in the paralleled busses. That most likely means that the connections are made with conductors (wire or bus bar) of too small a gauge.

Actually, yes there is a difference. The volts will be very close to the same because the potential is the same across the posts. The applied current is NOT the same. It will be reduced at each subsequent battery. By properly connecting the batteries to a charger, the load will be balanced across the cells of each battery. Correctly wired battery banks will also discharge equally, increasing the life of the batteries.
Using a low current charger on a pair of batteries may not matter much, if at all. However, to some boondockers it will. If you go 3 or more batteries they will charge/ discharge unequally. If you go higher current, it also will.

Proportional drop across parallel batteries charged by simply putting the charger on one battery. This is unbalanced charging:




Balanced (sort of) charging. Note that if only 2 batteries are used then it would be balanced. This is the way my TT and TV batteries are charged.


To ideally balance the charge/ discharge of the bank, they would be wired differently. This is how the boat is done.

[Sarahcat]

Originally Posted by The Evil Twin

Actually, yes there is a difference. The volts will be very close to the same because the potential is the same across the posts. The applied current is NOT the same. It will be reduced at each subsequent battery. By properly connecting the batteries to a charger, the load will be balanced across the cells of each battery. Correctly wired battery banks will also discharge equally, increasing the life of the batteries.
Using a low current charger on a pair of batteries may not matter much, if at all. However, to some boondockers it will. If you go 3 or more batteries they will charge/ discharge unequally. If you go higher current, it also will.

Proportional drop across parallel batteries charged by simply putting the charger on one battery. This is unbalanced charging:




Balanced (sort of) charging. Note that if only 2 batteries are used then it would be balanced. This is the way my TT and TV batteries are charged.


To ideally balance the charge/ discharge of the bank, they would be wired differently. This is how the boat is done.

Yes, the voltage drop, due to the resistance of the conductors between batteries will create lower voltage at the battery terminals farthest from the charger connection. That will happen regardless of where the feed is attached, which makes the case for NOT charging a parallel battery array. It’s also the reason that I did not want two 12 volt batteries in parallel on my travel trailer. I asked for two 6 volt batteries in series, which would be the same charging/discharging current through the array. With more batteries in an array, using a series connection of 6 volt batteries with those series connected 6 volt batteries paralleled with others. I’m speaking primarily of a 12 volt terminal voltage, however, a 24 volt array would be similar, with 4x 6volt batteries in series. I’m not really knowledgeable about RVs. I’m just an electrical engineer, speaking of circuit theory.

All that said, when I removed my two 12 volt batteries from our travel trailer for the winter, I float charge each of them with separate small maintainers, which are relatively inexpensive and avoid the variations between batteries. When I reinstall the batteries in the spring, I am using much larger conductors than did the dealer and when these batteries fail, I will be replacing them with 6 volt batteries in series. The dealer install was faulty, because they used conductors that were too small for the parallel connection, but they only said ‘we always do it that way’.

[aircommuter]

That’s why I use this in my shop. I used to have the variable voltage unit with a bunch of batteries in series. This is a smarter system of the modern times.

[Sarahcat]

Originally Posted by aircommuter

That’s why I use this in my shop. I used to have the variable voltage unit with a bunch of batteries in series. This is a smarter system of the modern times.

Totally! I only have two batteries, so two $5 (1/2 price with a coupon at Harbor Freight) battery maintainers. Your solution is more elegant, but I went cheap, since I’m still a novice with RV-ish stuff.