Forum Discussion

DSMC_Whiz's avatar
DSMC_Whiz
Explorer
Apr 08, 2014

Battery Charging and Management

First off, let me thank all of you that have been posting to this board through the years. We just purchased our first TT (Lance 2185) and picked it up last weekend. I have been reading your previous threads for the past few weeks, and I have learned quite a bit.

My question for the experts on here, is on how to create the easiest and most effective power system for my trailer. I have dual Interstate 27 batteries to work with, and believe that running them in PARALLEL is the most efficient method. I store our TT, so I will be removing them back to our garage during storage periods. I am planning to purchase a Honda 2000 generator for charging while boondocking.

First, I envision running some type of a quick connect, likely just a simple ring connector attached with a nut. I would then put the TT feed over the top of that nut and hold it with a second nut. I would then have the other end of those quick connects compatible with a connection plug on the charger. Does this seem like the most reasonable approach and if I do that, can I just plug the charger into the generator as well while leaving the batteries connected to the TT, or are there problems posed by having a charger on those batteries while they are connected to the TT house power?

Second, I am looking for information on 24V chargers you all like to use. What are the faster amperage chargers? How long do you take to charge yours fully?

Finally, what battery maintenance should I anticipate and what are some more useful tools for that?

Thank you in advance.
  • beemerphile1's avatar
    beemerphile1
    Explorer
    Apr 09, 2014
    DSMC Whiz wrote:

    ...are there suggestions for higher amperage 12v chargers that I should consider using while boondocking....


    Before that question can be answered, you have to tell us what converter the RV has?

    More amperage is better but you can only go so high of a percentage of battery amphours. If the total AH are say 170 for two group 24 in parallel then the charger should be 20% of that which is displayed as C/20. C/20 would be a charger with 34 amp output. Your converter may already have that covered. You can go higher but C/20 is the commonly recommended rate of charge.

    For a good portable charger you may want to look for a Vector 1093DBD.

    I think you are making it a little too complicated. I suggest you connect your two batteries in parallel, go camping and see how it does using the converter. It often happens on forums that people read what others are doing and think it is necessary. Any modern RV is capable of performing fine for the average owner just the way it comes from the factory.
  • time2roll's avatar
    time2roll
    Nomad
    Apr 09, 2014
    DSMC Whiz wrote:
    I am planning to use the generator only when boondocking, but I want to be able to recharge the batteries at a quick pace, and from what I understand, it is much quicker to charge them directly, then it is to charge them if I plugged the generator through the TT power input.
    This will depend on the converter and wire connection in the RV vs. what portable charger you plan to use.

    I recommend upgrading the converter if needed long before fiddling with a portable charger. Although with the right equipment you can get a pair of low batteries to 90+% charge in about three hours of generator time with either system.

    And I will give a plug for 100 to 300 watts of solar to reduce the generator time to the point you may start leaving the generator at home or running only to use the microwave etc.
  • time2roll's avatar
    time2roll
    Nomad
    Apr 09, 2014
    DSMC Whiz wrote:
    I guess that there is no way to charge them in serial on the TT while still running them in parallel, is there?
    NO
  • mbopp's avatar
    mbopp
    Explorer
    Apr 09, 2014
    I have two G29 12V batteries wired in parallel along with a marine-grade disconnect switch.
    What make is your converter? If it's a WFCO then using a separate battery charger may give you better charging / shorter run time on a generator. WFCO's aren't known for readily going into "boost" mode. If you're going to use a separate charger I'd disconnect the factory converter from the circuit either by a battery disconnect switch or putting the converter on its own AC circuit breaker.

    My previous HTT had a cheap single-stage Elixir converter. I supplimented it with an IOTA deck-mounted 55A one. On the new TT I mounted the IOTA to the ceiling of the front pass through which gave me a 3' cable run to the batteries. I put the factory WFCO converter on its own breaker so I can turn it on or off, it's off when using the genny and IOTA for boondocking battery charging.

    Converting to LED lighting can go a long way towards conserving battery power. I put LED's in the new TT before its first trip.
  • DSMC_Whiz's avatar
    DSMC_Whiz
    Explorer
    Apr 09, 2014
    I am planning to use the generator only when boondocking, but I want to be able to recharge the batteries at a quick pace, and from what I understand, it is much quicker to charge them directly, then it is to charge them if I plugged the generator through the TT power input. At home, I do have a pretty good lower amp tender that I use for my motorcycle, and it had various modes for other batteries. Thanks for the advice to just keep them on there in parallel while at home.

    Beemerphile, you are right, 12v in parallel is still 12v. I guess that there is no way to charge them in serial on the TT while still running them in parallel, is there? Being that the case, are there suggestions for higher amperage 12v chargers that I should consider using while boondocking, or do I just take the home charger with me?

    Thank you for your counsel. There is so much to learn still.
  • beemerphile1's avatar
    beemerphile1
    Explorer
    Apr 09, 2014
    DSMC Whiz wrote:
    I apologize. I meant to say running them in parallel is the goal, not series. I am looking to maintain the 12v system. The 24v charger would be so that I can charge both batteries at home, and via the generator, at the same time.


    No need, just charge them separately or in parallel.

    Two 12v batteries in parallel are still 12v.
  • time2roll's avatar
    time2roll
    Nomad
    Apr 09, 2014
    DSMC Whiz wrote:
    I apologize. I meant to say running them in parallel is the goal, not series. I am looking to maintain the 12v system. The 24v charger would be so that I can charge both batteries at home, and via the generator, at the same time.
    For home maintenance get a 12v Battery Minder brand charger and leave them connected in parallel. The small ~1.3 amp is fine.

    Why use the generator at home?
  • DSMC_Whiz's avatar
    DSMC_Whiz
    Explorer
    Apr 09, 2014
    I apologize. I meant to say running them in parallel is the goal, not series. I am looking to maintain the 12v system. The 24v charger would be so that I can charge both batteries at home, and via the generator, at the same time.
  • westend's avatar
    westend
    Explorer
    Apr 08, 2014
    Do you plan to full-time, boondock a lot, or have plans for a large solar array? Going to 24 volt has some intricacies to overcome and usually isn't done with a small bank of batteries. I'm just curious about your need.

    I'm thoroughly convinced that the easiest and most effective way to have TT power and keep the batteries charged is to use solar. I know it isn't for those with a totally shaded spot but, once set up it is virtually a no-maintenance system. There is no moving batteries, no running of auxiliary chargers, solar treats the batteries better, and once past the capitalization, free power.

    If you're going to quick connects for the outboard charger, Anderson Powerpoles are a good connection system. A hydrometer is a good tool for battery maintenance, Frease Glass Works has made the industry standard for decades.

    You do know that, if going 24V, you'll have to dismiss the converter that is in your rig and have a DC-DC converter that feeds all of the appliances, lights, fans, pumps, emergency brake system, etc.?
  • 2oldman's avatar
    2oldman
    Explorer II
    Apr 08, 2014
    I have 8-12v AGMs in a 24v array, so there's no maintenance. Here's my 24v charger. It can take many hours to charge. I also have 800+w of solar.

    My trailer's system is 12v (aren't they all?) so I use one of these little guys to step it back to 12.5vdc.

    I don't know if 24v is all that much more efficient, but it's nice to not have to wrestle with wire the size of your thumb.

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