Forum Discussion

mchero's avatar
mchero
Explorer
Nov 07, 2016

Charging my Interstate wet cells

Have a Xantrex Freedom inverter/charger that's not charging my Interstates at proper voltage. As per the specs Interstate guy handed me they should bulk up to 14.8 but looks like the Xantrx only gets them up to 14.2

Unfortunately, I cant set a custom charge rate on the Xantrex, just battery type.

During the day my Classic Charge controller charges them and I can set the proper charge rate. I did that last night and I'm waiting for them to go into float so I can get a proper temp corrected specific gravity.

We are off grid and in the PM when I start the genset for the evening charge I typically run the generator till the Xantrex kicks into float.

I want to get those buggers up to capacity so it looks like I'll be shopping for a 3 stage charger that I can custom program. I need one that will also output the amps so I don't have to run genset longer than needed.

Id LOVE to upgrade the Xantrex but currently don't have the funds.

Also, if the Interstates are toast it looks like I might be purchasing Sams Club 6 volts or perhaps pickup some t-105's

Suggestions welcome!

Thanks All!

28 Replies

Show More
  • MrWizard's avatar
    MrWizard
    Moderator
    Nov 07, 2016
    you might consider a little generator time early in the day
    to get some heavy amps in and raise the voltage
    then perhaps the solar would get them to 14.8 earlier in the day, so they would be at 14.8 for a longer period
  • mchero's avatar
    mchero
    Explorer
    Nov 07, 2016
    theoldwizard1 wrote:
    Trojan batteries also like a higher than typical bulk charging voltage (14.82V or 7.41V) for their batteries.


    EXACTLY, that's why I'm looking at an alternative to my evening charge. As stated above, one setting for wet. The T105's need the same 14.8 bulk, 13.5 float.

    Perhaps I could makeup a cheater plug for the temp sensor.

    I hear the Onan ramping down I think the Xantrex went to float....Yep

    Goodnight
  • theoldwizard1's avatar
    theoldwizard1
    Explorer II
    Nov 07, 2016
    Trojan batteries also like a higher than typical bulk charging voltage (14.82V or 7.41V) for their batteries.
  • mchero's avatar
    mchero
    Explorer
    Nov 07, 2016
    I'm having zero issues with the solar side. Does a fantastic job charging the Interstates during the day.

    It's when I start the genset for my "evening charge" the one that gets me thru the dark nights out here! The Xantrex is only pumping them up to 14.2 not the required 14.8 I think I'll pull the temp sensor to get a tad more Absorb voltage.

    I will take a look at BFL's suggestion.

    Solar got them up to 14.8 for about 2 hrs but then the sun starts to go down. so I can't use the Classic to do an EQ charge.

    If I pull the temp sensor it will Absorb at 14.4 Now "IF" I could somehow fake the temp sensor into thinking the bats where at 50 deg F it would Adsorb at 14.8

    Still trying to figure out what the Xantrex EQ voltage is


    Thanks guys
  • westend's avatar
    westend
    Explorer
    Nov 07, 2016
    I think you'll find that most 6v's crave a diet of voltages close to 15V when charging. If your solar can't fill them up, then you'll need an alternative. Those Megawatt power supplies will do it and aren't a budget buster. A mod to install a potentiometer is about all you'll need to get that needed voltage.
  • BFL13's avatar
    BFL13
    Explorer II
    Nov 07, 2016
    14.8 is the spec voltage for 25C/77F. When it is colder, that voltage is higher. More like 15.3 at 35F. You need a 14.8v charger with temp comp or else an adjustable voltage charger that you can set yourself as required.

    I use a PowerMax adjustable voltage model. They come in various amp sizes.

    EDIT I see you have four 6s, so you will want the 100 amper.

    To get their SGs back up, if they need "recovery" you will need to crank the voltage up to 15.5 and leave it there for some hours. Actually 16v would be better, but the PM ADJ only goes to 15.5, which is normally high enough.

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,366 PostsLatest Activity: Oct 05, 2023