Battery Maintenance ~ Best Practices?

azreddot · 10-13-2019, 08:03 PM

We have a 2015 Jayco WhiteHawk. There are two 12dvc batteries on the front frame of the trailer connected in parallel. After having some issues with all the little parasitic draws (LED lights on radio, TV, etc) I had my local battery shop install a master on/off switch tucked inside the A-frame of the tongue about two years ago. Been trying to keep the water topped off. We camp year round so removing them between trips is not particularly convenient.

I went out today to check them, as its been over a month since I checked on them. My multimeter said they were at 11.8 volts, not good as I've been reading.

As a regular matter of practice, Would it be better to (A) plug into shore power and let them charge that way or (B) use my battery tender instead?

If I use the battery tender (which I also use on my boat) should I disconnect the batteries from each other, keep them connected but alternate which battery I attach the cllips to or will they charge both simultaneously? I saw on the Deltran website a diagram that place the positive clip on one battery and the negative on the other.

I don't keep the tender on continuously as the trailer is parked in front of my house and would require I always have an extension cord running across the front yard, possibly attracting unwanted attention. Plus it gets used on the boat batteries. So as far a frequency of charging should this be a monthly maintenance effort?

RetiredOne · 10-13-2019, 08:23 PM

The first thing you want to check is to see if the charger is actually working on the rig. Take a voltage reading, then plug into shore power, and take a second reading. Hopefully you'll see the voltage increase, otherwise, then you'll know why the voltage is so low on the batteries.

Second, you can use the battery tender to charge both at the same time. Doesn't matter, when hooked up in parallel which posts you use. Keep in mind, it will take a while to bring both up (possibly a few days), since the battery tenders don't have a high output. I would try to get them back up to charge with the onboard, higher amperage, charger.

Once you get them topped off, then you could probably put the battery tender on maybe once a week to keep them topped off, unless you have a big parasitic load, that's pulling down the charge.

**JFlightRisk** · 10-13-2019, 08:26 PM

The converter in your Whitehawk is a multi-stage charger/maintainer, just like your battery tender. You sure can leave the TT plugged in, and your batteries will be/stay charged.

A 12 volt battery with a reading of 11.75 to 11.89volts is considered essentially dead. Not a good thing, but try to put a charge into them, and see if they do come back. Let them rest for a day, and then check them again for signs of life. If resting voltage ever reaches 12.1, they have deep-discharged one cycle and that a battery is good for only so many cycles, with the typical RV/marine battery good for no more than 30 cycles.

On disconnecting the batteries from each other, if they are the same brand, age, and same state of voltage, yes, you can leave them connected to each other, if you want to use the battery tender. If one is consistently weaker than the other, then separate them first.

In the winter, I pull the TT, and motorcycle batteries, and they get stored down cellar in my shop. I alternate the tender on them for a month at a time. It's been working well that way for a long time.

azreddot · 10-13-2019, 10:42 PM

Thanks guys. The batteries were shut 'off' with the master switch these past few weeks. Wondering if we have another draw on them that I'm not aware of. I'll check them first thing in the morning and then swap out the battery tender and plug in the trailer to the house just to try and get a better charge and see if I can recover them before our next trip.

**JFlightRisk** · 10-13-2019, 10:49 PM

If you want to test for a draw, take the positive cable off the post, and put a 12v test light in line between the cable end, and the battery post. If the test light lights up, there's a current draw from something. Pulling the fuses one at a time until the test light goes out will isolate the circuit that's still live.

freetime58 · 10-14-2019, 06:56 AM

Quote:

Originally Posted by RetiredOne

you can use the battery tender to charge both at the same time. Doesn't matter, when hooked up in parallel which posts you use.

It does kinda' matter, in parallel set ups for optimal performance and longevity, it's advisable to use the + post of one battery and the - post of the other battery to draw power and/or when charging. That way the two batteries perform better as one big battery, both charging and/or discharging equally........if you just use the posts of one battery, that battery will always discharge further that the other(s), likewise that battery will always charge more than the other(s).

I know you'll find many folks that say it's doesn't matter, many sites that say it can be done either way, but most will agree that using the + and - posts on separate batteries is just the better way to do it.

RetiredOne · 10-14-2019, 11:11 AM

Quote:

Originally Posted by freetime58

It does kinda' matter, in parallel set ups for optimal performance and longevity, it's advisable to use the + post of one battery and the - post of the other battery to draw power and/or when charging. That way the two batteries perform better as one big battery, both charging and/or discharging equally........if you just use the posts of one battery, that battery will always discharge further that the other(s), likewise that battery will always charge more than the other(s).

I believe that's an old wives tale. The batteries are connected together by cables. When you clamp on the charger to the posts on a single battery, it's an immediate charge to the second battery, as if they are one.

Not sure why someone thinks putting the clamp on the opposite battery makes a difference, they are cabled together, and will accept the same voltage/charge, unless there's a internal issue with one of the batteries. That's the ONLY way one will discharge more than the other, it's not because of how the charger is hooked up.

freetime58 · 10-14-2019, 11:15 AM

Quote:

Originally Posted by RetiredOne

I believe that's an old wives tale. The batteries are connected together by cables. When you clamp on the charger to the posts on a single battery, it's an immediate charge to the second battery, as if they are one.

Not sure why someone thinks putting the clamp on the opposite battery makes a difference, they are cabled together, and will accept the same voltage/charge, unless there's a internal issue with one of the batteries. That's the ONLY way one will discharge more than the other, it's not because of how the charger is hooked up.

You're not correct............hopefully this helps you understand.

https://www.impactbattery.com/blog/t...s-in-parallel/

kweinert · 10-14-2019, 11:26 AM

I hadn't really heard about the connection point so I just did some looking.

It's at about 2 or 3 to 1 that recommend having the positive and negative coming from the end batteries (and not the same battery) in a parallel situation.

Of course there's no real way to know how old the information is, nor how reliable it is. This is the internet after all

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