Trailer battery slow to charge
 

Over the last few days on our last camping trip, our deep cycle batteries needed charging. No big deal, but I ran the truck for about two hours every day for 3 days and the batteries never fully charged.

The most I ever got was 3 out of 4 lights on the battery gauge.

After the third time charging, and still only 3 lights, I pulled out the voltmeter and found that the voltage at the batteries with the truck running was 12.08 volts. Coming out of the plug was 14.2 volts.

In the next few days I'm going to try what the converter manual suggested, which is to disconnect the battery wires, then plug in the shore power and check that the voltage is 13.2 or 13.6 just to rule out the converter.

But that really only would matter if I'm charging with shore power, correct? Is there something I might be missing? Is it only supposed to trickle charge from the truck? If so, it still only showed 3 lights after a 5 hour drive home.

The batteries are brand new 6 volt Interstate deep cycles. The thing that gets me is I just installed all new led interior lights to reduce power consumption, but the batteries seem to discharge quicker than before, and I'm being even more power conscious now.

Just doesn't make sense. I think they chould be fully charged after about an hour.

Have you checked the plug connection between the truck and trailer they may not be connecting properly.

Different set up all together than yours but my battery in the trailer will give me power for days on end, I also have a solar panel on the trailer to help charge the battery.

One more thing to check, thanks!

Solar power is on my wish list, and will be asked about in a new thread later, just have to get this current wrinkle ironed out.

If you have 14.2 at the seven pin and only 12.08 at the trailer batteries you have a poor connection either at the seven pin or at the batteries. The output from the truck can be substantial and should be more than a trickle charge. With a reading of only 12.08 at the batteries they are not even being charged.

The converter output is irrelevant in this case as it plays no role unless you are on shore power.

Steve

What about water level in the batteries? Do these 6 volts still take distilled in them? I once had a battery that would discharge quickly and that was the reason for it.

Scott,

If I am reading the OP's initial post correctly, he has a severe voltage drop from the truck to the batteries, but you are absolutely correct. Batteries low on water or out of water will not hold a charge for long or at all.

If he has 14.2 at the seven pin, however, he should see that at the lead to the batteries. It is simple enough to test. Remove the lead from the batteries entirely and check the voltage on the lead. That takes anything to do with the batteries out of the equation. :)

Steve

Good read.

Hoping to check that out tomorrow.

Previously, just for my own curiosity, I checked the battery voltage before connecting the trailer cord, each was just under 5 volts. Series was just under 10. With the cord connected, voltage was 12.08. Voltage never came up, but I didn't check again because I disconnected and used jumper cables to charge instead.

What makes it inconvenient is the trailer is at my in laws house, so I can't easily check what it's doing.

The only thing I can think of is the voltage drop to 10 volts averaged with the 14.2 leaves the 12.08 I was seeing on my meter. Drove me batty when I was trying to figure out a lighting issue on a 24 volt system, and it's doing the same thing to me now.

I'll get it figured out, but like I said, it's not in a convenient location.

Normally seeing on 10 volts on a 12 volts series system means the batteries have gone to heaven as is also suggested by 12.08 when tethered. Just disconnect the batteries and verify you have no drop in voltage down the charge line on the seven pin. If you have your 14.2 without the batteries and the voltage will not come up above 12 volts, you need to replace the batteries, although it would be nice to know how many amps the batteries are sucking off the charge line.

I am assuming you have kept them watered.

One really nice thing to keep around is a smart battery chargers that will try to charge the batteries and tell you if it is not possible.

Steve

Would it be possible that the WFCO 8900 have a smart charger built in? I haven't plugged in since May or early June.

Virtually all charger now are smart chargers, but the type you buy at Advance tries to charge the battery for a few minutes and if it does take, they shut down and give a battery problem indication. The on-board charger will continue to attempt to charge.

You can also just load test the batteries after attempting to charge to determine if they are good, or just take them to Advance and have them test the batteries.

I agree.

Pull the batteries and take them to a auto parts store or local garage and have them do a load test on them individually.

since you said the batteries are new deep cycle, i am going to say there is nothing wrong with them besides being discharged.
my bet is a bad ground wire either from the batteries to trailer frame, or from truck to trailer .

I think you are likely correct, but may want to rule out all the possibilities. If the OP is running a shoreline when they camp and the batteries are not charging off either the shoreline or the truck, one would indeed think in terms of a bad connection at the batteries.

Any time I fix or change something and then there is a problem, I go back to the last thing I "fixed". :) If the batteries were just changed out, that is where I would start. One time though I did get two batteries and one was bad right out of the gate.

Fortunately an easy troubleshoot. :)

Steve

<p>Might want to check the wire between batteries. We have had those go bad at the connectors on farm tractors.
we have had bad batteries right from the start once in a great whilep>