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chunker · 04-07-2019, 06:56 AM

I'm in a confusing voltage issue with charging and regulated volts. History. This winter I replaced both chassis batteries and removed one house battery that was bad. Chassis batteries were marginal weak and 4 YO. We started on a trip yesterday and I'm having fluctuating volts shown on the dash voltmeter. 13.5-12.5. This developed after about an hour. Stopped at a rest area and my walk around showed the towed light cable had come loose from it's position, fell to the pavement, and was in two shredded pieced. Before going out I had checked the EMS inside and had low house voltage so I fired up the generator. I was also getting some fluctuation voltages on the EMS and it showed "hot" battery. When I disconnected the lights cable from the coach, the fluctuations stopped, hot light went out, and got normal charging from the generator.

After our lunch we started back out with the generator off and everything is normal except that later in the day under light engine load, decelerating and/or idling I'm getting some voltage fluctuations again. 13.5 - 12.5. I speculate that part of my fluctuating volts and erratic charging was caused by the power cable which frayed and shorted. After arriving in NOLA, I checked the EMS and had the "hot battery" light, inverter/charger message said no charging due to the fault and house batteries were just under 12V. When I plugged into shore power everything went normal. Hot light out, normal bulk/float modes. Next morning everything normal in the flat mode.

Any suggestions on why I might be getting the fluctuating charging volts while driving. Something similar happened 2 years ago when crossing Kansas on a hot day. Stopped at a Walmart for the night and had to put fans in the battery compartment to "cool" things before the hot light went out and the batteries would accept a charge. I did not have a repeat problem the rest of the trip. Last years trips had no issues except for some slow starting which prompted the battery replacements. Yesterday temps were in upper 70's. I'm in NOLA for a few days then off to TX.

chunker · 04-07-2019, 06:59 AM

Adding: I got some butt slices and repaired the cable so now I'll have brake/turn signal lights for the Jeep. Didn't like heavy NOLA Saturday afternoon traffic with no towed lights.

**Spdracr39** · 04-07-2019, 07:06 AM

Make sure you check the water levels in all the batteries including the new ones. You could also have a loose connection on either hot or ground side.

chunker · 04-07-2019, 07:15 AM

Quote:

Originally Posted by spdracr39

Make sure you check the water levels in all the batteries including the new ones. You could also have a loose connection on either hot or ground side.

I am going to do that today. The new ones are sealed so nothing to check. I'll recheck the house batteries. I previously had 3 and one was bad, really bad, so removed it from the bank. This trip won't involve any real boon-docking so I'll manage with 2. When we get back I'll probably go with 4 GC2 6v. When I did all the battery servicing this winter I had all cables off, cleaned the trays, etc. so I may have left something loose. Sure hope that's it. Thanks for the reminder.

EDIT; One house cable connection wasn't as secure as I like so I loosened all connections one at a time, wiggled the on the posts and retightened them. Water in house batteries good. We'll see what happens Tuesday

Jon_C · 04-07-2019, 08:19 AM

Im just wondering if the voltage regulator in your alternator is starting to go out? I have a hi amp output slternator and my volts run around 13.7 to 14 on my scangauge while driving.

And check your alt belt make sure its tight and not slipping. A bad belt tensioner could also be culprit.

Pkease let us know what you find and if u need additional help

barmcd · 04-07-2019, 08:31 AM

Replacing one battery in a bank of 2 or 4 is not the recommended procedure It normally leads to the new battery failing pretty quickly.

chunker · 04-07-2019, 08:42 AM

Quote:

Originally Posted by barmcd

Replacing one battery in a bank of 2 or 4 is not the recommended procedure It normally leads to the new battery failing pretty quickly.

I didn't replace one battery, I removed 1 from the house bank. Remaining 2 were load tested good/excellent and similar ages. I replaced both chassis batteries with 2 commercial GP31 batteries. House are typical "dual purpose" ?deep cycle? GP29 and they'll be replaced within a year, sooner if they fail.

chunker · 04-07-2019, 08:49 AM

Quote:

Originally Posted by Jon_C

Im just wondering if the voltage regulator in your alternator is starting to go out? I have a hi amp output slternator and my volts run around 13.7 to 14 on my scangauge while driving.

And check your alt belt make sure its tight and not slipping. A bad belt tensioner could also be culprit.

Pkease let us know what you find and if u need additional help

Belt was replaced last fall along with fluid servicing and had them check the pulleys and tensioner. Those good. Guess I won't know if my issue is resolved until Tuesday when we hit the road again. I had considered the voltage regulator and I assume it's a regulator that is on the alternator. Not an electrical guru. On a Corvette I had many years ago, 69, it was a replaceable regulator without replacing the alternator as I recall but been a while obviously. I have had the coach 4 years and the 13.5V has been a consistent driving voltage read on the analog gauge and a digital readout module. Same readings on the EMS.

Ljwt330 · 04-07-2019, 09:08 AM

I had thought of the alternator/voltage regulator as well, except that you were getting the "hot battery" light on your EMS and the house batteries would not charge.

Just a guess, but you may have an issue with the isolator relay or whatever device you have that enables charging the house batteries from the alternator. Worth a check, IMO.

Gary RVRoamer · 04-07-2019, 09:14 AM

The engine alternator is only loosely regulated and typically varies from 13.6 to 14.4 in normal operation. It's not a sophisticated multi-stage regulation like most newer RV systems. It just ramps u p the volts and lets the batteries self-adjust the amp rate according to their state of charge. Works fine for starting batteries, but only adequate for house charging.

The hot battery light indicates a battery that is unable to accept a normal charge, regardless of source. Low on water, sulphated plates, etc. Get your house battery bank squared away and see if there is still a charging problem. I suspect not.

chunker · 04-07-2019, 09:38 AM

Quote:

Originally Posted by Gary RVRoamer

The engine alternator is only loosely regulated and typically varies from 13.6 to 14.4 in normal operation. It's not a sophisticated multi-stage regulation like most newer RV systems. It just ramps u p the volts and lets the batteries self-adjust the amp rate according to their state of charge. Works fine for starting batteries, but only adequate for house charging.

The hot battery light indicates a battery that is unable to accept a normal charge, regardless of source. Low on water, sulphated plates, etc. Get your house battery bank squared away and see if there is still a charging problem. I suspect not.

4 weeks ago I was doing the battery servicing and that's when I load tested everything and made the current changes. Both house are good on fluids, load tested strong, and the area cleaned up. I can't help but think that the shorted towed cable was part of the culprit. I did recheck and tightened all the cables. One was not as snug as I like. If these batteries continue to act up I'll replace them along the way. I also wonder if the temperature sensor could be giving a false indication preventing the batteries from accepting a charge. I forgot my IR thermometer but will get one soon. Batteries were cool to the touch but my hands are not calibrated for battery testing.

Gary on these alternators do you know if the VR is a separate replaceable unit? I googled the topic and saw some examples. Fortunately I have a side radiator but access to the back of the alternator will still be tight. Meanwhile we are heading into NOLA for a fun filled day before the storms hit this afternoon.

Dutch Star Don · 04-07-2019, 11:00 AM

If your house batteries are the originals, they're way past needing replacement. If they've been replaced once, they're still long in the tooth (6 yrs). There is room in your coach to install (4) six volt batteries. Go to Costco or Sams Club and buy the four batteries. You don't need the most expensive for your use. I don't think you'll resolve your issues until the batteries are replaced. I think the overheating of your batteries is due to one being bad.

Since you'll be rewiring the system to take four batteries, just before you attach the last negative cable, run a volt meter from the main positive (+) cable is attached to the battery bank to where you intend to connect the negative terminal and ensure you have 12 volts, not 6, 18 or 24. This will tell you that you've connected the batteries correctly, before matching that last connection.

Jon_C · 04-08-2019, 06:47 AM

The voltage regulator will be part of the alternator i think its inside but not sure.

Jon_C · 04-08-2019, 06:52 AM

Don are the Sams batteries the good golf cart batteries? Im thinking about changing my house batts for more capacity and to “real” deep cycle compatibility.
Ive been looking at a trojan J185h ac so far.
Thank you. Maybe should have started new thread tho