Electrical system discharging WAY too quickly

[edpelo]

I’m having an issue with my electrical setup. A few days ago my system began going from a full charge to 50% overnight instead of in it’s usual ~3 days. We have been on the road for a little over 4 months without issue until now.

A little about my setup. I have two 124 amp hour Everstart deep cycle batteries in a vented box. The main draw on the system is a 12v electric compressor style fridge with a very efficient compressor. It draws around 40 amps in 24 hours. We also have a Fantastic Fan that we run at night if it’s hot. There’s a couple LED lights and a small pump for the sink but those are such small draws they’re not really relevant. The stereo and GPS are wired to the house batteries too, but we really only use those while driving and the alternator should be supplying the amps in that case - which brings me to charging.

We have a voltage sensitive relay that establishes a 1 way connection between the engine battery and the house batteries when we’re driving (and the engine battery is fully charged). I also have a 195 watt solar panel on the roof that pushes 15 amps in full sun. Finally, I have a inverter/charger for plugging into the grid.

I also have a device that senses when the batteries are at 50% and disconnects all loads. It has an override switch in case I desire to go past 50%.

Here is an example of what is happening now: I was parked at a campsite with electrical and plugged in overnight. The 3 stage charger indicated the bank was full. It was floating at 13v. I unplugged, then drove for about three hours. During that time it was also sunny. I parked and had maybe an hour or two of indirect light on the panel. At this point, normally, I could stay off the grid for about 3 days before the 50% switch would cut things off. It doesn’t even last through the night. I wake up to find the 50% switch kicked in and the system around 12.0v.

With three different functioning means of charging, I have to assume it’s not an issue with charging. That leaves either a bad battery or something sucking the life out of them. So, I figured I had a bad cell. I inspected the batteries and topped them off with distilled water. They seem fine. No heat, they read the same (connected or disconnected from the system). I even took them to a battery store and had them checked. My spanish is basic so I had a hard time determining what kind of test the guy did on them, but I did note the tester he used. I looked it up and it’s not a load tester, but it certainly appeared to be much more than a volt meter. It was a Bosch Bat131. The Bosch said they were both good. He used a hydrometer and showed me that they really needed charging.

I thought maybe the fridge was draining them, but I can hear the thermostat turn off and if it were running constantly we’d have frozen solid drinks. Again, this all points to a bad battery. Does the Bosch Bat131 provide a true indicator of a battery’s health? Any ideas on how to move forward from here?

My next step is to run only one of the batteries and see if things appear more normal. That would indicate which battery is bad. Tomorrow, I also plan on turning the fridge off. If one of the batteries is bad, I presume the system will still drain even with little to no load on it. Any other ideas? HELP!!! It’’s really hot in Costa Rica and the fridge and the fan are about all that make over landing here tolerable!!! 🙂

[wa8yxm]

Let me tell you about my setup, the reason for this will become clear shortly.

I have a pair of Interstate GC-2's set for replacement tomorrow
I have 3 Group 29's, All in parallel, feeding an inverter and the house.

Well, I park on both 30 and 50 amp sites, From time to time I've forgotten to turn off water heater when turning on Microwave with the resulting CLICK OF DARKNESS from the post outside where I'm plugged in.. The inverter held for like 30 seconds (not long enough) so i had to restart everythign when I got back in.

Doing some diagnosis, I found one of the G-29s had a shorted cell.. Replaced and all was good.

Then more recently it started happeneing again, only now instead of holding 30 seconds it was more like 0.30 seconds.. Yup, one of the GC2s has a shorted cell.

So, why am I typeing this.

Sounds like one of your Everstarts has a shorted cell.

[Duck]

I only have a basic battery setup. I keep it at a storage lot when not in use and noticed that the battery voltage was dropping a little each week. Pulled the two batteries out and found that one of the batteries was bad. Took the good one home and charged it and it was still holding the charge a few weeks later.
Don

[Admin]

Moved from Class B - Camping Van Conversions

Admin
RV.net

[edpelo]

booster wrote:
Check the voltage at the batteries while charging, it should be within .1 volt of what you see at the charger or solar controller output.

I'll double check this tomorrow just to be sure

[edpelo]

CloudDriver wrote:
One additional thing to test - make a note of the voltage at the chassis and house battery terminals, then start the engine and check the voltage at the chassis and house battery terminals again. The voltage at the chassis battery will rise if the alternator is working. If the voltage of the house batteries doesn't rise to be close to the chassis battery, you aren't charging from the alternator while driving.

Our Class C has a relay that connects the chassis and house batteries together when the ignition is on. In 11 years, I have replaced this relay three times because charging of the house batteries became unreliable.

I have a volt meter wired from the house batteries to my dash so I can see it while driving. Soon as I fire up the van I can the see the voltage increase. Lately the batteries have been so deadened that they only show 13+ for a bit before getting to around 14.3, but I've checked with the volt meter and the alternator is definitely sending 14. (My dash volt meter is cheap so the numbers aren't super reliable but it's clear the relay opens).

[CloudDriver]

One additional thing to test - make a note of the voltage at the chassis and house battery terminals, then start the engine and check the voltage at the chassis and house battery terminals again. The voltage at the chassis battery will rise if the alternator is working. If the voltage of the house batteries doesn't rise to be close to the chassis battery, you aren't charging from the alternator while driving.

Our Class C has a relay that connects the chassis and house batteries together when the ignition is on. In 11 years, I have replaced this relay three times because charging of the house batteries became unreliable.

[edpelo]

DavisK wrote:
Your charger is not on while you're on the inverter is it? It will drain the batteries trying to charge them.

Yes and no. It's a combo inverter/charger. It can charge while acting as an inverter. Tonight I'm charging them charge only setting rather than the both setting, though the both setting has worked prior till now.

[edpelo]

Handbasket wrote:
Have you checked both ends of the ground cable for clean & tight?

You know, I checked every single cable and connection except for the actual ground to the frame under the van. I will check that first thing tomorrow. Good thought.

[booster]

Take a good look for bad connections. If you have high resistance to the batteries, the voltage of the charger and solar will run higher and kick them into float early, leaving the batteries much less than full.

Check the voltage at the batteries while charging, it should be within .1 volt of what you see at the charger or solar controller output.

[DavisK]

Your charger is not on while you're on the inverter is it? It will drain the batteries trying to charge them.

[Handbasket]

Have you checked both ends of the ground cable for clean & tight?

You might want to ask the mods to move this to the tech section for more attention from numerous tech people. They'll probably want to know some more info, like what van this setup is in.

Jim, "The sooner you fall behind, the more time you'll have to catch up."