Batteries won't hold charge - need help

[sgordon_lazydaz]

Hi All,

Newbie here so please excuse any ignorance. I have a 1992 class c Lazy Daze with a Chevrolet G30 cab.

I purchase her in March and drove every week/weekend with no problems for about 3-4 months. Went to go move her one day and both car battery and house battery were completely dead. Discovered I had left a small fan on for two days (oops) so it made sense. I replaced both batteries and made sure nothing else had been left on. Drove around for a couple days, then- bam - wouldn't start again. Both batteries dead- this time nothing was left on and nothing was draining power. Had a mechanic come out and alternator was reading as dead so I had the alternator replaced and once again replaced both batteries- started up no problem. Next day I drove her for about 3 hours, still no problems. Day after that, both batteries dead again. After doing some research I discovered the purpose of the isolator. So, my question to you all is- do we think if I replace the isolator (seems easy enough to replace myself) that this will solve the problem? Or do we think it's necessary to have it towed to an RV mechanic? I'm in a bit of a tight spot as I'm in the process of moving into her full time and leaving a failing relationship so will take any help I can get to have this fixed asap.

I've gone ahead and ordered a new isolator (same as the current one installed - diode) that will arrive tomorrow. I will try and replace my car battery though Autozone warranty for the 4th?? time but not sure if they will give me another within the warranty.

Please help!

[sgordon_lazydaz]

Hi everyone. Ole girl is back on comms 🙂 Sorry for the delay as the past month has probably been the most difficult of my life. I'm settled now full time in my RV at a park. I wanted to thank this community for helping me trouble shoot this and let everyone know that the problem was indeed a bad isolator. Hope this helps anyone who is having the same issue.

Sorry again for the delayed response.

[Grit_dog]

Looks like ole boy went non comm

[Bordercollie]

Try to find a good RV electrical systems technician. Some RV repair shops can refer you to a good one. This may save you a lot of frustration and get the problem(s) isolated and corrected quickly. Watch what the tech does and you may learn from it. Good luck!

[Bordercollie]

Call some RV repair shops and ask for the number of a good RV electrical troubleshooting/repair guy. This may cost some money but may solve the problem quickly. You will eventually learn how the chassis alternator charges the house battery(s) and chassis battery while you are driving, and how the converter/charger converts 120vac "shore" power to 12volts to charge your house battery(s) and power your internal lights, furnace blower, fresh water pump, appliance controls, and other 12 volt DC items. Not simple but critical to enjoying your RV.

[Grit_dog]

Lotta possibilities here, including the advice to find the "drain" on the batteries.
Look back at probability of that though. If nothing was draining the batteries a few months ago, what have you done since, that would?

I'll list a bunch of stuff to be mindful of or check
1. "New" alternator could be bad. Strong chance if it actually, assuming it's a reman alternator. If since the alternator, you only drive it a few hours, could be enough juice used to kill the batteries.
2. Dead battery doesn't necessarily mean it needs to be replaced, although deep discharge doesn't help the longevity. Do you not have a simple battery charger and somewhere to get power from?
3. Disconnect house battery and run it (with start battery charged). Does the starting battery go dead without being hooked to the "house?" And vice versa. Charge house battery, disconnect it from the isolator and does it just go dead or not?
4. How hacked up is the electrical in this unit? The more jerry rigged it is, the more chance of an errant power draw or bad connections, etc.
5.

[pianotuna]

Test the isolation device before replacing it.

I prefer a solenoid for disconnecting house from starter.

[2_many_2]

Some older RV refrigerators have this:
"The climate control switch (sometimes called a humidity switch).is used to control frost that may collect during very high humidity situations. The RV refrigerator climate control Switch controls a 12-volt heat tape behind the metal frame around the refrigerator and freezer doors."

This switch is often a small toggle switch semi hidden on the frame of the door on the fridge. Even when the fridge is off, if this switch is left in the "On" position, it continues to draw power.

This was a common problem when the switch was overlooked causing dead batteries for seemingly no reason.

[bobndot]

Still a bit confused on how to check where the source of drain is coming from as this is all new to me but will study over everyones notes and try and locate the power drain.

You can use an inexpensive multi-meter . Hook up meter using the amp setting. Disconnect the negative cable off battery of choice to test things on the coach or chassis side.
Hope this vid helps and explains the ‘how to use’ a mm to test.

https://youtu.be/KF1gijj03_0

[bgum]

You installed an inverter is that when your problems started?

[Gary45]

Just remove the (charging) wire from the house battery, you should be able to charge the vehicle battery and start it. You can hook your charger up to vehicle ground and the disconnected house battery charging wire to charge house battery. Then one of the batteries will discharge quickly pointing you to the problem.

[sgordon_lazydaz]

Capacitor,

This may be a stupid question but if I remove all the wires from the isolator, can the alternator still communicate with the car battery to charge it or is it wired alternator>isolator>battery(s) ?

Gary,

This is the charger I have- I've only used it on my house battery but can try with the car battery.

https://www.amazon.com/gp/product/B0797KK3N2/ref=ppx_yo_dt_b_asin_title_o06_s01?ie=UTF8&psc=1

Still a bit confused on how to check where the source of drain is coming from as this is all new to me but will study over everyones notes and try and locate the power drain.

[Gary45]

The isolator is the only place where the house battery is connected to the vehicle battery, should be 3 wires/connections, disconnect the wire from the house battery. There will be a wire from the alternator, center connection on mine and a wire going directly to vehicle battery. If you disconnect house connection at least both batteries will not drain.
Do you have a battery charger or jumper cables, odds are the problem is on the house side.

[capacitor]

The isolator may be bad allowing the coach bat to drain the chassis bat but this doesn’t explain where the drain is. Remove wires from the isolator and charge coach bat. Once completed check voltage and check again in a few hours. You need to find where the drain is, coach or chassis.

[sgordon_lazydaz]

Copy that- thanks so much for the tip.

I've purchased the terminal disconnect switches and will replace car battery in the mean time.

Love this community!