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Coach battery not charging


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#1 Joelene

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Posted 29 January 2011 - 11:53 AM

I have a 1992 Dolphin 6 cyl. Recently drove it from Alabama to NJ. Was told the coach battery was brand new which I believe. Coach battery was functional (appeared to be) on the drive home. I was told the coach abttery charged while you were driving. That was a couple months ago. Have started the RV from time to time w/o difficulty, in order to charge the coach battery (so I thought). Now I have no lights etc in the coach. Will the coach battery charge just from idling. I am also told that there may be a switch (on the firewall?) to charge the coach battery.... I believe it turns on and off to prevent draining the truck battery. (Is that what an isolator is?) Also I saw on carfax that there was electrical check of the coach several years back. Can anyone tell me about this switch.....where it is, what it looks like? Also is this 92 Dolphin known for electrical problems? the only thing that works on my monitor panel is the black water reading. Is it possible that this has something to do with it? Is the switch that I was told that was on the firewall inside the engine compartment side or the coach side? I know I sound totally stupid....but I am new at this....and it's not tlike I have any reference manuals etc....any suggestions on that....anywhere to acquire copies? Any help would be soooo much appreciated. Thank you, Joelene in NJ Also could switch be inside battery compartment? I pulled battery out slightly....it's a tight fit....could I have tripped some switch by doing this? Thanks!

Edited by Joelene, 29 January 2011 - 11:57 AM.


#2 Maineah

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Posted 29 January 2011 - 02:02 PM

Yes you have some type of isolator there are two types the most common one is a relay type it turns on with the key with a fair loud click. The other type is solid state and will look box like with cooling fins and several wires connected to it both types will be under the hood some where. With out a volt meter you are kind of in the dark (no pun intended)as to what is going on so if you can find some one with some electrical knowledge it not too hard to sort out. The ideal with any type of isolator is to allow both batteries to charge while the engine is running and separate them when it's not so you don't kill the truck battery while you are parked. There are other little parts involved with the system too that will have to be investigated along with the isolator to make sure it all works correctly. Have you tried plugging the MH into a house outlet to see what happens? There is an on board charger that works if you are plugged in that makes power for your lights too. The monitor panels are notoriously inaccurate and should have no effect on your charging issue.

#3 Derek up North

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Posted 29 January 2011 - 02:07 PM

The isolator is normally located under the hood near the engine's battery. There should be a thick wire from the alternator to the isolator. This brings the 'juice' from the alternator to charge the batteries. I works like a switch. From the other side of the isolator there should be t more thick wires. 1 goes to the truck battery, giving it juice to charge it. The other will disappear down under the firewall on it's way to the coach battery. There should also be a 4th smaller wire which will bring a 'signal' from the engine to tell the isolator that the engine is running. With no 'signal', using the coach battery will NOT drain the truck battery (so you'll be able to start the truck). With the engine sending a signal to the isolator, juice will flow to BOTH the truck and coach battery.

2 possibilities come to mind.

1 - bad isolator;

2 - The isolator is not getting a signal. (Has the wire been pulled off by accident? Is there a wire hear the isolator not attached to anything?)

Do you have ( or know someone) a multi-meter (aka VOM meter) and know how to use it?They're almost essential to troubleshoot electrical problem.

BTW, I hate electrical problems. But an alternator will charge (at idle) as long as the red 'ign' warning light on your dash is off. But not quickly!

#4 Joelene

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Posted 29 January 2011 - 02:29 PM

Thanks so much. I know about plumbing & electrical in the human body but not re autos. I will get some help and show then both your posts. I will look for isolator etc. Can do that on my own. I'm learning alot from this site from just reading others posts. Thanks again, will keep you posted of progress, Joelene

Yes you have some type of isolator there are two types the most common one is a relay type it turns on with the key with a fair loud click. The other type is solid state and will look box like with cooling fins and several wires connected to it both types will be under the hood some where. With out a volt meter you are kind of in the dark (no pun intended)as to what is going on so if you can find some one with some electrical knowledge it not too hard to sort out. The ideal with any type of isolator is to allow both batteries to charge while the engine is running and separate them when it's not so you don't kill the truck battery while you are parked. There are other little parts involved with the system too that will have to be investigated along with the isolator to make sure it all works correctly. Have you tried plugging the MH into a house outlet to see what happens? There is an on board charger that works if you are plugged in that makes power for your lights too. The monitor panels are notoriously inaccurate and should have no effect on your charging issue.



#5 dayoff53

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Posted 29 January 2011 - 05:00 PM

I had this same problem in my '92 Winnebago Warrior. Turned out the isolator was fine, but there was a circuit breaker inside the coach battery box that had been smashed by the battery the last time the battery was put in - a $5.00 part. It was a little tough to reach at the back of the battery box, but a cheap and easy fix. Your Dolphin may have the same problem, but the breaker (a little rectangular box held on with two screws) may be in a different location.
David in Idaho
'92 Winnebago Warrior WT321RL

#6 Joelene

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Posted 29 January 2011 - 06:18 PM

Everyone tyhank you so much....any more thoughts...keep em coming....I appreciate all. Joelene

#7 waiter

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Posted 29 January 2011 - 07:41 PM

I just did this today.

On my 88 Dolphin, the isolator relay in on the drivers side firewall.
BatteryBox4_Small.JPG


Theres also a fuse on the drivers side fender (lower right of the photo)
Cruise4_Small.JPG


and another fuse (2 fuses, one for the battery feed and one for the cigarette lighter) on the coach battery box. (you need to lift the cushions and the seat bottom to get to these.
BatteryBox1_Small.JPG



Before you start checking fuses, I'd take a voltmeter and measure the voltage at the coach battery.

Measure it with the engine running (13.5 - 14.5 volts), and also without the engine running.(12.8 13.5)

(If you can plug in AC, also measure it with the AC plugged in and the engine NOT running (13.5- 14.5)


You may find that your coach battery simply wont hold a charge. The voltage readings will tell you this.

JOhn MC
88 DOlphin 4 Auto

John Mc
88 Dolphin 4 Auto


#8 Maineah

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Posted 30 January 2011 - 08:30 AM

When I had issues with my coach charging system I decided that cheap little parts under the hood that rust were not the way to go so I moved the entire system in doors. I installed a device that replaces the standard solenoid it's called a combiner. This neat little solenoid is "smart" it relies on voltage to switch it. When the truck is started it will not connect the batteries until the truck battery reaches 13.4 volts for at least 2 minutes then it connects and charges both. After the engine is off it disconnects the batteries when the coach battery drop to 12.7 volts. It is bidirectional so when the charger/converter is working once the coach battery reaches 13.4 it connects the truck battery and charges it too. The length of the wire to the coach remained the same so there was no difference as far a power transfer I did however install a 40 amp fuse right at the truck battery to protect the wiring to the coach. If any one is interested most boat yards carry combiners.combiner.jpg

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#9 Joelene

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Posted 31 January 2011 - 04:38 PM

Thanks again everyone. It may have stopped charging after I pulled that coach battery out partially and shoved (not gently) back in. I did find the isolator mounted on the firewall, thankfully, because someone provided a pic. The little thing looks original (because it is significantly rusted and the connections look like they could be an issue too. I do have a volt meter just have to figure out how to use it ; ) or get some qualified help. Thanks again to everyone....you have al been great! Joelene in NJ

#10 Maineah

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Posted 31 January 2011 - 05:32 PM

Help would be good if this is some thing you have never done before it's a bit of a learning curve. There are probably a couple of small boxes that have wires on them that go to the isolator that are way rusty the nuts will most likely not come off with out destroying the little box (it is a circuit breaker) but fear not most parts supply shops have them they are 35 amp breakers.




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