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Joelene

Coach battery not charging

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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

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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.

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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!

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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.

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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.

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

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I just did this today.

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

post-4544-012402000 1296358558_thumb.jpg

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

post-4544-036493700 1296358595_thumb.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.

post-4544-090425700 1296358663_thumb.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

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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.post-669-012708800 1296404972_thumb.jpg

post-669-027520100 1296404906_thumb.jpg

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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

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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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Sounds like a good time to learn some new tricks. If its an inexpensive digital voltmeter, your in business.

Open the hood and read the voltage on the truck battery terminals without running the engine (red meter lead goes to plus, black to minus)

then start the engine and read it again.

Do the same on the coach battery. measure it without the engine running, then again with the engine running.

Post your readings and I guarantee, you'll get many ideas on whats wrong.

Do NOT plug into shore power when you take these readings.

John Mc

88 Dolphin 4 Auto

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I do have a volt meter just have to figure out how to use it ; ) or get some qualified help.

All you'll need to know to start is how to test for voltage (AC & DC) and continuity/resistance. :ThumbUp:

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Hey Waiter; When we previously discussed battery charging, isolator etc you sent me 3 pics. The middle pic, bottom right. That is where a fuse is correct? Could it be a little circuit breaker? Do you know what fuse should be rated at? Also, getting ready to order isolator. Do these have different ratings (electrical)? Saw something very similar on Napa but it was isolator for elec brakes on a tractor trailer. I am going to order from Amazon but they had a little fuse box there that looked like that little fuse, but it was a little breaker and it said on Amazon, that the two were usually bought together. Want to have evrything I need before I start. Haven't looked at that tiny fuse yet. Do I need to know anything about my alternator for selecting the isolator? Thank you so much, Joelene

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The isolator is $20 and it is very rusted looking. Needs to be replaced anyway whether it works or not cause if it's not bad now I'm sure it will go soon. Thanks again!

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Circuit Breaker - probably 40 amp ( Camco 65200 or similar) (Should be rated slightly less than your alternator, i.e. if your Alternator is rated at 50amps, I would go with 45 or 40 breaker.

Does your isolator look like the one I have i.e. Small can with two big terminals and one small terminal. Be very careful as sometimes these things get confused as a strater relay.

This is the one you want:

http://www.rvtruckparts.com/ProductDetail.asp?PID=20563&SID=88&DID=131&CID=218

John Mc

88 Dolphin 4 Auto

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OK, heressome measurments. Something just doesn't sound right;

truck battery 12.6 off

14.2 -14.4 on

coach battery 5.0 off

11.65 w/ truck running

. Thank you for all the help. Joelene

at isolator 1.95 on

7.54

I measured at the isolator on the left post (to battery) and the right post which goes to another small fuse box (?) on the metal by the firewall; the middle post appears to be spliced into a group of wires coming from the alternator

Can anyone diagnose me with just this info

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isloator 1.95 running and 7.54 off but both these reading were fluctuating on the meter. Thank you everyone! Joelene

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truck battery 12.6 off

14.2 -14.4 on

coach battery 5.0 off

11.65 w/ truck running

If these readings were taken at the battery's, they look like they could be real. (not OK, but real)

The truck battery looks OK and appears to be charging (12.6 OFF 14.2 ON)

Readings from the coach battery terminals (5.0 OFF 11.65 ON), the Coach battery is DEAD DEAD DEAD :thumbdown: :thumbdown:

It appears that the isolator is switching, because we see the coach voltage raise.

With the truck running, the reading at the coach battery should be close to the truck battery, IF the Coach battery is fully charged.

However, If the coach battery is drawing a lot of current (its trying to charge) you could see a voltage drop in the wires between the truck and the coach battery.

There could also be loose or bad connections in the coach battery circuit, i.e. circuit breakers, fuses.

*** With the truck running, measure the voltage (to ground) through the entire coach charging circuit at the following locations.

Truck Battery

Truck side of breaker (mounted on fender)

Coach side of breaker (mounted on fender)

Truck side of isolator

coach side of isolator

Truck side of circuit breaker (may be mounted on coach battery box)

Coach side of circuit breaker (may be mounted on coach battery box)

Coach Battery

My coach battery box is located under the aft table bench seat. There are two circuit breakers, one for the battery and one for the cigarette lighter plug above the frig.

Because of the 5 volt reading on the coach battery, I suspect that your coach battery is DEAD and may not hold a charge. Usually when you draw a standard Lead Acid battery voltage down low, it greatly diminishes its chances of recovery.

isloator 1.95 running and 7.54 off

If these readings are at the two large terminals of the isolator, then you need to replace the isolator.

1.95 volts running - This is the voltage drop across the contacts of the isolator, this should be zero when the isolator is energized.

11.65 (Coach voltage) + 1.95 (isolator drop) = 13.6 volts (This is more like it. ideally, this would equal your truck voltage)

**************************

From what I have seen, you have two problems, a bad coach battery and a bad isolator.

John Mc

88 Dolphin 4 Auto

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Hey Waiter John; Thank you for your help and following my dilemma. RV sored at my friends house so can't get there every day. I have been trying to determine if my alternator is 60A. Believe it is original? from what I can read label says, "Toyota K Regulator builtin in 27060 650(2/7?)0" When I took last readings I figured coach battery was dead. Readings I took at the isolator were on the two larger bolts. The bolt on the right of the isolator looks like it has a little breaker there, very rust (haven't taken it apart yet), before it goes through the firewall. I will take readings on both sides of tghe breaker, as well and let you know. Now if my alternator is 60A, do I want that breaker to be about 50A? Saw Camco Manufacturer P/N: 65226 at rvupgrades.com. Trying for find parts locally in NJ. I have a Napa store near me and saw their part # UP 89685 (isolator) but I am not sure if this is the same part, as it states used for electric trator trailer brakes?...but it looks like the same part! Will send you some more readings asap and Thanks Again for the Help! Joelene PS When I bought this Rv in September the Seller told me the coach battery was brand new and I know it's probably toast for sure now now but I had coach power driving from Florida/ Alabama to NJ and had power for a little while when it was sitting. Didn't drive it since ....like Oct but have started it up every 3? weeks? Just some more background. Will send more readings soon and getting an education! Thanks, Joelene

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Good Deal.

If your Alt is 60, then get a 50 amp breaker.

Your battery may have survived - pull it out, check the fluid level if you can. put it on a charger and charge it up. From your previous readings, the isolator may not be allowing the battery to charge fully when connected to the truck circuit.

If your going to let the RV sit for weeks without being plugged in, Go through the coach and make sure everything is turned off. May not be a bad idea to either disconnect the coach battery or install a disconnect.

Make sure your frig isn't switched to 12 volts (some can run on the battery) Also make sure your furnace is turned OFF (the blower is 12 volts). Any aftermarket radios, TV Antenna Amplifiers, clocks that are connected to the coach 12 volt system could be running the battery down when its stored.

I leave mine plugged in to shore power, but unless you have a modern converter, (the thing that converts 110 Vac to 12vdc) leaving it plugged in will cook the battery as the older converters will overcharge the battery (This is the main reason I upgraded my converter)

John Mc

88 Dolphin 4 Auto

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I don't know how many amps alternator is. Will try to figure this out, later? It says Toyota on it, may be original....but got an isolator and 50A breaker today. Even if I have say, an 80A alternator....this should be okay but might blow faster???.... Have the new breaker in between the isolator and where that wire enters the coach. Will finish putting new isolator in tomorrow. No continuity in the old breaker. Found 2 more breakers mounted on the outside of my coach battery box. Will check them tomorrow but breaker from under the hood very rusted. Can I still install the 50A breaker there regardless? Thanks, Joelene 92 Dolphin

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Regarding the battery box breakers. One is in the battery circuit and the other is fir the Cigarette lighter plug..

You also have one more breaker behind the converter . that one is the converter supply.

Sound like youy got this narrowed down

John Mc

88 Dolphin 4 Auto

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