Battery Boost

[alan1]

I just purchased a new to me 2007 MADP. First problem is I think a bad house battery or two, easy to fix. But all batteries are being pulled down, both house and chassie. My guess is the battery boost relay is bad and tying both together. Reasonable guess? Location is Elect. compartment, but it has two relays in it, which one is the battery boost?

[GaryKD]

Hi alan1,
This is, most likely, more than you wanted.

Go to the place you feel the relay is located and have a partner press the battery boost switch. You should hear a click. If you touch the relay you may feel it engage.

or

Unless you have found a smoking gun, I would not make the conclusion you have made. If you have a meter that can check AMP draw and VDC, for me, I'd get a baseline on the batteries:

0. Fully charge the batteries and take them to your auto parts store and put them under load. This will tell you the state of the batteries. Make sure the cells are correctly filled with distilled water.

or

1. Disconnect the chassis and coach batteries from the coach. Do not disconnect them from each other, just from the chassis and coach.
2. With a portable charger charge the chassis batteries to a full charge.
3. Disconnect the portable charger and fully charge the house batteries.
4. After a couple of hours take a meter reading across the chassis batteries. The reading should be 12.6 VDC or more.
5. Once fully charged remove the charger and let the house batteries set for a couple of hours. Take a meter reading and it should be the same as step 4.
6. Let the batteries set for a few days or up to a week if possible.
7. Take the same readings as in steps 4 & 5. The readings should be 12.6 VDC or higher for both readings.

If #7 is true then:
8. Turn off the coach and chassis battery switches (if you haven't done this already).
9. Reconnect the batteries to the chassis and coach.
10. Is there an AMP draw with the chassis and coach battery switches off? This would be more than the minimal drain caused by any parasite appliances. If so, you'll need to find the drain.
11. Turn the chassis battery switch to the on position and repeat the AMP drain measurement. It may be a bit more than with the switch off. However, the solar panel, on the roof should maintain the charge state for the chassis batteries.
12. Do #11 for the coach batteries.

If there is a AMP drain on either or both, you'll need to start pulling fuses until you find the guilty circuit.

If there is only the usual parasite drain or no drain, return to step 0 and check the batteries under load.

Lastly, your coach should have a B.I.R.D. If the coach is connected to shore power and the batteries are not holding a charge, suspect the charger or the batteries first.

[alan1]

GaryKD, thanks for the time spent on your post. I will feel and listen to the relays tomorrow. I need to add that I am on 50 amp power and that after disconnecting for a while to run both banks down, both banks charge at the same voltage. I thought the BIRD would prevent the chassis batteries from charging until the house batteries were up to a full charge.

[GaryKD]

Hi alan1,
You are welcome.

My BIRD works the same as yours. I can not say if this is correct or not. I never got into that much detail about the BIRD. I do know my charger has the capacity to charge both chassis and coach batteries at the same time.

I forgot to mention the weather in my previous post. Cold weather will play games with batteries. For me, if it is below 60 degrees F, I do nothing with batteries. Only after the temperature is consistently above 60 degrees F do I take and readings to determine a trend where action may need to be taken.

[alan1]

After having the wife hold the boost switch, I heard nothing. I located the fuse that powers the boost relay and pulled it, I then heard the relay open and both banks were on their own. The house batteries measured .45 volt (yes less than 1/2 volt). Chassis was 13+ volts. I thought I would need new house batteries when I bought the coach. Two batteries were made in 1/06 close the the date the coach was made. The other 2 were made in 1/02. I guess the prior owner put 2 of his old golf cart batteries in before trading. I will next check the dash switch to see if it went bad in the closed position.

["007"]

You could have a battery drawing down other batteries and its a good idea not to mix different batteries.

The BIRD.

12V side of life

[alan1]

All house batteries were replaced. I then checked the dash switch and found it to be ok. Next I checked the BIRD system. It is my understanding that if neither battery is being charged, the batteries will be fully isolated. I turned off the charger portion of the inverter with the engine off and the isolator relay remained closed. I also removed the wire going from the BIRD to the relay and it opened the relay. Think the BIRD is defective?

[GaryKD]

Hi alan1,
I'm a bit confused. The last post mentioned you replaced all the coach batteries. So now you have new coach batteries in the coach. Is this correct?

If this is correct, we need to get a baseline on the charger/converter. When connected to shore power, is the converter/charger providing at least 13.5 VDC to the coach batteries?

[denochs]

I would like to throw something in on this thread that needs to be on every battery related thread on this site.

With cold weather playing havoc with our batteries there are more questions and problems croping up. Good advice has been given for each of them. Assuming most RVers are not as savy as people like Gary you may find yourself making the same 'bonehead' mistake I just made today.

Anytime you use another battery charger for the house batteries other than the charger that is on the coach, simply hooking up the charger to a positive post and negative post is not all there is to it. With 4 batteries hooked up in a series you will need to hook the negative to a negative post on one of the batteries that is likewise connected to a negative post on another battery. The positive needs to be connected to the positive post the leads out to the battery control center or where ever it goes other than to another battery.

My house batteries drained down to 4 volts and I could not even turn on the battery disconnect until I charged the batteries. Couldn't even connect shore power because the electric reel did not have a manual over ride. So, lesson #2, leave the electric cord out far enough to connect shore power if the batteries run down.

Thanks to American Coach tech support. Nice folks.

[alan1]

Yes, I now have 4 new coach batteries. The charge current is float at 13.7v.

[GaryKD]

Hi Alan1,
Congrats to you. It sounds like you are good to go. Now that we know the coach batteries and charger are good, the chassis battery should also be taken care of, over the next day or two.

[alan1]

The chassis batteries are going to be load tested, but they are only 5 months old. Kinda think they will be ok. It just seems wrong for the battery isolator to always be closed. At certain times it should be in a open position like when no charging is being performed, for instance.

[GaryKD]

Hi alan1,
You could be correct. It is just in the last 5 years, I have read about only 1 BIRD going bad. Hopefully you are not #2. If the unit is at 13.7 VDC (connected to shore power) all the batteries should be doing fine.

[alan1]

I went ahead and purchased a new BIRD ($44 shipping included). It arrived and after removing the old and hooking up the new one all is the way it should be. The new BIRD opens the relay as it should after removing the charging of the inverter like I was boondocking and running the house batteries down, this way the chassis batteries stay charged. My guess is the house batteries being at .45 volts did a number on it.