coach batteries

Discussion in 'RV Tips & Tricks' started by H2H1, Oct 29, 2007.

  1. H2H1

    H2H1 Senior Member

    I thought I sent this question before, but I can't find it so I sending it again. I had this problem last year just about this time. The house batteries was replaced and it seems to had taken care of the problem as not starting up the MH. Well this weekend the co 2 detector was making the alarm and I FOUND OUT THAT THE COACH WOULD NOT START. I put the chassis battery on the charger and let itcharge the battery. Well after awhile I went back and took off the charger and the MH started. an hour later it was dead again. I checked all the appliances nothing was on, besides I have it plugged into a 30 amp receptacle anditstays hook up until we take off. question is what is wrong with the batteries or battery. Is this a common problem with house batteries, if so and solution on how to maintain them?

    thanks Hollis
     
  2. rjann

    rjann New Member

    RE: coach batteries

    Sorry, but it's not clear which batteries are bad.
    You can't start the engine, so the chassis battery isn't working, right?
    You don't have anything on in the camper (coach), so those batteries are ok, right?
     
  3. H2H1

    H2H1 Senior Member

    Re: coach batteries

    Mr Jann let me start over again, Last year when I bought this MH it wouldn't start, the dealer hook up a charger and charge the battery. no problem, but once I got it home 2 days later same problem. I jumped it off and took it back to the dealer who replaced the house batteries. Since then I haven't had any problem until yesterday. also how offend should the house batteries be serviced? thanks Hollis
     
  4. Kirk

    Kirk Senior Member

    Re: coach batteries

    On all motorhomes that I am familiar with, the CO detector gets power from the coach batteries and the chassis is started by a separate battery which is just for the chassis. There should be an isolator device between the two batteries which closes when the chassis engine is running to allow it to charge the coach battery(or batteries) and that then opens when the engine is shut down to prevent the coach loads from discharging the chassis battery. These are two separate batteries and if working properly the appliances in the coach will not discharge the chassis battery. At the same time, if you put a charger on the coach battery and not on the chassis battery it would not help get the chassis engine to start. Either you have two separate problems or you are looking at the wrong battery.
     
  5. Kirk

    Kirk Senior Member

    Re: coach batteries

    On frequency of servicing batteries, it depends upon the use. For your coach batteries I would suggest that at first you check electrolyte levels once a month and if they do not loose water in that time, wait longer between checks. It is important that that a wet cell battery be kept at proper levels and if it is allowed to go dry, that will destroy the battery.
     
  6. C Nash

    C Nash Senior Member

    Re: coach batteries

    Hollis, I agree with the others. You should have two house batteries and one battery for the engine. Do you have a disconnect switch for the batteries? If you disconnect it will the battery die? Have you checked to be sure you have good post to cable connections? As Kirk said be sure to keep regular ck on electrolyte level.
     
  7. Guest

    Guest Guest

    Re: coach batteries

    Hollis ,, how old are u'r house batteries???
    Also , are u'r sure the alternator is working ,, to charge the engine battery???
    If u'r plugged into shore power do u have any probs with the house batteries???
    I have found a way to keep both the sets of batteries up while in storage ,, the house batteries charge ,, via the shore power ,, but the engine battery will not ,, unless u have a very new coach ,, and even some of them don't have this option...
    PM me and i'll let u know how to take of care of the engine battery ,, while on shore power
    ;) ;) :)
     
  8. H2H1

    H2H1 Senior Member

    Re: coach batteries

    the house batteries are almost 2 years old. I checked the level and they look good. I did notice some corrosion on one post and quickly clean that one. I notice that info board that both house and engine are`showing just over 11 volts. I thought they should be just over 14 v. How should I connectthehouse batteries up to a charger to give them a good charge? thanks
     
  9. Guest

    Guest Guest

    Re: coach batteries

    the house batteries should charge with u'r converter ,, if it has the charger option ,, it will not however charge the engine battery ,, ok i'll let my secret out .. i have installed a trikle charger,, that u can get from any auto parts store ,, it is actually called a battery maintainer ,, u can install it near u'r engine batt. and then run another extension cord to it and plug it in or u can do a i did on my coach and many others,,, I ran a piece of 12 gauge romex from the place that the shore line plugs into ,, ther should be a junction box there ,, but anyway ,, i tied the romex into this Jbox and then ran it under the coach ,, and put in a extension type cord plug in at the end near the batt ,, maintainer ,,, anyway ,, the way it works is that any time u'r plugged into shore power or have the genset running ,, u'r always charging the engine battery ,,, but bty whe u'r on the road ,, BE sure to unplug the batt.. maintainer ,, cause if u use the genset while traveling ,, u'll short out the alternator ,, due to back feed ,, i have also ,, installed dissconnect switches inline also ,, so the customer does not have to unpug just flip a switch ....
    Thats it ,, if anyone need more details on this PM me ;) :)
    Bty ,, ck u'r converter it should state if it has charger options
     
  10. Kirk

    Kirk Senior Member

    Re: coach batteries

    First of all, a fully charged wet cell battery should measure about 13.6V when in good condition. It will be less as the battery ages. Yours should easily reach at least 13.3V at that age. But you will never see 14V from a wet cell battery unless it is under charge. At the moment it reaches full charge the charge voltage should be approximately 14.4V but the moment charging stops that will begin to fall and after the battery "rests" for about two hours and returns to normal temperature it will read more like 13.6V. At 11V the battery should be able to start the chassis engine and the coach batteries should be able to start the genset(if you have one). A wet cell is considered to be discharged when it falls to 10.5V. What really happens is that the battery voltage falls more rapidly as the battery discharges and the max current flow also falls. A weak battery might reach the 13V or so level when charged, but if it is not in reasonably good condition, as soon as you apply a load that voltage will drop to some point that does not supply the proper current. I have seen batteries who's voltage will drop by 3 to 5V as soon as a significant load is applied. That is the reason for shops that test batteries using a "load test" to see what the condition is. Another way that you can find out some of this is to put a volt meter across the battery and read the voltage, then with that meter in place, apply a moderate load to it and watch the voltage. If it falls to less than 10.5V very rapidly, that battery is not good. Another way to test is to remove the battery from the circuit by lifting the negative cable. Then use a battery charger to charge it up for 24 hours or so and check the voltage after it has rested for two hours, then note what it is. Let that battery sit with the cable off for 24 hours and check the voltage again. If it has dropped more than .3V the battery is weak and if more than 1V it is bad. That isn't as good as a load test but it is a quick layman's method to get an idea.

    To charge the pair of coach batteries, lift the negative cable to the loads but leave the two terminals connected together, neg./neg. and pos./pos. Attach the positive of the charger to the pos. of the batteries and the neg. to the neg. By so doing you will charge both batteries but remember that when you charge a parallel pair of batteries, neither one will charge to any more than the weakest of the two batteries can accept.

    But none of this explains the reason that your chassis battery will not start the chassis engine? That is a separate electrical system if things are properly wired.
     

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