Bounder: 1999 Bounder Electrical Question

[fountainjim]

I recently purchased this unit and it's in excellent condition. After a season of use, the house batteries no longer hold a charge (at least that's what I think). I decided to replace the 2 deep cycle batteries with 1 deep cycle for testing purposes. Will add another once I have peace of mind the charging system is working. I had one of the old batteries inline with the new battery, but after 30 minutes of running generator, it died as well as power to the coach. Once I removed the old battery from the system, generator cranked back up and haven't had a problem.

I have used a multimeter to test the charging voltage to both the chassis battery and house battery. When plugged into house power or with engine running, I get 13.66 volts to both positive cables. Once cables are applied to their respective batteries, I still get 13.66 volts to the chassis battery, but only get 12.81v to the house battery. Without the cable connected, I get 12.67 to the house battery.

The question is, why does the reading change on the house battery to a lower value (even with all devices off inside RV)? Do you think the charging system is charging the house battery sufficiently?

Appreciate some guidance.

Jim

[Fugitive861]

I'm no expert, but my first thought is that the chassis battery is not fully charged yet and that is pulling down the voltage. If left connected for extended period the voltage may come up. Do you know if you have a 3 stage converter/charger or an older, non-automatic converter/charger?

[Old Bounder]

Your coach came from the factory with two 6V batteries, wired in SERIES, for the house battery bank. If you are now just running with one house battery, it sounds like it must be a 12V battery.

You need to ensure you have the correct batteries and that they are wired correctly. If you truly have mixed 6 and 12 volt batteries, you may have tripped some DC circuit breakers in your Battery Control Center (BCC) or caused your converter to stop working.

Do you have 12V lights in the coach when plugged into shore power?
Do you have 12V lights from battery power when NOT plugged in?

Verify the above, then post the results. Identifying your problem should be rather simple when we have all the facts.

[fountainjim]

Thanks for the reply

1. Everything is functional on the coach.
2. Chassis battery is new and fully charged.
3. I purchased unit with a pair of 12v batteries. I plan on switching them to 6v, but not at this time.
4. The only battery for the coach is 1 new, 12v deep cycle marine battery, connected to pos and negative.

[fountainjim]

Additionally, converter is charging, as I get 13.66 to both the chassis battery and coach positive battery cable. Once cable is attached to coach battery. Voltage drops to 12.67 volts, yet chassis battery still maintains 13.66v

[Old Bounder]

Originally Posted by fountainjim

Additionally, converter is charging, as I get 13.66 to both the chassis battery and coach positive battery cable. Once cable is attached to coach battery. Voltage drops to 12.67 volts, yet chassis battery still maintains 13.66v

The system may be operating as designed.

The converter voltage would be available on both cables with the converter running, because anything above 13.2 volts would close the isolator/charge/aux start solenoid (connecting both chassis and aux batteries). The chassis battery is obviously already charged to the converter output voltage.

When you connect the house battery cable, the house battery begins to charge and the converter output voltage drops below 13.2vdc (12.67 in your example). When the voltage drops below 13.2v, the solenoid drops out and the chassis battery remains at 13.66v, at least for a time.

I think you need to give that house battery time to charge up, before condemning your charging system.

You can test my theory by turning on your coach headlights and measuring the chassis battery again. My guess is that it wont stay at 13.66v very long.

If the house battery never charges up to the 13.66V, then you may, indeed, have a problem. My first guess would be that it's a battery, and NOT, a charging system that is causing the anomaly, but it could possibly be a weak converter.

I can't resolve your dilemma over the measurements you observed in your first post, except to say that when measuring/comparing, cause and effect, between house and chassis batteries, and between shore power and alternator (engine running) charging, one must ensure that the alternate source is completely OFF or REMOVED while measuring the other. Putting a temporary load on a standing battery, to remove any residual surface charge, prior to testing is also helpful.