I posted a message this summer (Foretravel Tech Talk / Batt Charging:Does 50a make a difference?) and have decide I asked the wrong question. More about that at the end of the message.
Background first:
I installed a Trickl-Start battery charger(?) this summer. Most of the time it appears to do what it I think it is intended to do - keep the start batteries charged. This summer's query was prompted by the fact that over a 2 week period the start batteries dropped down to below 12v. The two week period was in campgrounds with a 30amp connection. Don't help me yet...I have more stuff.
When I got to 50amp land the voltage at the start batts was consistently above 13.
Currently:
I have a covered spot in a storage facility with only a 15 (Maybe 20, correct plug) connection. I have all the correct adapters (15 to 30, 30 to 50 which copies L1 to L2, 4-wire 120/240 50amp shore power cord)
Observation:
Thanks to Dave Abel I have a voltmeter that plugs into the cigar lighter .
I have for some reason which now escapes me, decided that the plug is connected to the start batt (this is a '96, only one lighter plug).
The volt meter read something like 13.6/7/8 as the coach sat connected to the 15amp plug.
Problem:When I turned on the the ignition switch the voltmeter through the lighter socket dropped to low 12's / high 11's. I observed this several times. When I turned it off the voltage jumped up again.
Confession:
I havn't gotten the voltmeter out yet to the batteries themselves.
Question(s)
1) What would account for the different battery readings for what I think is the start battery? The dash voltmeter seems to reflect the lower numbers (but it is only active when the switch is on in any event)
Aside:
The more I thought about it the more comfortable I became with the thought that amps are amps are amps and that until you try to use too many the system doesn't care what kind of wall plug you connect to.... SO, if there is a difference it is volts...
2) Is there anything that is VOLTAGE sensitive in the converter/charger system. 50 amp is also 240 volts. A 30 amp connection would use the same 110 line for both L1 and L2 . What would that give me if something was trying to detect a voltage between the two. Is there anything that cares?
Thanks for the brain power...
Elliott,
NO, your charger, converter and/or inverter-charger all operate on 120 VAC. That is one hot, a neutral and a ground.
They have no idea that you are plugged into a 50 amp (since they are fed by only ONE hot) or a 15 or 30 amp outlet, where the single hot on the male end connects to both hots on the female end.
Brett
Re: 1) When the key is off, there is almost no load on the start battery. The voltmeter at the lighter socket would provide a very small load. The voltmeter reading would be very close to the value measured at the battery. When you turn the key on, there is load of instruments, solenoids, and "stuff" required to operate the "vehicle" part of you motorhome. There will be voltage drop through the wires from the start batteries to the front of the coach. If any connections are resistive (loose, corroded), there will be additional voltage drop as a result of current in the wires. The value at the front of the coach would be lower than that measured at the battery if the lighter socket shares wires with circuits activated by the ignition switch.
With Trik-L-Start, I would expect the voltage on the start battery to be a bit lower. My understanding is that Trik-L-Start uses a diode inserted between house batteries and start batteries which would provide about 0.5V drop. If the house batteries float at 13.6VDC, the start battery would float at about 13.1VDC. Conversely, if the Trik-L-Start is keeping the start batteries at 13.6VDC, the house batteries might be floating at 14.1VDC, which seems a bit high. A check at the battery terminals might be in order.
Re: 2) Our coach is wired OEM style, such that L1 to L2 is 240VAC with 50A shore power, and L1 to L2 is 0VAC on generator or 30A/20A/15A shore power. I am unaware of anything in the coach that would care whether the voltage from L1 to L2 is 240VAC or 0VAC.