What did you do to your bus today

[davidbrady]

(06-05-2018 02:42)RainbowrvGreg Wrote:  Here is the problem with charge wires. if you start the car while hooked up to the bus and he battery has an issue, the charge wire carries the amperage and burns up or degrades. one solution I have used is installing a onboard smartcharger https://www.harborfreight.com/4-amp-full...63350.html hard wired and plug it into the inverter powered receptical I installed on the back of my bus.
https://www.zoro.com/hubbell-wiring-devi...ifications
weird thing about these receptacles is the ground is on top.

My simple solution to this is a 5A automatically resettable circuit breaker in series. Another simple solution is to wire a 1057 12V 21W incandescent automotive lamp in series. If the voltage difference between the car and bus is minimal then the bulb resistance is <3.5 ohm and the circuit supplies the 50ma trickle charge with 0.2V voltage drop. If one attempts to start the car, the toad battery dips but because of the logarithmic nature of the bulbs resistance the tungsten filament heats up and limits the current to a max of 21W/12VDC = 1.75A. It's dirt cheap simple trick that takes advantage of the nonlinear resistance curve of a light bulb, probably best explained over here: https://www.eetimes.com/author.asp?secti...id=1331961

(06-05-2018 02:42)RainbowrvGreg Wrote:  I was thinking of installing another hardwired 4 amp chargers to the start engine battery bank and power it off of a non inverter receptical but I am not sure if it would cause an issue to the charge processor of the inverter driven battery chargers when the banks are left combined. I guess I can set up a bosh relay to disconnect the charge 12v current when the combiner switch is lit up at the dash??

I would probably disconnect with a relay as you describe. I don't have a lot of faith in these cheaply made chargers to expect them to protect themselves when faced with other chargers in the mix whether alternators or Xantrex inverter/chargers. My bus has a cheap Guest charger charging the chassis bank but Prevost wired it to an inverted receptacle which is relay protected to be on only when the ignition key is off.