Date:         Thu, 18 Dec 2014 17:41:14 -0600
Reply-To:     ddbjorkman@VERIZON.NET
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Bjorkman <ddbjorkman@VERIZON.NET>
Subject:      Re: power inverters
Comments: To: d23haynes57@HOTMAIL.COM
Content-type: text/plain; charset=UTF-8

Thanks Dennis.  You too are a real helpful guy.  I must admit I did the math also (had to look up the formula) but wasn't sure about how those watts were used up.  I really needed a good approximation of what used how many amps in the system.  Good info on RV wiring also.  Guess I'll skip the crock pot.  It sounded like such a good idea for interstate travel.  Still going to get the inverter, but a smaller version.  Smoke is a great warning indicator, but one I do not need.

Dave B.


On 12/18/14, Dennis Haynes wrote:

Keep in mind that if using an inverter while the alternator is charging the wiring all the way from the alternator to the battery and inverter needs to carry that load. Whenever the alternator does not keep up both the house and chassis battery will try to support that load so that path needs to be engineered to do the job also. Keep in mind the later vans with AC have the 90 amp alternators because there are times that capacity is needed.

If you are adding any permanent wiring to the inverter on the 110 volt side it needs to designed and listed for use in a recreational vehicle. Part of the requirement that the output needs to have a neutral that is tied to the chassis as ground. The van is small. Just plug whatever into the outlet on the inverter.

In theory 90 amps at 12 volts is 1080 watts. You need about 15 to 20 amps to charge each 65 A/H battery through the bulk stage. You will need 7 to 13 amps for lighting. More if you did the high power bulb thing for all four lights. Heater fans or air conditioning can be another 20 amps and if the radiator fan is needed for high speed you can have 35+ amps there. If that crock pot is 400 watts then there goes 40 amps. Yes it may cycle but when on the alternator and batteries will try to support that load until something smokes.

Dennis