Charging with internal or external charger
We're going to brave some cold this weekend to get a first outing in our new (to us) Keystone Passport, but likely will end up in a campground without AC power. Realizing we're not going to make it 2...
Forum Discussion
It depends on the situation, but I get much better results with a 25 amp car charger than the 55 amp (supposedly 3 stage) one built in. Its of the order one third the time to get to a usable charge level with one 80 AH AGM battery. In my case it goes full 25 Amps till over 80 charge. The built in one never got over 15 amps and is below 10 much of the charge cycle. Near total waste of generator time.
Why?
There is 20' plus of number 6 wire between the battery and the built in convertor. That results in a lot of voltage drop and batteries are charged on a small differential voltage so this drop is very important. I don't know how typical my (cheap manufacturers ) installation is, but from general discussions I expect it is fairly common and while it can be helped with thicker wire that would only be worth it if your going to use it dry campng a significant amount.
The car charger can, and in my case does, go to higher voltages than just about any built in unit and in my case will go to 15.2 volts to try to force the 25 amps in.
The car charger connects directly to the battery terminals, there is minimal voltage loss.
The car charger has built in current monitoring, when it gets down to 10 amps or so I turn off the generator as this is in the 95% plus charge range. The built in unit often does not let you know the charging current, so you either start adding shunts and voltage meters and finding a place to put them, or you take a blind guess at when they battery is charged.
Note there are lots of cheap car chargers out there that are single voltage or very low current, I am talking of an intelligent one, but it was still only $115 on sale, simple and cheap.
Why?
There is 20' plus of number 6 wire between the battery and the built in convertor. That results in a lot of voltage drop and batteries are charged on a small differential voltage so this drop is very important. I don't know how typical my (cheap manufacturers ) installation is, but from general discussions I expect it is fairly common and while it can be helped with thicker wire that would only be worth it if your going to use it dry campng a significant amount.
The car charger can, and in my case does, go to higher voltages than just about any built in unit and in my case will go to 15.2 volts to try to force the 25 amps in.
The car charger connects directly to the battery terminals, there is minimal voltage loss.
The car charger has built in current monitoring, when it gets down to 10 amps or so I turn off the generator as this is in the 95% plus charge range. The built in unit often does not let you know the charging current, so you either start adding shunts and voltage meters and finding a place to put them, or you take a blind guess at when they battery is charged.
Note there are lots of cheap car chargers out there that are single voltage or very low current, I am talking of an intelligent one, but it was still only $115 on sale, simple and cheap.
