time2roll wrote:
BFL13 wrote:
"But, be careful shopping for a charger, they advertise peek amps that are unrealistic. Some say 80 amps and are really only 20"
Do you have any examples of that, and what the set up with wiring etc was?
Usually those will be portable chargers with a start/boost setting for getting a car started with a low battery.
That reminds me of what I sometimes do when drycamping in our motorhome to charge our 230AH AGM battery bank faster (for really fast charging I just idle the main engine for awhile):
I start up our little 650 watt Honda and plug the motorhome's 30 amp cable into the Honda. The motorhome's 45 amp Parallax stock converter then starts dumping 10-12 amps into the AGM batteries at around 13.6 volts applied to the batteries - while still powering small items in the motorhome with the little Honda through the main 30 amp cable.
Then I also plug into the little Honda my old 2-10-50 amp Sears charger/starter and attach the Sears charger's output clamps - via some cabling - to the AGM battery bank on the other side of the motorhome.
Then - I set the Sears charger to it's 50 AMP ENGINE STARTING MODE - but of course this little charger can't dump 50 amps into the AGM batteries because the batteries' low internal resistance drags down the Sears charger's output voltage so much that the batteries won't accept anywhere near 50 amps from the charger.
What I now wind up with during charging is still around 13.5 volts being applied to the batteries - but at an increased charging current rate of 15-17 amps into the battery bank ... from the RV's converter in parallel with the Sears charger.
The whole process is making use of the parallel circuits' relationships resulting from the converter's output resistance, the Sears charger's output resistance, and the AGM batteries' internal resistance ... but what I get is about a 50% increase in charging current through addition of a little portable Sears charger that otherwise should have gone in the dump a long time ago.
I all plays together like a champ. I could do the same thing using the built-in Onan generator and the Sears charger, but the little ~30 year old Honda makes "about no noise" while running 5-6 hours on 0.51 gallons of gas.
P.S. I got the idea to hookup charging sources in parallel from either Pianotuna, or BFL13 - a long, long time ago. Thanks ... to one of you!
