Additional battery

[cruising7388]

Originally Posted by Bud

Thanks for the suggestion cruising. I used 4 gauge, it appears that Roadtrek used 4 or 2. When the existing batteries give up, I'll probably go with exactly what you suggested and agm batteries, no accessing the LOUSY battery location of the original battery to water. If I had to listen to the loud converter fan much, I would do it now. The tv with sat receiver or tuner amplifier and charging a laptop ........ does not activate the charger much. And the batteries are charged or near charged when I stop and use shore power.

I need to go somewhere. Maybe that big rv show and see some leaves turning.

4 gauge will serve perfectly. With regard to the PD9200 converters, they are available in 45, 60, 70 and 80 amps. If memory serves, the dimensions for the 45 and 80 amp unions don't work for the space available in the Parallex but the 60 and 70 amp identically sized units will fit right in at the bottom of the Parallax compartment. Since your feeder line will support it, I would opt for the 70 amp version since the AGMs you will get will easily accept the bulk charge rate from the 70 amp model. But Randy at Best Converter can confirm this and also at this point he may even have a better solution for you. I think he also has an improved replacement ATC fuse board for the rehab you plan when your current batteries reach the end of their useful life.

[markopolo]

Temperature compensation is a good feature to have on a charger.

My thoughts on all this stuff have evolved over the years and temperature compensation would pretty much be a must have feature when upgrading or building a new system now. I like the PD units but as far as I know, they still lack temperature compensation.

I've kept the batteries in my van at 12.8V float this summer because of the lack of temperature compensation on the PD unit in the van.

Parallax does offer units with temperature compensation but I have not looked into all of the specifications of the units so I don't know if they would be a good upgrade or not.


If one's budget permits upgrading to an inverter / charger that has a sufficient wattage rating to cover all of what is needed in the coach and that has temperature compensation and built in automatic transfer switch then that is a nice setup. Every outlet/AC circuit in the coach can be powered by the inverter which is convenient. That usually requires wiring and fusing upgrades as well.

Boosters '07 RT had a mix of 2 and 4 gauge. The '04 I owned had 6 gauge. I suggest confirming the rating of all the self resetting DC breakers in the system. I found one 30A self resetting DC breaker in the mix in the '04 that should have been rated for 50A. The coach was under warranty and RT mailed me a replacement 50A self resetting DC breaker no charge.

[Deano]

Quick comment on batteries.
Two 6 volt deep cycle in series are better than two 12 volt in parallel as the two 12s will self discharge if not isolated.

[markopolo]

Both 6V and 12V lead acid batteries suffer from self discharge.

Paralleled batteries will seek a state of equilibrium basically meaning that the stronger battery will end up at the resting voltage of the weaker battery. That's pretty much why the strong recommendation is to parallel batteries of the same age, brand, type, capacity, match wire size and length and match terminations. You the minimize the impact of the negative effects that way.

There's always going to be an imbalance of the individual cells in both 6V and 12V batteries.

6 volt batteries in series themselves can end up surprisingly out of balance.

Some time ago, E-trek owner photolimo posted the voltage readings of his two groups of series connected 6 volt batteries on solar float charge.

Group 1
6.33v + 6.43v + 6.94v + 6.88v = 26.58V

Group 2
6.43v + 6.34v + 6.94v + 6.88v = 26.59v

You'd have to think that the over-voltage batteries will have a much shorter life.

[cruising7388]

Originally Posted by prfleming

On our 2016 210 with UHG we have 2 banks of 6 volt 200 AH batteries (400 AH @12V total). These are paralleled with about 6 feet of 4-00 cable on each bank. About once a month I put a heavy load on the inverter, say 150 amps, and measure the current with a clamp on meter to check battery balance and health of each bank. I figure if the current is within 5 amps per bank, the batteries are good. So far no problems, est batteries are 3 years old.

Technically, it's a series-parallel setup. To their credit, Roadtrek doesn't chintz on cable gauge. What's the input voltage at the inverter during the test? Did you take delivery of the coach before they dropped the AGM warranty from 5 years to 1 year?

[prfleming]

We just got back from 4 day trip to Door county. I'll take some new measurements. Need to check on the battery warranty.

Yes, happy with the RT 12V wiring. They also ran a 4/0 from the UHG to the rear battery junction block. The only mod I did was to run a voltage sense wire from the battery junction block to the Balmar controller voltage sense terminal. RT had the Balmar voltage sense terminal connected directly to the UHG B+.

[cruising7388]

Originally Posted by markopolo

Temperature compensation is a good feature to have on a charger.

My thoughts on all this stuff have evolved over the years and temperature compensation would pretty much be a must have feature when upgrading or building a new system now. I like the PD units but as far as I know, they still lack temperature compensation..

No question about it, all modern chargers should implement temperature sensing particularly to optimize maintenance charging voltages and this feature would most likely more than pay for itself with longer battery life. But while this is easily done by the original builder, it can be a major PITA to implement it subsequently.

Both my Prosine and Magnum units had this feature but these were much more expensive than replacement/upgrade chargers like PD, Iota and WFCO. Ideally, these chargers should at least incorporate battery temperature sensing circuitry and an RJ 11 port to allow owners to accomplish this if they are willing to do the grunt involved.

[markopolo]

I think that measuring 6 volt batteries individual voltage would be an informative exercise.

Example: 12.6V could come from 2 x 6V batteries in series with each at 6.3V. It could also come from 2 x 6V batteries in series with one at 6.4V and one at 6.2V. That could indicate that one battery is aging faster or maybe resistance at a terminal etc. If it is a wiring or installation problem that is too difficult to fix then rotating the batteries periodically might be a viable solution.

Also, I think that a gentle defined timed load test repeated periodically would provide useful info showing how well the battery bank is holding up. I established baseline info on the two banks in my van here: http://www.classbforum.com/forums/f8...html#post27559 - I've going to repeat the tests soon to see if the performance/capacity has dropped.