Originally Posted by kjohn73
I have two different spec batteries in my old 97 gas Suburban, and they have never failed since they were installed probably ten years and 180,000 miles ago.
There are a lot of new RV owners that think a battery is a battery and are not aware that there are a lot of different options and a lot listen to their dealers that most of the time have no clue as to what they are selling. When you are talking about your automotive
batteries, it is like apples and oranges. The battery in my '65 Mustang lasted about 10 years. The automotive batteries have many thinner lead plates which allow for major discharge over a very short period of time and allow for a rapid recharge. Whereas deep cycle batteries have less plates and are MUCH thicker and release there power over a longer period of time and require a longer period of time to properly
charge them. The reason for installing 2 batteries with the same Mfr/Date/Ah is because the internal resistance of each battery will be very close to that of the other.
When you put 2 batteries in parallel and they are not the same Mfr/Date/Ah they each have different charge characteristics (internal resistance) so you have 2 possible conditions you either overcharge or you under charge the battery bank, as the battery charger is not looking at an actual battery voltage but a average of the two batteries, the newer battery with a higher voltage will be lowered and the older battery's voltage will be increased. As soon as the charging stops the older battery will start to drop to its normal level while taking power from the newer battery. Unlike two matched batteries where there is very little resistance difference between the them.
You will still get 12VDC but your Ah over a period of time will be affected
and eventually the newer battery will be drawn down to the characteristics of the older battery, and they will die together.
2013 Jayco Eagle 284BHS
250Watt Grape Solar Panel, MorningStar MPPT 60 Charge Controller
1500 Watt Ramsond PSI, 2 Trojan T145 Batteries (260Ah)
2 - AirSight Wireless IP Cameras (used as rear view cameras)
EnGenius WI-FI extender, D-Link wireless (n) modem
MagicJack Internet Phone
2012 Ford F150XLT, EcoBoost w/3.73
157" Wheel base, HD Towing Package
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