Hi Chris; There is a lot to consider of what the problems may be. First you need to visualize and compare your electrical system to that of plumbing. Since you cannot see electricity it is difficult to understand it. Therefore for that reason I am making this recommendation. Battery is nothing more than a storage container. The larger the container the more it can store. The volume stored, is amount of amperage available.
This stored amperage [volume] came from the charger which had to utilize pressure to fill your battery [tank]. Since that could only be done by means of pressure [pump] which is set for the safe level of pressure for which the container is rated for. In which case is 12 Volt
. Therefore a 12 Volt
battery rated at 800 amp, can be compared to a tank which can hold 800 gallons of water at required pressure of let's say 12 PSI. For as long as the pressure exists, the battery should give you it's rated amperage per hour. However, once the pressure has diminished below 12 volt
the battery will not deliver rated volume, because delivery depends on the pressure behind it.
The battery however is only a source of stored energy. From here on are wires, fuses etc. All of that is responsible for distributing that mass of energy under pressure, just the same way that plumbing distributes the water. If you have no pressure you have no flow. No volume, no flow. Size of wire can be compared to size of pipe. The larger the pipe the more volume it can deliver in given time. The high demand for volume through a larger diameter pipe, will however drain your 800 gallon tank much quicker than a small diameter pipe at the same rate of pressure. This is proportional to demand and size of pipe supplying the demand.
If your pipe is too small for the demand, two things will happen. You will not get enough volume needed and in case of electricity, and the wire will become overloaded and the demand for energy flowing through it, will create heat because the component draws more than the wire can supply. End result, blown fuse or burned out wire. On the other hand the pipe supplying the energy may be large enough but it has restrictions in it [clogged up]. The result is the same. The wire is only as good as it's loose or weak connection. If the wire has 12 strands and it is rated for 20 Amp and six of them are broken off at the connection then that wire can only supply 10 Amps. Also, as the demand exceeds the wire's rated capacity it creates heat, which even further drops the available amperage by increased the resistance in the wire. Hence, low available amperage creates heat. If any circuits which get hot, there is some form of restriction in that circuit.
Since you own a older unit you must carefully inspect all wire connections
which are accessible to your inspection. Make sure they are not frayed, broken or loose. This includes all grounds as well because they are the continuation of your pipe, and a viable part of your closed loop circuit. Chances are you have loose connection in your distribution panel, which may be affected further by heat generated by weak connection. Second issue may be your Univolt. They were not most reliable source of charging or power supply, and I would recommend upgrading it.
Visually check all connections first and if you find anything unusual PM me and I will try to help you. Thanks, "Boatdoc"