Here is a website with a guideline for when to use solder or crimp.

http://svconline.com/mag/avinstall_crimp_connectors_not/

Don't know that all of it is absolute, but it is a good reference.

Battery Types:

There are 3 types of batteries in common RV use; Flooded Cell, Gell Cell and Absorbed Glass Mat.

Flooded Cell Batteries:
By far the most common battery used it the flooded cell battery. It comes in many “flavors” from deep cycle to golf cart. Each has their own particular composition.

An automotive battery is a type of flooded cell. It is most easily recognized by the removable caps and the liquid electrolyte. The chemical composition and mechanical construction of the car battery makes it able to provide a very quick transition from chemical energy to electrical energy at very high (300-500 amps) current. However they do not do well in sustained, low level (10-20 amp) discharge applications.

Deep Discharge batteries have a different chemical and mechanical composition. The lead is mixed with different alloys, the plates are a different shape and the internal structure of the battery is different. A deep discharge battery will not do well if subjected to a 300 amp discharge.

Although there is an intermediate battery called a Marine Starting Battery that has some of the characteristics of both the automotive battery and the deep discharge battery. It does both, but does neither as well as the two alternatives when used for their specific applications.

Gell Cell Batteries:
Gells are similar to deep discharge batteries except that the electrolyte is not a liquid, but a gell. There is no filler cap and no maintenance. Although the battery is “spillproof” it must be mounted for use in its normal vertical position. Inverted or on its side mounting will severely reduce its life.

Gells are very susceptible to overcharge and overdischarge. They do not do well in high current applications like starting heavy engines. They are not good for hi vibration applications. The no maintenance and spillproof features made them quite popular with the high end RV motorhome manufacturers. However in severe vibration applications like off road RV's, boats and aircraft, their frailty was problematic.

The gel is created by the addition of finely divided silica or sand mixed with a sulfuric acid solution. The gelled electrolyte is highly viscous and during charge or discharge often develops voids which impede acid flow and result in reduced battery capacity. As these voids progress, more and more plate area is left dry and unable to provide a path for the ionic flow thus progressively reducing the capacity of the battery.

Absorbed Glass Mat Batteries:
This battery type was a recent entry in the battery world. The need for a battery that would survive high vibration, run in any position, provide very high current draw, allow very high charge rates and be sealed, so that it did not vent explosive gasses came about with the advent of the stealth aircraft and some highly aerobatic missiles.

This battery is much like the flooded battery with some major changes. First, the electrolyte is contained in a saturated microfibrous silica glass mat. This made it possible to provide much better support for the plates. Also, the plates could be thinner and there could be more of them so the surface area of the plates could be greatly increased. This provided the very high charge/discharge rates as the conversion from electricity to chemical back to electricity is very dependent on the surface area of the plates. The electrolyte is still liquid and remains so for the life of the battery.

There is a valve in the battery that creates a positive pressure in the cell that confines any gasses produced during operation. These gasses are then recombined into water. Since the glass mat is only about 90% saturated with electrolyte, the oxygen produced during charge can readily migrate to the negative plate and recombine into water. This recombination method along with charge voltage control substantially reduces water loss making the battery non-spillable and maintenance free. The batteries can be located in regular living space without special venting.

This closely packed plate arrangement means that there is a much lower internal resistance. I left two of these batteries in an unheated shed through two Maine winters. Upon my return I was able to use one of the batteries to drive a light for many hours as I worked in the shed. Internal discharge is less than 3% per month at 77 degrees and substantially less at lower temperatures.

The number of discharge cycles for the AGM is considerably greater than for either flooded or gell batteries. At the 50% discharge level one can expect about 300 discharge cycles for the flooded cell, about 350 for the gell and between 1000 – 1500 discharge cycles for the AGM.

The trade off is that the AGM batteries are slightly heavier and larger than an equivalent rated flooded cell. AGM's require a closely monitored voltage regulated charging system and they are considerably more expensive. I found a 105 amp hour Lifeline AGM for $289 + 54 for shipping = $343 each. A standard flooded cell deep discharge battery goes for about $60-80.

Battery Ratings:
Batteries are rated by how long they will provode a specific amount of current. Most RV batteries are rated at a 20 amp discharge rate. This means that a 105 amp hour battery will provide 5.25 hours of current before reaching its fully discharged state. This is usually about 10.5 volts. However discharging a battery to its fully discharged state will greatly reduce its lifetime. The standard discharge level is 50%.

A 105 amp hour battery therefore has only about 52 amp hours of useful energy. It can provide 1 amp for 52 hours, 2 amps for 26 hours or any other combination of amps * hours that approximates 52 as long as the demand is at 20 amps or below. The rating will be considerably different if you are discharging at 100 amps. So be sure to see what the actual discharge rating is before you purchase a battery. Some are rated at the 20 amp discharge rate some at a 5 amp discharge rate, some at 100. It mostly depends on the type of service for which the battery is intended.

So lets say you estimate your demand for a 24 hour period is 100 amp hours, and that you want to have 3 days of power. Then you would need 300 amp hours. But to remain above the 50% discharge rate, you need to double that and have 600 amp hours of battery.

Next: Inerters.

This is good stuff. I really appreciate it.

Hey Nomad- If i`m not mistaken Optima are AGM and can be found for $130-$170 depending on the model.

http://www.dcbattery.com/optima2.html

Also Nomad, are you going to talk about discharge amps when you talk about inverters because if I`m not mistaken in your discussion of Battery Ratings above you were talking about direct 12v discharge and not the "converted" 120v discharge. I am curious about an appliance that utilizes 120v/5amps what that is through the inverter to the 12v/batteries???

I am sorry to report that I have lost my internet connection. Seems like the LNB on my satellite system has failed. I am using a friends connection, for the moment. Therefore I have to end this thread. It is probably long enough as it is.

If (when) I resolve the internet connectivity issue, I will continue the thread on my web site which at the moment is very out of date.

I will post a note here when I get back online.

Glad you found the posts useful. I will continue to write, hopefully I will get to update my web page in the not to distant future. I appreciate all the comments. Much of them will be incorporated into the stuff I put on my web site.

Web site is www.nomads-notebook.com


...Ron, aka Nomad.