| If you have a caravan, Camper Trailer or RV you | | | | potentially you may only have a usable 40 |
| might often want to take it off the beaten track | | | | Ampere Hours. |
| and get down and dirty with nature. I'm talking | | | | AGM (Absorbed Glass Mat) batteries on the other |
| about the wilderness experience; selecting a | | | | hand are in my opinion the battery of choice. |
| campsite that offers little in the way of services - | | | | They last longer than the other types. They are |
| especially electrical power. In these cases you will | | | | sealed and so can be stored just about |
| have to rely on your battery power, and if you | | | | anywhere, even on their side if you want. All they |
| plan on staying a few days and still want the | | | | require is venting to atmosphere. Because of their |
| convenience of light, fans, radio and maybe DVD | | | | construction these batteries charge faster and at |
| player, etc, you will need to boost your power | | | | a lower voltage so will charge closer to that magic |
| reserves somehow. In this article I will discuss | | | | 100% of capacity when using conventional |
| how you can accomplish that. It may not suit | | | | chargers. They can also be occasionally discharged |
| everyone's needs or pocketbook, but if it gives | | | | below the 50% threshold without long term |
| you food for thought it will be a good start. | | | | damage. Consequently an AGM battery will last |
| First off let's have a look at some battery facts. | | | | longer if treated well (typically 8 to 10 years). |
| There are three main types of battery, | | | | Now the bad news. They are more expensive |
| conventional wet cell, deep cycle, and AGM, and | | | | than conventional batteries. |
| left to right reads from least to most expensive. | | | | In my pop-top camper trailer I use two 110 |
| The conventional type battery is usually found | | | | Ampere Hour AGM batteries wired in parallel. This |
| under your vehicle hood and has to provide a | | | | gives me at full charge, a usable 110 Ampere |
| heavy current surge to start your engine. These | | | | Hours (220 AH / 2). This preserves the life of my |
| batteries are not intended to be deep cycled and | | | | batteries and provides me plenty of power, plus a |
| will have a very limited lifetime if exposed to that. | | | | small margin if I need it in emergencies. The |
| Deep Cycle batteries are not meant for heavy | | | | camper is fitted with a "smart charger" so that |
| current drains but can be discharged to lower | | | | when I am connected to mains power the |
| levels. These are usually found as auxiliary | | | | batteries will charge close to 100% capacity. I also |
| batteries in a vehicle or caravan. Both of these | | | | charge the batteries from the vehicle alternator |
| battery types need to be vented to the open air | | | | when traveling and this requires some safeguards |
| because they can generate explosive gases during | | | | - you do not want to discharge your starter |
| the charge/discharge cycles. Also bear in mind | | | | battery below its operational level, so a battery |
| that batteries do not like being discharged and will | | | | isolator to protect it is essential. |
| rapidly deteriorate if repeatedly discharged below | | | | I have used this system on several occasions for |
| about 50% of their capacity. So, if you have | | | | extended stay camps and had plenty of power |
| either of these batteries with a 100 Ampere Hour | | | | for lighting, water pump, radio/CD player, TV |
| rating, you only really have 50 Ampere Hours of | | | | DVD player and so on. You can work out your |
| capacity. That is the rule of thumb you should | | | | battery drain by identifying all the appliances you |
| use. Now add to this the fact that if you are | | | | want to run, what their current draw is multiplied |
| charging from a vehicle alternator, the electrics in | | | | by the use time. |
| the charging system will only charge the battery | | | | For full details including schematic see my |
| to around 80% of its capacity. This means that | | | | resource box below. |