Just Starting Solar Research
Man, there's a lot to read and digest with possibly installing a small solar panel. I very recently replaced my original 1-stage converter/charger with the Progressive Dynamics PD4600 series conve...
Forum Discussion
Hi Mitch,
Amp meters only tell you the instantaneous "draw", so they don't help with when to run the genny.
Voltage is a bit "sneaky". For example there is a thread going right now where the voltage under load after 30 minutes of use was 8.6. After a 30 minute "rest" that bounced back to 10.6. I would NEVER take my battery bank that low. Basically voltage under load tells one very little. Voltage without load (or charging) has to be done with 24 hours of rest time to give a valid indication of state of charge (and even then--it is affected by temperature). 24 hours of rest is pretty hard to do when you are camping.
So neither amps nor volts tell you what you wanted to know--i.e. when to run the generator.
The other approach is an amp-hour counter such as a trimetric. But most of them don't count "correctly" as they don't allow for the Peukert effect. Over time, they drift farther and farther out of calibration. They also require you to know exactly how many amp-hours your battery bank is. And, guess what? That changes with temperature. If you must have an amp-hour counter then Victron makes the best one that does do a Peukert calculation. There is also a device called a "smartgauge" available in England--but I've been unsuccessful in trying to buy one in North America. (Also I would need at least two such meters)
There are two accurate devices to measure state of charge. One is a temperature compensated hydrometer, and the other is a refractometer. Both measure the specific gravity of the battery acid. This presupposes you wish to access the battery bank on a daily basis and wear woolen clothing so you will not become "holy", that you will wear PROPER eye protection and acid proof gloves. I'm something of a fanatic--but I do NOT need a 12 step group for this type of procedure. It gets done once or twice a year.
My solution was to do a good and careful energy audit. I know about what I use. I have enough solar to cover all of my needs until I get into heavy duty inverter use. I do track the voltage first thing in the morning, but I've never run a generator for the sole purpose of battery recharging. If I run the air, of course I run the converter. If I'm driving, of course the alternator recharges.
My style of camping is lots of travel--with rarely two days in the same place. I use lots of 15 amp shore power in front of clients homes, and I've modified the rv to take best advantage of that.
In your shoes, I'd get a $15 cigarette lighter type volt meter and not let it get below 12.2 volts under (heavy) load.
Amp meters only tell you the instantaneous "draw", so they don't help with when to run the genny.
Voltage is a bit "sneaky". For example there is a thread going right now where the voltage under load after 30 minutes of use was 8.6. After a 30 minute "rest" that bounced back to 10.6. I would NEVER take my battery bank that low. Basically voltage under load tells one very little. Voltage without load (or charging) has to be done with 24 hours of rest time to give a valid indication of state of charge (and even then--it is affected by temperature). 24 hours of rest is pretty hard to do when you are camping.
So neither amps nor volts tell you what you wanted to know--i.e. when to run the generator.
The other approach is an amp-hour counter such as a trimetric. But most of them don't count "correctly" as they don't allow for the Peukert effect. Over time, they drift farther and farther out of calibration. They also require you to know exactly how many amp-hours your battery bank is. And, guess what? That changes with temperature. If you must have an amp-hour counter then Victron makes the best one that does do a Peukert calculation. There is also a device called a "smartgauge" available in England--but I've been unsuccessful in trying to buy one in North America. (Also I would need at least two such meters)
There are two accurate devices to measure state of charge. One is a temperature compensated hydrometer, and the other is a refractometer. Both measure the specific gravity of the battery acid. This presupposes you wish to access the battery bank on a daily basis and wear woolen clothing so you will not become "holy", that you will wear PROPER eye protection and acid proof gloves. I'm something of a fanatic--but I do NOT need a 12 step group for this type of procedure. It gets done once or twice a year.
My solution was to do a good and careful energy audit. I know about what I use. I have enough solar to cover all of my needs until I get into heavy duty inverter use. I do track the voltage first thing in the morning, but I've never run a generator for the sole purpose of battery recharging. If I run the air, of course I run the converter. If I'm driving, of course the alternator recharges.
My style of camping is lots of travel--with rarely two days in the same place. I use lots of 15 amp shore power in front of clients homes, and I've modified the rv to take best advantage of that.
In your shoes, I'd get a $15 cigarette lighter type volt meter and not let it get below 12.2 volts under (heavy) load.
