Hi i am new here .any one have any idea how to make a generator auto start i need to start when battery ran low so it can ran my home and charge back the batteries .the generator is a 4.5kw,inverter as charger in it 40amp it 24v so would need the gen to cone on at about 23.5v.

 

Making a generator auto start is a very complicated project that involves electronic circuitry and mechanical controls for the engine throttle and choke. It is beyond the ability of many. What is your experience level?

 

I have good understanding of electronic.i was think of make a circuit that can replace the key start on it .the switch have 3 position off/on/start i looking for a circuit that can read the voltage of battery then start it when low and turn it off when full

 

I have good understanding of electronic.i was think of make a circuit that can replace the key start on it .the switch have 3 position off/on/start i looking for a circuit that can read the voltage of battery then start it when low and turn it off when full

You could use one voltage comparator to turn the ignition ON and OFF. The comparator would have hysteresis so it would turn ON at the minimum voltage level and turn OFF at the fully-charged level (is that about 27V?).

You would also need a circuit to operate the START circuit. That could operate simultaneously with the ignition going ON but would need a timer to shut everything off after a few seconds if the generator doesn't start. One way to determine if the generator started is to use a comparator to determine if the voltage has increased from the low voltage level. I would expect a small jump in the battery voltage when the generator starts charging. You could determine how much the voltage increases by measuring it during the start.

Just my thoughts on the problem.

 

I find a circuit on this site http://www.electroschematics.com/8347/24v-battery-level-indicator/ it a battery level indicator was think link a relay to led to make gen start so when low level led come on the generator would start and stop when high volt led cone on what do u think cruts chow

Can it work

 

To properly charge the battery, a charger needs to go through a charging profile (which may be different). You can use the circuit to start the generator based on battery voltage, but you need to somehow go through the charging profile once the generator has started. You need to first limit current to prevent generator overloading, then when batteries get charged more, you need to limit charging current even more to avoid overcharging batteries. Some chargers, such as forklift chargers, use very complicated charging profiles.

 

I find a circuit on this site http://www.electroschematics.com/8347/24v-battery-level-indicator/ it a battery level indicator was think link a relay to led to make gen start so when low level led come on the generator would start and stop when high volt led cone on what do u think cruts chow

You could use that as the voltage detector. But you still need a start and start detect timeout circuit. Since you seem to have limited electronic knowledge I suggest you purchase such a device. Here's some search results and here's a specific example.