Battery Charging on Gen Set

Must be a small genset to use 12 volt starting.

Yes, go for an automotive type alternator. Find one with an internal regulator for ease of wiring. Should only have two wires. 15 Minutes? I would look for 40 amps or so. 20 to 30 if you run it for 30 minutes.

If you have a charger on it, and it is working, just remove the alternator, or disconnect it if you can't find a new belt.

Our company manufactures Ignition duty batteries with built in charger.

You can have separate charger for your battery and stop using dynamo with controller. You did not mention battery Ah, so that I can suggest better way.

Your post is a little confusing, "When the generator runs the it also supplies charging power to the battery. The battery charger supplied with the generator is 24v, the battery is 12v " Is the 24 volts from an alternator mounted on the engine? Or is this an external battery charger, not engine driven? Is the engine starting circuit 12 volts? I do not understand why the generator supplier would supply a 24 volt charger for a 12 volt system? I see that your in Thailand, can you purchase from eBay? I just did a quick search on eBay and found trickle chargers, most under $30.00(US dollars), click→Here← for the link to eBay. And as far as using a DPDT relay, I think just removing the battery charger clip would be easiest when you run the gen-set, without having to extra wiring.

Hi,

The battery is 12 v, it is a 70Ah battery, the generator is a standby generator and is unattended, it starts and transfers the load automatically. I thing the power outages are to short to allow the generator alternator to charge the battery. I thing I will try a test, disconnect the gen. alternator and keep the battery on the charger all the time.

Thanks for the help.

If I was you, I would replace the 24 volt alternator with a 12volt alternator like JWthetech said, that would solve the voltage conflict and also look at using a trickle/maintainer battery charger. If you have a prolonged power outage, you'll want the 12 volt alternator on the gen-set to the battery charged. I still don't understand why the gen-set came with a 24 volt charging system and a 12 volt starting system? Anyhow, good luck with it. DJ

one more question about this charging system, do you have 2 battery banks, one group of two, wired in series,(24 volts) for the CAT engine starter and one 12volt battery to power the control circuit. I just can't see Caterpillar installing a 24 volt alternator for a 12 volt starter, something just doesn't make sense here??

Let me first understand your present system. As I get it, you have a engine-generator set which has a 12 V starting battery. The battery has a charger without trickle charge facility.The generator along with other system load also supplies power to the battery charger. The generator runs only for 15 minutes in a week and hence the battery gets charged only for 15 minutes in a week while every time gets heavily discharged during a start up. The battery is 12 V while the charger gives 24 volts. Now the battery either does not get fully charged or gets overcharged. Is this the problem? Can't you get a charger with both trickle and boost options and put the charger on utility mains? You should have a facility for putting the charger on the utility mains as well as on the generator supply as per the need.You can also get a charger which automatically changes over from boost to trickle charge depending upon the state of the battery charge.

We used an automatic charging circuit with a battery voltage sensor. Whenever the battery voltage fell below the set value, the circuit would switch a relay to charge the battery at full charging current. Once the voltage rose to the set value the relay would switch off.

Typically the on time was about two minutes immediately after the generator was started, which drained the battery somewhat. Except routine inspection no attention was needed. A bonus was that hardly any distilled water topping up was needed even after months of unattended operation.

Greetings AP#1,

I am surprised that the 24V charger has not smoked the 12V system on the generator.

You may want to consider disconnecting the 24 volt charger and installing a common automotive 12V charger.

In addition, think about installing a time switch on the charger.

I don't see a need to install an automotive voltage regulator nor a relay to to disconnect the charger when the gen-set runs if you go with an automotive charger.

I have a 13.5KW gen-set for backup power.

The unit came with a cheap plug in 12V battery charger.

I also had a problem with over charging.

After replacing the battery twice in one year, I decided to put the charger on a time switch.

The charger comes on 2 hours every other day. This maintains the battery in a charged state and I no longer have a problem with cooking the water out of the battery.

I know I could have replaced the charger but I had a time switch handy so this was an inexpensive fix.

Are you CERTAIN, there aren't TWO 12 volt batteries in series? I've never seen a CAT generator (or any other stationary commercial diesel generators) that aren't 24V as others have said.

Edit timeout hit before I could add this...

All indications are it should have a 24v battery set, are you certain someone previously didn't replace a pair with one thinking if it would start then its enough.

I say this because you already have a 24v alternator, a 24 volt charger, and likely a 24 starter as well. I see nothing that indicates it really should only have one 12v battery.

What model # generator is this....which CAT engine Model # does it have.

We can get a lot of information from that information.

I would almost suspect someone borrowed one of their 12 volt batteries and didn't tell anyone, which would explain their comment in the OP, " i will not go into the problems I have had due to the control and AVR circuits." and maybe that same person borrowed more than just one battery. I also wonder what happened to OP, they haven't said anything since post #4.