Lead Acid Charging system......

I am working on a Battery charging/monitoring system for a project I am working on(Personal) I am going to be monitoring a voltage from a snowmobile motor that is going to be rectified and used to charge a Lead Acid battery and also to switch between the rectified DC voltage directly from the motor amd the battery (When the Voltage level of the Direct rectified falls below a specific level) To explain in more detail I am using a Two cylinder 462cc snowmobile motor on a Dunebuggy and I am looking to control the electrical system (Running lights, brake lights, etc and adding some special functions) I am going to use a small PLC for most of the work but am not sure if I should just take the Voltage from the motor and rectify it and charge the battery and just pull all my voltage from the battery or have it able to switch all the electrical between the battery and the motor (keeping the PLC connected to the battery). I know it is sort of off topic but since I am using a PLC for some of the control and the fact that I know some of you control guys have used PLC's in a Battery power configuration you might have some Ideas of products or ways of going about it. Thanks in advance for the help

Back in my uni days I did a fair bit on solar energy applications and hybrid motor vehicles (theory only for the hybrids, unfortunately). This is not too far out from what you want, although I used analog ICs rather than a PLC for control.
This information is from memory, so please check everything before you use it.
Firstly, I think a PLC is the wrong tool for most of the work. You can use it for switching devices in and out of the circuit, and monitoring, but in this situation you will still need to build or buy some rather specialised equipment. Sort of like the way you buy a VSD to control the speed of a 3 phase motor.
You can power the load from the alternator while also charging you batteries. To do this, you need two separate power converters. First is a rectifier/DC level control. This can be as simple as a standard SCR bridge rectifier.
The second device is a battery charger. This can either be run from your alternator or from the rectified DC.
In addition, You will need to use some power diodes to ensure the current flows only in the desired direction. I would suggest one diode for the battery, one down stream from the DC rectifier, and one down stream from the charger.

The final trick is to balance voltages so that you get the current to flow in the correct direction. Remember that a fully charged 12V battery at no load actually puts out around 14.4V. Minus 0.3V for a good quality diode, and you can expect your DC bus to be around 14V on the alternator, dropping to 13 or 12 V as the battery is used.

Hope this helps,

Doug

Here is a good Link on Regulators.

pinworm21 said:

...but am not sure if I should just take the Voltage from the motor and rectify it and charge the battery and just pull all my voltage from the battery or have it able to switch all the electrical between the battery and the motor (keeping the PLC connected to the battery)

Click to expand...

Your first idea makes sense (and sounds like the right approach), but I'm not sure what you mean with your second scenario. Could you elaborate?...

What exists on the engine? A generator or an alternator? You could make you life a lot easier if you can find a way slap a standard GM 1-wire alternator on the engine... :nodi:

beerchug

-Eric

Overall it doesnt matter if snowmobile, car, truck etc...the battery and the alternator will be parallel connected...unless you do some strange wiring thing.

With them in parallel you connect to the 12 or 24vdc system and use power as needed, the idea is to KNOW how much power (current) is used and have the alternator able to provide that AND trickle charge the battery. If you have a demand of 20 amps on the system then you should use an alternator capable of 35 amps output.

Overall engine electrical systems can do this without help, monitoring is another issue.