Introduction into Batteries and Charging Systems

[junglejuice]

This morning I fitted my replicated BTS which is essentially a pair of 47k resistors in parallel which results in a resistance of approx 23.5k.
This netted me a running voltage of 14.3V which is perfect, far better then the 13.7V I was originally getting and just tops the 14.2V I was getting when it was OBD1.

As a further experiment to run twin voltages in the car with a higher voltage applied to the AGM in the rear I fitted a temporary diode after the alternator which drops the running voltage by 0.7V, but as the PCM monitors and regulates the running voltage it caters for this and returned the voltage back to 14.3V but the benefit is the terminal voltage at the alternator is 15V, when allowing for 5 metres of cable, two fuses and a dual battery controller should be perfect and again this tops the previous OBD1 system by 0.3V.
Just need to find a suitable diode based dual battery controller now to finalise this mod but it will be set up so the rear battery doesn't charge via this unit to maintain the higher voltage to the rear....

[junglejuice]

Originally Posted by anthonygubbin

Since we get minus 5-9s here; would I be best to remove the sensor and replace it with a 20ohm resistor? I don't want to have it charging at 14.5v or thereabouts when the temps are minus 9deg at 6am. Would you recommend going any higher charge than 14.2v?

Regards A

As modern vehicles can run at up to 14.4V anything up to that should be fine, why not try a 10k resistor in series with the BTS, this will allow some variation if required or you can do what I have done and run a 20~k resistor without the sensor....

[del97td]

just borrowed one of those obd scanners and my voltage sits between 14.1 and 14.4 when driving

[shakes]

Asking a bit of a silly wiring question but I don't understand.

Why is 'audio' 4ga wire (not speaker wire but the power feed for the amp) so much cheaper than standard automotive 4ga wire?

I can't find a simple table anywhere with the apparent differences.. Can anyone spell it out for me.

Basically looking to use it to feed from my main battery to the second battery.

[Doctor W]

Originally Posted by Deezelweazel

Just as an info:

Taken from the Optima site:
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Charging Info


The following charging methods are recommended to insure a long battery life (Always use a voltage regulated charger, with voltage limits set as described below):
All OPTIMA® YellowTop Batteries
These batteries are dual purpose. They are designed for engine start and cyclic applications and for use in vehicles with large accessory loads.
Recommended charging information:

Alternator:
13.65 to 15.0 volts, no amperage limit.

Battery charger:
13.8 to 15.0 volts, 10 amps maximum, 6-12 hours approximate.

BlueTop Type: BT SLI 4,2
These batteries are designed for engine starting applications. They are NOT recommended or warranted for use in deep cycle applications.
Recommended charging information:
Alternator:
13.3 to 15.0 volts, no amperage limit.
Battery charger:
13.8 to 15.0 volts, 10 amps maximum, 6-12 hours approximate.

Blue Top Type: BT DC 4,2 / BT DC 5,5
These batteries are dual purpose. They are designed for engine starting and deep cycling applications and for use in boats with large accessory loads.

Recommended charging information:
Alternator:
13.65 to 15.0 volts, no amperage limit.
Battery charger:
13.8 to 15.0 volts, 10 amps maximum, 6-12 hours approximate.


All limits must be strictly adhered to.
-----------------------------------------------------------------------------

As you can seet he standard regulator voltage of the Jeep is enough to charge the Optima. But raising the output voltage of the regulator is also within the limits of the battery. So no harm.
I do find it interesting to see the amperage limitation of 10A when charging with a battery charger!

Yes, it's interesting stuff..... this seems to be the same info as on the pamphlet I got when you buy the Optimas - at least if you ask for it.

I also wonder why the 10 Amp limit on Battery Charger current but no limit stated for alternatos......strange.

BTW Deezle, one of the tech gurus/public relations people from Optima / Johnson Controls seems to monitor the website ExPo (Expedition Portal) which I think I've seen you on once in a while - he may be able to give you replies/answers which you said (in a much earlier post) in this really excellent piece of research/writng/dissemination of knowledge were simply not forthcoming from the suppliers/manufacturers.

[junglejuice]

Originally Posted by shakes

Asking a bit of a silly wiring question but I don't understand.

Why is 'audio' 4ga wire (not speaker wire but the power feed for the amp) so much cheaper than standard automotive 4ga wire?

I can't find a simple table anywhere with the apparent differences.. Can anyone spell it out for me.

Basically looking to use it to feed from my main battery to the second battery.

In my experience anything to do with audio is generally much dearer for the same thing, 4ga is 4ga is 4ga assuming that it is actually measured correctly which is approx 16mm2.
I use double insulated 35mm2 welding cable for all my automotive high current applications for many years now with no issues and welding cable is generally cheaper.
Also if someone tells you that welding cable is resistive and can't be used then that is a 100% indication they have no idea....

[shakes]

You can buy complete 'audio' kits with a 100amp fuse and RCA leads etc for $40.
Couple of chinese sellers are doing the cable for ~$1/m

As opposed to the $15/m+ locally

Trustworthy? Or is it some sort of copper looking alloy that will melt at the first sign of a decent current?