Battery Charging Problem (Help)

[chris9119]

Can anyone assist...... the story so far.....

I have two batteries on BB. The second battery serves all of the lights, invertors, etc, etc, etc.

The alternator is delivering 14.22 volts and this is reaching the second battery (via split charge relay). However, it was on delivering 12.6 volts to the primary battery (not via split charge). I removed all connections and cleaned up, replaced normal washers with star washers on all connection points (alternator, staarter, etc, etc).

Voltage on main battery recorded at 13.2 volts. However, after doing 30 miles with fan and radio on, if I turn it off, the starter clicks, but will not spin to start. I put jump lead across live terminals (primary and secondary battery, and he starts.

Battery testers says battery is fine......therefore, why am I not getting 14.22 volts to primary battery and why is 13.2 volts not enough to keep battery topped up.

Any assistance would be helpful.... Thanks in advance :?

Chris

[gords]

The battery in my Discovery worked fine at first, but it slowly started to strain and only just start.

The local battery garage checked it a couple of times with their tester and it said the battery was fine.

Eventually, I put a new battery in and the poor starting went away immediately! So, just because the tester says it's OK doesn't mean it actually is :roll:

[beast5680]

check its definatly the battery and not the starter playing about, have you swopped over the batterys and tried it?

[Andy.]

check its definatly the battery and not the starter playing about, have you swopped over the batterys and tried it?

Was going to suggest the same, swapping the batteries over  :?:

Good luck and let us know the out come.

[hobbit]

Another thing would be try and connect a new earth cable from the main battery to the engine itself. Might be a weak earth strap somewhere

[chris9119]

Thanks all for feedback.

Have swapped batteries and after a week, that one has same fault. Have put two new earth straps on to engine. Fitted new starter (thats 3 in seven months!!)

Still confused so further advice would help.....

Chris

[Wanderer]

Clutching at straws but could it be the split charge relay has got duff connections causing high resistance which means Battery 1 isn't getting a full charge.

When this happened to me it turned out to be a number of different hings that only seemed to clear fully by swapping the relays on the started circuit as well as the starter motor.

It could be earth leakage somewhere.

Ed

[chris9119]

Hi Ed

The split charge relay only serves the second battery (14.22 volts). The primary battery is still feed in the same way (13+ volts).

I can't see why one battery gets 14+ volts and the other 13+ volts (on the cable).

I would have thought that 13+ volts would be ok to keep the battery charged if I'm only using the radio and fan.

Still :?

Chris

[Wanderer]

The first battery will not charge as well as the second one due to the volt drop.

It's strange that the main battery is getting less voltage. It could be either of the pos or earth cables that has a bad connection.

Thinking about it. I've seen the wires start to break where the alternator cable connects to the battery.
Could it be that that is causing the volt drop? Try running a new thick wire on the supply to the battery or measure the voltage at the back of the alternator.

Ed

[Range Rover Blues]

You need to check all the connections by measuring the voltage accross them with a good voltmeter.  Somewhere a supposedly good connection will show a drop of about 1 volt, or several connections will show part of a volt each.

[Lostboy]

This is a far more interesting problem than trying to get this 70V power supply thats sitting on my desk working!

Check the cable from the alternator to your main battery, that may have a high resistance. Also, it might be worth checking the split charge system - disconnect this from the alternator and see if the problem goes away, though if your getting 14.4 at the second battery this would suggest that's not a problem.

Use a multimeter and check the resistance from one battery negative terminal to the other batter negative terminal, it should be low, less that an ohm (and what you can measure accurately on a standard multimeter!) is good - though watch out, most meters tell lies when you measure resistances less than about 5 ohms. I'm wondering if it could be some form of body/chassis corrosion between the two earths of the battery.