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MG MGB Technical - Charging 6v batteries

Are there any issues in connecting a 12v battery conditioner to the 2 6v batteries in my 68GT (across the two in series, of course)? I'm thinking of going for the CTEK3600
They charge up in series while the car's in use, so I can't imagine any issues, but I thought I'd better run it past the forum first. Any feedback on the CTEK3600 (or similar) in use would be handy...............
Andy Hinson

I use a battery conditioner on the 2 6v in series. It works fine. Mine is an Oxford Optimiser which is intended for motorcycles, but it does not seem to mind the extra ampere hours when connected to the B. I clip it on under the bonnet to gnd and the brown wire on the solenoid.
Stan Best

An even quicker and tidier way to charge it is connecting the battery charger at the fuse box. The hot fuse will (brown wire) feed back to the battery and will not pop fuses or overheat wiring and it is very easy to reach.
M Whitt


If it will make you feel more comfortable, you only have one 12 volt battery the same as the later models. The only difference is your 12 volt battery comes in two boxes, whereas the later 12 volt batteries come in only one box. The connection between the two 6 volt batteries in your car is made with a short piece of cable; in the later models, it's made with an internal bus bar.

All lead-acid batteries consist of a number of 2 volt cells, connected in series to give the proper voltage. In a 6 volt battery, it takes 3 cells. In a 12 volt battery, it takes 6. In a 24 volt battery, it takes 12 cells.

When you buy batteries from the store, you carry home 2 six volt batteries, but the instant you make the connection between the two, you have, by definition, one 12 volt battery.

Similarly, if you open up a 9 volt transistor radio battery, you will find six individual cells connected in series to produce the required 9 volts, each dry cell producing 1.5 volts.
Dan Masters

ooops! I meant to say "Andy"
Dan Masters

Thank guys, I like the idea of charging via the fuse box. The contortions involved in getting access to the batteries with the car in a small lock up garage are no good for my back.........
Andy Hinson

This is a worth while question, even though DC conditions will be identical the sensing charger and battery(ies) form a closed loop sysyem with a frequency response and the possibiliy of oscillating. Mine doesn't others may as you have the inductance of the wire stopping the charger seeing all of the capacitance of some of the cells. In practice the values of these impedances are such that it's unlikey to be a problem. In fact mine does not mind charging through the main underfloor power feed,others may, I would not bet against it.
Stan Best

Hi all.

I have been regularly trickle charging the battery of my 1980 GT via the cigarette lighter socket (with the cable going through the window) without problems.

I use a fused cig lighter plug, just in case the lead gets trapped or something and shorts to earth.


This thread was discussed between 09/07/2006 and 10/07/2006

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