MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Battery Brain review

Just thought I'd post a quick review of the "Battery Brain Gold III" - I did an archive search before deciding to buy and couldn't find anything. I have no connection to the manufacturers other than having just bought one and fitted it to my '66 GT.

The "Battery Brain" is essentially a clever battery cut off switch. It fits between the positive battery terminal and the cable - my car is negative earth but according to the manufacturers it will work on positive earth cars too. I guess in that case it switches the earth. The model I bought has two functions:

1 - Monitor battery voltage and disconnect if it drops too low. The idea of this is that in case of a parasitic drain or if you leave something on (such as the headlights) to make sure you always have enough power to start the engine. The other, of course, is to ensure the battery doesn't become deeply discharged, which will shorten its life.

2 - Allow disconnection and reconnection of the battery using a remote control fob.

The first function has little interest to me - I believe that if you have a parasitic drain you should fix the problem, not the symptom! The second function is the reason I bought it - as a simple anti-theft measure, but mainly for easy disconnection of the battery when parked up or in case of emergency. Having recently seen the result of a fire on what was a lovely B my mind is more focussed on safety than it was.

The unit has a reset button mounted on the top - this means that the anti-theft feature can be defeated if the device can be accessed. However, with the inconvenient location of the batteries on the B and the possibility of mounting the unit remotely if desired this is manageable. The unit is surprisingly well made - for example, the reset button is protected by a plastic screw cap which is tethered to the body by thread so you can't lose it and is sealed by two rubber O-rings. The kit comes with two remote fobs, the unit itself and assorted fitting hardware including insulated mounting blocks, angled terminal extensions and even cable ties!

Installation involves undoing the positive battery cable, attaching the unit using whatever mounting hardware fits best, attaching the cable to the other terminal on the unit and connecting the earth flylead to the negative post. Finally, a cable is run from an ignition-switched feed to the unit - this ensures it never disconnects the battery when the ignition is switched on. As an alternative, you can buy a vibration sensor, the theory being that it detects vibration of the running engine and achieves the same thing. I ran a cable, as that was free.

It took about 1 1/2 hours to fit, but most of that was spent running the switched live feed from the fusebox. The unit fits perfectly, the mounting hardware must cover almost any eventuality and so far it does exactly what it says on the tin. If you have a clock or radio with memory a fused bypass cable is included, but I didn't use that. Pressing the button on the remote fob and hearing a satisfying "click" as the battery disconnects is, frankly, magic!

The kit is quite expensive - it cost 60 but that included VAT, next day delivery by UPS and apparently an unconditional money-back guarantee. I emailed a couple of technical questions and received a knowledgeable reply very quickly. See http://batterybrain.co.uk/ for more info. There is a similar site for our friends across the pond.

Conclusion - Expensive, but I don't feel "done". Assuming it is reliable, it provides an unobtrusive, easy to fit battery switch with ultimate convenience. I love having a remote control instead of the alternative big red key and large hole drilled in the heelboard. The kit really is extremely well thought out and the comfort factor of knowing the car is less likely to burst into flames if an errant mouse takes a nibble at the cables in the garage is worth it for me. Highly recommended.

As usual, YMMV!

Cheers,
Tim
T Jenner

What a clever idea. It sure solves a lot of problems in one little box.

Tony
Tony Oliver

I've looked at this before but considering how tight the space is on my 1980 mgb roadster (12v battery under rear shelf) I didn't think it would go.... Only place i thought of was in the boot (trunk) with the required hole drilling etc...
Curious, Tim, where did you mount it??
cheers
Jon
jwhitehead

I was convinced I would have to mount it remotely in the second battery box (my car has been converted from 2 six volts to a single 12) but in the end it fitted perfectly on top of the battery. Attached is a picture (one more to follow). Please excuse the quality - mobile phone picture with a horrible colour cast from the inspection lamp!

The red boot at the bottom is just an insulating cap for the main battery terminal with a cable tie to stop it slipping off. The black fly lead from the battery brain to the negative battery terminal (which is at the top of the picture) is the earth for the 'brain; the white wire attached to it is the aerial for the remote control. The black wire with blue spade connector is a positve feed from the fusebox (hot when ignition on). The battery's vent is on the side (top of the picture) so the 'brain isn't blocking anything except a couple of the cell caps (and it only rests lightly on the top anyway).

Cheers,
Tim

T Jenner

This picture shows side-on - the battery cover fits fine without touching the 'brain (although only just!). The 'brain is only fixed by the bolts holding it to the positive battery terminal - I thought this might make it a bit flimsy and move around but it's very solid. The clamp provided with the 'brain is a very good design - it has a step on one side which allowed me to mount the 'brain flat on the battery case even though the battery terminal is set a dip (ie. lower than the top of the case).

Cheers,
Tim

T Jenner

I wouldn't bother for either of my MGBs as a simple manual switch (which they both have in the heel-board) is just as good and probably better for an emergency disconnect and a tenth of the price.

However I'm experiencing the same problems with my ZS which is only used occasionally in the summer and perhaps only once per week in winter as I did with the V8 when I stopped using it every day and it looks a possibility for that, also for Son's classic BMW which is only used occasionally. I've been pondering where to put a manual switch on the ZS, and had virtually decided it would have to hang from the middle of the cable from the battery to the main fusebox, as unlike the MGB there is no easy and convenient place to put it. At the moment with a new battery I'm disconnecting the earth cable, as is my son. A Type 3 with key fob disconnect as well as reconnect would be much more convenient, and I'd rather disconnect the battery by choice rather let the battery keep running down, even to 12.1v.
Paul Hunt

Installation is, obviously, much easier if the battery is under the bonnet as you don't have to run additional cables. One thing to watch is that "switched" connection isn't supplied with any insulation so you would need to be careful not to accidentally short it on the underside of the bonnet, etc.

They also do a version with a wired push button connect/disconnect - it's the same price as the remote control option but does have the slight advantage that it draws zero current. The remote model draws (from memory) around 4 milliamps at idle.

Cheers,
Tim
T Jenner

Amazon sell them for US$50-60
Tony Bates

Also at
http://www.batterybrain.net/?source=battery_brain
Tony Bates

Interestingly, they seem to have different models in the US to here. At Tony's link, the Platinum seems to be equivalent to the "Gold Model 3" I have. There is a Platinum version in the UK too which as far as I can tell is the same as the Gold 3 but includes the vibration sensor and has a bypass built-in (instead of a fused bypass wire which will blow if you forget about it and try to start the engine without reconnecting the 'brain!).

Cheers,
Tim
T Jenner

This thread was discussed between 22/06/2009 and 24/06/2009

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.