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Fitting an 065 12 volt battery in an MGBGTV8
The topic of 12 volt battery conversions for the MGBGTV8 has been covered in V8NOTE250 by Gordon Hesketh-Jones who installed the larger 065 battery and then later a detailed installation note of the marginally smaller 063 battery in V8NOTE329 by Victor Smith. At the turn of the year 2006/07, Malcolm Venables decided he wanted to make the change and obtained a 12 Volt Battery Conversion Kit, but then began pondering over which battery to fit - an 063 or an 065? His contacts with Gordon provide a useful sequel to the earlier V8NOTES. (12.1.07)

Malcolm Venables contacted Gordon saying "I have been in correspondence with Victor Smith and have purchased the 12v battery conversion kit from the V8 Register and now have to decide which battery to fit. The footprint of the 063 type is attractive as it appears to be fairly easy to fit, but Victor mentioned you had fitted the 065 type which would of course provide a greater reserve of power. Presumably this is fitted in the same way by lowering into the carrier end on and rotating it as you do so. The positive terminal would then appear to be hidden under the rear apron and I was wondering whether the presents any problem. Any advice on these issues from your own experience would be appreciated."

Gordon Hesketh-Jones responded "nice to hear from you. I changed to 12v batteries some 16 to 17 years ago and later wrote V8NOTE250 which I attach. As you say, the 065 case is bigger BUT it means that the battery delivers far more power - important if, like me, you also use the car in the Winter. My current battery came from ATS last year - it was the Heavy Duty version with a 4 year guarantee, and cost just £54.99 for a 55 ampere-hour rating. As you can see in the V8NOTE, I had to flatten the metal riser in the base of the battery box in order to get the bigger battery in, and yes, you have to hold the battery almost vertically above the
small square hole before swinging it horizontal - I think that maybe the modern heavy duty ones are gel-filled because it did not leak when I tilted it. All larger batteries now come with carrying handles so the tilting and swinging is easy, but in the early

Table of Bosch battery data. (Malcolm Venables)

years I had to fix ropes around the batteries for insertion or removal. I found no problem by having the positive terminal partially covered by the top of the battery box, however I did in the early days Evostick a bit of rubber underneath the bodywork above the terminal - just in case - but need not have bothered!

Obviously the standard battery retaining clamps can no longer be used but I just fabricated a metal bracket to lie across the top/centre of the battery and screwed to two ends into the sides of the battery box - this will keep the battery in place if I have the misfortune to roll the car!! I hope this all helps but drop me a note if you need more comments".

Malcolm Venables replied "Many thanks for your response which was most helpful. I have decided to go with the 065 type and I have sourced a Bosch (silver technology) battery from our local Costco which sells them much cheaper than elsewhere - about £41. The Bosch code for this is 6HN UK ref 075, but has the same footprint as the UK ref 065 and it is rated at 60A/hr and 640A so it should have adequate power reserves. They also had available a 5BN which has the same footprint but is lower rated at 55A/hr and 540A for about £32.

The car, by the way, is a standard Factory MGBGTV8 (Teal Blue 0183) with some minor suspension modifications, which I have owned since 1980. Doesn't time fly, but it has seen little use over the last 8 years due to business and family commitments. However I am making a concerted effort to get it back on the road this Spring! Thanks again for the information."
Sequel from Malcolm Venables (25.1.07)

I found it useful to turn the rubber mounts which sit under the battery through 180 deg so that the short section of the L points downwards. This allows the battery to be mounted as far back in the carrier as possible.

Bosch 065 replacement 12v battery in place. (Photo: Malcolm Venables)

I placed some hardwood 10mm packing between the rubber and the carrier as this ensures the battery sits horizontally in the carrier. It is probably not necessary with the 063 type but the 065 is longer and can sit higher at the inner end of the carrier as the carrier mountings slope upwards. The attached picture shows a plywood template I cut out for the battery so that I could see exactly where it would sit in the carrier.

I replaced the convoluted metal conduit that runs between the battery carriers to protect the positive cable, with a similar plastic one, I just happened to have some lying around, but it should be obtainable from an electrical supplier. Whilst I am working in the area I think I will fit the battery isolator switch I have had for some time to the vertical panel in the now empty off side battery compartment.

Packing panel in position. (Photo: Malcolm Venables)

Comparison of the original 6v battery with the new 065 Bosch 12v battery. (Photo: Malcolm Venables)

You can see from the comparison above that the Bosch battery is not as high as the original 6v battery so clearance between the terminals and the underside of the metal access panel is not an issue. There is still a good 2.75inch clearance from the top of the battery posts to the underside of the metal coverplate. That is also the case even with the timber packing under the rubber strips.


One other point, despite the integral handle built into the battery, I found it very useful to wrap a short luggage strap around the outside of the battery to assist with removal from the battery bay. Once the battery is almost end-on (vertical) it is difficult to reach the handle so having the strap gives you something to pull the battery up with.

Safety reminder: do not forget that when lowering and turning the battery, or during removal, do protect the battery terminals to avoid the danger of contact with the metal bodywork surrounding the battery box.

I refitted the exhaust this week so was finally able to start her up again. She started with little problem, for the first time in several years. The 12v battery certainly turns the engine over much better than I remember even with new 6v batteries, so like Victor I feel that this is a very worthwhile modification.

Gordon Hesketh-Jones adds that the current price of 6v batteries from MGB Hive is £39.50 each or from Moss at between £42.95 and £50.95 each depending on the model. Fitting a single 12v battery for £41 to £55 therefore saves money even after buying the V8 Register 12v battery conversion kit with all the parts you need, as well as giving a longer more reliable life and avoiding the need for regular topping up. The "wet" batteries are of course "old" technology without the benefit of most of the improvements over the past 30 years. My old 6v batteries rarely lasted more than 24-26 months so that was my reason for contributing V8NOTE250. With the three notes, I hope members will feel able to tackle this useful modification with confidence.

V8NOTE250 - fitting an 065 battery

V8NOTE329 - fitting an 063 battery