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MG MGB Technical - Relocate battery to trunk

With occasional useage, the battery on my B sometimes needs charging or a jump to get it running if I am in a hurry. I hate having to remove the access panel to get to the battery so I was thinking of relocating the battery to the trunk. I checked the archives but found no details. Does anyone know how long a positive cable would be needed and if a larger battery would be needed to compensate for the addes resistence of the cable? Any other implications or suggestions?

Thanks
Ed Emery
Ed Emery

Ed,
Rather than lose trunk/boot space, why not add a jump/charge post in the engine compartment? You can get a through bulkhead connector at most parts stores. Install it on the inner fender/wing where the battery cable, that attachs to the starter, will reach. Attach that cable to the bulkhead connector and run a cable from there to the starter. You then have a jumper/charging connection that is well removed from the battery and easy to get to.
Leland Bradley

About a year ago, I replaced the standard positive battery cable on my 1970 roadster. This is the one from the positive terminal of the battery to the starter solenoid.

I looked in every autoparts store that I could find for one. The longest that anyone stocked was (I think) 54 inches. This was just barely long enough. In fact, another two or three inches would have been better.

I did not investigate special ordering a longer one, so I don't know if that is possible. You could probably locate some 2 or 4 gauge wire and make up one, using separate connectors on each end.

I wanted factory installed connectors on both ends, because I have never had very good luck with the kind that clamp onto the cable.

To put a cable into the trunk and still maintain the same path, through all the wire supports and so on, you would probably need a cable close to 7 feet in length.

I don't think that the longer cable would have appreciably more resistance, so a normal battery would still suffice. Its not really the physical size of the battery that counts, its the CCA (cold-cranking-amps) rating. You can get a cheap, $39 425 CCA battery at a discount store or go for a top of the line 700 CCA for $89-99. Both are still group 26 size batteries.
Paul Noble

If all you want to do is trickle charge the battery for 4 or 5 hours periodically, you can use a 2/10 amp charger - one cable to ground (of course) and the other to the fuse holder end (one of a pair of clamps that the bus fuse snaps into) that corresponds to the brown wire(s). No additional work or parts, but a jump-start connection in the engine compartment would be handy.

Wayne
Wayne Pearson

If you want a longer cable why not just get your hands on some 4 ga power wire from the local stereo shop and wrap it with wire loom tape for added protection and put the ends on it that you want?

I'm sure 4 ga would be plenty, but if you had to, 2 ga and 1/0 ga is available too.

Justin
Justin

Not a good idea to locate the battery in the trunk.
Explosive gases tend to accumulate and the area is way too constrained. The tank sometimes tends to leak or the rubber elbow from the filler may be slightly too rotted.....a little jiggle from loose wires......BOOM!

Also, batteries tend to leak and the results can be rather ugly.
Not much room left for anything else as well.
Luis

I had the same experience as Paul for my '69 - the longest stock cable with the appropriate terminals was - just barely - long enough, from Pep Boys as I recall after some searching. But any good auto electric specialty shop should be able to make one up from stock parts, in whatever gauge and terminal type you want, probably while you wait. They do it all the time for commercial vehicles and custom installations, out of the proper vehicle-grade materials.
Jon Sjoberg

I have the battery i the boot in my '66 GT. It's great, because I can hit the fuel pump and drive at the same time.....
Tomas

Some junkyard digging can turn up the auxillary battery jumping post from a late 80's Audi 5000. Audi's battery was also mounted beneath the back seat, and they provided this bit of convenience to allow owners to jump start their cars. It sits up on frame rail on the RH side just ahead of the engine. If you are lucky, whoever stripped out the starter (the solenoid post is where Audi tapped in this aux. cable) will have left you the cable and the jumping post, both of which are worth having. Just another alternative.
Bob Muenchausen

My '74 came with the battery in the trunk. I haven't taken a look at the cable, but I'm almost sure it's one piece. I was going to suggest asking a heavy truck repair shop about long cables. The PO did put it in a plastic battery box, so that contains the acid spills.

But the real reason I chimed in is to say that I'm planning to move my battery back under the seat one of these days. The battery and box take up a lot of space in that little trunk. Whenever I go to stow something, I find it would have fit perfectly in the well to the right of the spare tire, but the battery is taking up that space.

I like the idea of the remote jump/charge post. That and a cutoff switch should keep you from having to get under the access panel in most circumstances. I'd think you could put the jump/charge posts together with parts from a decent electrical supply store.
Matt Kulka

Has anybody checked out the length of a Miata cable? The battery is definitely in the trunk.
Ken Thompson

I bought a '74 GT and a prev. owner had located the battery in the engine compartment. There is plenty of room, and it seems far more logical than putting it in the boot(trunk).
Sim

The PO had put the battery in the trunk of my 73 B. In addition, he had run a short cable from the starter terminal to a convenient point under the bonnet. It is attached with an insulated clamp around the cable and the free end is terminated with a soldered sleeve which is normally covered by a slide-on vinyl cap. It proved most useful as the power source for a timing light.
Barry Quartermaine

i did this with my 68 b rd and i had to change it back because you loose the space for the spare tire
scot

I relocated the battery on my 64 MGB into the engine bay. A pic can be seen on the site in the pic-section for MGB, here´s the URL: http://www.mgcars.org.uk/pics/neuhaus3.jpg
Joern

Thats exactly where mine is Joern. Although that engine bay is somewhat cleaner than mine!
Sim

I like Joern's setup better than the relocation to the trunk. Much safer and cleaner. That said, why bother at all? A quality Group 26 12V, with an electrical system in proper working order, will hold a charge for many months. When I store my car for the winter the battery comes home, and is still capable of starting the car three months later.
If needed for convenience, i would prefer Leland's suggestion for a jump post in the engine compartment.

Another source for longer cables would be a supplier of arc welding equipment.
Andrew Blackley

Thanks for the comments. While Joern's solution is very appealing there is no room in the 75 to place the battery there. The master cylinder sits there. It seems that the jump post in the engine compartment is the way to go. No loss of trunk space and easy to connect to.
Ed Emery

Anyone ever consider the results of a cracked fuel fill hose and a spark producing and acid fume producing battery in the confined area like a MGB trunk? Could be real exciting!
gerry masterman

Ed, you should have room: remember my car is a rhd example. On your car you should be able to simply place the battery on the other side, where the distributor is.
Joern

Many years ago, I ran a battery cable from the starter to a small terminal block located ahead of the fuse block. I can charge/jump from that location as well as have a power source for timing lights. etc.

I also followed Paul Hunt's suggestion and added a cigar lighter plug to my charger.

Dan

Any heavy truck shop will be able to make you a cable of whatever length you need, with soldered ends. I'm a firm believer in over kill, so if you got them to make it out of 0-guage, (single-ought, welders call it) you could have battery cables 30 feet long without having to worry about the resistance problem.
Dave

Not to start any kind of argument, but in response to gerry about the hazards of putting the battery under the hood, it seems like a common enough place on most cars, and not exactly poorly ventilated, like the trunk.
Peter Ballinger

I had an XJS Jag, which had a boot mounted battery, if i remember correctly it had some sort of vent which went out via a tube - i think. So if there were some concerns about boot mounting then perhaps something along the lines of the XJS setup would be of some help.
Ian Sanders

My comment was not about putting a battery under the hood, rather in a poorly vented enclosed area with a 2" rubber fuel fill line runing through it. In the summertime when your fuel tank heats up the fuel fumes enter the trunk area through cracks in the filler neck hose. Maybe not now, maybe six months from now, maybe never, but it sounds like an invitation to a bonfire to me. If I were going to do this, I'd have the battery in an enclosed box with a flow through vent and a liquid drain to the outside.But then again, both of my B's are worth too much to me to take the risk.
gerry masterman

Enthusiasts of the boot battery should have been present when I took mine out- there was a hole underneath it big enough to put your fist through, thanks to the PO's clever idea.
Ken R
Ken Rich

Ken R. is right! My PO did the same thing and the damage to the trunk floor was horrible. Back to single type 26!

I guess if my heart was set on a trunk mounted battery, I'd use a battery box and anchor the battery stoutly to prevent spills. But I think the fumes will still cause problems.

Craig
cwcolby

Sorry gerry, my mistake, the dangers of reading bbs threads at while falling asleep. Somehow I transmogrified trunk into hood, and fuel filler line into feed line. serves me right for posting while sleeping...
Peter Ballinger

...the AH 3000s had the battery mounted in the boot. I hadn't heard of any problems with those cars.
Leland Bradley

The Healeys probably pre-dated marine battery boxes, and i bet they suffered spills and condensation like any other car- unless the battery well was bottomless like the MG six volt mounts. I can remember back to the 'fifties when my plummer mate soldered up a lead battery tray to mount the battery after the acid had eaten away at the steel under-bonnet mounting tray of his Austin, and I remember my early Honda Civics' trays getting eaten away, but then Hondas died of rust in those days.However, my VW Campers had twin batteries in plastic trays and there was never any problem. My Cooper battery was in the boot, in a well, with some kind of mat under it, encouraging acid eating, but then I wore it out in three years, and it was an engine and CV joint problem that intervened between acid damage and my ownership. The solution is both protection and ventilation, and the boot can't give you the latter. The VW had good ventilation, and the MGB 6 volt bottomless holders offer superb ventilation, as does a front mounted battery. Do some checking with Healey and Cooper owners.
Ken R
Ken Rich

I think the battery in the trunk takes too much room. I had it in my A and an older B and did away with both. The charging/jumping post is a better idea. However, if you want new cables of any length, go to a battery shop. We have them in our area, mostly run as Interstate battery franchises. They will make up custom cables in any length, any guage, and with any end fitting. Price is a fraction of the cost of auto part store cables.

As an aside, I used to use welding cable for all mine. It was much more flexible and easy to route than standard. This is due to the use of much finer strands in the cable. I was warned about doing this by a friend who owns the local battery shop I use. He stated that their experience was that these cables were much more prone to internal corrosion due to these fine strands. Their experience was that normal battery cable gave better service than the more expensive welding cable.
Arthur Shaffer

Many of the new batteries are advertised as "sealed" which means you don't add water and shouldn't have fumes or spills. The Miata uses a "gel" battery that is located in the trunk, and vents are not necessary. Probably the Optima battery would give you the same results, and it should be available in the group 26 size. I think Optima advertises that you can even turn the batteries upside down and they still work correctly.
Ken Thompson

I don't think fumes are a problem with the battery in the boot - how many million Minis (original and true Mini I mean) were made? They all had the battery in the boot along with the fuel tank. Taking up space and promoting corrosion would be my reasons for not doing it. I like the battery in the engine compartment though - wonder why they never put it there originally?
Mike
Mike Howlett

The battery (or batteries) within the "cockpit" area will result in a better polar moment of inertia - meaning that the handling of the car could be affected by having the battery(ies) at either end. This is probably only a problem if you autocross your B.
Charles Edwards

I have often considered removing my two 6V and replacing with a single 12V in the engine compartment.

Then I remember the last winter and how I wish I had even more weight in the back for rear wheel traction, every little helps.
Steven Williams

This thread was discussed between 10/06/2002 and 19/06/2002

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