RMs used to have a configuration of four 6volt batteries for the 24volt output. What is the availability of these old batteries? I understand that they would be very expensive. Any one know or still have a bus with them?

John

David Colin reminded me that RMs originally had 3 x 8Volt batteries from Chiswick. When Chiswick was in decline they converted to 4 x 6volt.

Most people now like us, use 2 x 12 volt, easily obtained. A search will find a lot of discussion on batteries on here and the ones to use.

My bus number (if any): RTL 960, RMC 1458, RM 1585 and several RTs

The disadvantage is that there will be four batteries to fail. In twin applications it is common to find that the 'good' battery fails quite soon after the 'bad' one, because it has suffered unequal charging, which is why they are generally replaced in pairs....except you now have four.

Thanks all for your usual excellent input. I have to say that anyone with a Routemaster and little knowledge of mechanicals and electricals of these buses would be lost without this forum. Of course this is one of the less technical queries I can expect to have.

Having now heard that one 6volt battery can cost more than a 12volt battery then it dictates that two 12volt batteries make economic sense. Originality can only go so far, though I've never heard of 8volt batteries being used. I'd imagine that one 24volt battery (if such a thing?), would be rather big and very heavy.

John

My bus number (if any): RM108

I found a firm in Ware (I think) a few years back that done the "original" 727 type 6 volt batteries with flat terminals. They were indeed very expensive. when fitted I found one was cracked and had to be returned. There were further problems nd two others had to be replaced under warranty even though they were from a reputable make. This was on rML2532.

We subsequently bought an AEC generator set from someone up north to provide 3 phase for the workshop and that came with some dry"type 6 volt batteries. These fitted the RM battery crate and despite having sat in the garden for over a year were good enough to start the bus first time when fitted. I don't know what make they are, but they were designed for emergency/standby us. They've been on the bus 2 years now and have never gone flat.

On the BEA RF and GS we used 2 12 volt Bosch batteries; they're a lot cheaper than the 6 volt 726 type and readily available. Battery technology has progressed over the years like most other things.

One 24 volt battery would be very expensive to buy and bloody heavy to lift!

My bus number (if any): RML2532

The 8V batteries used on the Routemaster as well as later buses, DM, M, T, LS (and I assume models prior to the RM) were made at Chiswick works. LT free issued these, I was told, to the vehicle manufacturers so the entire fleet was standardised.
The 8v battery comprised a box with carrying handles and 4 x 2v cells fitted into the box. These were linked -ve to positive with three open bar type links. The main (first) positive and (last) negative terminals had flat PSV type, two bolt connectors fitted.
The open links allowed us to test each cell with a 2v cell tester. It comprised 2 sharp pins spaced correctly on the rear of a large voltmeter which was simply placed upon the 2v section terminals. This made the batteries a repairable item with batteries being returned to Chiswick for cell changes and reissue.
The crimped connectors were made by Erma (long gone I believe) but Chiswick works appear to have made their own for solder connection. They appear to have been made using a short piece of copper pipe around 15mm diameter with the first 20mm left round for the cable to be soldered into and at that point flattened with a slightly rounded end and two holes drilled for connection. They were then tinned. I will try to find some photographs.
The change to 4 x 6v was the result of the planned closure of the battery shop and alteration advice sheets along with fitting kits were supplied upon failure of the 8V units. Th Some buses had new battery crates while some had timber inserts to retain the new 6v batteries.
If two volt cells were available it would be relatively easy, if expensive, to replicate but I have no idea where to buy a 2 volt 200 (or so) Ah battery cell.

My bus number (if any): M1001. RML2276, T806

My bus has been standing for a while but I usually start it monthly and run it for 45 minutes to an hour, moving it around to reposition the tyres. However, the two reletively new 12volt batteries were found to be flat recently, and I'd always used the battery isolator. What I failed to realise was that the tacho is wired seperately and does not pass through the isolator, so the batteries had very slowly discharged. Not had a bus with a tacho before so did not give this any consideration. I've now disconected the tacho as the bus is for private use only.

Thanks for the above replies.

John.

My bus number (if any): RM108