From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
The performance and capacity testing of 12-volt and 6-volt batteries, including details on cell weaknesses and discharge rates.
| Identifier | ExFiles\Box 164\4\ img118 | |
| Date | 11th September 1933 | |
| -2- Hs{Lord Ernest Hives - Chair}/Wst.3/MA.11.9.33. Cont'd.{John DeLooze - Company Secretary} The 12 volt Slem was then fitted to experimental chassis 1 J.111 ran 4,773 miles on that chassis. It was then removed from the car, fully charged, acid density corrected and again put on high rate discharge. This test failed completely the discharge only lasting for 2 minutes 50 seconds. Numbers 3,4 and 5 cells being considerably weaker than the other three cells, although all cells showed negative weakness. This number 3 cell has been considerably weaker than any other cell from the time when it was given its first charge. On capacity test after 14 weeks service the battery showed no capacity loss from the previous tests it gave 63.6 ampere hours as compared with 63.9 ampere hours; but the negatives still showed themselves to be very weak. We attach curves of this battery's performance. Phantom II size one 6 volt unit. This battery has been in service 16 weeks and has run 3,986 miles. Its starting capacity has fallen to 14 mins. 40 secs. compared with 20 mins. when new. The internal resistance of this battery appears to be more than the 12 volt slem in spite of the fact it should have a larger capacity which usually results in a smaller internal resistance. On high rate discharge the current falls to 100 amperes in 1 1/2 secs. and at the end of 6 mins. is 97 amperes. This is the same as when the battery was new the difference being that it falls off quickly after 12 mins. On this test the negatives show themselves to be exceptionally weaker than on the previous initial test. On capacity test there is a fall from its initial value of about 25% of capacity. This discharge test was discontinued owing to one of the cells becoming prematurely discharged before the other two, but as this cell is the weakest of them all it determines the capacity of the battery. The battery gave 52.3 ampere hours compared with 71.5 ampere hours on its previous initial test. | ||