42
Surrette and Rolls Batteries
Model Volts Res. Min. 20-Hr. rating
"n"
EHG-208
6
345
208
1.42
EIG-225
6
350
225
1.54*
EIG-262
6
395
262
1.72*
24/90
12
165
90
1.16
27/12M
12
190
112
1.23
30H/108
12
230
108
1.08
HT/4D
12
348
170
1.15
HT/8D
12
450
221
1.20
*Use Max allowed
"n"
of 1.50
Peukert's Exponent
log
t
2
- log
t
1
log
I
1
- log
I
2
n =
log 20
- log 7.45
log 25
- log 11.25
=
=
1.301
- 0.872
1.398
- 1.051
= 1.24
Example of using Reserve Minutes @ 25 amps
and the 20-hour rate to calculate "
n
".
First convert Reserve Minutes to hours, then find the discharge current at
for the 20-hour rating. Finally, use a calculator to solve the arithmetic.
Trojan T-105:
Reserve Minutes = 447 min @ 25 amps.
t
1
= 447 min = 447/60 = 7.45 hrs
I
1
= 25 amps
20-hour rating = 225 Ah
t
2
= 20 hours
I
1
= 225 amp hours/20 hours = 11.25 amps
