Gary,
'73 & '74 models were shipped with three batteries. One up front for a
chassis battery (start the engine), one up front for a living area battery
(cabin lights, fans etc.) and one aft of the Onan for the sole purpose of
starting the Onan. Users found that the small dc output of the Onan would
not adequately re-charge the dedicated battery. Sometime in '74 they
recalled all '73s had '74 and retrofitted them with a 10 gauge red wire from
the house fuse panel to the Onan battery. This connected the house battery
and the Onan battery in parallel. Poor design. The small Onan and the
larger house battery were significantly mismatched and both failed too soon.
Beginning in '75 GM moved the house battery to that compartment aft of the
Onan, changed it to a large D4 size (100# ?) and connected it to the engine
alternator and battery boost switch up front.via a long, 0 ga. red / 1 ga
black cable (really just a jumper cable) with appropriate circuit breaker -
relay protection.
The '75 and up plan is a great improvement. '73 and '74 owners will be well
served to change to this configuration and use either two 12 v. marine deep
cycle batteries, parallel (+ to +)or two 6 v. golf cart batteries , series
(+ to -). Again, just my recommendation: golf cart batteries. IF YOU DO
THIS, FIND THE CIRCUIT DIAGRAM FOR THE '75s + in the X7625 Maintenance
Manual AND FOLLOW IT. DO USE BOTH THE CIRCUIT BREAKER AND THE RELAY FOR
SAFETY SAKE..You don't need the Rear Battery Junction shown in the diagram.
Use 0 ga cable all the way. Welding supply houses are a good source of the
cable.
byron maxwell/chaparral
'73 & '74 models were shipped with three batteries. One up front for a
chassis battery (start the engine), one up front for a living area battery
(cabin lights, fans etc.) and one aft of the Onan for the sole purpose of
starting the Onan. Users found that the small dc output of the Onan would
not adequately re-charge the dedicated battery. Sometime in '74 they
recalled all '73s had '74 and retrofitted them with a 10 gauge red wire from
the house fuse panel to the Onan battery. This connected the house battery
and the Onan battery in parallel. Poor design. The small Onan and the
larger house battery were significantly mismatched and both failed too soon.
Beginning in '75 GM moved the house battery to that compartment aft of the
Onan, changed it to a large D4 size (100# ?) and connected it to the engine
alternator and battery boost switch up front.via a long, 0 ga. red / 1 ga
black cable (really just a jumper cable) with appropriate circuit breaker -
relay protection.
The '75 and up plan is a great improvement. '73 and '74 owners will be well
served to change to this configuration and use either two 12 v. marine deep
cycle batteries, parallel (+ to +)or two 6 v. golf cart batteries , series
(+ to -). Again, just my recommendation: golf cart batteries. IF YOU DO
THIS, FIND THE CIRCUIT DIAGRAM FOR THE '75s + in the X7625 Maintenance
Manual AND FOLLOW IT. DO USE BOTH THE CIRCUIT BREAKER AND THE RELAY FOR
SAFETY SAKE..You don't need the Rear Battery Junction shown in the diagram.
Use 0 ga cable all the way. Welding supply houses are a good source of the
cable.
byron maxwell/chaparral
