Very Quick Battery Discharge (Apparently)

[Jimpics57]

My (1994) 3.0L has been standing in the garage for some 6 months awaiting a new front diff, been starting it regularly and running the engine for 10 minutes each time and had no problems. Last weekend the batteries wouldn't even crank the engine! Connected up my 2.4 Surf via good jump leads across both batteries and 15 minutes on high rev tickover got the 3.0L started. Disconnected the jump leads and after 30 seconds it (3.0L) cut out again, reconnected for 5 minutes re-started ok then once disconnected stopped again! Third recharge got the motor running and left it run for 15 minutes before reversing back into garage.

Turned ignition off after another 10 minutes (no tax so driving to recharge not an option) and engine restarted but batteries seemed weak. Put meter across them in turn and the voltage was dropping 11.9 11.8 11.7 as quick as I am typing this! Both batteries eventually bottomed out after a while at 1.6 volts.

Recharge from other Surf today wont get the 3.0 to crank over, disconnected both batteries and they are holding 11.9 volts, they were both new last February. Reconnect them to the vehicle and they drop to 3 volts, disconnect them they climb back up to 11.7/8 volts on the meter again!! Am I missing something obvious!!

I am thinking Alternator or ECU (the ECU was tested and overhauled 18 months ago - a starting problem (wonder if I just answered my own question!! its failed again!!!)

My Automatic Battery charger gave up the ghost too - when it rains it pours!!

Any other checks I can do? - not an expert on electrics, have disconnected all ancilliaries and accessories to eliminate any possible short circuits as a precaution!

Jim (Plymouth)

[BUSHWHACKER]

Could be the starter contacts, relay contacts or starter solenoid sticking causing power drain.

Try the starter relay (Large black relay next to the fusebox) from your 2.4 truck, plug it into the 3.0 and then measure the battery voltage again.

[NiftyNev]

disconnected both batteries and they are holding 11.9 volts, they were both new last February. Reconnect them to the vehicle and they drop to 3 volts, disconnect them they climb back up to 11.7/8 volts on the meter again!! Am I missing something obvious!!

I think the batteries are dead flat. Even a flat battery can show 12 volts on a multimeter, but once a load of any sort is connected, then they will drop voltage quickly.

Get them fully recharged then test voltage when trying to crank. If it drops below 10 volts then there are stuffed.

Nev

[Jimpics57]

Quick respose Thanks Guys

Off to try the relay swap ! Will have to borrow a charger though!

[Jimpics57]

Relay Swap

Swapped relays, 2.4 starts ok although ECU made a few noises - reconfiguring I suppose. 3.0 no different , batteries reading 1 volt so I must fully racharge them and try to find the source of the drain (if one exists) - Thanks guys

[NiftyNev]

I must fully racharge them and try to find the source of the drain (if one exists) - Thanks guys

Probably this.

My (1994) 3.0L has been standing in the garage for some 6 months awaiting a new front diff, been starting it regularly and running the engine for 10 minutes each time and had no problems.

Nev

[Apache]

Are you certain the batteries bottomed out at 1.6V, or do you mean 11.6?

If 1.6V, they are knackered and will never hold charge again. Better buy some new ones.

As far as fresh charged batteries dropping half a volt in minutes, that's normal, though 11 point something straight after charging indicates they shagged too.

[Dobbslc]

Lead acid batteries don't like being left flat it will oxidise the plates inside, if there is even a small drain and there usually is (clocks, ecu or just earth leakage)that will kill them off over time. If the truck was only started every now and then for 10 mins that will take out more then the charging system will put in. It sounds like the batteries are fubar I'm afraid.
I have an Opimate 4 charger for my bikes that keeps a low charge on them, it comes with a set of ring terminals to perminantly fit to the battery so you can just plug in.
Rob