Flat batteries again.

[dobbslc]

The Surf is dead again
I've just checked the battery voltage and it's 11.9v , I know the batteries are on the way out but can't afford £250 for a new pair right now. I've hooked up the multimeter for DC amps and measured the current draw with everything off and it's 0.05? My work addled brain can't decide if that's 5 or 50 milli amps ( I think it's 50) someone help!
If it's 50 is that a bit too much on a 30 year old truck with little electronic cobblers to drain it?

 

[voipio]

0.05A is 50 milliAmps, so not much. It would take ~1,000 hours to fully discharge a 50Ah battery, at that rate. Does the truck have remote locking, either infra red, or RF? That could account for a 50mA drain. Is there any alarm system installed, or a vehicle tracking gizmo? 11.9V isn't necessarily bad, if it's after a couple of days of standing idle, if it's a good battery. Do the interior lights dim when trying to start? Check that the battery terminals are tight.

 

[dobbslc]

It does have central locking, alarm and immobilizer and two 70ah batteries. It was last used 6 days ago and started fine.

 

[Kram]

£250 for a pair of batteries? Does it need two? You might find one is in acceptable condition and the other is pulling it down. Try fully charging and then independantly do a discharge test.

Easy solution is buy yourself a jump starter like the Yaber or Gooloo. Since I got mine, I've had absolutely zero issues, never needed it for my own aging battery and used it to help out 20 or so other people, 3 in the last week!

Ofcourse the one day you dont have it in car will be the day its needed

 

[bourbon]

 

[dobbslc]

I've got a Noco booster / jump starter. I bought these genuine Toyota batteries together a good few years ago for £70 each from Roughtrax but they don't seem to sell batteries anymore. Prices have gone up alright

 

[Ubique]

50mA is right on the limit for 'stuff with electronics', 11.9V is also low - and of course, that is the current draw at the time you measured it, ideally you need to record current draw for a few hours to get a better idea of actual draw over time (30mA is the accepted target for most vehicles), also make sure the vehicle is locked and check after it's had 30 mins or so to 'settle down'.

 

[dave h 2]

Get it started and put the multimeter across the battery and rev it you should get over 14V. Maybe the Alt is not charging.
11.9 is bad so as above, maybe one battery is bad

 

[premmington]

50mA is right on the limit for 'stuff with electronics', 11.9V is also low - and of course, that is the current draw at the time you measured it, ideally you need to record current draw for a few hours to get a better idea of actual draw over time (30mA is the accepted target for most vehicles), also make sure the vehicle is locked and check after it's had 30 mins or so to 'settle down'.

+1 for 30mA passive drain as a target...

 

[dobbslc]

I'll have another go testing it tomorrow if I get a chance, the alternator was refurbed a few years ago but never gets to 14 volts, it's normally at about 13.7v but I think some of the older Toyota's do have a low charge rate as there's some Aussie websites that do a mod for them to boost it up a bit.

 

[Ubique]

13.7V is most likely scaled for an old-style lead-acid battery - that's a forward voltage of 2.28V per cell, so actual charge voltage is 0.18V per cell assuming 80% charge.
I'm assuming both batteries are connected in parallel? If so, start the engine and monitor the charge voltage (and current if you have a DC clamp ammeter) as you disconnect each battery negative one at a time - don't have both off at the same time!
If both batteries are OK - or equally bad, then the charge voltage and alternator output current will be roughly the same for each battery, if there's a big discrepancy, then investigate the battery drawing the most current.

You still need to investigate the extra 20mA parasitic drain though, 50mA is too much.

 

[willie.macleod]

These wee tools are handy for checking current drain on circuits - https://cpc.farnell.com/tenma/ten01...ith-standard-blade-connector/dp/IN04874?fi=wp