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1970-1995 Range Rover Classic
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Discussion Starter #1 (Edited)
So this is the story of the battery of my trail rig.
Bought it 2.5 years ago with an yellow top Optima battery and an aftermarket stereo wired so that both +12 and +ACC were constantly wired to the +12 (so you could listen to the radio with the key off - how convenient, I though).
Realized after a while that the battery was weak and woulnd't start the truck if it sat for more than a couple of weeks and replaced the battery with a FIAMM one (supposedly a good brand). All great afterwards.
Fast forward 2 years, I'm installing an Android radio (wired the correct way this time!) and realized that the radio hard reboots during cranking. I mean, when I cycle key on and key off it reboots almost instantly, like only the screen was off, but if I crank it does a cold start (initial logo, Android is starting, please wait, boot animation.... yadda yadda).
I checked the voltage at the battery during cranking and found out that it drops to around 9v in those seconds. No wonder the radio reboots - it lacks voltage. The battery is 13.7-14v with the engine on and starts dropping as soon as the engine is off, reaching a minimum of 12.0v after a few hours that the engine has been shut down.
Even with the battery at 12.0v and a cold engine, the truck starts with no hesitation and back when I had flooding issues it cranked away for a long time and the battery never felt tired.

I'm currently torn between two interpretations of the above:
1)the battery is fine, the radio rebooting is inevitable and I will have to solve it by rigging some capacitors and diodes to give it momentary power during cranking
2)the battery has been toasted by the improper installation of the old radio, just like the previous Optima battery was. I need a new battery and that will also solve the radio rebooting issue.

I guess I could just stick in a known good battery in and see what happens... but I don't think I have any around.

Thoughts?
Thanks!
 

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1989 Range Rover Classic
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356 Posts
Voltage sag in lead acid batteries when under load is inevitable, however it sounds like that amount is a bit extreme, perhaps caused by previous stress/wear on the battery itself. Perhaps an auxiliary power supply for the radio (small remote battery pack into the radio with diodes on the power coming from the car battery) that would power the radio seperately. You could potentially rig it to charge when the car is running with a small current-limited DC to DC converter.
 

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When I lived in parts of Europe where the climate was more battery friendly I used buy Varta (now I believe Bosch). Lasted easily 12 years in a standard car. Then Far East (hot) now Texas (Bloody hot) and I just buy the largest that fits and cheapest I can find, typically Walmart. Run it till you get weak starts, typically I would say 2-3 years and buy another one- they are quick to swap at the parking lot. Heat ain't great for batteries and I don't trust 'good batteries' to be much different from standard to cheap batteries given than they probably source a lot of same components.

With the warranty that Walmart provides I sometimes get a free new battery when it fades within 2 years - already had that happen to me twice.

On my Range Rover Classic I fitted a timer relay on the power that feeds my radio, electric windows, interior lights and headlight (relay). It keeps the power on these circuits for 20 minutes after I switch off the car. Hella relay so at least quality is good, adjustable as well.
 

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Verify that your starter motor is ok for bearings condition etc so that it's not drawing more than ideal.

An old mod is to use two earth straps to engine block (and check yours are ok) as it will usually spin faster with less resistance if these are in any way compromised.
Pull the fuel pump fuse and crank it a fair few times, then feel the earth for temperature to see if they are any good.
Same for positive feed down to starter motor.

As JS5D found, Varta are very good for life and capacity, I use them on most vehicles that I look after. And recommend to other's that find the same.

Amusingly the longest life one was 12 years!
 

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1970-1995 Range Rover Classic
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119 Posts
Discussion Starter #5
Verify that your starter motor is ok for bearings condition etc so that it's not drawing more than ideal.
I should remove the starter from the engine to do that, right?
It is a bit noisy indeed. But it's still working flawlessly.
 

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Yes, ordinarily to fully inspect you'd need to remove.

They still work really well even when impaired, kicking out so much torque will mask many problems.

The main shaft is usually running in sintered bronze bushes that would originally have been assembled after soaking in oil, that they subsequently retain. The material does last a long time, but eventually can become compromised.

If worn would need replacement which should also be soaked prior to installation. If they don't display any play it's worth getting oil into them in situ if you can.

They do make a surprisingly big difference if significant wear it present, with it spinning noticeably faster and with less electrical draw to accompany that.

It could just swing it enough to get what you need.
 

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1970-1995 Range Rover Classic
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119 Posts
Discussion Starter #7
Just an update. Instead of powering the radio from a +12v I randomly found in the center console, I ran a new wire directly from the battery to the radio. With a fuse of course. That seems to have solved my problem.
 
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