yet more 24v battery questions...

[No. 3]

Thanks to the rattle of the diesel (I presume) the common cable connection on the high side battery came slightly loose and that battery went flat (they are new NAPA batteries- their top line standard lead acid though I forget what they call them). I charged it up and float charged it a couple of days with an electronic charger rather than my dumb charger and it is holding a charge but not keeping up with the other battery. I would expect that after flatting to 7.x volts. (I don't drive that much, had I it would have been caught sooner.) My question is whether that battery is shot or if folks have had good luck with charging the pair in parallel to equalize them after a flat battery?

The past few day's voltage readings are:

25.02v pair, 12.39 RH battery, 12.64 LH battery after recharge & rest of LH battery morning 07/26

25.44v pair, 12.58 RH, 12.84 LH up after drive, afternoon 07/26

25.13v pair, 12.63v RH, 12.50v LH overnight rest 07/27

24.11v pair, 12.12v RH, 12.01v LH 24hrs+ rest 07/29

I think that my alt is behaving, on the road the stock gauge is up to 28v but I need to test it with a real meter. I checked the common cable and it is at 0.07 ohms resistance in cable with no voltage drop across cable (disconnected: >1 ohm resistance, or > 0.03v drop across cable = bad cable for those searching the forum looking to see if that cable is good or not)

Amperage test 07/29: 0.01mA leak @ accessory battery circuit (reefer/etc. battery with isolator & step down charger) 0.01/0.02mA leak at main battery circuit The amperage loss at rest seems sustainable so I think that my troubles are just with the batteries themselves. Is a parallel charge the answer or I am back to the store for new matched batteries? DC battery systems are not something I have a lot of experience with, perhaps obviously. Thanks as always!

Jeff

 

[o8ko8k]

Thanks to the rattle of the diesel (I presume) the common cable connection on the high side battery came slightly loose and that battery went flat (they are new NAPA batteries- their top line standard lead acid though I forget what they call them). I charged it up and float charged it a couple of days with an electronic charger rather than my dumb charger and it is holding a charge but not keeping up with the other battery. I would expect that after flatting to 7.x volts. (I don't drive that much, had I it would have been caught sooner.) My question is whether that battery is shot or if folks have had good luck with charging the pair in parallel to equalize them after a flat battery?

The past few day's voltage readings are:

25.02v pair, 12.39 RH battery, 12.64 LH battery after recharge & rest of LH battery morning 07/26

25.44v pair, 12.58 RH, 12.84 LH up after drive, afternoon 07/26

25.13v pair, 12.63v RH, 12.50v LH overnight rest 07/27

24.11v pair, 12.12v RH, 12.01v LH 24hrs+ rest 07/29

I think that my alt is behaving, on the road the stock gauge is up to 28v but I need to test it with a real meter. I checked the common cable and it is at 0.07 ohms resistance in cable with no voltage drop across cable (disconnected: >1 ohm resistance, or > 0.03v drop across cable = bad cable for those searching the forum looking to see if that cable is good or not)

Amperage test 07/29: 0.01mA leak @ accessory battery circuit (reefer/etc. battery with isolator & step down charger) 0.01/0.02mA leak at main battery circuit The amperage loss at rest seems sustainable so I think that my troubles are just with the batteries themselves. Is a parallel charge the answer or I am back to the store for new matched batteries? DC battery systems are not something I have a lot of experience with, perhaps obviously. Thanks as always!

Jeff

1. I would venture to guess your meter is not capable of measuring 0.07 ohms (Most are not). that accuracy takes a milliohm meter which has more than two leads and is quite expensive. if your meter is reading 0.07ohms, you can assume the cable is fine.

2. I have had success putting a 12v trickle charger on one battery one night, then the other battery the next in order to normalize their charge and keep the delta between them to a minimum.

3. asking if your battery is good after discharging it to 7.x volts is ugh... Ill say maybe maybe not.

4. calling 1 or 2 milliamps of draw, "a leak", is an overstatement in my opinion, as this is perfectly normal. as a rough guess, lets say your battery has 120ah capacity. Thats 120,000 milliamp hours. At a drain rate of 0.03 amps, your battery would completly drain in 4.566 years or drain to 1/2 in 2.28 years.
(im off by a order of magnatude here ) thank goodness nobody handed "ME" the slide rule for the space missions...

5. to my knowledge, your batteries will never be matched perfectly.

6. If you are really really curious... The test method you have chosenfor comparing battery voltage is great! Measure it on some interval you feel comfortable and look for trends. Does one always stay higher voltage than the other? if the difference wanders out side say 5% of one another, then trickle charge the lower of the two and continue monitoring. if you cant hold 5%, your battery that went to 7volts probably didnt survive the event.

<EDIT>
7. Only other thought is, from your test data, both are dropping to low 12v after sitting 24hr. I think you have ruled out a paracitic draw so perhaps both are shot? i would think they should be able to hold in the high 12's without issue in a 24hr rest period. If all else fails, take em to autozone er somthing and hang em on the ole battery tester. they run a high current through em and it provides some feedback as to their condition...

 

[No. 3]

Thanks o8ko8k,
Just checked again and have dropped down to 24.03v the pair, 12.07 RH & 11.97 LH (the one that went flat) with no driving today. Slowly they draw down.... I may charge them in parallel to see about getting them close to equal. The meter really is capable of 0.01ohm; it is a true RMS meter that was expensive- I am a GC & and worked for some years as an electrician. That is likely why my methodology is so thorough- one thing you learn troubleshooting electrical systems is to be thorough. That said my work is in the AC world and as a GC we haven't installed any solar systems, we'd leave that to a sub if we worked in that world but it just doesn't come up for us.

My guess is that you're right in being skeptical of the second battery after such a draw down. I sure am. Let that be a lesson to the diesel owners out there, tighten the hell out of everything and then check it later. Or, as in this case, check it later again- I did check it about a month after I put the new batteries in. I may just baby them until they aren't supportable. I don't have to park on the street (like many do in SF) and putting the fancy trickle charger on them isn't so difficult....

If anyone else has any other ideas about things that I should look for I am all ears, I really only understand the basics of auto charging systems and don't have the experiential knowledge to troubleshoot. Thanks,
J

PS: o8ko8k is your truck an HJ60 or a FJ with an HJ motor- can't tell from your signature. If it is, is it a 24v Canadian JDM import, a 12v Aussie or a wrong side of the road Euro 24v?

 

[o8ko8k]

My HJ60 is from Japan. Its right hand drive. It has the 2h diesel. I added a turbo to it just this month. I'm still fooling with the tuning. it has a 24v (2x12v in series) electrical system.

one of my first mods was to make a 12v breakout circuit for it so i could run my 12v stuff; ham radio, cb, and other gizmos in the truck. i originally just tapped one of the batteries for this power source but this turned out to be a problem. in the learning process, I found this website handy for all things battery related. There's lots of info on all kinds of batteries including Lead-acid.

http://batteryuniversity.com/learn/

There was a thread around here which contained the details of my learning process but i forget where it went.

plus... I had some bad math up there in that last post too... 0.01 is 10 milli ohms so divide it all by 10. (oops) so more like 5 months

All the same, good luck. and YES you have a very detailed aproach to the problem solving! Good background makes for easier troubleshooting! Im sure you will be just fine sorting this one out!!!!

 

[No. 3]

This was how I dealt with the 12v draw- the PO had hamfisted a bunch of the electrics including the 12v radio. This set up has worked well and was relatively cheaply achieved with close outs, second hand stuff and things from around the shop. I haven't installed my CB (HAM would be great, I have to get a lic.) and will do that when I open the dash up to install the turbo gauges. The second battery circuit is great on long trips though, cold food with no ice, power to charge cameras & laptops since that is where photography has gone, and lights to cook & read. I can't recommend it enough.

I'll check out the battery link, I saw your turbo thread- I was the one who chimed in about a precup warning. Beware of them. Wish I was nearer, not a lot of HJ60's around...
J

 

[Douglas S]

Ohms are not a good way to test a cable. Even if the lugs are connected by one strand you will get roughly a 0 ohm reading.

A voltage drop test is the way to go.

 

[o8ko8k]

Ohms are not a good way to test a cable. Even if the lugs are connected by one strand you will get roughly a 0 ohm reading.

A voltage drop test is the way to go.

ya thats a good point. My neighbor's tractor is always giving him trouble at the connections. When i doesnt start, he comes and gets me. All i do is feel around for the hot spot, then i rebuild the connection.

 

[bj40green]

Batteries that are 12.6 Volts after a 2 hour rest are in a good shape (almost new).
Normal used battery (not abused by excessive drain) should stay around 12V after one day. When they drop under 11.8V after one day they are considered bad.
So far my limited knowledge about batteries.

Charging in parallel won't solve your problem. What you can do is use a smart charger that can equalize the cells and recondition the (abused/molested/drained) battery.
I use a B&D (it's the only one available in my area) for this with good results but there are other and maybe cheaper brands on the market.


Rudi

 

[No. 3]

Hi Rudi, thanks for weighing in. I am going to keep plugging at them with my fancy charger- essentially the same as yours. My partner & I are looking at relocation possibilities and Costa Rica is high on her list. I may want to pick your brain off the thread if you are willing. Thanks,
Jeff

 

[hj 60]

As far as I know a wasted battery 12v can be resued for some months if you feed it 24v charging, this is what (lousy) dealers do with cars and motorcycles, after 3 months most people dont realise they were kind of mislead and buy a new battery.
A car battery can break down if it comes below 80% charging and when you go under 12v after all charging tricks it is broken/worn out I think.

Does your car start? If it does not the whole discussion is irrelevant and you need a new pair anyway (?)
Do you have guarantee left? I dont consider the batteries as pairs, they are 2 different parts an I never charge them both in pair but maybe it works.

If I have a failing 3000 mAh (lrp type 71115) NiMH battery for a remote car (charger does not charge anymore) I charge it 5 seconds with 1 amp 12v and it works (charges) for months again, this can be done three times, so 1,5 year more driving with a "wasted" battery.

 

[No. 3]

I finally had cause to drive somewhere today and checked my alternator's output voltage at idle and warmed up. At low idle of ±500PRM the alternator was putting out 27.8v at about 58° this is 0.1v less than the factory spec of 27.9-28.5v @ 77° under idle to 2000RPM. Is it reasonable to ignore that tenth of a volt and chock it up to the summer cold here in SF even as it is at the bottom end of the OEM range? I haven't opened it up to do the IC regulator check and would rather not.... This all is a good argument for adding digital gauges to augment the old dial gauge in the cluster. Thanks again!

 

[motorcoach123]

At low idle of ±500PRM the alternator was putting out 27.8v at about 58° this is 0.1v less than the factory spec of 27.9-28.5

Many 24v systems are very happy testing at 27.2v-27.8v with an electrical load at about 1000 rpm.....may I suggest a permanent solution to the battery balance problems by installing a battery equalizer/vanner:
http://www.vanner.com/manuals/65-80.pdf
That will give you battery balance as well as 12v off the vanner of up to 60-100 amps, depending on how deep you reach into your pocket.
This is the way most 24v commercial vehicles (buses) handle their battery balance/12v needs, as they have high 12v loads and need that battery balance for starting.
Your batteries must be matched, i.e. same make, model and exact age (some would argue, batch number!). I would hesitate to condemn one of them until it was tested electronically using a tester like this:
http://www.midtronics.com/ using their MDX-700 tester or similar machine.....with one of these testers, batteries can be tested with only partial charge, unlike a carbon pile tester that needs to have a fully charged battery for accurate testing. Many shops are diagnosing batteries/charging systems using these electronic testers, they are accurate, as well as having capability of testing alternator ripple and a host of other tests.
FWIW.

Gord

 

[No. 3]

Thanks Gord,
I know that I have to pony up for a balancer sooner or later, Redarc makes one too as does Solargizer that folks have fitted to the 24v HJ60's. I have an isolator & charger providing me 12v for a house battery for the fridge & all so I will be in the market for a balancer only which ought save me a bit over the Vanner unit. I'll check to see if my mechanic has so sophisticated tester as the company you linked makes. So far so good with things here though- I don't want to replace these for exactly the reason that they must be same batch (these are, of course) and tossing a nearly new battery to accommodate for one that was drawn down hurts for so many reasons.... Best,
Jeff PS: That's a fancy looking truck- are there any pictures to ogle?