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Post by Deleted on Feb 26, 2019 7:31:28 GMT
Connect the load side cable of the isolator to the supply stud from the battery bridging out the potential high resistance connection, takes minutes with a 17mm spanner to join them together on one stud - then measure b+ to alt case and report back ππ¨π¨π¨π» Thanks Gazza, just done this and also took the opportunity to tighten the alternator belt a bit too. After running the engine for 30 mins so far Iβm getting 14.0v between b+ and the case, and the clamp meter tells me the battery is taking about 4 amps charge ATM. I ran my domestics off the new battery for about 4.5 hours last night. I estimate I would have used about 10 amps in that time. When I woke up this morning the voltage at the new battery was 12.6v. In comparison, the dodgy one I took out would have been reading about 11.7v !! So definitely on itβs way out. Iβm going to change the isolator switch anyway but not sure whether the alternator needs a refurb yet. Iβm wondering that as the old battery had lost most of its capacity that it got charged up much quicker than the new one, which may explain why I was seeing 14.4v after just 2 hours. Maybe if I left the engine running for several hours Iβd see the same charging voltage eventually. In fact when I put it in fully charged yesterday it did reach this voltage. So a 0.1v drop across the switch π I'd be inclined to clean every cable lug with a bit of emmery cloth - every little helps said the woman as she piddled in the sea π Don't forget the negative connections, the juice has to go around in a big circle π
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Post by Deleted on Feb 26, 2019 7:36:30 GMT
Just a little pointer, you were saying that you couldn't read the battery voltage at the battery from inside the cabin, only your load voltage. If you lengthen the meter leads so that they extend from the battery into the cabin your reading will be as near as a nats cock, the battery voltage. You will get virtually zilch volt drop along the meter leads as the current is so tiny, that will enable you to read battery voltage in comfort (advisable to take the positive lead via a small inline fuse as this stops catastrophic escape of amps with much hissing and melting of insulation, if you should accidentally short it to earth.) Iβm guessing you can also get bluetooth/wireless voltmeters so you can get a reading at source on your smart phone? www.amazon.co.uk/Battery-Guard-Bluetooth-Voltage-Display-Batteries/dp/B00ZETXNAQYou are relying on the accuracy of a random bit of Chinese kit though
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Post by JohnV on Feb 26, 2019 8:04:47 GMT
good on you for answering the "Bluetooth" question Gazza ...... If Bassplayer was asking me, he has failed to realise that I'm a dinosaur
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Post by Deleted on Feb 26, 2019 8:11:40 GMT
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Post by Deleted on Feb 26, 2019 8:13:52 GMT
good on you for answering the "Bluetooth" question Gazza ...... If Bassplayer was asking me, he has failed to realise that I'm a dinosaur Not at all John. I very much believe in keeping things as simple as possible (easier to fix when it goes wrong!).
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Post by Deleted on Feb 26, 2019 8:23:00 GMT
Thanks Gazza, just done this and also took the opportunity to tighten the alternator belt a bit too. After running the engine for 30 mins so far Iβm getting 14.0v between b+ and the case, and the clamp meter tells me the battery is taking about 4 amps charge ATM. I ran my domestics off the new battery for about 4.5 hours last night. I estimate I would have used about 10 amps in that time. When I woke up this morning the voltage at the new battery was 12.6v. In comparison, the dodgy one I took out would have been reading about 11.7v !! So definitely on itβs way out. Iβm going to change the isolator switch anyway but not sure whether the alternator needs a refurb yet. Iβm wondering that as the old battery had lost most of its capacity that it got charged up much quicker than the new one, which may explain why I was seeing 14.4v after just 2 hours. Maybe if I left the engine running for several hours Iβd see the same charging voltage eventually. In fact when I put it in fully charged yesterday it did reach this voltage. So a 0.1v drop across the switch π I'd be inclined to clean every cable lug with a bit of emmery cloth - every little helps said the woman as she piddled in the sea π Don't forget the negative connections, the juice has to go around in a big circle π Yes thanks Gazza. It does seem as though the old battery was the bulk of the problem. Iβll get that isolator changed today anyway as itβs now arrived. Iβve got some switch cleaning fluid somewhere, that should help with the contacts. I do think the way forward is to go Lithium but I canβt bring myself to pay so much for 70ah. Β£70 for 15 months use of a lead acid starter battery seems Ok really. Maybe the new technologies will get cheaper over time.
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Post by JohnV on Feb 26, 2019 8:27:54 GMT
So a 0.1v drop across the switch π I'd be inclined to clean every cable lug with a bit of emmery cloth - every little helps said the woman as she piddled in the sea π Don't forget the negative connections, the juice has to go around in a big circle π I do think the way forward is to go Lithium but I canβt bring myself to pay so much for 70ah. Β£70 for 15 months use of a lead acid starter battery seems Ok really. Maybe the new technologies will get cheaper over time. I don't think I could have persuaded myself to spend out on 4 new Lithiums, second hand they worked out not a huge amount more than good lead acids. They are a massive outlay still, although the maths work out for a long term saving ..... it's just that initial hit
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Post by Deleted on Mar 5, 2019 12:37:40 GMT
Just an update on this. I discovered that after I gave the alternator a hard tap with a wrench that the charge voltage shot up (still not quite what Iβd expect though). Instantly I noticed the charging current increase.
So I decided to swap the alternator for a old refurbished one. Straight away this alternator gave me 13.9v (battery about 70% capacity). The charging current much higher.
So I reckon that the brushes in the other alternator were worn hence the tapping helping the contact a bit. Iβm taking that one for a test and refurb. At least Iβve got this one working Ok.
I doubt the faulty alternator helped my old battery issue either although Iβm pretty sure it was on itβs way out. I might trickle charge it somewhere and check before I throw it out
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