any good?

[Jim GM4DHJ ...]

anybody got one of these ?

[Harry Bloomfield]

Jim GM4DHJ ... used his keyboard to write :

No, but the spec. sounds good. I cannot see a clip on current probe, so no idea how they assess that.

[tabbypurr]

Measure oc battery voltage Measure battery resistance Measure cranking voltage Calculate cranking current

NT

[T i m]

A mate has a more expensive one that he considers to be good.

For charging I believe they monitor the 'lift' in voltage from loaded with engine off to with it running.

I like how they describe the DB15 connector as an OBD connector. ;-)

If there is *any* sort of current carried up the fairly heavy leads, I'm guessing they must have wired the DB15 plug and socket with multiple pins shorted each side / end?

Such a tool might be 'ok' for people who don't know how to use a DMM as I'm not sure how useful most of the other things that you couldn't do with a DMM are?

Cheers, T i m

[tabbypurr]

Internal battery resistance is key to starting ability & is a way to measure battery ageing. So you can use that to assess usefulness of out-of-car batteries. Once fitted, cranking voltage is adequate to give some idea of startability, though it's no precise guide. Some oldies give the battery a real hard time during starting, and some modern diesels require high cranking voltage to start at all.

NT

[T i m]

<snip>

Sure, but who would use that and when? 'Most people' just start their cars until they don't start, then give it to a garage (or call their breakdown service) and garages are likely to have better tools in any case?

I have a discharge tester for that. Not a lot beats them for a RW test. I also have a ACT capacity tester but rarely take any notice of anything other than the capacity reading.

Quite ... and if it no longer starts your car you get a new battery [1] and this could be 35 quid towards it. ;-)

Cheers, T i m

[1] Or we would do some diagnostics with a DMM / battery charger ourselves first (assuming no other tools). Cranking voltage, charging voltage (on and off the vehicle) and even the charging time (from supposedly flat) gives some big clues (as to the capacity).

p.s. Whenever I've tried to take a functional battery back within warranty because of capacity loss, I've found it very hard to persuade them that it is now way off what it should be. Basically, if it isn't 'faulty' they often consider it ok. I guess they might consider capacity loss 'wear and tear' but it could also be some disconnected plates, especially with sealed batteries when you can't see in each cell.

[dennis]

It relies on the built in sensors by the looks of things. The cars computer can probably tell you the state of the battery without it.

[dennis]

Well maybe it connects to the OBD port like it implies in the picture.

[dennis]

Not IME they don't. Three times I told the garage the battery was failing and they "tested" it and said it was OK.

Then the car wouldn't start.. Oh its because you don't run it for far enough to charge it was the excuse.

The next time it was your dash cam is flattening it.

The third time I called the RAC and they came out and did a twenty minute test on the battery, the tester decided the battery was less than

50% of its capacity so they replaced the battery.

Told the garage to get a better tester and someone that knew how to use it.

[Harry Bloomfield]

[e-mail] laid this down on his screen :

Easy.

How do they do that - place a small load on the battery, then measure the voltage drop? Cannot be much of a load, in such a small device.

Easy

I assume from knowing the resistance above?

I thought they might have a current probe of some sort, to get an accurate figure.

[Bill Wright]

I see it works for other species. That's impressive.

Bill

[Harry Bloomfield]

dennis@home expressed precisely :

The ECU doesn't store that sort of information, that I am aware of, it might store a failure to start, but that unit only seems to clip onto the battery, so it cannot interrogate the car's ECU's.

[Bill Wright]

The what?

Bill

[dennis]

What, using the ODB port? It does say it has an ODB connector.

[Harry Bloomfield]

dennis@home presented the following explanation :

No sign of an OBD plug in the photos. The only setting seems to be for the species of crank current reading you want to be displayed.

[Jim GM4DHJ ...]

what?

[Steve Walker]

It could be a failt large load, but only for a very short time.

SteveW

[Jim GM4DHJ ...]

no it doesn't...

[Jim GM4DHJ ...]

That is what I was thinking ......

[Harry Bloomfield]

dennis@home formulated on Friday :

Not that I could find, I even tried 'Find' on the page and that found no mention.