Battery life

[ericmark]

Two completely unrelated battery problems one on a wheel chair helper with 20AH battery fully sealed, been in storage for some time tried and motor worked. No charger with it so connected to power supply maximum 1A at approx 13.8 volt left for a day on charge tried to use and got about 100 yards some what short of the 10 miles in advert.

The second a caravan leisure battery this fully discharged and with top up bungs so this on on standard battery charger.

In both cases I want some way to test before I try to use and my battery drop tester is long gone and anyway not really the thing I should use on a traction battery.

The 20AH sealed is real problem as don't want to over charge and no idea of correct charge rate. Will guess original charger was a stage charger but not going to be used very often only when visiting hilly places previous owner and carer both dead so one one to ask how these carer operated chairs worked even when new.

Mother has got a self controlled electric chair but she tires easy controlling it and often asks me to take over and driving it in a straight line walking along side is not easy.

 

[securespark]

Know anybody with a CTEK charger?

If you can borrow one, they are great! They are intelligent and never over-charge.

They can also bring back batteries from the dead (around 2V) and disulphate and recondition.

 

[Monkeh]

The 20AH sealed is real problem as don't want to over charge and no idea of correct charge rate.

So when you replace the battery you knackered, read the datasheet and it'll tell you.

 

[Aragorn84]

charging a 20ah battery at 1A is hardly going to damage it... It'll float charge indefinitely at 13.8v too, so there was nothing wrong with what he did IMO.

 

[Monkeh]

charging a 20ah battery at 1A is hardly going to damage it... It'll float charge indefinitely at 13.8v too, so there was nothing wrong with what he did IMO.

13.8V is high, and no, they won't take it indefinitely.

Nor did I state the charging knackered it. The long sitting around discharged probably did, though.

 

[Aragorn84]

13.8V is standard float charging voltage for a sealed lead acid?

Intelligent chargers usually run at 14.4v or thereabouts during their "bulk charge" stage, then drop to 13.8 when the battery becomes full.

Automotive lead acids are fed ~14.1v indefinately by the vehicles alternator (which can typically supply 60-100A if required) with no issue.

Alarm SLA's are also run at ~13.8v indefinately by the onboard power supply.

I simply cant see 13.8v and 1A will have caused any issue.

 

[Monkeh]

13.8V is standard float charging voltage for a sealed lead acid?

It's high according to Yuasa datasheets, and there's temperature correction too (matters a lot more in banks).

I simply cant see 13.8v and 1A will have caused any issue.

Read, please.

 

[ericmark]

The Lidi battery charger failed, and mother had her other wheel chair altered so I could control from back, so battery forgotten until I had other battery charging problems and I found the sulphated battery does not gradually recover but it can sit for a week and do nothing then recover within 24 hours.

So two Lidi battery chargers replaced the failed one, needed one in a hurry when away with caravan hence two. Once the batteries I wanted were up and running again I thought may as well have another go at the 20 Ah battery, I had to put it in parallel with a 7 Ah to be able to connect it, and early June 2018 I tried to charge it, at first monitoring how it was doing, however it seems it was not to be, no wonder looking at age of this post.

However I did not take it off charge, and today it seems to have recovered, three months on charge and nothing, then over a few days it has recovered, as to how well I don't know, need to drag out the wheel chair so set it to run caravan lights, but it has laid unused for 5 years and it was not tip top then.

Did try powering caravan lights, with 5 lights on 11 volt, with 10 lights on dropped to 10 volt, however returning to 5 lights it ran for half an hour without the voltage dropping further, it would not run the wheel chair, but clearly would work anything with a low load. Returning it to charger 11.9 volts quickly rose, but held at the 0.8A charge rate to date so around an hour, it is clearly taking a charge.

 

[ericmark]

It charged at 0.8A for around 2 hours, it then dropped to 0.1A, it has held at 13.8 volt all day yesterday no sign of either dropping or raising, however as to if there is any point is another question.

 

[ericmark]

After the initial recovery I thought it would in time like the 7 Ah batteries drop to zero charge rate, it seemed to show a different voltage every time I looked however the battery charger is constant current, so just three options zero, 0.1A and 0.8A the 3 and 3.8 amp options it does not auto return to. However it can change the average charge rate by switching between 0.1A and 0.8A and this is exactly what it is doing, I can watch the voltmeter built into charger and see with three bars showing the voltage slowly raises from 12.8 to 14.4 at which point 4 bars light, and the voltage decays again to 12.8 at which point all is repeated again. The energy monitor has too slow of a refresh rate to show the jumps between on/off the average charge today seems to gone to 6 watt, so 10 - 11 September 2018 was the first point when it started to charge then it remained straight line until 3rd October 2018 at which point it started to charge again.