Maintaining little used car batteries

[Harry Bloomfield]

As I have so many batteries around the place, I have decided to order up a battery analyser unit. An Ancel BA201, direct from the manufacturers outlet in Poland (to avoid the import tax).

 

[ericmark]

I expect the larger batteries to take days to charge, and to battery analyser, I have had them in the past, they discharge battery slightly with a resistor then monitor the recovery, however not that accurate, I have a known faulty AGM battery off the Jaguar XE that I use for caravan, and it works A1, and on the caravan one would never realise faulty, seems to work motor mover without and problem, but failed to start Jag. It seems the Jag will not even try to start if the battery is below a cut off voltage.

 

[Harry Bloomfield]

It seems the Jag will not even try to start if the battery is below a cut off voltage.

Maybe due to the batteries internal resistance being too high? I would guess that cranking a large car engine over, requires maybe 3 to 5 times as much instantaneous current and a caravan mover. The above analyser is supposed to be able to check the internal resistance, state of charge and total capacity, plus know when the battery has a static charge across it, knocking the charge off, before tackling any measurements. For high current tests, it uses the cranking current, asking you to try cranking the engine over.

It seems that most of the battery dealers, mechanics and breakdown companies have given up using the old fashioned low value large resistor in parallel with a volt meter, for these micro-based analysers.

 

[ericmark]

The old resistor and voltmeter needs sight of cells, and with AGM batteries you don't have sight of cells, my worry, although not too much of a worry as battery second hand to start with, is if the caravans built in charger is suitable. I have already with caravan before this one had a problem with the charger, one battery cell went short circuit and then it roasted the other five. The small Lidi charger is clearly OK as maximum output if cell goes short circuit is 0.8 amp, but the scooter charger was 5 amp and the battery case warped with heat and pressure, the caravan charger is 35 amp, so if a cell fails that is a lot of power.

Also look at the Halfords website and so many battery chargers say not suitable for AGM batteries.

As to Jag I think a voltage dip, it is not a started engaging and there being a clear slow crank speed, it would not even try and start the car, it seemed really odd, as would start car, go for a run, then stop car while out, and it would not restart car, turn off anything using power, wait 5 minutes, and then it would spin the engine over, I really did not think it was a battery fault, but new battery cured it, and since then heard of other cars doing the same.

I like having 2 batteries for the caravan, now caravan in storage not so much a problem, don't need motor mover, but in other house kept at back of house, and once alongside house could not change battery, so always started with fully charged battery. Big problem now is we forget to remove battery terminals before leaving, and there is a slight drain on the radio. If radio connected to master switch supply, every time we crank engine, or plug in or unplug caravan the radio goes into demo mode and switches on half full volume which is still too loud.

So why is this battery charger

Not suitable for vehicles with START/STOP technology, or for long-term connection.

even this

charger at £220 is not suitable, OK Halfords tell you, and that's good, but what about all those battery chargers already owned, how do you know if OK or not? Same with battery testers, how do you know if suitable for AGM battery.

 

[Keithmac]

My Mitsubishi GTO has been on an Optimate 3 for over 10 years now with no issue, I sometimes leave it on for months, sometimes just a day. Never seen it drain the battery when turned off but still connected (no leds are displayed with power off).

For serious use, recovering dead batteries and car reflashing I use my charger below, this recovered 2 Transit Minibus batteries (Scouts bus). One showed 2.9v the other 5v before charging. Normally I'd have just written them off bit they were both less than a year old and our group is skint due to the lovely virus going around!.

 

[Harry Bloomfield]

As to Jag I think a voltage dip, it is not a started engaging and there being a clear slow crank speed, it would not even try and start the car, it seemed really odd, as would start car, go for a run, then stop car while out, and it would not restart car, turn off anything using power, wait 5 minutes, and then it would spin the engine over, I really did not think it was a battery fault, but new battery cured it, and since then heard of other cars doing the same.

That effect is common - cranking the engine over even if slow, loosens things up. The cranking warms the battery up too, so it is better able to deliver higher currents. My diesel has never ever failed to start, it fires on the first pull needing next to no cranking, doesn't need me to wait for the heating coils to time out.

Turning the caravan's 12v master switch off, also means the radio forgets its stations, because it cuts the permanent 12v supply too. I have thought to fix it with a pack of dry-cells, or maybe even a supercapacitor, but never got around to doing it. Its just press and hold a button to retune it anyway.

SMPSU is a 20amp, which I leave powered permanently it has to keep the alarm system charged, but the main 120amp/hour battery I disconnect - I reconnect it once per month just to top it up on the 13.8v. 13.8v is no where near able to actually put a full charge into it, so that's where the smart charger comes in, before a trip.

 

[ericmark]

In the caravan I was turning off the battery isolator, then found it was only connected to motor mover, there is a relay/fuse box, and I had a problem with it when bought, it turned out to be a simple blown fuse, but working out what had been done before I mapped out what everything did, and there are two fuses which are not controlled by the habitation relays so I moved the spade connector to one of those fuses, had to do some thing because of the demo mode the radio goes into with a power cut. Other wise as you say would just retune.

The idea of an alarm is to let you know when the unit is being tampered with, and not sure if disconnecting battery would ensure most alarm/trackers would still work, my caravan has not got one, so does not need a battery or mains connected. I after having a cell fail agree with the idea of a very low output charger when stored, however after my experiments charging batteries and seeing how the sulphur can take weeks to all turn back to acid and lead, I leave the batteries on charge, I have two Lidi chargers and they charge the batteries about a week at a time in rotation, but the AGM normally stand for 2 months between charge where the flooded charged every month.

As to cars, the Kia Sorento never had a problem, I have put on charge over lock down, as it was standing for so long, but didn't need it. The Jaguar XE is wife's car, and after the battery charge soon after getting it no more problems, however it sent a text to my wife's phone to say it needed a run to charge battery, so used the Lidi Smart charger to top it up, but the problem is not used much, and the Honda Jazz was my dad's I would guess around 2002 and still on original battery, that needs a charge around every two weeks now, it is still full of fuel from before lock down, I did not use it at all for most of lock down, and now used for a 1 mile run a week to local heritage railway where I volunteer. So only to be expected it will need charging, main worry over lock down is the adblue going off in the Jag.

I also have batteries removed from stair lift ear marked for powering my radio, 7 Ah each, and two brand new 35 Ah which I am about to fit into the mobility scooter battery cases, so total of 10 batteries to be maintained, once the mobility scooter batteries are fitted, then can only use the supplied charger with them, and have to get the scooter into the house to plug in, even though the batteries both are removable, there is no way to charge without being on the scooter, really poor design, so instead of leaving the scooter in the car and just bringing batteries inside to charge, I have to unload whole scooter. I know the charger is a stage charger of some kind, and shows a green light when charged, I tried to charge in car, using an inverter 150 watt to the supplied charger, and it worked fine when the batteries were fully charged, but once used it tripped out the inverter.

 

[Harry Bloomfield]

I also have batteries removed from stair lift ear marked for powering my radio, 7 Ah each, and two brand new 35 Ah which I am about to fit into the mobility scooter battery cases, so total of 10 batteries to be maintained, once the mobility scooter batteries are fitted, then can only use the supplied charger with them, and have to get the scooter into the house to plug in, even though the batteries both are removable, there is no way to charge without being on the scooter, really poor design, so instead of leaving the scooter in the car and just bringing batteries inside to charge, I have to unload whole scooter. I know the charger is a stage charger of some kind, and shows a green light when charged, I tried to charge in car, using an inverter 150 watt to the supplied charger, and it worked fine when the batteries were fully charged, but once used it tripped out the inverter.

I have a stair lift installed and a mobility scooter, both were provided for my previous partner, not long before she passed away. In the years since then, I have tried to keep them maintained in case I might eventually need them. I asked the stairlift engineer if there was some way to completely isolate the batteries, so the mains power could be turned off and he said just switching it off at the chair isolated them. In fact switching off the mains and switching the chair off, left the brake solenoid engaged and wrecked the first set of batteries. Lucky it was still under maintenance contract, so they replaced the failed batteries for free.

The scooter actually became useful for me, after I was rushed into hospital with an internal bleed, which left me weak for months afterwards. I accidentaly left that turned on one time after moving it and it was on for weeks, that did the batteries no good at all and the proper charger for them would not touch them. I ended up using my Lidl charger, with a temporary 12v battery in parallel, to get the charge going for each battery in turn. Plugging it into its proper charger, it now behaves as it always has - yellow then after a few seconds green to say charged. The Lidl does seem to have worked, but I would be wary of going far on it. I'll see what the battery analyser shows for the two batteries, when it turns up.

Not happy with not having any way to be sure my ciggy plug has made proper contact with the socket, so I have been wondering how to address that. I'm now waiting for some 7555 CMOS timer chips to be delivered, so I can make a 12v flashing LED, for my car's new charging regime....

Dumb charger only comes on for 15 minutes per day, plugging into ciggy lighter socket - which are never reliable connections. So my mico-power flasher connects to the charger's output terminals, to just confirm it has 12v from the car battery via the lighter plug. Idea is a 30mS LED flash, every one second or so.

I drive car into garage, park up, plug the charge lead in and just have to confirm the LED is flashing.

 

[ericmark]

I use one of these

it allows me to monitor remotely what the charger is doing, I also have one which can be remotely switched on/off for my AC so I can before setting off home see the temperature and turn on remotely when required. Be it my beer brewing or battery charging remote monitoring is handy, not bought to do that, mainly bought to check the freezer is OK after having one where insulation failed.

 

[Harry Bloomfield]

Be it my beer brewing or battery charging remote monitoring is handy, not bought to do that, mainly bought to check the freezer is OK after having one where insulation failed.

I have a set of those (I think) stashed away unused, in my loft workshop. They report back to a display, which monitors the current and allows on/off switching.

Beer/wine monitoring! Can I suggest you investigate an open source project, the iSpindle? It floats in an oversize tests tube, in the brew and reports SG, brew temperature and battery volts, via your wifi router, then to a variety of free websites which can log and graph the progress of your brew. The 'test tube' tilts in the brew and from that it can determine the SG. My results are very accurate indeed, to 3 decimal points of SG. I just set the brew going, drop the iSpindel in, seal it up and watch the progress from anywhere where I have access, either on my phone or my laptop. No need to open the brew up any more, to check the SG.

 

[Harry Bloomfield]

Not happy with not having any way to be sure my ciggy plug has made proper contact with the socket, so I have been wondering how to address that. I'm now waiting for some 7555 CMOS timer chips to be delivered, so I can make a 12v flashing LED, for my car's new charging regime....

The TS555CN's timer IC's arrived this morning, so I have just built my 12v flashing indicator circuit. Superbright white LED + 10K, 1M, 47K + 1uF for the 555's timing. It flashes away confirming when it 'sees' 12v across it, drawing an average current of 150uA from the battery, once per second, lit for just a few mS. No more hoping my ciggy lighter made contact, I can check at a glance as I plug it in.

 

[ericmark]

Well just fitted two new 35 Ah batteries into the mobility scooter, before fitting they were charged with Lidi charger as as said needs to be charged on the scooter once fitted, it would not get out of the drive, too steep, and the scooter volt meter dropped a fair bit, so put it on charge with scooters own charger

I have been surprised to see it take so much charge with new batteries which have only driven the scooter some 30 yards, it was showing 13.1 volts on Lidi charger both batteries in parallel at 4 watt, so now taking 4 times the charge it was taking with Lidi charger, I will test the scooter again tomorrow.

 

[ericmark]

My Mitsubishi GTO has been on an Optimate 3 for over 10 years now with no issue, I sometimes leave it on for months, sometimes just a day.

Instructions say

It is not recommended that a charging battery be left unattended for long periods or overnight.

A charging time of no more than10 hours is recommended, at no more than 10% of the battery’s ampere hour capacity. i.e. 60 Ah battery should be charged at no more than 6Ampsfor no more than 10 hours.

This product is suitable for charging 12V normal lead acid and AGM batteries of capacities between 20-90Ah(Ampere hours)only.

I think in real terms it is daft to have a charger which can't be left unattended for long periods or overnight, I will guess it is because it can charge at 12 amp which is a fair rate if the battery has a shorted cell, which is why I use the Lidi charger as it is such a low charge rate, it is unlikely to cause a problem even with a shorted cell.

The problem with a stage battery charger is the limited battery size, if battery too small it can be over charged, but the same also applies if the battery is too big, as the current will not drop low enough for it to drop into final stage.

At £48 new the charger you show is quite cheap for a 12 amp charger, they are normally around the £80 so would assume it is not a stage charger, I would have no qualms at using to recharge a car AGM battery for 8 hours if completely discharged, or a flooded for weeks, as the latter can be topped up, but it does need monitoring, at least twice a day, where the likes of the ctek and Lidi chargers don't need that daily monitoring.

 

[Harry Bloomfield]

I think in real terms it is daft to have a charger which can't be left unattended for long periods or overnight, I will guess it is because it can charge at 12 amp which is a fair rate if the battery has a shorted cell, which is why I use the Lidi charger as it is such a low charge rate, it is unlikely to cause a problem even with a shorted cell.

Me too, it is a lot of potential heat that 12amps can generate in a battery with a shorted cell. If I intended leaving it charging unattended for any length of time, then I would want to make sure the charge current fell to a very low safe value first.

20 years ago I designed and built myself an up to 12v 60amp pulse charger. It's output was only (battery) voltage controlled. I never left that unattended when it was in use, I built it mostly for emergency starting a car with a flat battery - ten minutes charging a flat battery, then you would be able to start the car.

Yesterday evening, with a bit of time to kill - I went searching for information on maintaining such batteries. Varta's battery site seems to be offering some sensible reading, without getting too technical. It agrees with me that batteries should never be left on a permanent charge. It says that recharge requires 1.25 times the amp/hour of the amp/discharge - so if you discharge a battery by 10amp/hour, it will need 10x1.25 = 12.5amp/hour to replace that discharge.

 

[ericmark]

After an over night charge

it seems reasonably clear the battery was not charged in the first place, now the Lidi charger has three options

for batteries less than 14 Ah,

for batteries 14 to 120 Ah, and

"12 V" (14.7 V / 3.8 A) For charging 12 V batteries with a capacity of between 14 Ah–120 Ah under cold conditions or for charging AGM batteries. There is also a 6 volt option but that is not user selected.

It seems the voltage raise 14.4 to 14.7 is required for AGM batteries.