Lead acid cab battery - keep on taking charge?

[Cush]

Does a lead acid ever stop taking charge?

Thinking of adding a battery master device at the solar controller for a lithy hab and SLA cab. Van stored indoors and no ehu. Will the cab battery keep on taking charge at about an amp / hour indefinitely as the voltage differential is always large enough to meet the operating parameters?

Appreciate learning from your experiences

Cush

 

[ivorantony]

Parasite drain or battery on its last legs, all modern vans have a small electrical loss running alarm systems and computers / Radios in the background even when switched off,

 

[Richard n Ann]

Yes it will keep charging if the voltage is too high, it will eventually lead to electrolyte loss. Depends on the numbers though. My optimate float charges at about 13.4v and rests the battery for 30 minutes every 30 minutes.

 

[DBK]

Does a lead acid ever stop taking charge?

Thinking of adding a battery master device at the solar controller for a lithy hab and SLA cab. Van stored indoors and no ehu. Will the cab battery keep on taking charge at about an amp / hour indefinitely as the voltage differential is always large enough to meet the operating parameters?

Appreciate learning from your experiences

Cush

The Battery Master will pass a current to the cab battery if there is a voltage difference between the two of half a volt or more. As the Lithium battery (assuming no solar is working) will have a voltage of around 13.4 when fully charged and the cab battery around 12.5 then yes, the Battery Master will keep putting a trickle charge into the cab battery.

Is this a problem? I don't know but it might be potentially. Is there any light in the storage, even a few roof lights might be enough. I guess you could fit a switch to isolate the BM but you may come back to a dead battery. It might be easier just to disconnect the cab battery but check insurance if you have an alarm/tracker as you may not be covered if the vehicle is stolen and you've disabled the security.

You could just monitor the voltages, assuming the storage isn't too far away, and take it for a run every now and again.

 

[autorouter]

A battery has its own internal voltage generated by the chemical process. That's commonly known as the 'resting voltage', and varies between about 12.7V when full down to below 12.0V when flat.

To charge a battery, you need to apply a voltage of a bit greater than the resting voltage. It is common to apply a 'float voltage' of 13.2V to 13.6V to keep a battery topped up without pushing in too much charge and overcharging it. Different battery types have slightly different float voltage requirements, it depends on many factors including temperature and acid concentration.

The important thing is the voltage difference between the applied voltage and the battery's internal resting voltage. The amps current going into the battery depends on the voltage difference. If the battery is flat, it will probably take the maximum, about 1 amp. If the battery becomes full, its resting voltage rises, it takes less, until when full it takes only a few milliamps. A lead-acid battery 'self-discharges' at the rate of a few milliamps anyway, so the BatteryMaster just compensates for that self-discharge, and the alarm/tracker, and doesn't overcharge at all.

Many mains-powered battery maintainers apply a float voltage of 13.4V, and the battery is quite OK. If you allow for the BatteryMaster voltage drop of about 0.5V then there should be no overcharging problem.

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[Cush]

Thanks one and all. I might get a maintainer and have a play and give moe a good run every so often. A good excuse to get out in the winter.

If I get the cab full with a battery charger I now feel that a vanbitz won’t drag too much out of the lithium.

Thanks again,
Cush

 

[Dave and Jen]

I fitted a Batterymaster today as the engine batt was slowly losing a bit. Happy to say within about 1/2 an hour the voltage was up to 12.5v -job done - no more worrying about a flat battery.
Highly recommended and if you buy through the site you get a discount. Quite easy to fit -only 3 wires to connect.
Cheers, Dave

 

[Cush]

I fitted a Batterymaster today as the engine batt was slowly losing a bit. Happy to say within about 1/2 an hour the voltage was up to 12.5v -job done - no more worrying about a flat battery.
Highly recommended and if you buy through the site you get a discount. Quite easy to fit -only 3 wires to connect.
Cheers, David

Are you taking charge from a lithium? If so, what is the lithium dropping to please or Are you keeping the hab charged by solar or ehu? Nice discount at offgrid Nigel ivy too
Appreciate the real world feedback. Thanks

 

[Dave and Jen]

2x105 lead acid habs charged by solar not sure how much they have dropped. Will check tomorrow but I think they will still be at 13.5v as before.
Dave

 

[Cush]

2x105 lead acid habs charged by solar not sure how much they have dropped. Will check tomorrow but I think they will still be at 13.5v as before.
Dave

Ah, thanks. I don’t have solar indoor but a lithium sits that high with nothing replenishing it. So in theory could keep pumping out several amps / day if the lead acid keeps absorbing it, even when near full. Hopefully if given a full charge before storage it will be auto router’s milliamperes.

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