Charging An Auxiliary Battery..?

Gday all,

Anyone please..
Can I charge my auxiliary battery (Optima Y. Top) with an external ac-dc charger (Bosch C7) while the battery is still connected to the in-vehicle battery charger (Redarc BCDC1225)..? She is not my daily and since my Safari is on a 24v system, all 12v accessories including a dvd player and the alarm system are running out from the aux battery. I have the Bosch charger so was thinking to make use of it while the Safari parked in the garage for a week or sometimes longer. I've asked Redarc but just couldn't wait till they reply my email.

Might be better off sending Yendor a PM.
This is his Thang. lol

Wating for Redarc's reply would be worthwhile, their aftersales tech advice is very good.

My guess is that to do as you suggest will have no impact on the BCDC1225, but you should ensure that none of the appliances running off your aux battery will be harmed by charging voltages (unlikely).
Alternatively at the current low prices a 60w solar panel connected to your aux battery via the BCDC1225 would be a cheap fit & forget solution.

However, if during your weekly drive, you drive for a few hours returning home your aux battery will be getting a reasonable charge on the way home, & a smaller panel could be used to ensure it is topped up if you arrive home without it being fully charged. With AGM batteries like the yellow top Optima's their self discharge is very low. Once fully charged they can happily be left for 3 months at a time.

Cuppa

Wait for a reply from Redarc or if someone else can give solid answer but with my Piranha management system I just hook up the charger to the main cranking battery and the system works fine and charges the aux battery once cranking is full as normal operation running with the alternator/transfer over, etc.

Just hang 5 to be sure though mate.

Quote:

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Originally Posted by AB

I just hook up the charger to the main cranking battery and the system works fine and charges the aux battery once cranking is full

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Different set up Andy. Ade's crank batteries are 24v & his aux 12v so he cant just put the 12v charger onto the crankers. Also the redarc is a dc to dc charger (with solar capacity), not a voltage sensitive relay system like it sounds your Pirahna is.

Cuppa

Quote:

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Originally Posted by Cuppa

Wating for Redarc's reply would be worthwhile, their aftersales tech advice is very good.

My guess is that to do as you suggest will have no impact on the BCDC1225, but you should ensure that none of the appliances running off your aux battery will be harmed by charging voltages (unlikely).
Alternatively at the current low prices a 60w solar panel connected to your aux battery via the BCDC1225 would be a cheap fit & forget solution.

However, if during your weekly drive, you drive for a few hours returning home your aux battery will be getting a reasonable charge on the way home, & a smaller panel could be used to ensure it is topped up if you arrive home without it being fully charged. With AGM batteries like the yellow top Optima's their self discharge is very low. Once fully charged they can happily be left for 3 months at a time.

Cuppa

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Thanks heap Cuppa.

My concern is on the BCDC. I used to charge the 24v main batteries with the external charger when I didnt have the BCDC and the Optima and there has been no drama to all 12v gadgets that was running via couple of reducers at that time. Just to be cautious and hoping to see years of life from them (more than couple of years now), I had both main batteries charged at least once a month with the Bosch charger as the stereo, alarm system and both reducers were using some amount of power from them continuously even after the engine is switched off. Now thinking of doing the same thing to the Optima but getting a solar panel would be the best option I guess..fit & forget solution, cant agree more on that.

If I wanted to run my 60L fridge all the time in the trol, what size of solar panel should I use? Lol..seriously, is it even possible to do this? Let say for a week without starting the engine and parked under a porch and the Optima is YT S5.5. Kinda stupid but Im just curious..

Quote:

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Originally Posted by AB

Wait for a reply from Redarc or if someone else can give solid answer but with my Piranha management system I just hook up the charger to the main cranking battery and the system works fine and charges the aux battery once cranking is full as normal operation running with the alternator/transfer over, etc.

Just hang 5 to be sure though mate.

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24v is a beaut for my winching, stater motor sounds cool too but could be a bit pain on some other things..their bulbs are freakin hot too..lol. By the, you haven't reply my pm mate.

It will be fine. I would just wait for the Redarc to turn off before connecting the C7 to the auxiliary 12 volt battery.

The C7 is also a 24 volt charger isn't it?. If so you can connect the C7 to charge your 24 volt batteries and the Redarc will charge the 12 volt auxiliary battery.

Quote:

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Originally Posted by Yendor

It will be fine. I would just wait for the Redarc to turn off before connecting the C7 to the auxiliary 12 volt battery.

The C7 is also a 24 volt charger isn't it?. If so you can connect the C7 to charge your 24 volt batteries and the Redarc will charge the 12 volt auxiliary battery.

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Yeap..its got 24v capacity too. Now that one I'd never thought of..will give it a try.

If your battery charger has a 24v charging capability it would do no harm to connect it to your crank batteries, which would then get charged themselves, plus would charge your aux battery viar the BCDC1225 too. if you were charging your two crank batteries separately @12v forget that.

If you want to run a 60l fridge for a week at a time on solar you are talking about something quite different to just ensuring you keep your batteries fully charged & in good condition. Essentially you you would need sufficient solar input to replenish the night time battery usage AND run the fridge on a daily basis. The fridge will probably draw around up to around 40 to 60 amp hours per day in hot weather depending on the fridge temp setting. (Freezer settings potentially more). If we look at the higher usage level (sensible) of 60aH per day this is how much your solar would need to generate. I don't know your part of the word but will guess you might average 6 'sun hours' per day. 200w solar would give you this with a small amount of leeway.
However your Optima battery would be marginal in such a setup. It's capacity is 75aH, & if you want it to have a long life you won't use it to below around 50% capacity, giving you an available 35aH to 40aH to run the fridge overnight. This is ok as long as you don't have any cloudy days which prevent your battery being charged fully during the day. However as the weather cannot always be relied upon, extra battery capacity would give you a 'buffer'. An alternative to more battery capacity would be more solar input, most crap weather days still allow some solar input, & an extra panel increases this.
If it were me I'd try the 200w solar & your existing battery & monitor it to see how it goes. You may find it is sufficient to get you a week at a time with a slight decreasing of battery charge each day, topped up by a drive once a week. If it isn't wack on another panel. (The BCDC1225 will handle up to around 400w of panels).

Cuppa

EDIT: I see Yendor was simulposting with me. :)

Thanks heap guys. I've tried it and it works! Damn "L" lol..

Anyway, quite suprisingly..yesterday morning, I've set the fridge (ARB 60L) cut off voltage to medium which is 11.4v, 0c on the temperature and ran it with few bottles of water inside. A short 20 minutes drive to the town in the night and switched it off before midnight. Early this morning I switched it on again and at about around noon it switched itself off which I presumed due to the Optima has reached the preset 11.4v. Later afternoon, had a half an hour drive to and around town. Just now, as I connect the Bosch charger to the main batteries, turn it on and went into the trol to have a look to the BCDC, its already at its float charge rate. Thats was quick..??

Suggest for the sake of your battery that you set the battery protection setting on 'Hi'. 11.4v is into damage territory. (Portable fridge manufacturers are notorious for setting protection levels far too low, ARB are by no means alone in this).

I'm not familiar with the Bosch C7 charger, but it appears to be a pretty fancy smart charger, & as such should be ok to leave connected to your crank batteries & switched on if you are leaving your fridge running. If it has a 'supply' mode, get the batteries fully charged & then switch to supply mode, if not just leave it in float mode. It will work out when to revert to bulk charging rates. If the latter just keep an eye on your crank batteries, assuming they are wet type batteries, & top them up with distilled water to ensure the plates remain covered. This is because they will be getting charged to 100% rather than to the usual 70% to 80% that alternator charging does. In so doing gassing & gradual fluid loss is normal.

I have a couple of ARB fridges, including a 60 litre one, & know that the digital temperature readout can be misleading. This is not just an ARB fridge thing though. If you fill the fridge as much as you can with bottles of water or similar you can be more confident of the readout. I've found that with an empty or partially empty fridge it appears to get down to temperature rather quickly. If you have as little unused space as possible the internal temperature will remain more constant with less cycling of the compressor. When planning to use mine I usually fill the fridge (or freezer) with frozen bottles of water from our household freezer for 24 hours before refilling with food from the fridge or freezer to ensure a more stable temperature. This is far more efficient than using the 12v fridge/freezer to do the initial cooling/freezing.

Cuppa

Cuppa is the guru when it comes to solar, so I will leave that with him.

Quote:

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Originally Posted by Ade

If I wanted to run my 60L fridge all the time in the trol, what size of solar panel should I use? Lol..seriously, is it even possible to do this? Let say for a week without starting the engine and parked under a porch and the Optima is YT S5.5. Kinda stupid but Im just curious..

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If this the only reason you want solar for. I wouldn't worry about getting solar. I would just plug the fridge into mains power while it is under the porch.

Agree with Yendor. I wrote the stuff about solar before I realised your charger did have 24v charging.

Whilst away from home the bcdc1225 will suffice if you are driving for sufficient time each day. If camped in one spot for more than overnight you will need some solar input and or increased battery capacity. How much of each would depend upon your expected travelling style.


Cuppa

Thanks heaps guys. Appreciate that detailed explanation Cuppa, I've read loads of your post and threads. Same goes to you Rod..top blokes! I reckon there will be more questions to come soon..lol.

Bloody L