Battery charging

[Cometbreeze]

Installed a permenant fridge in the rear so I checked my batteries out, took them too Autosparky and both batteries checked ok although the water level needed to be topped up in both batteries, I've had the batteries isolated with a pirrana isolator and the aux battery level was a bit lower than the main crank battery.
I topped them up with distiller water and placed the aux battery on charge leaving it all hooked up and in the vehicle in the driveway, well 20 hr later and it still on Boost and has not switched to float ?
Can it take a lot longer to charge ? Or cause I topped it up maybe 10 mm I each cell it will take longer ?

Any elec gurus with some advice

Cheers

 

[Old.Tony]

Depends on a few things. High battery capacity with a low-rate charge will see that happen, but sometimes it's a battery that has an internal problem causing it to consume power.

It's worth checking the voltage it's showing while it's on boost - should be 14V or higher. Remove the charger, watch the voltage - it should drop to around 13.1-13.2V fairly quickly. After an hour, the battery should show 12.8-13V if it's in good condition. If it's showing below 12.8V the battery has a problem.

Topping up the fluid won't extend the charge duration by a lot (there will be some change due to the battery's ability to transfer power through the entire plate).

 

[Cometbreeze]

Great thanks very much Old. Tony I will check Volts, the auto sparky said they were fine so. ?They are the original batteries from new so the vehicle is a '09 duel battery model. So hopefully I'll get a bit more life out of them

 

[bods]

How bigs ya charger? Also, have you got the fridge running while it's charging? That seems like a long time, even from around 6v (I've had my aux battery down to that a few times now... Same setup as yours except 2010 model) it is on float by the next morning, but I have a fairly big charger (around 20a I think...)

 

[Cometbreeze]

She's a little 3.5 amp charger haha so maybe that's why ? Still haven't got my hands on a multimeter so I'll put it on again overnight and see what happens this time, cheers

 

[Cometbreeze]

Well I put it on again over night, still hasn't moved from boost ? Being a 3.5 amp maybe it could take severel days ??
I have another charger I use to trickle charge bike batteries but that is a c-Tek 0.8amp 7 stage would be slower again I'm presuming, might have to invest in a 20amp battery charger and multimeter.

Before I installed fridge in rear while towing the camper last time I returned home on 1.5 hr drive usualy the 2x 100ah camper batteries would be charged, but they weren't so I presume the cranker battery under bonnet would get charged first followed by all Aux batteries hence shy I'm checking them out, they are oem batteries so they are nearly 5 years old ???

 

[Old.Tony]

Okay, I'll try and piece together the info about the system, please correct me if this is wrong:

You are using a 3.5A charger to charge a pair of 100Ah batteries connected in parallel, so the total storage is 200Ah.

If that's the case, the charger will take (let's say the batteries have 30% capacity left) 140Ah / 3.5A = 40 hours to charge.

Age will slow that down somewhat. If the batteries aren't true deep cycle batteries they may have some sulphation present from excessive discharge, and this will slow the charge rate further. If that's the case, a C-Tek XS7000 or higher will have a "Recovery" mode which may bring the battery most of the way back to full health.

However, at 5 years of age, many lead acid batteries are pretty much shopping about for the best funeral plan they can get their hands on.

 

[Cometbreeze]

Yeh thanks Mate, sorry basic stuff I know but usualy my Navara duel battery with Pirrana ISO will charge the 2 camper 100ah amg camper batteries during a couple hr journey read for next camp ..... But last time it did not which led me believe I could have tired under bonnet batteries( stock std )as it alternator should should charge crank first then my Aux ( second under bonnet battery and 2 x 100 ah AGM camper via Anderson plug)(. And as we required a second fridge in rear I installed one and thought better check batteries and autoelec guy tested them ok, so I just topped them up with distiller water and tried to charge Aux battery over night, did not float, so did another over nighter and did not float again..... But like I said the charger is only a 3.5amp dual stager and my C-Tek is a XS 0.8mainly used for motorcycle battery maintenance. My electrical knowledge is limited !!!
Sorry if I confused you Tony you have been very insightful thanx.

 

[Old.Tony]

Don't worry about the confusion, it reigns!

Let's talk about the aux battery under the bonnet, because it sounds like that's the only battery you're trying to charge?

How big is that battery? Iif you don't know the Ah, look for a RC value on the top, and if not, just get the model number and a search will get the answer quickly enough!

There is EVERY chance that it's sulphated, being 5 years old and the OEM battery, and being charged by the alternator AFTER the cranker has had a go just gives it less life.

While you're driving and your alternator is turning over fine you'll find you can deliver 20-30A out the back fairly easily so it's no great surprise that those batteries charge in a couple of hours. If that's changed though, you'd have to wonder if something snagged a cable, or something has gone wrong with one of the batteries.

Personally, I'd throw my C-Tek XS7000 on each one individually and see how they went.

 

[Cometbreeze]

Yeh it's a 75d23l battery GS Thai battery with a CCA 600 ??? I did a search but it kept coming up with century batteries ? I don't think I've snagged anything as the car did bring the camper 200ah batts from end of camp at 50% upto 70% when we got home so it did something but not as much as usual.
I do have a projecta 25amp 7 stage charger in my camper and a 20 amp 12v-12v charger for The Deep cycle AGM x 2 but don't realy wanna pull those apart
So I'll save for a bit and get a decent multiple meter and charger for car!!!

 

[bods]

Multimeter would be your best bet, that way you can see what voltage you're getting out of the isolator too, in case it has an internal fault and isn't letting the full charge through. I've had isolators die on me twice (the second one I reckon was my fault so doesn't really count hahahah) but they stopped sending any charge to the second battery. I didn't realise until there amp stopped working and the little cooler in the back wouldn't turn on, even with the car running. Checked the second battery and it was about 6v lol. Dunno how it's still going to be honest, it has happened before and still works OK for running stuff when the car is off, I have a cheapo eBay volt meter thing hooked up to it now to keep an eye on the voltage, so I know if it isn't getting charge..

 

[Cometbreeze]

ok so i went camping on the weekend expecting the Aux Battery to shit itself while running my older engel fridge and i also plugged in a old fluoro lead light, in ran all night and with a short blast in vehicle next day i ran it again all night and light but woke in morning to warm beer, Light was on fridge but compressor not running. Not surprised i shut it down for the rest of trip.
on the way home on the 2hr drive my now camper batteries (2x100ah AGM) are @ 50% after 4 nights. when i get home they are @ 74%, usually they would fully charge on 2hr drive?

I come home and borrowed a Multimeter and did some testing firstly testing all batteries
13.2 cranker, 13.2 Aux ( also get 13.1 down the rear Aux outlets ) 0.00 at anderson plug as it is wired independently for camper.
Engine running: 14.1 Cranker, 14.1 Aux and 14.05 @ anderson plug for camper.

It all test ok to me or could my Aux battery still struggle with load as we have discussed they are the std batteries and some 5 years old ?
Should i go to battery world and get them tested properly?

just trying to double check before i splurge out for a new aux Battery

Thank guys

 

[Old.Tony]

Your testing points pretty clearly in the direction of the battery.

You could put a reasonably strong known load on it. A battery rated at 100Ah will provide 5 amps per hour over a 20 hour period before the voltage falls to 10.75V. 5 amps is about your high beam filament (55W with a little loss). You could fully charge the battery, connect a headlight globe to it (or 55W driving light) and let it go for a day, measure the voltage as it passes 10 hours then 15 hours and see if it's holding up.

I know that's a long time (relatively speaking) but the bonus is twofold: you do it yourself, and better still, it's free!