Right Steve, at least 2 of your batteries are past it; caused almost certainly by being over-discharged which has caused suphation of the plate surfaces. The third isn't brilliant either. After a full charge the specific gravity should have been at least 1.26 across all cells. Ideally you should have left the batteries at least a couple of hours before testing the SG and for that reason I rather discount the post-charge voltage readings as they are too high for these SG readings. See this table. I should explain that the higher the voltage, the higher the SG should be.

State of ChargeSpecific GravityVoltage

12V 100% 1.265 12.7
75% 1.225 12.4
50% 1.190 12.2
25% 1.155 12.0
Discharged 1.120 11.9


I would be interested to to know what the SGs were after your lamp experiment. Bet they would be at best 1.2. If so basically this would mean that after drawing the current of the work lamp for 1 hour the batteries were at 50% capacity. A 100 Amp/hr battery ought theoretically to be able to provide 100 amps for 1 hr, 50 amps for 2 hrs etc. I don't know what bulb is in your work lamp but if its a 55 Watt H3 bulb, that would draw 4.58 amps. You will see from this that the batteries simply aren't doing the biz. The voltage ought to be more than 12.2. The bottom line is that its time to get some new ones.....

A word about your charging system. If this is a simple voltage dropper fed off your alternator rather than a proper charger i.e. a device that varies the rate of charge (i.e. the amps) according to the battery's needs then there is a risk that the batteries could be over charged. Putting 15 amps constantly into a fully charged battery will just damage it. I don't want to alarm you unnecessarily as it may be that what you're using is rather more sophisticated than that. Why don't you ask on the SBMCC forum? Someone there might be able to help.

As far as the sounds go, why don't you simply buy a car radio with an auxilliary input for your I-Pod? This will use far less power and be perfectly loud enough.

All the best Steve and tell us how you get on.

Q
I can't get the table to format properly so its best to look here Battery Tutorial | BatteryStuff.com

Hi Q

Thanks for all the info. Comprehensive as always!

After fully charging, I left the batteries standing for about 6 hours then did the voltage and SG checks, connected the loads, and did the post-load voltage check. I didn't do an SG check after the load though, which as you say, would have probably yielded more interesting results. I went to a solar place here in Nairobi yesterday and found 3 100Ah batteries for +/- US$800, or 2 200Ah batteries for +/- US$1000. Pretty expensive, so in the interim I've left my 3 110Ah batteries with them to be properly tested. They seemed pretty confident they could test them properly, so I'll find out what they say on Monday or Tuesday.

As for the car radio route, my setup is a bit more complicated unfortunately. We have a single amp, with 2 sets of speakers connected to the same 2 channel output. 1 set is in the cab, the other in the box. I then have a 2-way switch which switches between cab or box. I have an input for the iPod in the cab and box, and just move the iPod between the 2. However, that said, I think I may have found someone here in Nairobi who wants to swap my high-power amp for a lower power one. I didn't think it would be tricky to find someone, coz I reckon it's a pretty sweet deal for whoever gets the bigger amp!

As for the charger, I think I've just got a basic converter that shoves the 15A into the batteries when I'm driving. Perhaps that's not good for the batteries, although that leads me to wonder about what happens with a car's charging system. When the alternator is running it's generating quite a large amount of amps (my truck's alternator generates 24V/55A, most 12V alternators generate in the order of 100A). What happens to the vehicle's batteries when that huge amount of current is pouring into the batteries while driving? Surely they too would be damaged?

Cheers
Steve

I always thought that the state of charge of the battery will determine how many amps it is being charged by. As the state goes goes up, so does it's voltage and the alternator and battery eventually come to a state of balance when it is fully charged.

Your normal truck batteries are charged from the alternator and you've no problems with these? But your leisure batteries are charged from the alternator via the 24/12V converter.
If they are being overcharged is it this that is the problem?

I can't say I really know for sure what I'm talking about and I may be asking more questions than giving answers, hopefully I'll be corrected by someone more knowledgeable. But I suppose an ammeter connected in line between the converter and the batteries will tell you if the amperage is dropping as the batteries become more charged.

Steve at that price you'd be daft to get some new batteries when basically all you're using them for is to power your amp. The batteries ought to be more than capable of powering the rest of your load (LED lights, fridge etc). I suggest you sort out the stereo etc and save your money. It's most unlikely that one or more of the batteries are going to die completely in the near future (they're not that bad) so what I would do is monitor the LB voltage and make sure that you don't completely discharge them.

Don't forget that you don't need to use leisure batteries. Sure they have thicker, stronger plates designed for slow long-term discharge (it's all explained in that link I posted in my last message) but a battery is a battery and a standard 'starter' battery will do all you need. Sure they're capable of providing instant high current but I've been using them on my truck for 3 years now without any problem. The one thing you mustn't do with them is discharge them fully as the plates will sulpate up more readily. The guy who runs my local truck electics place uses standard i.e. non-leisure batteries in his caravan as well.

I really don't know much about alternators etc but I'm just a bit queasy (spelling?) about a system where you've effectively got 5 batteries all being charged by the one source with the only regulation being, if you pardon the pun, the regulator. The Sterling system separates the starting and the leisure side and controls the amount of charge going into the latter depending on it's needs. With your system there's no such separation. Surely someone here with more knowledge than me can comment?

Q

Theres a lot of info on here too:-

Motorhome Forums, Motorhome Discussion, Motorhome Chat - Forums

I have a Sterling system. It charges the leisure batteries at as fast a rate as is safe by raising the voltage a bit till the leisure batteries get near fully charged. It protects the chassis batteries by letting them take the full alternator output for the first 2 min after starting and also refusing to charge the leisure batteries till starting battery voltage >13.2V. Their BB241230 takes power out of a 24V alternator system and reduces it to 12V (actually ~14V of course) and puts out a max 50A output (25A input @ 24 or actually 28V).
I'm sure Sterling's site or Mr Sterling himself can tell you how you have been damaging your leisure batteries by simply charging them with a convertor. One obvious thing is the voltage drop in the convertor. Another obvious thing that I previously mentioned is if your solar panels are in parallel (to charge 12V) their current output is too low for their size you being near the equator, one may be defective. You should be getting 7A EACH.
Sterling Power Products: Battery to Battery Chargers

Charlie

__________________
Unimog U500 w/Unicat

Q, I had my doubts about whether the power consumption would be a static 24A, regardless of the amplification level.

I would imagine that the output voltage level is directly proportional to the power consumption, and since the output voltage level is proportional to the input voltage level and the gain settings, I would say keeping both of these low would reduce the power consumption.

As previously mentioned, I took my batteries in to be tested. Driving back to the campsite, my alternator via the 24/12V converter was powering my 12V system. I was listening to my music, and realised that the 15A converter was capable of powering my 24A amp, and this along with running an electric coolerbox we have in the front which draws about 5A (Campingaz Powerbox 24l) and powering the GPS (minimal current I admit!)

This got me thinking... I've just done some tests with an ammeter between the battery and the amp, and checked the current. Dependant on the music (and therefore the input voltage) the current bounces around, but at the levels we listen to it's generally in the order of 5A, peaking at 7A.

Perhaps it's just the batteries, which have been used continuously for +365 days, that are getting tired now?

I'll report back once I've checked my panels and have the test results for my batteries.

Cheers
Steve

Hi folks

So as I said, I gave my batteries to a solar & battery place in town. They've just called to say that after 3 days of charging (each being charged separately), the batteries still won't get fully charged. What does that mean? Are they just buggered? Do I need to get some replacements?

Thanks
Steve

Steve we've lived in our truck for the last 12 months and the batteries are fine. We don't have a huge stereo, and have never discharged them below around half, but are totally fine. We initially had a 24v proper sized microwave though, with 6.5m of cable connecting it (!) but soon took that out!

Charlie do you have sealed batteries? I was thinking of the Sterling thing myself but thought I'd read you ideally wanted unsealed batteries so they could be topped up? Sterling being so good at acheiving 100% charging and occasional desulphating the battery is mildly boiled? Very good reviews though and would certainly help Steve if you could get one!?!

I have AGM batteries which is probably the best for my application because they are buried beneath a sub-floor, so not easy to get at for top-up if they were open cell. The Sterling charger does have a setting for AGM.

Charlie

__________________
Unimog U500 w/Unicat

Steve what a saga! I'm not sure what they mean about them being not fully charged but guess they mean that each battery is still taking a considerable amount of current. Quite what is "considerable" in the context of your batteries, who knows but if after 3 days they still aren't at full capacity putting it at its best, they've seen better days. But, and it is a big but, it rather depends on how they're charging them. If they're simply using a basic charger by now the acid should be bubbling happily away and if it isn't that suggests the plates are heavily sulphated. That said, your Specific Gravity figures don't suggest this to be the case. If they're using a smart charger (which does what a Sterling B2B charger does and which unlike an alternator system is capable of charging a battery to 100% capacity) it rather depends upon what current the batteries are still taking. 100% capacity using a smart charger is when the voltage is simply being maintained at a given voltage- this is called the float stage; it's sort of like achieving battery Nirvana. At this stage the charger will be putting out extremely modest charge. But without knowing how they're doing it I cant say more.

I have realized one thing about your system (touched on above) which is you'll never ever charge your batteries to 100% capacity using an alternator system even with your voltage dropper. With start batteries this isn't a problemo because all they ever have to do is churn over the engine. Once the engine's started all the electrics are driven off the alternator which in turn tops up the start batteries. And in your case the LBs too. The advantage of the Sterling system, as described by Charlie, is it that though fed 24 Volts off the alternator, it charges the LBs quite separately from the alternator and being a smart chager (i.e. the charge rate and time is all computer controlled depending on the receiving batterys state of charge) will achieve far higher charging capacity than an alternator ever will.

I appreciate this is all a bit theoretical Steve and what you want is some practical advice! Well your system has worked well so far and your batteries got you all the way down the west side and coped with a musical hammering waiting to get into Angola. Since then and assuming your solar system is functioning properly (worth checking as Charlie said) and if you're right that the music is so low current then your problem is down to the battery(s) being knackered. Simple. The question then isn't an electrical one, it's an economic/pleasure/comfort one. Put simply, is it worth you spending $800 (when it would cost half that in the UK) being as certain as you can be that the system will work as well up the east side? I know you can get obsessed about these things-I got uptight when the chip on my Sterling charger died in Mauri and I was totally reliant on my solar alone which cut off when I was driving. But it all worked out though I occasionally had to turn off the fridge! Don't forget even if they all die totally you can get all the power you need simply by running the truck engine. If you ask what I'd do, I'd keep my old batteries (assuming the solar and battery place hasn't done for them!) and buy 1 new one just in case. But it's your decision..........

All the best

Q

PS Are you eventually heading back to the UK? If so a beckons.
PPS How are the (tubed) tyres?

Hi folks

I bit the bullet and bought some new batteries - E-Solar AGM batteries. My old batteries are indeed past it, and heading into the wilds north of Kenya I think it pertinent to have an electrical system I can rely on.

Now, something interesting (perhaps!) As previously mentioned, I have a 24/12V 15A converter which converts my 24V alternator output into 12V for charging my batteries. Similarly I have a 220/12V converter which converts a 220V mains hookup into 12V/15A for charging my batteries. Neither of these are "smart" chargers - they don't vary the voltage or current according to the batteries state.

Now I also have a Steca PR2020 solar charge regulator, which IS a "smart" charger. (From their website: The auto-adaptive state of charge algorithm results in optimal battery maintenance and control over the module output) I was wondering if you know if it's possible to connect the outputs from my other charging systems (alternator and mains hookup) to the solar input of my solar charge regulator to take advantage of the smart charging?

Many thanks for all your help, it is much appreciated!

Best regards
Steve

Looking at the Data Sheet I don't see any obvious reason why you shouldn't connect up the output from the dropper to the input of the regulator though I've never actually heard of anyone doing it that way. The input current of the regulator can be up to 20 amps and the voltage anything less than 47 volts. I wouldn't connect up the mains hook-up (suitably rectified and dropped to 12V) with the solar regulator input though as you won't know how good the 220/12V comverter/charger is at producing pure DC. Anyway all you need the hook up to do is provide basic charging and powering your fridge/lights etc when you're parked up. The solar and vehicle chargers (if you do decide to feed the dropper via the regulator) can do the smart stuff.

Q

That's what I would think, but of course you never want to take the plunge without knowing for sure my solar regulator isn't going to end up a smoking mess!

I've got other issues now - after checking my solar panels, they are indeed only producing 7amps. Turns out I was defrauded and sold 2 x 60W panels, instead of 2 x 120W panels. Grrrrr, what a pain. That is no small part of the reason why my batteries were stuffed! Anyway, what can you do. I'll try fight the guy when I get back, but it was bought of German ebay in July 2008, and his account has been suspended, and any attempts to contact him has proved fruitless so far.

Anyway, that aside, I've now reconnected my panels to my Steca regulator and they're not producing any current at all. I've done an auto-test on the regulator, and it spits out error code 100 (with the 1 flashing). I've done some searching online but can't find what this means. Anyone had this error before and know what it means?

What a saga!!

Thanks again for all the help
Cheers
Steve

Suggest you re-connect the regulator Steve. If you don't have the blurb, this is what it says:

Connect the individual components to the symbols provided.
Observe the following connection sequence during commissioning:
1. Connect the battery to the charge regulator - plus and minus
2. Connect the photovoltaic module to the charge regulator - plus and minus
3. Connect the consumer to the charge regulator - plus and minus
The reverse order applies when deinstalling!
Please observe that the automatic adjustment to 12V / 24V systems does not function
properly, if this sequence order is not followed. An improper sequence order
can damage the battery!

This would suggest that the installation sequence is important. If this doesn't fix it, suggest you e-mail the company. The contact is via this page.
STECA E-mail the Solar Electronics division

Good luck

Q