Balance charger for charging Pb+power from alternator/solar?

[_g_]

I fancy getting a balance charger and now that I'm spending a fair bit of time in my motorhome it makes more sense - as it can replace a load of clutter, including things like my ebike charger.

However, what I've just been wondering is; if I get a decently powerful one (ie 1000w+, though for the moment shouldn't need more than 250-500w), will it do a good job replicating a 'smart charger' designed for lead acid.
I've looked at various solutions to charge the leisure batteries in the motorhome.

If it will, would it be possible to run it from the alternator to charge the lead acid batteries?
Would I be able to run it directly from solar panels, to initially get around buying a solar charger, if I got some solar panels.

To power it from the generator, for the moment I would use a Draper 30a 24v car battery charger, which I believe should be ok.

Money is a bit limited at the moment so trying to figure the best 'bang for the buck'.

The leisure batteries run at 24v as does the vehicle. I have a Honda EX4000 generator. The alternator is 'unkown' rating; I would ideally like to get a decently powerful one (ie 140a with a good proportion of that at idle for a sterling) and consider getting rid of the generator, adding a big inverter which could then have some extra batteries to play with.

(Yes, I know it's not your typical question around here, but I reckon this forum's got the best chance of having people that know... incidentally, I would love to make the motorhome a hybrid with a massive battery pack to also use for daily stuff, but that's rather a long way off .)

 

[dogman dan]

If you meant an RC charger, when you spoke of a balance charger, it will run on an ac power supply, plugged into the ac of your generator fine. I never tried any of mine directly from the dc output of my generator. It will run on your battery as well, provided you get one that runs on 24v, same as your DC system voltage.

The solar power should run it if it's enough amps and watts flowing at the moment. But it might shut off every time a cloud goes by.

The RC chargers are a bit fussy about their DC input voltage. Handy things to have around, but likely you will need a charge controller designed for solar. One able to tolerate solar panels variable input.

 

[_g_]

Cheers.

Ones typically used for RC stuff, yep.
The more powerful ones don't come with their own mains power supply, thus running it from a charger if using mains (generator) power.
The generator will only put out 8.3a @ 12v for DC, so not great for cost effective charging.

These bigger ones have maximum input voltages in the range 32-38v. However having had a look at it, I do think a proper solar regulator of some sort is going to be needed.

 

[el_walto]

8.3A x 12v is only 100Watts.

One of these might work way better for charging your PB. How many watts is your solar setup?
http://www.ebay.ca/itm/CMP-Solar-Panel-Charge-Controller-Regulator-10A-12V-24V-/390630787714?pt=LH_DefaultDomain_0&hash=item5af368ca82

You can then your your rc charger from your 12V Pb. RC chargers are not automated, you'd have to start and stop it everytime you want to start charging.

 

[_g_]

That was one thing I was wondering about - I know a lot of these can be programmed to varying degrees, or controlled by a PC and wondered how far that went.
Whether I could set it up to work reasonably automatically when plugged in to the leisure batteries and receiving power at the other end - be that from alternator, through a 240 charger or even solar.

Sorry, should clarify that the generator does 3500w or so at 240v - so if I then take that back down to 24v I've got plenty of power there.
But only does 8.3a max for DC @ 12v. The current charger I've got does about 5a @ 24v, but should be getting this Draper one that does 27.5a.

I don't have a solar setup just yet - am in 'planning' stages.
It will probably start at about 120-200w @ 24v. May get bigger later.
I only have sun until 5pm or so after which it's in shadow where I am now - so do want to make use of early sunlight before I'm up if possible.

I believe this should work like a solar mppt system to some degree and am looking for the most cost efficient method possible (otherwise I could just buy more fuel for the generator )

 

[el_walto]

Why don't you draw out your plan and post it here. Maybe other could give suggestions based on that.

 

[_g_]

Will see if I can draw something out - though part of the problem (apart from obviously not making it clear enough), is that the answers to the questions will help formulate my plan .

 

[dogman dan]

Though inefficient compared to just using AC from a grid, you likely will get the best results by going with a solar panel, then charge controller, then lead storage battery.

I think I understand this right. The battery is part of the RV, and when it runs, the RV alternator charges it. The alternator has a sort of charge controller built into it, preventing overcharging. You want a solar charge when parked, without starting the generator. The gennie is not built into the rv. If not, then you'd also be best to use an AC charger, to convert the gennies AC to 24v DC, and charge to the right level and stop in time.

To charge your bike or whatever, an RC charger can be found that runs on 24v DC, which should be more efficient than using an inverter to make AC, then using a charger that converts that back to DC all over again.

 

[_g_]

If I had the choice, I'd definitely go for grid-AC!

You've got it about right .

I've now got an answer back from one of the manufacturers and it generally confirms I can't do what I was hoping - the balance charger needs a steady output, so solar would have to already regulated both that and alternator would have to go through a battery bank to stabilise it before charging another. Further, the same applies to a basic mains charger.

However, one possible solution is to have them connected to the vehicle batteries, then have the charging done from that.

Just waiting to hear back if they think that's feasible and I'll post up their responses.

I suspect it's going to make more sense for me to get a Sterling alternator to battery charger and put the mains charger through that for 'smart' charging (it also considerably boosts the alternator output), and just have the solar going straight to the leisure batteries with a standard mppt controller.