Do we really need battery chargers

Eaglemax · Guru

Do we really need battery chargers

Peter_n_Margaret · Guru

We have no 240V input, so we have no 240V charger. Solar and direct alternator charging on odd occasions is quite sufficient.
A good solar bank for day to day charging plus the ability to charge from the alternator is all you should ever need.
It does not matter if you use the alternator when travelling, or not, if the solar is adequate. Your choice.

EDIT. While in storage, the demand for power is significantly lower, even if you keep the fridge running, so solar would normally be sufficient. We would typically disconnect all the loads and we have some clear panels in the shed roof, so there is plenty of light for a trickle from the solar from time to time. In any case, if disconnected when full an AGM is OK without charge of any sort for at least 6 months.
Cheers,
Peter

-- Edited by Peter_n_Margaret on Wednesday 15th of January 2020 12:10:11 PM

Eaglemax · Guru

Thank Peter

Aus-Kiwi · Guru

Not if you have enough solar . But Ive found on odd accounts we need a quick charge after an overcast day . Have 40 amp charger run it for 20 minutes or so . Much quieter running inbuilt geni than starting 6.5 diesel motor . Horses for courses .

PetenSue · Veteran Member

We have a 40 amp 240 v charger, a 40 amp dc dc charger and 4 solar panels on the roof of the caravan. I think they are 120 watt. Dont really know. All hooked up to 3 120ah batteries. We also carry a generator. Most of the time I m too lazy to hookup the Andersen plug for the dc dc charger. We rarely stay in caravan parks so the 240 v charger doesnt get used. So we mainly rely on solar. I like the idea of having a few options if we get caught out in bad weather. Mind you all this expensive gear was fitted to our caravan when we bought it. I dont know if there really is a need for all that stuff. Good question Tony. Regards Pete

Radar · Guru

Eaglemax wrote:
Not talking for car batteries.
Briefly- my first van build was- 11ft, 120W solar, 100A AGM, load- CPAP (no humidifier), 18 litre Waeco fridge, TV 5 hours/night as main draw. Had lots of trouble with battery going near flat (as low as 11.2V).
Second and current van. 300W solar, 130A AGM, load the same.
Result? battery in last 8 months of regular holidays hasnt gone below 12.5 volts even on cloudy days (80% charge).
I have car alternator to van battery charging ability with solonoid but havent needed it.
So my questions are-
1/ is the need for a smart charger justified if enough solar can do the job on its own?
2/ would you still connect the alternator charging while travelling regardless of the above?
I realise while in storage a charger could be needed.
Tony

Hi Tony.

We did have a 240 volt smart charger in our caravan for the first 2 years it and never was used, I needed a charger to start my car in the garage, so whipped out the expensive 240 volt charger from the caravan and hooked it up to the car. From there I placed the charger in the box label "not used caravan stuff". So far after 2 years I have no regrets about not carrying the charger.

We mostly go unpowered when we travel. 2x 100 amp batteries, 2x 170 solar panels, cable via Anderson plug to the car possibly helps with management of it all, seems to work for us.

No for me. Ralph.

-- Edited by Radar on Wednesday 15th of January 2020 04:45:04 PM

Whenarewethere · Guru

I've squeeze AB-negative blood out of a stone on my setup.

My Victron 100/20 controller adjusts the solar output to charge the battery to optimum charged state, all data is on the phone. I rarely bother looking at the phone any more. If your setup is top notch & you have a fairly good educated guess at cloud cover over the preceding days & you have the capacity with battery & solar you won't need any 240 charging.

I do have a 10amp charger which is setup so I can simply plug it in on starter battery & auxiliary batteries, I use it occasionally as the car basically sits in the garage & or does very short trips when not traveling & also stick it on the 4 x 26ah gel batteries sometimes but before I know it it says the batteries are charged. So in general they never needed a charge, but it is nice to get a confirmation!

swamp · Senior Member

HI
if u have correct size battery for your needs eg 120ah battery 50% discharge ideal then upto 70% is satisfactory. So that equals 60ah to 85ah usage .
SINCE U CAN ONLY USE WHAT U CAN CHARGE
200watts generates approx. 48ah
300watts 73ah
mppt and sun outside of 100% not included
recharge time taken 5.5 hrs
This system works well for a single battery system
add more battery add more solar
Remember u can charge 1x 120ah with 400-500 watts of solar approx. 28amps charge rate

Charge rate is all about the **available solar hours available*** . If u have a system 1 that takes 8 hrs to charge and the other system 2 can doit in 4 hr. If system 2 has cloudy weather it has another half day to catch up. Whereas system 1 is undercharged as soon as a cloud appears .
Always design a system to charge in 1/2 a day .

Eaglemax · Guru

Thankyou Swamp and other posters. The answers were comprehensive and confirmed up a lot of my own thoughts. Indeed valuable for me and likely many other readers.

It seems clear to me now with my first van as to why 120W solar and 100amp AGM didnt cut the mustard so to speak. I now have the right amount of battery and solar that exceeds my usage and that is the secret to a good system...with back up like the others have said- Genny, alternator charging, DC-DC, mobile panels, whatever you choose. In my case alternator charging as extra weight for a genny is out of the question for my ATM of 998kg..

Thanks all, good replies.
Tony

-- Edited by Eaglemax on Wednesday 15th of January 2020 10:29:16 PM

Dougwe · Chief one feather

G'day Tony,

I have the Collie wired up to charge the two 120ah batteries in the aluminium teepee and have 450w solar panels on the roof of the teepee with a 40a solar charger. I haven't even bothered using the car to charge for about 3 years now as I have found the solar does things beyond expectations. I have never seen the batteries below 12.7 at night and when driving along and only solar doing it's thing is usually 13.8+ most of the time.

Even now, I am connected to mains power but have 240v charger off. I let the Solar keep the batteries working well.

Keep Safe on the roads and out there.

Hylife · Guru

In a new van with 12 volt everything, since tossing out the 2 x 120AH AGMs and going to 2 x 100AH LiFePO4, with the 450W solar on the roof I've never had to use the inbuilt 240V Projector Charger.

The Lithium's will suck up 25A in moderate sun Vs the AGM's maxing out at 16A in full sun

Eaglemax · Guru

Lithium, I'll wait till they are cheaper lol

Had a lithium battery with a faulty controller in a model airplane. Controller and battery caught fire. Everyone urged me to land the plane, but nope, loved the event till it crashed lol.

Not a good example of Lithium performance, think the controller was faulty. They are popular in models due to the low weight and need smart charging also.

Dougwe, yet another that relies on solar only. It confirms that enough solar takes the worry out of it all and battery capacity depends on usage.
Tony

Hylife · Guru

Eaglemax wrote:
Lithium, I'll wait till they are cheaper lol

Had a lithium battery with a faulty controller in a model airplane. Controller and battery caught fire. Everyone urged me to land the plane, but nope, loved the event till it crashed lol.

Not a good example of Lithium performance, think the controller was faulty. They are popular in models due to the low weight and need smart charging also.

Dougwe, yet another that relies on solar only. It confirms that enough solar takes the worry out of it all and battery capacity depends on usage.
Tony

Each to their own, but just for other considering if Lithium is worth the expense:-

1) You can't compare Per Unit pricing, even though they are almost as cheap as reputable branded AGMs, because their for usable capacity they are actually much cheaper.
Lithium is now just $500 for 100AH but can 100% DOD for 2000 cycles so is actually 4x longer lifespan and only 60% of the cost.

Example for recognised brands:-

AGM FullRiver 100AH $400 each. Usable capacity without shortening 400 cycle lifespan is 50AH = $800 for two to get 100AH
LiFePO4 SolarKing 100AH $500 each. Usable capacity without shortening 2000 cycle lifespan is 100AH = $500 for one to get 100AH

Lifespans of both AGM and Lithium do increase if your DOD is less, but AGM still pales compared to Lithium which can last up to 8,000 cycles at 30% DOD.

Even if you compare the el-cheapo no-name AGMs for $250 each, two of them still work out to be the same price as a single LiFePO4 100AH, but LiFePO4 will last at least 4 times longer and weight 13kg instead of 76kg.

2) That old RC would have had completely different chemistry Lithium 'cells' to what is in use today.
As an ex RC nut myself I can't tell you how many of those old cells I destroyed in my Piper Tomahawk, but I was aware of their volatility and always had mine wrapped in asbestos pipe lagging.
Even 5 or 6 years ago the old Samsung phones with early gen lithiums became known as hand grenades because they exploded after you dropped them.

LiFePO4 is just as safe as Lead Acid. It is not volatile in air or water, can sustain very high temps, and won't catch fire even if you cut them in half.

Eaglemax · Guru

Hylife wrote:
Eaglemax wrote:
Lithium, I'll wait till they are cheaper lol

Had a lithium battery with a faulty controller in a model airplane. Controller and battery caught fire. Everyone urged me to land the plane, but nope, loved the event till it crashed lol.

Not a good example of Lithium performance, think the controller was faulty. They are popular in models due to the low weight and need smart charging also.

Dougwe, yet another that relies on solar only. It confirms that enough solar takes the worry out of it all and battery capacity depends on usage.
Tony

Each to their own, but just for other considering if Lithium is worth the expense:-
1) You can't compare Per Unit pricing, even though they are almost as cheap as reputable branded AGMs, because their for usable capacity they are actually much cheaper.
    Lithium is now just $500 for 100AH but can 100% DOD for 2000 cycles so is actually 4x longer lifespan and only 60% of the cost.
    Example for recognised brands:-
    AGM FullRiver 100AH $400 each. Usable capacity without shortening 400 cycle lifespan is 50AH = $800 for two to get 100AH
    LiFePO4 SolarKing 100AH $500 each. Usable capacity without shortening 2000 cycle lifespan is 100AH = $500 for one to get 100AH

    Lifespans of both AGM and Lithium do increase if your DOD is less, but AGM still pales compared to Lithium which can last up to 8,000 cycles at 30% DOD.

   Even if you compare the el-cheapo no-name AGMs for $250 each, two of them still work out to be the same price as a single LiFePO4 100AH, but LiFePO4 will last at least 4 times longer and weight 13kg instead of 76kg.

2) That old RC would have had completely different chemistry Lithium 'cells' to what is in use today.
    As an ex RC nut myself I can't tell you how many of those old cells I destroyed in my Piper Tomahawk, but I was aware of their volatility and always had mine wrapped in asbestos pipe lagging.
    Even 5 or 6 years ago the old Samsung phones with early gen lithiums became known as hand grenades because they exploded after you dropped them.

LiFePO4 is just as safe as Lead Acid. It is not volatile in air or water, can sustain very high temps, and won't catch fire even if you cut them in half.

Thanks again hylife, Good to get some up to date info. My AGM is only 8 months old 130AH cheapy at $259 at Low Energy Developments Preston. weighs 34kg. Heavy for my van so down the track lithium will be tackled at the end of the AGM's life.

Tony

blaze · Guru

The answer has got to be yes
if you draw down power from the the battery and then put it back in
you need to use a battery charger.
What sort of charger is up to you, whether it is solar, dc to dc or a 240v charger, they are all chargers.
I have solar and 24v to 12 v chargers in my motorhome and no 240v input
cheers
blaze

Aus-Kiwi · Guru

Do we really need to carry a spare tyre ? If you have the room, with in weight etc ? While in south WA some time back with overcast days for near a week . The batteries become very low . Starting up the motor to charge batteries seemed very uneconomical., Having a motorhome . room, weight and running generator is easy . But trying to get all in caravan ? One thing I found was having 40+ amp charger . It boosted battery charge big time in short time .

Eaglemax · Guru

Aus-Kiwi wrote:
Do we really need to carry a spare tyre ? If you have the room, with in weight etc ? While in south WA some time back with overcast days for near a week . The batteries become very low . Starting up the motor to charge batteries seemed very uneconomical., Having a motorhome . room, weight and running generator is easy . But trying to get all in caravan ? One thing I found was having 40+ amp charger . It boosted battery charge big time in short time .

Hi Aus-kiwi

is that a DC-DC with appropriate inverter? And if so how long would it take to charge with the MH engine running? what size batteries? Because you have a good point in that overcast weather for several days might just run the battery down and alternator charging could take a couple of hours. Haven;t had that issue yet but might

Tony

Whenarewethere · Guru

I have two Victron 9amp DC-DC chargers, started with one. If we camp longer I use the solar panels otherwise I let the car charge the batteries. If there's not much driving then the solar comes out. Just a balancing act between the various factors. The two chargers total generally charge at 7 - 12amps unless the batteries are charged. The car's voltage is a bit too high for a longer life of the batteries which is the main reason I put in DC-DC.

I have also thought of getting 12 to 24 volt DC-DC & inputting through the MPPT controller as it has a really good charging profile. Another experiment!