RE: Genarators

[stvekay]

Will a 700w generator charge 2 1101h batterys? (will only use it if on my own).

 

Thanks

 

Steve Kelly

[StuartO]

It will depend on how deeply you discharge your batteries and what sort of mains charger you use - but for any worthwhile use of the batteries it will take many, many hours running the generator to top them up again.

The existing mains charger fitted to your MH may not be optimised for this role, hence the suggestion that you would need to look at that as well as choosing a suitable generator.  Generators which offer a 12v output are a red herring and those 12v generator outputs are unlikely to be useful for battery charging; stick to generating at mains voltage to power a mains charger.

You would need a good quality, high output charger to optimise the recharging of two 110 AH batteries simultaneously, something like the biggest of the CTEK range.

Buying a cheap 2 Stroke generator might not be the optimum solution either; you will be running for many hours you you need to a generator choose for good fuel efficiency.

In summary it will be complicated and exxpensive to get this right and you will probably do far better by booking into a campsite for a night to connect to an EHU to do the recharging.

[tonyishuk]

Very rudimentary sums which someone can update.

 

You say you have 220 amp hrs, say quarter down , you need 55amp hrs to return to 220 amp hrs

 

So charging at 5 (60watts 12v ) amps, will take 10 hours , or at 10amps will take 5 hours.

 

This 12v , you would have to step down from 240v.

 

Doable with a generator, providing you have fuel to top up every couple of hours.

 

Just a thought.

 

Rgds

[chas]

Have you ruled out a couple of decent solar panels ?

[stvekay]

Thanks for replies.

I had hoped after 3 days off grid 2 hours would give me a good boost, I am afraid I don't understand the complexities of electric/amps volts etc. I don't want to run a generator to watch TV etc so thought this would have saved me booking into a campsite to charge up especially in France where not so many small sites open all year.

 

Thanks again

 

Steve

 

[spospe]

Assuming that you intend to plug your van into the generator and thus use the installed power system to recharge the batteries, it all comes down to the capability of said power system. 700 watt s of available power will recharge your batteries no problem, but over what time period?

 

700 watts at 12 volts equates to circa 58 amps, so if your power unit was up to the job and assuming your batteries were 100% efficient, then circa 4½ hours would charge them from flat.

 

The above is somewhat simplified, but 4 hours running time would do the job from the more usual 50% discharged state, provided the power unit was up to the job. The generator itself has plenty of power available at 700 watts, so it all comes down to your charging system in the van.

[stvekay]

Hi Re 2 solar panels. We have one. I don't know what charging system we have. Van is a 2007 rapido 9048.

We tend to travel a bit so will get a charge through alternator. Just trying to cover all bases in case we stay somewhere a week. Have seen a light generator on srewfix with good reviews. Not expensive like the Honda one. £800. I know you get what you pay for, but if you only spend less than £200 not the end of the world.

 

Thanks again for the advice.

 

Regards

 

Steve

[artheytrate]

Make sure it’s an inverter generator as some cheap ones are not and can damage electronics.

 

John.

 

 

[stvekay]

Thanks it is inverter (what ever that means) and 100% pure sine wave power (?)

£169.00 9.5k so may be worth a try.

 

Thanks again

 

Steve

[aandncaravan]

We created an efficient Generator solution for a Hymer owner a little while ago by adding a second mains charger to their set-up.

 

The two chargers used about 450watts in total when flat out charging.

 

The combined output was a potential 14.4v and 30 amps which could charge up two quality 100Ah batteries from 50% DOD in about 3.5 hours.

 

However, when you can charge up the batteries at any time, most people put the generator on every couple of days when the batteries are usually only about 20% discharged. Which theoretically could be put back in about 1.5 hours. Shallow discharging a battery in this way will ensure it lasts much longer.

 

But that depends a lot on the quality of the batteries, low technology ones like Platinum can take twice as long to charge as Varta LFD90.

 

Obviously the advantage with such a set-up is that you have that charging capability 365 days of the year, even in mid winter when a 100w Solar panel is delivering about 4Ah a day.

 

Doubling up the mains charger when you have a generator can reduce fuel and half generator running times.

Going above 2 x 18amp mains chargers won't give you much extra unless the battery bank is also increased.

 

 

[stvekay]

Big question! How do you put a 2nd charger in?

 

Regards

 

Steve

[aandncaravan]

The Sargent PX300 is a reasonably low cost multi stage unit at about £100 which you just connect to the Habitation batteries.

 

You can buy cheaper chargers, like the Sargent 151, but their charge rate is pathetic. They can take 4 times longer to charge a decent battery versus the PX 300.

 

Suggest you only fit a proper Motorhome/Caravan charger that does not have battery reconditioning/desulphation phases.

Those that claim to be able to be 'connected all the time' don't always tell you that they draw significant power from the battery once 230v is switched off.

One we particularly don't like is the Rovert range.

 

 

 

 

[witzend]

stvekay - 2018-08-11 4:11 PM

£169.00 9.5k so may be worth a try. Thanks again Steve

 

For that money will probably sound like a chainsaw Honda used to do a Generator just for battery charging

[weldted]

Hi, we have 300 watts of solar panel, with a Voltronic 350 Mppt controller, a 2000 watt pure sine wave inverter. The inverter is connected to the ENGINE BATTERY. This allows me when driving to run the onboard mains charger to increase the charging rate to the batteries. We were in Spain and Portugal mid Dec away for 67 nights without EHU. The setup was covered in my previous post. Not saying this may be suitable for everyone depends on you requirements and how much you travel but works fine for us.

[starvin marvin]

stvekay - 2018-08-11 8:04 AM

 

Will a 700w generator charge 2 1101h batterys? (will only use it if on my own).

 

Thanks

 

Steve Kelly

 

You don’t have to be on your own, but you soon will be!

[aandncaravan]

The average 100w Solar Panel set-up will put back about 25Ah per day outside of mid summer.

 

A good generator set-up may do that in about 45 minutes so the actual running time per day can be really short and can be chosen when it is most convenient for those in the vehicle and those around it.

 

 

[hallii]

Probably best to make a lockable box with plenty of ventilation. I was by a Dutch van in France, his generator cable was cut by a person unknown.

 

Generator noise and fumes are not well tolerated on Aires and some campsites ban them.

 

I never use hook up and I have never used a generator. I have two 80 w solar panels and stay fully charged during the summer months in France and Spain. That includes charging my ebike batteries, using my TV for 3-4 hours a day, led lights, and so on.

 

[stvekay]

hallii - 2018-08-12 10:20 AM

 

Probably best to make a lockable box with plenty of ventilation. I was by a Dutch van in France, his generator cable was cut by a person unknown.

 

Generator noise and fumes are not well tolerated on Aires and some campsites ban them.

 

I never use hook up and I have never used a generator. I have two 80 w solar panels and stay fully charged during the summer months in France and Spain. That includes charging my ebike batteries, using my TV for 3-4 hours a day, led lights, and so on.

 

We are thinking of winter I would ban them as well except if you are alone.

[stvekay]

aandncaravan - 2018-08-11 5:50 PM

 

The Sargent PX300 is a reasonably low cost multi stage unit at about £100 which you just connect to the Habitation batteries.

 

You can buy cheaper chargers, like the Sargent 151, but their charge rate is pathetic. They can take 4 times longer to charge a decent battery versus the PX 300.

 

Suggest you only fit a proper Motorhome/Caravan charger that does not have battery reconditioning/desulphation phases.

Those that claim to be able to be 'connected all the time' don't always tell you that they draw significant power from the battery once 230v is switched off.

One we particularly don't like is the Rovert range.

 

Sorry to be thick, but where does th px300 get its power to charge the batterys?

 

Thanks

 

Steve

[Wortho]

witzend - 2018-08-12 6:48 AM

 

stvekay - 2018-08-11 4:11 PM

£169.00 9.5k so may be worth a try. Thanks again Steve

 

For that money will probably sound like a chainsaw Honda used to do a Generator just for battery charging

 

You can still get generators that are just for 12v charging but they are made in Australia. It's basically a Bosch alternator mated to a Honda generator. They do 55, 80 and 120amp models. Only useful of course if you have a battery that can accept a high charge current. http://www.christieengineering.com.au/Brochures/GXH5055ND.pdf

[plwsm2000]

Don't assume that batteries will draw a constant current during the whole charging cycle, because they won't for most of the time. The assumption that say putting back 50Ah into a battery will take 10 hours at 5 Amps or 5 hours at 10 Amps is not correct as the battery charge current is not constant throughout the charge cycle.

If it was, a 100Ah battery discharged at only 90% would take 20Amps out of a 20A charger for 30 minutes and then draw virtually nothing after that. The battery will just draw whatever current it needs at the voltage provided by the charger. The charger cannot "force" the battery to draw more current that it wants to (that is without the charger increasing its voltage).

What you will find is that a discharged battery will take the maximum current available from the charger for a short time and then the current will gradually reduce as the battery charges up.

That is the main reason why for electric cars etc., they say things like "charge to 80% in 20mins". It might take several hours to get the extra 20%.

 

Leadacid chargers are usually a constant voltage charger with a current limit. Other battery chargers (i.e NiCd) use constant current/voltage limited chargers.

 

For battery discharging, it is almost true to say that 50Ah is the same as 5 amps for 10 hours or to 10 amps for 5 hours though. I say "almost" because the actual battery capacity depends on how much current you draw. At high currents, the effective battery capacity will drop. That is why manufactures specify the capacity at a certain discharge rate (normally C/20 hrs).

 

Leadacid batteries are also not 100% efficient in charging. You normally have to put in another 5% or so Ah. The charge efficiency also drops at lower temperatures.

[witzend]

Wortho - 2018-08-12 1:16 PM

You can still get generators that are just for 12v charging

 

Here's one

https://www.ebay.co.uk/itm/SUPERCHARGER-SUITCASE-50-AMP-12-VOLT-BATTERY-CHARGER-MOTORHOME-CARAVAN-BOAT-/202396135335

[Keithl]

witzend - 2018-08-12 3:17 PM

 

Wortho - 2018-08-12 1:16 PM

You can still get generators that are just for 12v charging

 

Here's one

https://www.ebay.co.uk/itm/SUPERCHARGER-SUITCASE-50-AMP-12-VOLT-BATTERY-CHARGER-MOTORHOME-CARAVAN-BOAT-/202396135335

 

They are usually for sale at Warners MH shows. I can't find 'SuperCharger' or the seller 'Europond Direct' in the listings but they may be at this weeks Malvern show.

 

Keith.

[stvekay]

witzend - 2018-08-11 7:48 PM

 

stvekay - 2018-08-11 4:11 PM

£169.00 9.5k so may be worth a try. Thanks again Steve

 

For that money will probably sound like a chainsaw Honda used to do a Generator just for battery charging

 

Have been reading reviews, some say really silent others noisey. Its a mine field!!!

[aandncaravan]

Wortho - 2018-08-12 1:16 PM

 

You can still get generators that are just for 12v charging but they are made in Australia. It's basically a Bosch alternator mated to a Honda generator. They do 55, 80 and 120amp models. Only useful of course if you have a battery that can accept a high charge current. http://www.christieengineering.com.au/Brochures/GXH5055ND.pdf

 

 

They are available but are poor value. As Phil says don't expect a 120amp model to charge at any more than the battery will accept. Those units tend to charge at, typically, less than 15 amps peak.

Even the top power 120 amp version. The advertising is very liberal with the truth.

They also connect directly to the 12v battery, when it isn't always convenient to leave the door open to run the 12v battery clamps in from the Honda unit.

It is best placed 25 metres from the van, not right outside the door on a 3 metre length of wire connecting to the battery.

 

 

A decent generator just uses the EHU cable and can be used to power 230v appliances as well, such as a microwave, etc.

 

 

With two two proper motorhome chargers, 2 x Varta LFD90 batteries, each battery, even one at 10% DOD (90% charged) will take a decent charge.

 

Plwsm2000 is wrong to say that the chargers are constant voltage. The poor ones might be, but the decent chargers we are talking about here, like the PX 300, and those fitted in Hymers, are variable voltage, decent charging units with high enough voltage to get decent current into a quality battery.

 

The battery technology is key in this, hence making that point in in my initial reply by saying a poor conventional battery, like a Platinum will take twice as long as the Varta LFD90's.

 

 

The mains charger just plugs into the nearest 230v socket.

I can see why you are going the generator route if you need power in Winter, as a typical 80w x 2 Panel set-up in Glasgow in December will deliver a measly 7Ah a day.

Hardly enough to replace the power drawn by an Alarm, let alone Heating and all the other Winter power consumption.

 

Because you are using this just for recharging the batteries for an hour or two every couple of days it will be easy to find a time when no one else is around, so noise shouldn't be a primary consideration.

 

If you look for 'Rain Hoods', they can drop the noise significantly and help conceal what is underneath.