One for the experts.... Battery, Charging, Fuses

[d95gas]

Hi,
I am just moving from a 110A wet battery to a Fogstar Drift 230Ah battery. I currently have a Numax 10A charger which kicks in when on EHU, which I am guessing will be well below par for the new battery.

Therefore, happy to upgrade the AC charger, and unsure whether to go for the 40A Fogstar or the Victron IP22 30A charger ?

In addition, what size fuse would be recommend on the +ve side of the battery? I did get a 300A with the battery.

Any advice or opinions would be gratefully appreciated.

 

[Jev88]

The fuse is to protect the cable - so what cable?

If you have Victron solar or B2B then makes sense to use their charger? Doesn't matter if charger is small if you don't mind slower charging with correct profile.

More expert advice due soon......

 

[d95gas]

Thanks Jev88,

Going to need to do some investigating on the cable rating today, and then I can come back with proper information. The slower charging wouldnt really bother me, I was just trying to ensure I do everything possible to make sure the system was reliable, which is more important to me.

The Numax doesn't have any options, its just plug it in and forget it. My B2B is a Renogy 40A and that will be set with the correct profile for the new battery.

 

[autorouter]

I think I would go for a Fogstar 50A charger. I'm sure the battery could take charging up to at least 100A, probably 200A. In terms of watts, a 50A charger only draws 50 x 14 = 700W, ie about 3A from a 230V supply. So it's never going to overload even a 6A hookup supply.

I know usually a 10A charger is just as good as a 50A, because once you connect to EHU it's usually for at least 12 hours. But for the odd occasion when you might want to charge up quickly, the 50A will be better.

The Victron charger is better if you will be charging different batteries, because it has settable charge profiles, but for fit-and-forget in a motorhome, only ever charging the one battery, I'd go for the Fogstar one.

 

[d95gas]

Thanks Autorouter

Re the question on cable sizes, as I am going to need to remake the battery cables I have been looking at 17AWG silicon sleeve

Will this be adequate or is it overkill

I have a 2000W inverter, compressor fridge, LED lights, USB sockets and a couple of 13A sockets

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[Miggs]

I have been looking at 17AWG silicon sleeve

Will this be adequate or is it overkill

I think you will need more than 1mm²!

 

[autorouter]

I think you are getting the wire thickness figures mixed up. For a 2000W inverter, the 12V input would be 2000/12 = 167A. Using 1 metre length of 16mm² cable (5AWG) would give a voltage drop of about 3.5%, so better to use 25mm² cable (3AWG) , which gives about 2.1% drop.

The 17AWG wire would be electrically OK for the 230V output side, because the 2000W at 230V would be about 9A. However in a motor vehicle, flexible wires should be no thinner than 1.5mm² (15AWG) for mechanical strength, because it is a high-vibration environment.

 

[d95gas]

Sorry wire should read 8AWG

 

[d95gas]

I think you are getting the wire thickness figures mixed up. For a 2000W inverter, the 12V input would be 2000/12 = 167A. Using 1 metre length of 16mm² cable (5AWG) would give a voltage drop of about 3.5%, so better to use 25mm² cable (3AWG) , which gives about 2.1% drop.

The 17AWG wire would be electrically OK for the 230V output side, because the 2000W at 230V would be about 9A. However in a motor vehicle, flexible wires should be no thinner than 1.5mm² (15AWG) for mechanical strength, because it is a high-vibration environment.

That all makes sense, don’t know where 17AWG crept in from, will put it down as a senior moment. Thanks

 

[headlight]

That all makes sense, don’t know where 17AWG crept in from, will put it down as a senior moment. Thanks

Just to let you know that unless Fogstar have changed their mains chargers then they are extremely noisy and I mean extremely noisy.
The fan sounds like a jet engine.
I have one.
I only used it once as it was to noisy to be in the van with it running.

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[d95gas]

Just to let you know that unless Fogstar have changed their mains chargers then they are extremely noisy and I mean extremely noisy.
The fan sounds like a jet engine.
I have one.
I only used it once as it was to noisy to be in the van with it running.

According to their blurb, they have changed them and they now run a silent fan which turns itself off and on as and when required. But appreciate you pointing that out, its a definate consideration.

My sleeping pattern is bad enough without having to listen to a fan at 2am :-(

 

[PlacidoD]

.....
I know usually a 10A charger is just as good as a 50A, because once you connect to EHU it's usually for at least 12 hours. But for the odd occasion when you might want to charge up quickly, the 50A will be better.

.....

I have come across several aires that permit EHU but only have it switched on for e.g. one hour in every 8 hours. A larger charger would be particularly useful in that scenario.

The aire just off the ferry at Dieppe is in that category. So if you have used lots of power in the ferry queue at Newhaven and then overnight at that aire having got off the sailing arriving at 22:00 you might appreciate having lots of power the following morning courtesy of a large charger!!

 

[d95gas]

I think you are getting the wire thickness figures mixed up. For a 2000W inverter, the 12V input would be 2000/12 = 167A. Using 1 metre length of 16mm² cable (5AWG) would give a voltage drop of about 3.5%, so better to use 25mm² cable (3AWG) , which gives about 2.1% drop.

The 17AWG wire would be electrically OK for the 230V output side, because the 2000W at 230V would be about 9A. However in a motor vehicle, flexible wires should be no thinner than 1.5mm² (15AWG) for mechanical strength, because it is a high-vibration environment.

Finally got around to mapping out the electrical kit in the van, and was shocked to find that when the install was done (not by me), there are no fuses/circuit breakers in there except the main fuse between van battery and the Renogy B2B.

So looks like starting from scratch, so just about to place an order for cables, given that everything is close so dont have any great lengths of cable to run, I have gone for 3M of Black & Red 25mm Sq (170amp), also 3M of 16mm Sq.

In addition I will order relevant circuit breakers to go into the system. Before I place the order today, I am hoping the electrical guru's here will pass judgement on the plan please, need to ensure I get it right.

Although not documented below, I have the Renogy Shunt 300 and the Renogy ONE Core to monitor the system.

 

[Lenny HB]

Finally got around to mapping out the electrical kit in the van, and was shocked to find that when the install was done (not by me), there are no fuses/circuit breakers in there except the main fuse between van battery and the Renogy B2B.

So looks like starting from scratch, so just about to place an order for cables, given that everything is close so dont have any great lengths of cable to run, I have gone for 3M of Black & Red 25mm Sq (170amp), also 3M of 16mm Sq.

In addition I will order relevant circuit breakers to go into the system. Before I place the order today, I am hoping the electrical guru's here will pass judgement on the plan please, need to ensure I get it right.

Although not documented below, I have the Renogy Shunt 300 and the Renogy ONE Core to monitor the system.
View attachment 1046271

25mm² cable for the inverter is way to small if your cable run is 3m you need 75mm².

 

[d95gas]

25mm² cable for the inverter is way to small if your cable run is 3m you need 75mm².

Sorry Lenny, bit of misleading in my text. The inverter run is around 2ft, I was meaning I had just purchased 3M of cable to sort the job out.

Everything is nice and close, so all cables will be kept as short as possible, within reason.

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[autorouter]

One problem is, it looks like your Fogstar mains battery charger is running from the inverter, which is powered from the Fogstar battery. I appreciate you only want to charge it when on EHU, and the EHU routes through the inverter. But if the EHU goes off for some reason, you will be left with the battery powering the inverter, powering the charger, charging the battery - not a good idea.

Better, since you are still at the planning stage, to separate the AC loads into 'Inverter' and 'Non-inverter' loads at the consumer unit. Then you can make the charger a non-inverter load, that only gets powered on EHU. Maybe other things too, like a fridge, mains heater element or water heater element etc. You might need to rejig the breakers in the consumer unit, or even get a bigger consumer unit if there is no space for extra breakers.

Be sure to only use double-pole breakers in the consumer unit, not single-pole ones. All the MCBs in the DIY stores will be single-pole, so they are no good for this. You'll need to go to a specialist electrics store like CEF, or a caravan accessory shop may have them.

 

[autorouter]

Another thing, you should ve careful around the alternator and starter battery. The alternator must remain permanently connected to the starter battery at all times. No fuse except the original vehicle fuse. Bad things happen if the alternator is disconnected from the starter battery while the engine is running. Prolonged pulses of up to 60V are quite possible, and you can imagine the effects of that.

So take any connections to the alternator from the starter battery. There's often a multi-fuse distribution terminal on the starter battery. If not, it's easy to add one nearby, maybe one of these:

Power Distribution Fuse Boxes | 12 Volt Planet

Primary power distribution boxes with in-built fusing.

www.12voltplanet.co.uk

 

[Lenny HB]

Sorry Lenny, bit of misleading in my text. The inverter run is around 2ft, I was meaning I had just purchased 3M of cable to sort the job out.

Everything is nice and close, so all cables will be kept as short as possible, within reason.

35mm2 would be better.

 

[d95gas]

35mm2 would be better.

Duly noted and will swap out the 25mm for the 35mm thanks

 

[d95gas]

One problem is, it looks like your Fogstar mains battery charger is running from the inverter, which is powered from the Fogstar battery. I appreciate you only want to charge it when on EHU, and the EHU routes through the inverter. But if the EHU goes off for some reason, you will be left with the battery powering the inverter, powering the charger, charging the battery - not a good idea.

Better, since you are still at the planning stage, to separate the AC loads into 'Inverter' and 'Non-inverter' loads at the consumer unit. Then you can make the charger a non-inverter load, that only gets powered on EHU. Maybe other things too, like a fridge, mains heater element or water heater element etc. You might need to rejig the breakers in the consumer unit, or even get a bigger consumer unit if there is no space for extra breakers.

Be sure to only use double-pole breakers in the consumer unit, not single-pole ones. All the MCBs in the DIY stores will be single-pole, so they are no good for this. You'll need to go to a specialist electrics store like CEF, or a caravan accessory shop may have them.

thanks for the very informative response. It never occurred to me about the possibility of the EHU dropping and then the battery powering the charger.

So what you are saying is, the likes of the battery charger, and heater which are the two main items I run when on EHU, move those directly to the consumer unit with double-pole breakers...... If I have understood correctly.

The lights, TV are 12v. The only other thing currently running through the inverter is the two mains sockets I have in the kitchen area, but only thing that gets plugged in is a low power electric kettle.

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[ivorantony]

Just to let you know that unless Fogstar have changed their mains chargers then they are extremely noisy and I mean extremely noisy.
The fan sounds like a jet engine.
I have one.
I only used it once as it was to noisy to be in the van with it running.

I have just replaced my 30 Amp Fogstar battery charger that was destroyed in an accident for a new 50 amp one, it’s like chalk and cheese, I cannot hear it running even at maximum charge,
Recommend this charger that’s substantially cheaper than the Victron 50 Amp,

 

[d95gas]

Fogstar just informed me the 50A will be back available early May so will keep a close eye on the site and grabbed one