My Head Hurts .....

[jo10000_6]

Hi all

My head really hurts - I feel I'm going around in circles and getting no where which annoys me greatly and as mentioned makes my head hurt.

I've posted a few times recently on :

My charger capabilities - Answer not great 7.2A charger

How long did my battery last - Answer not as long as it should

2nd Leisure Battery recommendations - Answer need better than last time

Battery Monitor - Yes Id like one

Questions on Solar - yes Id like it but do I need it.


Every time I feel I'm getting somewhere I take a step or 2 steps back and its all about making sure I make the right decisions - in the right order and for the right reasons.

All I want is a little more off grid time - not loads - 4 / 5 days Maximum.

My previous posts tell me my one battery wont do this.

My 7.2 Amp Charger will struggle

I don't have a proper split relay system although there's a crude wiring system to connect to get me out of trouble.


I was all for getting a second battery - treating myself to a battery monitor to feed my obsessions - getting them wired in together - getting the split charge sorted and having a new charger and in theory being ok until I read a an old post just earlier to say a fellow funster had a old Hymer only to find the split charge system for 2 leisure batteries and one cab battery that the alternator wasn't big enough. Another post said make sure when changing the charger that the wiring is big enough for the bigger charger.

See, backward steps all the time.

Which begs the question should I stick with one battery and pursue solar ? My roof is busy not sure what Id fit up there but the above is getting complicated by the second.

I honestly try and do the research but I'm feeling very dejected with the answers I find.

Tomorrow I will jump out of bed with a new lease of life but tonight I feel I've taken on more than I can chew.

 

[suavecarve]

As and when finances are available then if you watch a couple of hours of tv that will eat into your battery if coming off 240 volts via an inverter.
If you can get a 12 volt tv that uses next to nothing in comparison.

dependant upon your use of the van, I would try to prioritise battery over solar over tv in which ever order for YOU that makes sense. There would be arguments for TV first as it drains less, solar as it keeps everything available topped up each day (sun permitting) and battery to have full tank (but will it fill up without frequent charge)

Chicken egg and fox conundrum

Best of luck

 

[Glas Robin]

A very good question.

1. In theory you can measure it with a multimeter, by disconnecting the wire and putting the multimeter across the break so that the amps flows through the meter. That method is fraught with problems. For example, if you disconnect the battery while the alternator is running, the voltage can surge up to 60 volts or more. That will very likely cause all sorts of very expensive damage to your electronics and your electrical items. Even professionals rarely use that method.

2. You can use a clamp meter. The clamp will clip around the wire, and it measures the amps by sensing the magnetic field that the amps will produce. No need to disconnect anything. I use a UNI-T UT210E clamp meter. It's a nice neat meter that will measure small amps (1/100 of an amp) as well as large amps up to 100 amps. It has sockets for test leads and will measure volts and resistance too. It's the one I always carry in the MH.
Amazon product ASIN View attachment 283087
3. A panel mounted volts/amps meter. Many of these are only good for 10 or 20 amps, but you will need one that can measure up to 100 amps. Like this.
https://www.ebay.co.uk/itm/100V-DC1...ED-Amp-Volt-Meter-12V-Shunt-New-/252959050501. View attachment 283086
It has a 'shunt' through which you send all the current you want to measure. You have to disconnect the wire to connect the shunt into the main current circuit. Then there's a pair of thin wires going to the small terminals on the shunt, and another pair going to the battery positive and negative. If you wire this in permanently there's less chance of accidentally disconnecting it and causing a voltage surge.

4. Of course if you have already wired in a proper battery monitor then you can just read the amps on the display

I bet you wish you never asked that question

There is of course an even easier way... open the bonnet, get a torch out and hope the alternator has a label on it that is readable. If there is a Thor, there will be an output on the label, or even a model number you can google.

 

[jo10000_6]

Hi

When I wanted the alternator testing a while ago the auto electrician company said it was a pig to get to and would need to go on a ramp.

I had it checked when having a service but didn’t think to ask what it was rated at as didn’t need to know then

My heads not hurting as much now - I’m sure I will have other “my heads hurting” days though !

 

[haganap]

Go this route.

1) Decent battery.
2) if still not enough add another battery.
3) if still not enough add a B2B charger , this will balance the batteries, increase charge rate etc.
4) add a Solar Panel

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[jo10000_6]

Does the B2B charger work in conjunction with the existing split charge or separately ?

Thanks
Jo

 

[jo10000_6]

Knowing what’s a decent battery can hurt your head as well

 

[pappajohn]

Does the B2B charger work in conjunction with the existing split charge or separately ?

Thanks
Jo

Hi Jo, with a B2B you don't need a split charge.
In normal use as the starter battery charges the alternator output reduces as the battery doesn't need the current, this also reduces the current to the leisure battery via the split charge.
With a B2B the unit fools the alternator into thinking the starter battery needs a proper charge so the alternator outputs whatever the B2B is rated at..... Could be 30amps...could be 60amps.....depending which model you buy.
As the starter battery IS actually fully charged all this power goes to the leisure battery so instead of maybe 3 or 4 amps it gets 30/60amps and charges rapidly and fully.

 

[two]

I think you should remove the split charge supply to the hab batteries because the B2B could be confused about their state by the change in voltage that may be caused. Note my cautious words here. I don't think it matters too much, but the split charge route becomes completely unnecessary so I wouldn't invite such confusion by leaving it connected.

 

[autorouter]

The split charge system is a relay (ie an electrically operated switch) that connects the leisure battery to the starter battery while the engine is running. But its most important function is to disconnect the starter and leisure batteries while the starter battery is providing the huge current to run the starter motor when the engine is being started. You don't want the leisure batteries trying to send a contribution to the huge starter current, they're not designed for that, and the wiring is usually not up to it either.

A B2B has a diode (an electrical one-way valve) that does not allow current from the leisure battery to the starter battery, so the split charge relay is not required. It can sense the alternator voltage and can tell if it's generating power, and it sends the power through to the leisure battery.

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[jo10000_6]

Thanks for the explanation, Papa John.
It was explained in such I way I got it ! Much appreciated.


Regarding the split charge situation I had an auto electrician around 2 weeks ago for a couple of things.

My leisure battery has never charged when travelling although when I’ve had my head in the bonnet checking the cab battery (mine died not long after getting the motorhome and made me paranoid on it starting) I noticed a loose unconnected wire with “L” marked on it. I always said it was something to do with the leisure battery.

The auto electrician said it was a crude split charge and said ok to use in emergencies -and he tidied up the wiring but didn’t connect.(terminal ring direct to battery)

Next week I will connect and see what the battery monitor says.

Also next week I have a Motorhome engineer visiting who is adamant there should be a proper split charge.

He’s coming to do a few little jobs - well at least I hope he is - Ive been very proactive on what I need to get done - photos and descriptions and everything. I would like proactive not reactive.

So gentleman i should have a better understanding by Friday.

Thank you all for the B2B info and the comments regarding split charge.

Ta,
Jo

 

[jo10000_6]

So......my head is still OK and not hurting at the moment

I had a very nice man around on Friday and I now have a functioning split charge system that was there just not connected as it should be.

I spoke to him about a second battery.

My Hymer B544 has one installed in a little area next to drivers seat but there is only enough room for one.

I spoke to him about having a second battery and the wiring required etc and his suggestion after looking underneath the motorhome (under the bench seat area) was not to put in the bench seat locker area but because there was room to have it underslung in a battery box thus not taking any storage up.

I didn't get into the nitty gritty of anything really so can I ask you guys a couple of questions.

Is it better for the batteries to be side by side ? Approx. distance from current battery to bench seat area is 60-80 cm.

Very big "help for the beginner question" coming .........Does the charger charge one battery at a time - senses when charged and switches to the other or do both get the charger capabilities equally divided ?

I fitted the battery monitor to the one battery - albeit its not in situ - I just wanted to see what it could do .....again what does the battery monitor see when its fitted - its a BM1 Nasa type and whilst the negative battery lead goes to the shunt the positive battery terminal has a connection from the monitor - how does this work when there are two batteries?

I know these are probably basic questions but I like to try and understand what's happening even if I don't have the skills personally to sort.

Thanks in advance.

Ta,
Jo

 

[autorouter]

So......my head is still OK and not hurting at the moment

Don't worry, that's easy to fix. Here's some more brain pain

Both batteries are connected together in parallel. That means positive to positive, and negative to negative. When connected like this, the charger charges both batteries at the same time.

It's best if the two batteries are next to each other, but if not, make sure the connecting wire is very thick, to keep the voltage losses down. How thick depends on the amps likely to flow through them, but typically 16 mm2 (that is 16 square millimetres of cross-sectional area) is usually OK. That's as thick as some starter jump leads.

If batteries are next to each other, a simple direct connection between them is OK. If they are separated, two big fuses, one at each end of the positive connecting wire, is required for safety. No fuses in the negative wires, of course, just a direct connection.

The shunt is positioned wherever you want to measure the amps. Usually one side goes to the habitation loads, the other side goes to both battery negative terminals. It measures the total amps going into and out of the batteries.

The monitor positive wire goes to the positive side of the battery. Typically the two battery positives will be connected to a big fuse, which goes through an isolator switch and on to the habitation loads. The monitor positive wire can go to the switch, on the side away from the batteries, so that it is off when the isolator switch is switched off. Note that a small (1 or 2 amp) fuse is still needed in the monitor positive wire, even though there is a big fuse to the battery.

 

[jo10000_6]

Don't worry, that's easy to fix. Here's some more brain pain

Both batteries are connected together in parallel. That means positive to positive, and negative to negative. When connected like this, the charger charges both batteries at the same time.

It's best if the two batteries are next to each other, but if not, make sure the connecting wire is very thick, to keep the voltage losses down. How thick depends on the amps likely to flow through them, but typically 16 mm2 (that is 16 square millimetres of cross-sectional area) is usually OK. That's as thick as some starter jump leads.

If batteries are next to each other, a simple direct connection between them is OK. If they are separated, two big fuses, one at each end of the positive connecting wire, is required for safety. No fuses in the negative wires, of course, just a direct connection.

The shunt is positioned wherever you want to measure the amps. Usually one side goes to the habitation loads, the other side goes to both battery negative terminals. It measures the total amps going into and out of the batteries.

The monitor positive wire goes to the positive side of the battery. Typically the two battery positives will be connected to a big fuse, which goes through an isolator switch and on to the habitation loads. The monitor positive wire can go to the switch, on the side away from the batteries, so that it is off when the isolator switch is switched off. Note that a small (1 or 2 amp) fuse is still needed in the monitor positive wire, even though there is a big fuse to the battery.

Thank you autorouter.

I've read this twice going to read again...……...if I understand 50% of it that's good isn't it . Expect a question or two at some point. My head doesn't hurt but is going around with permutations - if I allow that to happen for too long my head will hurt again but all good at the moment !