Newbie battery charger questions

[wallport]

Hi all, I'm new to forum and to campervan ownership. We have bought a new T28 conversion and would like to understand the battery and charging setup. The items which depend on the battery in our van from the top of my head are: Fridge; Heater (its run off diesel but has a fan); Lights; Water pump for taps;

Having used our van across the british summer, its just had its first winter trip ...and with no hookup. I now realise I have no idea how its battery setup works. What I do know:

• It has a starter battery and a leisure battery (which I'm 99.9% sure is 12V lead acid and not lithium - its in a box which I haven't worked out how to get into)
• It has a Victron Blue Smart IP22
• It has a CTEK D250SE (the manual for this mentions the option of a CTEK Smartpass 120S but I haven't seen one of these unless its hidden away somewhere)

Firstly, to save the time and effort of trying to educate me from scratch - is there a dummies guide to this subject that anyone could point me to?

Some specific questions if anyone has the time and patience:

1. The leisure battery seems to be discharging quite quickly in winter when the van is not being used (less than a week) - is this normal?

2. Are we in any danger of damaging anything if we ever flatten the charger battery and recharge it with a normal mains charger or with jump leads from another vehicle?

3. The only indication we have of the charge level of the leisure battery is a set of vertical leds - a green one which lights when on hookup, an orange one which lights when there is a good charge level, an orange one which shows a lower charge level and a red on which shows it needs recharging. Without accessing the leisure battery box, is there somewhere I could connect a multimeter to get a more accurate view of the charge level? What readings would I be looking for?

4. So, the leisure battery can charge from the alternator or from hookup - when we don't have hookup, can anyone help me with any feel for how long the engine needs to run to charge the leisure battery from near empty to full? - with just idling or being driven? (this question arises from the fact that the battery only seemed to cope with one night in the winter using the heater and we'd really like to extend this when no hookup is available)

5. Am I right in thinking the CTEK D250SE is handling the connection to the alternator and the IP22 is handling charging from hookup? The IP22 manual talks about bluetooth connection and an app which I downloaded but couldn't connect - maybe it has to be on hookup? Would this be any use if I got it working?


That'll do for starters - many thanks in advance for any assistance.

 

[roadtripper]

1) If the leisure battery is isolated from loads it shouldn't discharge significantly - if you left everything on (especially a fridge) then it will

2) yes dropping below 50% charge damages lead acid very quickly for starter batteries and quickly for leisure

3) plenty of advice via search, cheap eBay 12v socket voltage meters are popular

4) you have a 20 amp CTEK and I would assume around a 100ah battery. On Bulk charging you should get 20ah per hour roughly. Bulk charging stops at 80%ish and not worth charging from engine (just running engine stationary for charging) beyond that. So quite a bit of engine run time. If flat 4-5 hours.

5) correct CTEK from engine VICTRON from EHU in your setup. You are very unlikely to have the high current smart pass from what else is fitted, the manual covers both that's all. The app is great if you are charging from EHU but as you are not it won't do much to help you.

The short basic summary is you have a competent but basic electrics setup suitable for summer camping, touring (with regular engine charging) or EHU.

Off grid winter camping without a few engine hours a day will need some investment. Plenty of threads around on that

I'd get some EHU provision sharpish if possible and make sure you get to the bottom of why it's going flat in a week, it will not take many incidents of a flat leisure battery to damage it significantly plus it will be putting a heck of a load on your main electrics charging it back up all the time.

 

[wallport]

Many thanks for that. Since the last few charges have been through driving and despite two lights may have been incomplete, we have charged from hookup and we'll see how long it lasts.

The following question was badly phrased:

2. Are we in any danger of damaging anything if we ever flatten the charger battery and recharge it with a normal mains charger or with jump leads from another vehicle?

I meant the vehicle starter battery. Any advice on this?

 

[roadtripper]

Lead acid batteries are optimised for broadly two uses; either for providing very high current for a brief period (starter) or low current for a long period of time (leisure).

Any battery isn't like a fuel tank, you can never fill a battery back up to where it was as it's a chemical reaction and each time you go through that cycle an amount of capacity is lost. That's the really important thing to understand with batteries, their life is governed by how many times that reaction cycle happens and how optimal it is.

In a traditional wet lead acid the reaction surface is the lead plates. And the damage is sulphur crystals growing on the plate which stops that area of the plate reacting (which removes current delivery capacity) and in extreme shorting to the next plate (which can short that cell and remove 2v - as a 12v lead acid is 6 x 2v cells)

To get the high currents starter batteries are packed with thin plates very close together to get as much surface as possible. This means they are extremely vulnerable to damage and shorting. I've seen starter batteries with high CCA (as you find in diesel and marine) fail after well under 10 completely flat incidents. They are never the same even after one incident. You really have to protect these style of batteries from even moderate discharge.

Leisure batteries are more forgiving as they have a much smaller number of more robust plates with more spacing. But still the general rule is to only use the first 50% of the capacity as the crystal growth increases significantly as the electrolyte changes on deep discharge.

If you have the modern stop/start then you will have an AGM battery. These are more resistant to damage as they are plates interleaved with glass fibre mat (like you use in fibreglass) and that physical separator slows crystal growth. However the other side of the balance is they are worked very hard indeed as all lead acid types generally only accept high current charge in the bulk phase (<80%) yet in our vans we are pushing high current charge in after the bulk phase.

Bottom line is in modern diesel vans your starter battery needs to be looked after like your first born child. Keep it as charged as possible and never ever let it get to a "no start" state of discharge.

If you are infrequently using your van you should make sure you can maintain both your batteries from charging sources other than the engine. Some folks go all in with solar to be more off grid, which also keeps batteries topped up. A simpler solution is to make sure you have EHU when stored for anything beyond a week or so. That will keep your leisure charged, you just need to work out what to do with the starter. If you have a 12v socket connected all the time to the starter, traditionally it's the one by the gear shift/selector but this seems to be changing in very recent 6.1s, then you can simply connect a good ~5A maintenance charger from CTEK/NOCO/VICTRON to your internal 240v EHU sockets and use a 12v socket adaptor to charge. For "fit and forget" many folks like the Ablemail AMT-12 trickle charger that will gently charge your starter from the leisure to stop any drain.

 

[T6Jay]

1. The leisure battery seems to be discharging quite quickly in winter when the van is not being used (less than a week) - is this normal?

Assuming it's a 100Ah Lead acid, if everything is turned off this sounds like a tired battery to me, a new lead acid battery would hold a charge for months if no load is applied. On the other hand, if the (compressor?) fridge was on, it will exhaust the battery from full in 2-3 days.

2. Are we in any danger of damaging anything if we ever flatten the charger battery and recharge it with a normal mains charger or with jump leads from another vehicle?

If you flatten the battery, even once, it could damage the battery. If your worried about damaging the CTEK and BLUESMART, no problem using a decent mains charger. With Jump Leads you are at the mercy of whatever supplies them, you'll get wild voltage swings, sparking, and hot clamps, all a bit risky really. In my opinion jump leads are for starting a vehicle in an emergency.

3. The only indication we have of the charge level of the leisure battery is a set of vertical leds - a green one which lights when on hookup, an orange one which lights when there is a good charge level, an orange one which shows a lower charge level and a red on which shows it needs recharging. Without accessing the leisure battery box, is there somewhere I could connect a multimeter to get a more accurate view of the charge level? What readings would I be looking for?

Our last van had one of these LED level indicators, they are almost useless.. A voltmeter on the battery will tell you a bit more, I think 12V with no load would mean the about 50% charge (which is as low as you should regularly go on a SLA). For better SOC indication fit one of these BMV-702 - Victron Energy

4. So, the leisure battery can charge from the alternator or from hookup - when we don't have hookup, can anyone help me with any feel for how long the engine needs to run to charge the leisure battery from near empty to full? - with just idling or being driven? (this question arises from the fact that the battery only seemed to cope with one night in the winter using the heater and we'd really like to extend this when no hookup is available)

- already answered above. But one night with the heater running? - if the battery was 'full' to start with, it's knackered, or the heater is, even if the fridge was running too.

5. Am I right in thinking the CTEK D250SE is handling the connection to the alternator and the IP22 is handling charging from hookup? The IP22 manual talks about bluetooth connection and an app which I downloaded but couldn't connect - maybe it has to be on hookup? Would this be any use if I got it working?

Yes that's correct, CTEK D250SE could handle a solar panel too if you had one. And yes the IP22 Bluetooth only works when it has mains on, the 12V side will not power it up.

 

[AeonMach]

1) yes if you've turned all the camping loads off

2) yes dropping below 50% charge damages lead acid very quickly for starter batteries and quickly for leisure

3) plenty of advice via search, cheap eBay 12v socket voltage meters are popular

4) you have a 20 amp CTEK and I would assume around a 100ah battery. On Bulk charging you should get 20ah per hour roughly. Bulk charging stops at 80%ish and not worth charging from engine (just running engine stationary for charging) beyond that. So quite a bit of engine run time. If flat 4-5 hours.

5) correct CTEK from engine VICTRON from EHU in your setup. You are very unlikely to have the high current smart pass from what else is fitted, the manual covers both that's all. The app is great if you are charging from EHU but as you are not it won't do much to help you.

The short basic summary is you have a competent but basic electrics setup suitable for summer camping, touring (with regular engine charging) or EHU.

Off grid winter camping without a few engine hours a day will need some investment. Plenty of threads around on that

I'd get some EHU provision sharpish if possible and make sure you get to the bottom of why it's going flat in a week, it will not take many incidents of a flat leisure battery to damage it significantly plus it will be putting a heck of a load on your main electrics charging it back up all the time.

Re 1), this was in response to a Q asking if it was normal that the leisure battery discharged in a week in winter...
...did you mean to say that yes this is normal?
Did you perhaps miss the key word 'unless'? ie "yes this is normal UNLESS you've turned all the camping loads off"?
...but conversely, no, this is NOT normal if there are no loads!?

 

[roadtripper]

Good catch @AeonMach

If the leisure battery is isolated from loads it shouldn't discharge significantly - if you left everything on (especially a fridge) then it will

 

[AeonMach]

Good catch @AeonMach

If the leisure battery is isolated from loads it shouldn't discharge significantly - if you left everything on (especially a fridge) then it will

Grand - I thought I was maybe going mad! Because the rest of your post was spot on and very authoritative!

My understanding is that you should expect maybe 3-4% per month (maybe slightly more in very cold winter?)...?
That applies to an AGM battery I think but Lithiums different (better? very little discharge?)?

 

[roadtripper]

Thanks, I've edited the original to save future confusion.

All batteries have some element of discharge. Of batteries in general use NiMH are probably the worst unless they are of the specific low self discharge design.

Lithium based chemistry tends to have low self discharge but leaving the cells at full charge or no charge for significant lengths of time does impact cell lifetime. Generally if you want to store lithium based cells you want the charge to be about a 1/3 of the capacity.

So if you have a lithium system that you can put into some form of sleep mode it might be useful to run it down to about 40% region before you do that. Having said that the lifetime of LiFePo cells is so good that you might not practically notice.

This is why you see some differences with Lithium chargers. The CTEK one doesn't hold a lithium battery at full charge but lets it drop back and then top up again, Sterling chargers have optional float stages. I'm mildy surprised that none of them seem to have a "long term storage" option that would hold the battery at around 40%.

 

[wallport]

Firstly thanks again for all this really useful info.

OK a little more information. We suspected from the information above that we had not been starting with a fully charged leisure battery and had been too reliant on driving to charge it so we put it on mains charge for two days. We had high hopes when after 4 days it was still showing 2 lights but just checked it again and its fallen to one light. BTW I got the Victronconnect app running and connected to the IP22 over bluetooth - most of what I saw there was just confusing but I haven't seen anything indicating that the battery is in poor condition so I wonder if something is draining it.

I think I need to put a meter on the battery and then probably go in search of anything which could be putting a load on it. Can I just measure the battery with everything connected or do I need to disconnect? Any tips on working out what could be draining it or at least eliminating things - e.g. could I pull the fuses out as I have been given some info about which appliances are on each fuse.

TIA

 

[roadtripper]

Would be useful at this point to post a few more details of your current set up and photos of batteries/chargers/principle wiring; it's much easier to help with those.

In particular details of which Victron IP22 you have and some screenshots of the app. Even the smallest is 15A and that should get a healthy charge into a (presumed) standard 100ah leisure battery in about 10 hours. If it's not then something is either drawing quite a strong load or the battery has already been damaged enough it won't hold charge.

I'm a fan of DC clamp meters for this sort of tracing, as you can usually get the clamp around single cables. I have the UNI-T one (example on Amazon) and you can measure current by the clamp and voltages with the probes.

If you can't get hold of clamp meter things will be a bit slower to debug but you're on the right track of pulling fuses and monitoring the state of charge to see which circuit is the issue.

I might be tempted to pull everything to start with and see if the state of charge stays stable then start adding back in. Start with the likely high loads like the fridge and then heater etc.

One final thought, you mention "two bars" from monitoring the battery so far. That sounds like you have one of the all in one mains/12v distribution systems and control panels in, details and pics of that would help if you have.

 

[wallport]

Some photos attached including the battery after I took the lid off its boxing.

Looks like one of those meters is over £50 but there are some cheaper versions - please can you explain how it will help so I can justify the expense. Are the cheaper ones any good?

 

[wallport]

... And some screenshots of the victron app.

 

[roadtripper]

So overall that looks like a tidy well organised install. It is the 15 Amp charger but that's reasonably matched to the standard lead acid battery. That's a Yuasu which is a well known brand.

Of note though is that it's one of the hybrid leisure starter types, hence why it has a cold cranking rating (900) which is quite high and an NCC class C rating. Those battery types are more for occasional use while on tour rather than sustained off grid. It also has an advised charge rate of 5amps which is rather low.

I have my doubts that that battery is matched to your desired use pattern though the good news is that the rest of the install would allow other battery choices if needed.

To get a good idea of the state of charge you ideally need to measure at the battery terminals. The meter I suggested is a good one if you need the clamp current meter and is reasonably priced for that feature. Looking at the install though you might have difficulty getting to the wires for the 12v fusebox, a more basic but good quality multimeter would be fine for voltages, it will just take longer to test.

Your battery type is 12v FLA so if you measure the voltage at rest (no load or charge) you should be able to determine the state of charge (it's what your battery meter is doing essentially)



To chase what's drawing the load I'd pull the 12v fuses (make a good note of what went where) and then see if the battery stays stable. If it does then you know the fundamentals are OK and can start adding the circuits back in starting with high load.

The most likely issue is the fridge, which hopefully you turn off when not in use as even a decent compressor is a high draw.

 

[roadtripper]

The history on your Victron is not showing any particularly long charge times. Most are showing half an hour of charging putting a few aH in before switching to maintain (the "charge" and "maintain" rows)

That's a surprise given you describe a very depleted battery, I would expect to see sustained charge cycles putting in over 50ah, your largest charge cycles is putting in about 30ah.

What other indications of a low battery are you getting? If those are recent charges logged by your Victron I wonder if most of your issue is that the fitted battery meter isn't that accurate.

So I looked up the actual voltage levels:
CBE Battery level test panel for 12V systems Green above 13V. Upper yellow above 12V. Lower yellow above 11V, Red below 11V

If you compare that with the voltages on the chart I would say those levels are very misleading for a leisure battery. The usable capacity of your battery is 100% (12.7v) to 50%(12.06v) - so the whole of your capacity is in the upper yellow band.

I would definitely cross check with a good multimeter.

 

[wallport]

Hmm, interesting thought that the light indications could be wrong - that never really occurred to me. Its also useful to know what they are supposed to mean as voltages. The only other indication we have seen is an error on the heater saying something like low power and refusing to turn on. The heater is an autoterm (not sure of model) which runs off diesel so presumably only uses the battery to power its pump and fan. It does show a voltage on its screen which was 13.2 when I looked whilst it was on hookup - I wonder if this is accurate though as I have seen it change quite significantly even whilst on hookup. I looked up the minimum voltage it would turn on which I think is 11v - if correct, this would agree with the red light voltage so would seem to provide some confirmation.

If you compare that with the voltages on the chart I would say those levels are very misleading for a leisure battery. The usable capacity of your battery is 100% (12.7v) to 50%(12.06v) - so the whole of your capacity is in the upper yellow band.
Does this mean that in theory we should never allow it to go below two lights?

Is there anyway I can check the battery voltage with a multi-meter without dismantling the cupboard the battery is in to get to the terminals (just don't want to do this often as its a pain)? Is there anywhere else I can connect to which is already exposed? This would also mean that it would be without disconnecting the battery but maybe just pulling all the fuses is enough - no hookup and with engine off obviously.

Whilst not entirely scientific, I did dream up the following test to see if there was some load on the battery. This is based on the fact that after two days charging on hookup (and thus hopefully fully charged) we saw the light indications drop from two lights to one light after 3 days. We could perform this test again with all the fuses pulled and see if that time increases significantly. Does this sound worthwhile?

It would be much better if something was monitoring and recording the battery voltage all the time - is there any cheap and easy to fit option for this (which obviously doesn't use much power itself )

 

[roadtripper]

The BM2 battery monitor is popular around these parts as a basic Bluetooth monitor that will do logging for pretty much the use case you describe. It will log continuously using the voltage to judge the state of charge and then you use the app to connect and see the data. It's not as accurate as a proper shunt from someone like Victron or Renogy but it's not bad for the money (around £20) and many folks use a full shunt on the leisure battery and a BM2 on the starter.

Personally I'd also arrange for it to have a inline fuse just in case, as delivered it has connections straight to the battery terminals without a fuse.

Example from Amazon:

https://www.amazon.co.uk/ARCELI-Bluetooth-Wireless-Diagnostic-Analyzer-Black/dp/B09YTWJ6BL/

I suspect you have had a couple of genuine low voltage incidents but now that you are looking closely the basic meter you have is not giving you enough resolution. A BM2 could help you determine if there really is an issue or you just need to get used to your battery system behaviour.

The voltage seen by the heater may well move around, at times of high load (heater firing up and fridge running) you'd expect the voltage to drop a little, all batteries will. So worth keeping an eye because that's what the heater will use to determine if it can work, but maybe not ideal is primary monitoring.

 

[roadtripper]

Does this mean that in theory we should never allow it to go below two lights?

With those voltage points the rule of thumb I would use is:
Green (4 lights) one of the chargers is running
Upper Yellow (3 lights) normal use
Lower Yellow (2 lights) time to recharge as soon as practical
Red (1 light) stop using the leisure battery unless it's an emergency, battery damage likely

 

[wallport]

Thanks - have ordered a BM2. Am hoping it fits in the battery box.

 

[roadtripper]

You should be fine, they're about the size of box of Swan matches