Journey Electrical upgrades JJOB

[Hitting the road]

Well...took the van away for a 3 night stay with some friends off grid. I hadn't been in the van for about 8 weeks, not since keeping it in storage while not plugged in to the mains. I had upgraded the house battery pack a while back from the factory 1 x 100amp AGM, to 2 x 140 amp AGM's and had used it a few times with that setup.
I had put the van on to power about 24 hours prior to leaving to get the fridge up and running...and pump a few amps back in to the batteries before heading off...all good...the fridge was cold when hooked up...and stayed that way on 12v from the tug to destination.

Anyway, got to camp late morning first day, set up, fridge and water heater fired up on gas, the 12v would only be running lights and water pump. I was not concerned about the 12v and didn't really pay a lot of attention to what the battery reading was on the panel on arrival...but pretty sure it was reading around 12.6v - 12.7v...should have been ok. That night the shower got used a couple of times, and some lights on...no great power usage. The "power left" indicator usually reads about 199 hours with the battery set up while using only a couple of LED's.

Following night at around 8pm all lights went out? The BMS must have switched off the power due to low battery...huh? That was only maybe 6 hours all up of lights usage! So I switched off the lights and also the battery 12v isolator for a bit then switched it all back on and had power to use the water pump to shower and some lights again. I turned off the battery isolator again over night to save on what ever charge was still there.
I am thinking the batteries must not have been fully charged, as there is no way it should have cut out after only a few hours usage.

So in the morning I found the fridge was off...fantastic...so it seems if you turn off the 12v supply the fridge, it will turn off even if on gas as it appears the "smart" fridge still needs a 12v feed to allow it operate on gas....well I'll be!

Next day I connected my 400w of external solar panels to the van as it was in the shade until after midday so the puny 160w panel on the roof wasn't doing much at all. I hadn't tried out my new set up,
I had attached an Anderson plug to the tool box up front and run wiring under the van back in to the battery compartment under the seats, added a 40 amp MPPT charger with Anderson plug to plug in to the batteries when utilised. All worked fine and was pumping amps back in to the batteries, the battery monitor was showing 13.2 volts in no time. But...of course as the new solar regulator was connected directly to the batteries the BMS wasn't recognising that there was charge going in to the batteries, only the charge in the batteries, so the monitor did not show any of that info, nor did the battery condition indicator reach "full"...even though it should have done.

I was aware I had to connect any additional inputs or outputs via the negative terminal on the BMS if I wanted to have correct info of power in and out showing up on the monitor, So after this little issue I have bought a Shunt from BMPro...Not cheap I might add, to connect between the negative terminal on the battery to all cabling...so the BMS should "see" the second solar regulator and give me correct readouts on the monitor. I plan to install an Inverter so that too can connect via the Shunt and should give me readouts of what is going out at any time.

Is there anything else I need to do to make this all function as expected? I am heading off grid for another 4 days in a couple of weeks so will be able to put to the test. I am aware too that the solar regulator in the BMS may be affected by the second solar regulator and vice versa and either one go in float mode earlier than it should...but have a way to fix that if it does occur...

Cheers

 

[Drover]

Partly why I don't like BMPro stuff and fancy monitors ...............

If you have your portable system set up to charge the batteries seperate from the BMPro it doesn't matter about the 2 regulators, when one shuts down it usually isn't doing much anyway and the other is just floating, so your batteries are nearly or are full, when in camp there is always a drain on the batteries anyway................................ my system doesn't seem to have any drama if I have 2 regs hanging off the batteries but then I can plug my portable into the roof system as well as run its own reg...............

I don't think I would connect an invertor via a shunt, an invertor should have its HD cable direct to battery to negate resistence and losses ...

Your batteries might have been showing 12.6 or something but probably just a surface charge effect, they really need to be on trickle the whole time, let them run down while in storage then charge back up doesn't do much good long time and with the BMPro too low they will get shut out and you have to bench charge them... especially if you have a compressor fridge, trickle charge while in storage is important.

Nice to see you have found the secret fridge business, auto fridges need 12v to run their brain........

 

[Hitting the road]

Thanks Drover...I hadn't paid attention to battery charge level on the monitor when setting up, so as you note the batteries were likely low anyway hence the surprise shut down.
It was a wake up call anyway as far as battery capacity vs lay up time goes The place where I store the van wants an extra $20 a month to have it on power 24/7...being the under cover storage rate is dear enough without adding extra outgoings I didn't opt for that. Though they will put the van near power so
I can hook it up and get the fridge running a day or two before pickup. which is handy.

There are two schools of thought it seems regarding leaving AGM's on charge the whole time or letting them run down to maybe 80% and recharging to keep them fresh. I would prefer to leave on charge but thought I'd try out letting them run down a bit then recharge. If the van was going to be laid up for 3 months or more I'd take the batteries out and bring them home to put on charge...bit of a hassle but thems the breaks. Trip next week will see a few days in a Park before heading off grid so the batteries will be charging that whole time.

Be interesting to see how the charge / drain rate goes starting with full batteries...I will put the shunt in to allow me to see what the second regulator is doing when the extra panels are out...But as far as inverter hook up, I'll have to read up on what this Shunt will cop Amperage wise...

 

[Drover]

I have heard some waffle about leaving batteries on charge all the time, multi stage chargers dont shove juice into batteries all the time, the actual charge state floats around, mine I notice float between 90 to100%... Disconnect your batteries so when you park it up you have a physical disconnect, batteries should be good for 2 months then, even though shutting down the BM should be the same.....volt meters are only an indication of float charge not of actual capacity, a battery turned off for 20 mins then checked will give a true state.....
If your AGMs have gone flat enough for the BM to shut them out bench charge each one seperately before refitting in van..... This gets them at their best.
At that price for power my next mod would be quick disconnect and carry handle for battery to go home with me...think outside the box for easy access

 

[Hitting the road]

Yeah, I am believer in leaving them on trickle actually, but I choose for the moment to let them sit due to trying to keep costs down. Normally there wouldn't be much more than a month between usage, but the Cape trip and subsequent disaster threw a spanner in the works.
I turn the batteries off from the BMS when I leave the van, but don't physically remove cables to any terminal...so as you write, "should" be similar result. I'll do a leakage test at some point to determine if there is any voltage loss when the batteries are turned off from the BMS.
The batteries are under where the dinette is, or in my case my swivel chairs. Not hard to access but a pita job in itself to remove them and refit them given their 33kg weight each.

I'll pay attention to the state of charge more in future...I still need to fit a DCDC Charger to this tug to charge an auxilliary, I am waiting to pick up my old tug which has a DCDC Charger in it to swap in to this one. I may even need to consider running power from the tug to the van batteries while towing to top them up as well on the run...especially if off grid camping for extended periods...

 

[Drover]

If you can plug into power to run up your fridge a day at least before hook up then they shoud be getting a good charge, would check what they are showing though, if down around 12.5 I would just connect up a decent charger to do the job, they could still stay all hooked up, it wouldn't hurt...........
If you need to charge van batteries up from the tug then the set up isn't going to be much chop when camping off grid has always been my view, well if you have solar on roof of course, different kettle if the panels are in the boot then some power from the tug will make sure your starting the camp with charged batteries hopefully but if you have to hook up the tug while camping then your set up isn't any good ............... My 120w Aldi panel will bring my batteries up by 0800/0900 of a morning if I set it right to catch first light, so heaps of panels is nothing compared to getting the aim right, by the time my roof array gets working everything is full, its main job is running the chargers for the gadgets....

One of mine is on a slide but the other is a 2 hernia lift out of the boot, a 2 battery slide and bigger cupboard for then is on the list, really should as its just a bit of metal bashing to extend the battery box and a longer slide from Bunnings...... a slide long enough for 2 batteries end to end will have to be a good 'un and some serious thought to bolting it down..... one day, in the fullness of time..................... but then I have been waiting for the Lithium Fairy to stop by, possibly held up by the same road block as the Lotto Angel has encountered.

 

[Hitting the road]

lol...if the lithium fairy drops by please direct them to me afterwards!

I am going to plug the van in to charge about 40 hours before blast off this time to give the batteries a head start! The BMPRO charger set up in the van is only good for 15 amps at max I think, though even 10 hours at 15 amps should be heaps to fully charge back 240 amps if at even 50%. But then these AGM's do like to spend a bit of time on "float" to be truly topped up.

I hadn't planned to hook up the tug when camped to charge batteries, i was thinking I should include that option especially while free camping driving between camps if the weather is ordinary with little sun happening...give them a pump up along the way.

My portable panels have always worked very well, the roof one is the factory 160w and is ok to trickle a few amps in provided it gets good sun of course. The roof mounted ones imo are always compromised as they are never at the right angle to the sun. Portable panels are the go, but to acheive the best result does mean chasing the sun.

 

[Drover]

Most times the charger won't ever get up to using those 15 amps unless the battery is really run down and certainly if they were to run that high for a few hours then if the battery wasn't already stuff then it would be, its only needed and it depends on battery also for the Bulk cycle, too long at high amps and it will boil ...... last run we had days/weeks of constant cloud with rain and while we may pplug into 240v in canberra its only for fridge and kettle/toaster so basically saving on LPG, 12v runs the rest and the 240v charger was never turned on, I was surprised that my set up kept everything happy the roof panels did most of the work and on the long runs on the road when we bolted from the rice paddies for QLD everything was happy at 100% when we lobbed in at Texas, so never needed to run the Genny, no 12v from tug available, so proved my set up is better than I thought as I seriously thought 3 days of cloud I'm stuffed...... I would never try to charge van batteries from a stationary vehicle in camp, its just not a good idea especially with these modern diesels..... I wouldn't do it with a petrol either...

 

[Drover]

BUt then if you are having an aux in the Jeep then I have always liked the Ctek D250S DC/DC unit, pricing better than those that have a name tax and they work very well, the van (BM Pro) would draw off the tug aux battery and the Ctek will take juice from either the alternator or a solar panel to keep aux juiced up .............. thought about it when I got this Jeep but the Yuppie Wagon didn't need another 30kg in the mix.

 

[Hitting the road]

Good to read your power set up functioned 100% as expected. Was going to call in to Texas on the way back from Lightning Ridge, but canned that trip due to the rains and road closures...

The DCDC charger in the old tug is a 25 amp Redarc, so yes has the name tax on it...set me back about $650.00 from memory. Dunno if it is still ok as it may have had a swim as well, but it is supposed to be water resistant...I hope that means being under water for 5 minutes! Sadly everything on the rear floor was submerged so it might be cactus.

If so I'll look at options...the Ctek you mention looks good, and is available for under $300.00 at the moment...good value. I'll be setting it up to charge the aux in the Jeep, but also to potentially run power to the van...just have to add another cable direct to the batteries via another Anderson plug up front...

 

[Drover]

If I was going to charge van batteries from a Tug with an aux battery, I would run a feed from the tugs aux battery to the BM pro's Aux input, that way the BM would charge the battery from the best source solar or tug, and the tug alternator wouldn't take a beating as it would just be supplying the DC/DC unit....... using a DC/DC charger to run an aux battery in tug then try to charge another battery in van is not ideal, far better for van to piggy back off the tugs aux and charge its own battery, no conflicts then.

 

[jazzeddie1234]

Would it be worth disconnecting the 2 batteries from each other after a full charge, waiting an hour to drop the surface charge, and then checking the voltages on each one? I had a battery fail recently and the good one was masking the problem but I noticed the voltages were much lower than usual and separating them quickly showed why

 

[Drover]

Would it be worth disconnecting the 2 batteries from each other after a full charge, waiting an hour to drop the surface charge, and then checking the voltages on each one? I had a battery fail recently and the good one was masking the problem but I noticed the voltages were much lower than usual and separating them quickly showed why

If your ever suss about your batteries thats the best way to easily check and why bench charging individually will get each to a full charge and display if one is dodgy.......... it is amazing how many dual batteries are actually wired incorrectly as well, small cable and some items drawing off just one battery, a sure way to throw things out.

 

[Hitting the road]

A very good idea jazzeddie1234, the batteries are both under 2 years old, one celebrates it's 2nd birthday at the end of the month, the other in 6 months. I think they have a 2 year warranty so will have to put the skates on to check them prior to expiry in case on is crook...

 

[Hitting the road]

Lucky I wired this dual battery setup so I do know the cabling is as short as possible and as heavy as it should be and the connection method is spot on too...but I will take them out at the end of this trip and do a bench test on them.

 

[Boots in Action]

Lucky I wired this dual battery setup so I do know the cabling is as short as possible and as heavy as it should be and the connection method is spot on too...but I will take them out at the end of this trip and do a bench test on them.

Hi @Hitting the road , IMHO, if you have two AGMs which have been lying around for a few weeks, you will need more than 24 hours to Fully charge them with only a 15A max charging system, (that's only 7.5A max per battery!!!). More like AT LEAST 48 hours or more to get the full saturation of power into the plates in the ABSORPTION phase. Initially, you may get a high charge current, but when max charging voltage has been reached with high input current, charging current slowly drops lower and lower (voltage is still held high) until approx only 1 amp is being fed into the battery/ies, or what the BMPro has been programmed to do. All this occurs BEFORE the system switches to FLOAT, and even then, even though small but frequent pulses of charge are put into battery/ies, any drop in voltage or failure to hold charge will result in ineffective Float charging. In other words, the battery/ies never reach and hold a FULLY charged condition. Personally, I always have my AGM in van charged by my 7 stage "SMART" charger for at least 48 hours after it reaches Float condition before I disconnect it. The Setec Series III is not capable of charging AGMs properly (they need 14.7 volts) as the Setec voltage cutout for max charge is only 14.0 volts which is more suited to Gel type and even then is a bit low. Also, I have my MPPT solar controller set at 14.6 volts max charge and 13.7 volts float, both settings subject to automatic battery temperature adjustment (plus or minus) as detected by sensor taped to top of battery and connected to controller - not ambient!!!. When battery temp above 25C, slightly lower charge/float voltage and when under 25C a slightly higher charge/float voltage is applied. Also, current leakage in the electrical system - switches, appliances etc- can cause slow but real discharge of batteries all the time.

 

[Hitting the road]

Thanks Boots in Action...you'd be 100% right... I should have done some sums to figure out what I needed to do. I ducked down yesterday and put power on to the van to crank the fridge as well as put some amps back in to batteries.
The batteries were only on charge for maybe 20 hours before pick up last time which as I suspected and you point out would not have been enough time to fully charge the batteries, and as Drover pointed out the charge showing would have been more surface charge so would have dropped off pretty quickly. The standard monitor that came in the van doesn't really give an accurate picture of real battery condition.

I have another condition monitor on the MPPT charger that I connect which would give a more accurate reading, so will look at that too this time.

I had no clue as to the real charge in the batteries on pick up...which is not like me I might add, only a vague recollection that the monitor showed maybe 12.7v.

This time the batteries will be on charge for around 44 hours before pick up...though the next stop for it will be a powered site for 4 days so the batteries will be back on charge that whole time....then on to unpowered for another 4 days. I'll be putting the solar panels out this time too as I want to keep the batteries topped right up before it goes back in to storage again.

I don't think there is any leakage as there is nothing running from the batteries themselves once they are switched off...but can't be 100% sure as the switch to turn them off is a factory installation, so that switch may well be leaking. I have gone over and regularly checked on the battery charge while stored and it would sit around 12.6 at a minimum once it did fall to that level. What I may have to do is wire in a proper battery isolation switch as well to ensure they are properly disconnected...

 

[mikerezny]

Hi,
can you confirm the the BMS is a BMPro J35? In this case, the switch is not a battery switch but is a load isolation switch. From memory, this disconnects MOST loads from the battery and will still draw some current to power the J35. It would be worth measuring the current draw. I have an inexpensive clampmeter capable of measuring DC current which greatly simplifies the task.

This of course assumes that a previous owner has not wired something directly to the battery terminals!

There are charts floating around on this site showing the State of Charge (SOC) voltages for Lead acid, Gel, and AGM batteries. But I have attached the chart I use. SOC voltage is dependent on battery temperature. You stated reading 12.6V. If that was indeed SOC without the effects of surface charge, then that would indicate around 75% SOC.

For me the best time to measure SOC when off-grid is early in the morning before any power is used and any solar panels have kicked in. Over the years measuring it at a consistent time, I have a very good idea of what voltage to expect. Note that the batteries need to be off charge and off load for about 30 minutes to ensure SOC is being measured without the effects of surface charge.

To manage 12V power off-grid, one needs to have accurate and reliable estimates for all three factors: charge in, usage, and battery SOC.
I know the power draw of every 12V item in my van. And based on typical usage, can easily determine usage per day which runs at between 2Ah and 4Ah. I have a power analyser on my solar panel which shows my battery voltage before I connect the portable panel in the morning and thus gives an estimate of the battery SOC. The same analyser reports total accumulated Ah in from the panel.

When at home, I connect the panel up every 2-4 weeks to keep the battery fully charged.
Before we head off on a trip I put the fridge on around 3 hours before to get the fridge cooling and this also charges the battery.

When driving, the battery is charged from the car alternator. Fortunately, I don't have a smart alternator, so the charge voltage is around 14.6V. I have a Setec ST25, which has a protection diode in the charge line which drops 0.7V. So, when driving, the van battery will be around 13.9V which is barely float voltage. But it does help. However, if the van battery was depleted, 13.9V would be sufficient to supply enough current to charge the battery.

cheers
Mike

 

[Drover]

12.6 is okay really, a drive down the road would bring em back.... Have had 2 AGMs which had been blocked from the BM pro, at 11.6 or something, just hooked a charger on each overnight and by morning they were at 100%..so it was owner stuff up not battery fail.......
I like to run my fridge up for 2 days before hooking up so the whole cabinet is chilled down fully and in that time your batteries would be more than happy. Unless they are ignored for a few months they should be okay... As Mike said numerous graphs showing SoC not all agree with each other with ranges from 12.7 to 13.2 on some so I look at 12.6 to 12.8 as a happy medium....... and again monitors are mostly guessing things by using an algorithum..... I did an audit on my power use and I could burn a tad over 40amps for a 24hr period if I gave everything a flogging, I think my usual is under 30, I forget, checked it out, all okay so now have only a vague memory..... the radio surprisingly draws a lot of juice, think its the amp that does it but rarely gets used, Foxbox/Vast box and TV are the usual power eaters, along with diesel heater at ignition and the invertor will use a bit but it runs to charge laptop/camera etc so only used middle of the day so no drain on batteries at all, the new unit is very effiecient which is good, it has a screen to show whats what ............

 

[Hitting the road]

Thanks Mike...yes I have a J35B in my van, That's what I don't yet know...haven't had the opportunity yet to investigate what the 12v switch actually does. I do know that when i switch it off the monitor panel goes off along with every other 12v light and output, as last time I switched it off even the fridge shut off while on gas.

I wired these batteries in so I know there are no phantom connections anywhere. As I noted above I may just put a proper battery isolator switch between the negative terminal and the shunt....that way I know there will be zero leakage when isolated.

The low voltage disconnect according to the specs for the J35B is 10.8v, + - 2 volts...it does read that there is still a small voltage drain after disconnect of 8 milliamps...obviously to keep the BMS alive.

It is embarrassing actually as I am always all over this stuff...my real problem is I haven't spent enough time in this van off grid to know it, if I add it up I think it is a total of 5 days off grid in all...seriously ...that will change as I am not really a caravan park person.

With my previous camper trailer I ran both a large 12v fridge and a separate 12v freezer, lights, water pump, phone charge etc I knew where every amp went never running low in power...all off solar input...weeks off grid with that and knew it inside out. Same battery set up - 2 x 140 amp AGM's. I used to record morning and evening battery levels along with spot check solar input through the day. I carried a generator but never had to crank it up.

The van should be using virtually nothing as when off grid the fridge and water heater are on gas, it is only a few lights at night, water pump and phones using some power. In reality the puny 160w panel on the roof should just about put all that back in! I'll get on top of it this trip away...take some notes.

I do wish I could keep the van at home as it would make sorting these sorts of things a cinch, but not possible as I live in a Townhouse with shared driveways etc so have to pay to keep the van elsewhere. Any maintenance in storage is difficult or impractical too due to it being squeezed in between other vans, boats etc.

I am going to set this tug up and wire the van after this trip away so that I can charge the van batteries while on the run if I wish as well...