Charging Starter and Leisure batteries with same charger - Victron

[moodsterT6]

Hi, Inspired by @Deaky build post, I was planning on installing a Victron IP65 Smart charger next to the Starter Battery and a 2nd one to charge the Leisure batter (110AH AGM). I've discovered the CTEK D250SE will still charge the leisure battery as long as the volts on the starter battery are above 12.9v regardless of the switched live input providing +12V or not. I guess this is expected behaviour for the VSR aspect on the CTEK. My question is why install a 2nd Victron Charger for the Leisure battery, If I install the 15AMP version of the Victron charger, the starter and leisure batterys (both AGM) will be charged albeit slower than using two chargers. Any thoughts ?

Cheers,

Nick

 

[Dellmassive]

you can do it either way . . . but there are benefits and losses with any of the solutions.


i showed the "auto VSR" effect over here . . . using either solar or EHU to raise the starter battery voltage up to the point when the DC-DC charger kicked in. (with engine/IGN off)

https://www.t6forum.com/threads/guide-dc-dc-charger-for-leisure-battery-how-i-done-it.15066/page-5#post-257730

.

The results showed that one charger on the starter could charge both batteries . . . but not as efficiently as two separate chargers.

we found that the DC-DC charger would start cycling on/off/on/off as the starter battery rose and fell off (when doors were opened and closed etc modules waking up.)

there is also the efficiency losses going from "EHU to charger to cables to DC-DC to cables to battery".

so one charger will work, but it needs to be a bigger charger and have decent cables installed.


...


so do can try that option . . .


***

or go for two separate chargers . . . . . (say 3.8-5A for starter) and (5-15A for leisure)

this option is more efficient but more expensive, you need two chargers . . . but one can be smaller than the other, plus there is no DC-DC converter losses . . . and you can use smaller gauge cables . . . and less total cable distance. so more efficient over all.


did you know Victron and NOCO do a twin output charger? (that will charge AGM/AGM ie same chemistry batteries)

heres a Victron 15A 3x output example:

Victron Energy Blue Smart IP22 Charger 12/15(3) 230V - BPC121544022 : Amazon.co.uk: Automotive

Victron Energy Blue Smart IP22 Charger 12/15(3) 230V - BPC121544022 : Amazon.co.uk: Automotive

amzn.to

**

heres a NOCO example . . . maybe not so usefull as its 2x 2A

NOCO GENIUS2X2, 4-Amp (2-Amp Per Bank) Fully-Automatic Smart, 6V And 12V Battery Charging Units, Battery Maintainer, Trickle Charger And Battery Desulfator With Temperature Compensation: Amazon.co.uk: Car & Motorbike

Buy NOCO GENIUS2X2, 4-Amp (2-Amp Per Bank) Fully-Automatic Smart, 6V And 12V Battery Charging Units, Battery Maintainer, Trickle Charger And Battery Desulfator With Temperature Compensation at Amazon UK. Free delivery on eligible orders.

amzn.to

NOCO - Genius Multi-Purpose Battery Chargers

Our most advanced battery charger yet. Its a charger, maintainer, and desulfator. And it's incredibly powerful and compact.

no.co

***


or fit a larger charger on the Leisure battery . . . . and use a Smart box to reverse charge the Starter battery, as recently shown here . . . .

[Guide] Battery Maintainer (for Starter battery) -- How I Done It --

[Guide] Battery Maintainer (for Starter battery) -- How I Done It -- Right so its that time of year again . . . . . . . . Winter & (Lockdown 2020) The van might be layed up not being used, which will lead to a flat battery in around 3 weeks. The cold weather doesn't help the battery's...

www.t6forum.com

****************


What about a simple black-box-with-smarts?

well this is where ABLEMAIL ELECTRONICS comes into play,

They have come up with a great little magic box that will solve your problem's.

Its called a AMT12-2 Battery to Battery Trickle charger.



AMT12-2 12V 2AMP Trickle Charger - Battery Maintainer - Battery Saver | eBay
Find many great new & used options and get the best deals for AMT12-2 12V 2AMP Trickle Charger - Battery Maintainer - Battery Saver at the best online prices at eBay! Free delivery for many products!
rover.ebay.com


Again you just connect the two batterys (plus a ground) and the black box will trickle charge your starter batterys,

its small in size,
its got M6 bolts/nuts for the battery connection.
less than 2mA standby draw,
up to 4A charge rate (5sec pulse every 15sec),
ignition overide input,
built in protection,
Its Programmable too . . .






.

 

[moodsterT6]

Thanks for the information, very much appreciated

 

[Dellmassive]

here is some current real world test results . . . (DEC 2020)

the van has been sat parked for over a week . . so battery wise not great . . down to 11.9v ish


i grabbed the Victron 12v/15a/1op charger and plugged it in to the starter battery hook in point.





.

this is the current setup under the bench . . . the 50A Renogy DC-DC / mppt. (the AUX battery is under the drivers seat, an AGM Xtreme 110ah)



.

you can see the charger starts up delivering 15A current but rapidly drops and settles at around 10A (@ 14.2v) . . .





which starts charging the starter battery . . .




....


BUT . . .

because the starter battery voltage rises . . . the Renogy auto VSR kicks in and starts charging the AUX battery . .

which can bee see here in the BMV . . . at 7.4A (( this is the charge current from the starter battery via the DC-DC to the AUX battery))





***************

so we are delivering 9.8A from the EHU charger to the starter battery . . .

but 7.4A is going via the DC-DC to the AUX battery.. . . .

if charging the starter was the main concern you can see that the charge power is being split . . . so the starter is not getting the full charge . .


This will carry on until the AUX battery is almost charged (top of absorb cycle) and it starts to draw less current . . . at which point the starter will start to benefit from the full charge power.

**************


This is the BM2 readout from the AUX battery . .




***********


up close on the Renogy you can see the status lights showing ALT power available . . . and charging the AUX battery . . .






....



so you can see that the single charger method works . . . . . but if you have twin low batteries and are drawing a 12v load from your leisure electricals . . . . . dont expect the charger to charge up the starter battery very fast . . . but this works well as a maintainer style charging system.


.

EDIT:

half hour later the EHU Victron charger has moved over to float mode . . .




which has dropped the output volts to 13.6 @ 5.7A . . .




.

you can see the drop on the starter BM2 readout.




....


BUT the BMV shows that the AUX battery is still being charged via the DC-DC . . . ( @ 3.8A )




.

which can be seen here on the AUX BM2 readout . . .






......

*****************


Edit : . . .

Here is the BM2 readouts the following day . . .


starter:



AUX:







*****************

 

[Dellmassive]

start with a couple of BM2 units to monitor what going with your electrical system . . .

Battery Monitoring -- How I Done It --

Battery Monitoring -- How I Done It -- Part #1 Battery monitoring is a very important part of your 12v system . . . . whether its just the vans starter battery or your leisure setup keeping an eye on the power in your battery bank will keep you from breaking down and make sure your weekends...

www.t6forum.com

Auto Battery Monitor BM2 Bluetooth 4.0 12V Device Car: Amazon.co.uk: Electronics

Auto Battery Monitor BM2 Bluetooth 4.0 12V Device Car: Amazon.co.uk: Electronics

amzn.to

Then maybe add in a power meter at a later date . . .

Victron Energy SHU050150050 SmartShunt Battery Monitor, 500A, Bluetooth : Amazon.co.uk: Business, Industry & Science

Victron Energy SHU050150050 SmartShunt Battery Monitor, 500A, Bluetooth : Amazon.co.uk: Business, Industry & Science

amzn.to

.


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.

 

[moodsterT6]

Thanks, that is interesting. I have the Victron battery monitor so can see what’s happening charge wise. I like the Victron kit but had a few issues with the Smart battery Protect complainimg about short circuits (which there are none). I think I’ll fit the single Victron 15 Amp for the starter battery then have another one which can be connected to the leisure battery when required to speed up the charge if both batteries are low ish. Thanks again for your help.

 

[Dellmassive]

im starting to notice another possible issue during testing this single EHU charger method.

I've had the 15A charger connected for 24hrs. the starter battery is 100% and the AUX battery seems 100% full (according the the BMV)

The charger had moved from bulk, to Absorb, to float, to Storage.

this is the Victron charger showing storage mode after fully charging the system. . . . . . 100% full and holding at 13.2v


**



what I've noticed is that when the charger moves to storage mode of 12.6v - 13.2v (to keep the starter battery maintained)

its "below" the "AUTO VSR" point of the DC-DC charger . . . so the Renogy DC-DC is now showing that the RED ALT light is out . . . . so its now NOT charging the AUX battery.






...


to try and stir things up I've added a load to the AUX battery . . . . a 300W inverter and a Makita 18v charger for my drill battery.

its drawing about 5-10A and is starting to drop the AUX battery voltage & % . . .







as you can see here the EHU charger is not compensating for this draw as the DC-DC is effectively OFF and allowing the AUX battery to drain down independently and without being recharged . . . .


its just ticking over maintaining the starter battery @ 13.2v and 0.37A







ill charge up some batteries to see what happens . . . . .


But it looks like the only way to restart the cycle is to either RESTSART the EHU 15A charger (turn off/on)

Or

Cause a drop in the starter battery voltage to kick in the charger back into bulk mode . . . . (opening doors and interior lights made no difference . . . so maybe headlights?)


TBC:

heres an update 4hrs later, draining the AUX battery via the inverter . . .


the Renogy is showing a LOW AUX battery . .




after charging about 5 of these batteries . . .



.


The EHU charger is keeping the STARTER battery 100% and happy at 13.0v




.



but look at the AUX battery . . . . . . .


....


checking the specs . . . we see that the turn on point for the DC-DC is 13.2v. (13.2v AUTO VSR & 12v with IGN feed)




over here: https://www.t6forum.com/threads/guide-dc-dc-charger-for-leisure-battery-how-i-done-it.15066/


so it looks like we are right on the tipping point . . .


The charger is set at 13.2v float/storage . . .

but with volt drop across the cables and connections . . . . we must be under the 13.2v trigger voltage to kick in the VSR function. . .



TBC:

testing the Starter battery voltage (at the battery) is 13.03v . . . (so we are loosing 0.2v from the charger)

and will most likely loosing another 0.2v across the cables to the Renogy DC-DC . . . .




So one option my be to tweek the setting on the Victron charger to increase the Float/Storage voltage from 13.2v up to 13.6v and see what happens....




TBC:

Yep that's solved that problem . . . . . =]

another +1 for the Victron chargers and the ability to change the parameters . . .


storage mode changed to 13.6v . . .




The DC-DC has kicked in and started charging the AUX battery again. (13.6v @ 4A)

here we can see the BM2 readout and voltage increasing . . . .










here we can see the AUX net effect of charging with a +2.75A (plus +2.6A the inverter is drawing)


***********


So the final result is . . . .


Yes this works provided your main Starter EHU charger can keep the Starter battery voltage up high enough so that it is above the DC-DC AUTO VSR trigger voltage



***********


TBC:




ill leave it running and update later . . . .


.

 

[moodsterT6]

That is interesting, the CTEK D250SE will still charge my leisure battery as long as the starter voltage is 12.90 (from my testing) so even in float / storage mode on the Victron charger, the CTEK is still active. I guess your DC to DC charger requires as you say, above +13 ish volts for the VSR to liven up. I’ve fitted one of the Victron panel mount battery connection things to the leisure battery so I can easily connect a 2nd charger should I need too.

 

[jimc91]

another CTEK D250SE related question I'm afraid. I have just fitted a victron m6 lead from 12volt planet to my starter battery (negative to body ground) so that I can just plug in my victron charger to keep starter battery in good condition if I don't use the van during lockdown. On checking my BM2 monitors I noticed that as well as topping up the starter battery it also tops up my leisure battery in the same way as if the van was running, however I thought that the red cable on the CTEK, which I connected to an ignition live in the fuse box, is used to tell the unit the engine is running. CTEK experts, should the charger be able to charge both batteries when connected to the starter?

 

[moodsterT6]

another CTEK D250SE related question I'm afraid. I have just fitted a victron m6 lead from 12volt planet to my starter battery (negative to body ground) so that I can just plug in my victron charger to keep starter battery in good condition if I don't use the van during lockdown. On checking my BM2 monitors I noticed that as well as topping up the starter battery it also tops up my leisure battery in the same way as if the van was running, however I thought that the red cable on the CTEK, which I connected to an ignition live in the fuse box, is used to tell the unit the engine is running. CTEK experts, should the charger be able to charge both batteries when connected to the starter?

View attachment 98011

When you connect the charger to the starter battery, the volts will increase above the 12.9 volts required to activate the voltage sensitive relay on the CTEK. The CTEK will then start pulling power from the starter battery to charge your leisure battery regardless of the red wire being live or not. What the switched live wire (red wire) on the CTEK does is tell the CTEK that the engine is running, so if the alternator stops charging the starter battery because it’s at 12.6 vaults (as an example) the CTEK will still pull amps of the starter. Eventually with the CTEK pulling amps off the starter, the voltage will drop and the alternator will start charging the starter again.

have a read through this thread from the beginning , @Dellmassive done some testing over xmas for me and fed back his findings into this thread, it makes for some interesting reading regarding using a single charger to charge both the starter and leisure battery’s

cheers,

Nick

 

[jimc91]

When you connect the charger to the starter battery, the volts will increase above the 12.9 volts required to activate the voltage sensitive relay on the CTEK. The CTEK will then start pulling power from the starter battery to charge your leisure battery regardless of the red wire being live or not. What the switched live wire (red wire) on the CTEK does is tell the CTEK that the engine is running, so if the alternator stops charging the starter battery because it’s at 12.6 vaults (as an example) the CTEK will still pull amps of the starter. Eventually with the CTEK pulling amps off the starter, the voltage will drop and the alternator will start charging the starter again.

have a read through this thread from the beginning , @Dellmassive done some testing over xmas for me and fed back his findings into this thread, it makes for some interesting reading regarding using a single charger to charge both the starter and leisure battery’s

cheers,

Nick

Nick

Thanks for the excellent explanation. I'm really happy with the CTEK and the victron charger so nice to know its working correctly

 

[moodsterT6]

Your welcome. I’m going to install a Victron 7amp charger behind the starter battery permanently connected. For trickle charging the starter / leisure I think it will be fine. If my leisure battery is at a low SOC I’ll charge it first using a separate charger before charging the starter. This should help minimise the CTEK from switching on / off due to voltage changes on the starter battery caused by the CTEK pulling more amps than the 7amp charger can provide.

 

[Dellmassive]

another CTEK D250SE related question I'm afraid. I have just fitted a victron m6 lead from 12volt planet to my starter battery (negative to body ground) so that I can just plug in my victron charger to keep starter battery in good condition if I don't use the van during lockdown. On checking my BM2 monitors I noticed that as well as topping up the starter battery it also tops up my leisure battery in the same way as if the van was running, however I thought that the red cable on the CTEK, which I connected to an ignition live in the fuse box, is used to tell the unit the engine is running. CTEK experts, should the charger be able to charge both batteries when connected to the starter?

View attachment 98011

The red IGN wire on the ctek tells the unit the engine may be running and allows it to keep charging the AUX battery from a lower starter battery voltage. To account for the stop/start swings when the van is driving.

Its not a hard on/off switch.

As we see above even with the IGN off if the starter battery voltage rises high enough the AUTO VSR kicks in.

 

[SpikySteve]

@Dellmassive
Sorry to bring this back up, but what would you recommend, I’m in planning stage and thinking about the Charging off ehu, would one charge be ok to charge both, I see you altered the volts to force it to stop charging starter to then charge leisure.

is that the best solution, or should I get two chargers .

thanks

 

[Dave Lawson]

Have a read of the battery maintainer “how I done it” further up the page, after reading this I did it with one charger and the AMT

 

[SpikySteve]

Have a read of the battery maintainer “how I done it” further up the page, after reading this I did it with one charger and the AMT

Will do, thanks

 

[Dellmassive]

@Dellmassive
Sorry to bring this back up, but what would you recommend, I’m in planning stage and thinking about the Charging off ehu, would one charge be ok to charge both, I see you altered the volts to force it to stop charging starter to then charge leisure.

is that the best solution, or should I get two chargers .

thanks

whats your planed setup?

if you have a dc-dc charger fitted then one EHU charger on the starter could charge both. -


https://www.t6forum.com/threads/dc-dc-charger-for-leisure-battery-how-i-done-it.15066/


some people like to keep it simple and just fit 2x chargers. -


https://www.t6forum.com/threads/battery-chargers-how-i-did-it.10812/


or a some people just run one EHU charger on the Leisure and use a "reverse charge" to back feed the starter. -


https://www.t6forum.com/threads/guide-battery-maintainer-for-starter-battery-how-i-done-it.23652/

Charging Starter and Leisure batteries with same charger - Victron

Hi, Inspired by @Deaky build post, I was planning on installing a Victron IP65 Smart charger next to the Starter Battery and a 2nd one to charge the Leisure batter (110AH AGM). I've discovered the CTEK D250SE will still charge the leisure battery as long as the volts on the starter battery are...

www.t6forum.com

Solar is a whole other subject . . . but worth considering.

[Guide] Mobile Solar Panels ? . . . - How I Did It -

Mobile Solar Panels ? . . . - How I Did It - There is loads of background to this . . . . . but for now here is a vid for you all. =] Just remember W = V*A and as a general rule a good 100W panel will give you up to 6A charge with good sun. 25w = 1.5A 50W = 3A 100w = 6A 200w = 12A 300w = 18A...

www.t6forum.com

++++

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[SpikySteve]

Have a read of the battery maintainer “how I done it” further up the page, after reading this I did it with one charger and the AMT

Good read that

so 1. Charger. Connect to leisure battery, and solar panel connect to leisure battery and amt trickle charges the starter,

sounds perfect, thanks

 

[SpikySteve]

@Dellmassive
Will be a full conversation van

looking at 160-200w solar panel

and then looking to charge both batteries