Trickle charge starter Lead acid battery from lithium house battery bank

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jiri-crafter asked Oct 27, '20

Trickle charge starter Lead acid battery from lithium house battery bank

Hi,

I'm in the process of fitting electric affairs to VW Crafter and chose victron products. So far I fitted smart solar mppt 100/50 controller, 630W solar array, 360ah 12v lifepo4 battery bank, Orion isolated 12/30 charger, BMV712 monitor and Multiplus 12/2000/80A inverter /charger.

Now looking for solution of maintaining starter battery whilst car is not used and multiplus inverter won't be running. I don't see any easy setup which would offer multi-stage charging /maintaining except BLUE SMART IP65 CHARGER 12/5 plugged into inverter which requires running inverter 24/7/365

I understand that multiplus inverter /charger doesn't offer reasonable solution.

Just wondering about the interference of following setup :

Currently running intermittently Orion isolated DCDC 30A charger when solar is not producing enough. How about using Orion DCDC converter the other way from house batteries to starter? I have the feeling it's possible only once DCDC charger is off, maybe double latch relay connecting / disconnecting both systems respectively from ignition feed /running engine feed?

Still would rather use car charger 5A with 7 stage then converter (size, weight, price difference).

Also how is the multiplus gonna be happy with only charger drawing measly nothing when run virtually without load for months?

Thank you

Jiri

charger

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David commented · Nov 10, 2020 at 05:28 PM

I don't think Victron really has anything specifically suitable, but there are products that could be "repurposed"

If you are looking just to maintain the starter battery I don't think you need to worry about have a multi-stage charger involved. Too complicated and not practical.

The suggestion of a small PV Panel feeding the starter is a decent one.

If you wanted to use a Victron Product you could use a little MPPT and connect the load output to the starter, configuring the Load with appropriate parameters so it only works when the Leisure battery is above a certain voltage.

Maybe use a "proper" Battery Maintainer? I have a setup with Multiplus, SmartSolar, BMV etc, and I use a Battery Maintainer connected to the load of the MPPT (could be direct but on the load means I can monitor and control it more and the Load output was free anyway). That device keeps the battery charged when without it it will loose voltage. Below is an example of the effect. Once the charger is on (this could be just as easily Solar coming in), you see the Starter battery slowing ramping up as the Battery Maintainer pulses its charge.

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Answer 1 · 2020-11-03T10:26:04Z

dgnevans answered · Nov 03, 2020 at 10:26 AM

The easiest way to do this is to add a BLUE SMART IP65 CHARGER 12/5 plugged into your mutliplus. this way when you are running your loads off your multiplus it will also charge your start battery which should not take much at all. You will need to have your Orion connected with the ignition sense so you dont end up with a weird loop.

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jiri-crafter commented · Nov 05, 2020 at 02:22 AM

Great advice, however I'm looking at scenario of storing car and keeping starter battery refreshed whilst away (out of the country) for few months and trying to avoid running multiplus with virtually no load.

Just wondering would be search mode on inverter suitable for BLUE SMART IP65 CHARGER 12/5 or does it requires clean pure sine modulation?

Another option I guess would be get small inverter like Phoenix 12/375 VE.Direct and run it from there instead.

Thank you Jiri

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dgnevans jiri-crafter commented · Nov 05, 2020 at 06:22 AM

If you are leaving it for a number of months at a time then a smaller inverter like the phoenix would be better as lower standby watts. If it were me and price not a problem I would make sure I have a GX device connected through either wifi or cellular monitoring everything and connect this to the VRM so you can see what your system is doing well you are away. And I would use the aux input on the BMV to monitor your starter battery voltage. you may be able to use one of the built in relays on the GX to control the Pheonix remote on off. not 100% sure though.

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Answer 2 · 2020-11-05T07:45:51Z

dgnevans answered · Nov 05, 2020 at 07:45 AM

they will generally use vedirect connection to the MPPT and Phoenix and Orion and bmv. they then use Ve.bus to the mutliplus. very handy for monitoring your install. Some mppt use the VE.Bus and some battery BMS use the ve can just depends on your hardware as to which connections you use.

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Answer 3 · 2020-11-10T15:28:56Z

spirou answered · Nov 10, 2020 at 03:28 PM

Starter battery will likely use very little unless you have alarms etc. wired there instead of aux/house battery. Instead of complicating everything just get a small 10W panel, put it on the dashboard and connect to starter battery.

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Answer 4 · 2020-11-10T16:33:16Z

kevgermany answered · Nov 10, 2020 at 04:33 PM

This is getting complicated.

A small Orion unit would do it. The ones with adjustable output are supposed to be good as battery chargers according to the documentation.

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Answer 5 · 2020-11-10T22:43:47Z

jiri-crafter answered · Nov 10, 2020 at 10:43 PM

I get it, solar panel on dash was my consideration also however I would like to have chance to check battery charge whilst away and possibly switch on /off small inverter and (battery charger as well) remotely.

Another issue is how to sense starter battery voltage and shared within victron VRM without connecting car chassis ground to fully isolated victron system.

Best would be to have voltage feed as smart battery sense to cerbo directly if possible. Just thought, would small Phoenix charger gonna report voltage of battery connected to in cerbo when connected through ve. direct?

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Answer 6 · 2022-03-09T11:13:19Z

h-copter answered · Mar 09, 2022 at 11:13 AM

Hi @Wildebus I am interested in your comment "I use a Battery Maintainer connected to the load of the MPPT". So is that some sort of DC-DC charger? Please can you provide details. Thanks

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David commented · Mar 09, 2022 at 12:03 PM

So a Battery Maintainer is basically a device that sends a small charge current from one battery to another. I would not really describe it as a charger as such, but it does in essence slow-charge the battery. There are a few options and makes around, and some are better than others. The one I use is the Ablemail AMT-12, which I consider to be the best on the market and which is just about the only one available that is suitable for use with both Lithium and Lead batteries; and with both standard and smart alternators (you select which one of 8 different programmes is most suitable for your installation). It sends a pulse current of upto 3A to the Starter battery.

You can read more about it on this link - https://www.wildebus.com/product/ablemail-amt-12-battery-maintainer/. It is a link to my website shop, yes, but the reading is free and if you want one, you can buy at any place that sells them.

PS. The fact I said I run it through the MPPT load terminal is not important or required. It was just the way I had it wired when I posted the comment. Right now it is not on the MPPT but is connected directly to the Leisure +ve, Starter +ve, and common -ve connections on the B2B charger.

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kevgermany ♦♦ commented · Mar 09, 2022 at 01:49 PM

I use a Votronic trickle charger for this.

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David kevgermany ♦♦ commented · Mar 09, 2022 at 09:19 PM

As I mentioned, the Ablemail AMT is just about the only one that is suitable for use with Lithium, the other common units, including the Votronic Standby Charger, are not.

If you have a Lead Leisure/House battery. that is ok, but on a Lithium setup, they don't work as designed. See their own disclaimer here - https://votronic.de/index.php/en/products/peripheral-units/cut-off-relays

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Answer 7 · 2022-06-27T09:48:47Z

anayrat answered · Jun 27, 2022 at 09:48 AM

Many thanks @Wildebus for the AMT12-2 solution.

I just wonder if there is an issue to connect the ground between vehicule and lithium battery? I think it is better to have an isolated circuit (I have Isolated Orion DC-DC charger).

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