Voltage Sensitive Relay or Battery to Battery Charger for LiFePO4?
- Thread starter JoeAdams
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100% DC-DC charger if you want to charge the battery properly.
And don't want to cook your alternator.
More info....
www.t6forum.com
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And don't want to cook your alternator.
More info....
[Guide] DC-DC Charger (for leisure battery) -- How I Done It --
DC-DC Charger (for Leisure battery) -- How I Done It -- ************************************************** Dellmassive`s -- "how I Done It" -- Thread ************************************************** Kit List And Stuff -- How I Done It & What I Use --...
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Dellmassive - that is such an amazing article - thanks for the link. Would you go for a combined Solar MPPT charge controller with built in DC-DC like these:
uk.renogy.com
azeco.co.uk
uk.eco-worthy.com
Or a dedicated DC-DC. Thinking this one looks good since can charge in both directions which would come in useful when I accidentally drain the starter battery. I know Sterling do good quality kit from using it on a boat:
sterling-power.com
12V DC-DC Solar Battery Charger|Renogy UK
Battery chargers charge and maintain the batteries in your RV or van. The battery charger can be used as a back-up charging source for the battery bank.
uk.renogy.com
Solar Panel Charge Controller – SRNE MD 30A
Solar Panel Charge Controller – SRNE MD 30A including DC-DC charger for charging LiFePO4 service battery from the vehicle alternator
azeco.co.uk
12V 20A & 40A DC to DC Charger On-Board MPPT Battery Charger
Power Up! 12V 20A & 40A charger offers multi-stage charging for AGM, GEL, Lead Acid, Lithium & Calcium via car alternator or solar panel.
uk.eco-worthy.com
Or a dedicated DC-DC. Thinking this one looks good since can charge in both directions which would come in useful when I accidentally drain the starter battery. I know Sterling do good quality kit from using it on a boat:
Battery to Battery Chargers - Saturn Range
Market leaders in power distribution for off-grid purposes. Providing class leading AC/DC and DC/DC chargers, highly customisable charge options and high performance lithium batteries. Sterling aims to be an accessible performance brand.
sterling-power.com
I’d recommend dedicated chargers then if you have issues with one you don’t lose all your charging options. I went with Victron so no experience with the ones you linked. If you want to be able to trickle charge the starter battery then the Ablemail AMT12-2 is a good standalone option for £65.
glad you liked it.Dellmassive - that is such an amazing article - thanks for the link. Would you go for a combined Solar MPPT charge controller with built in DC-DC like these:
12V DC-DC Solar Battery Charger|Renogy UK
Battery chargers charge and maintain the batteries in your RV or van. The battery charger can be used as a back-up charging source for the battery bank.Solar Panel Charge Controller – SRNE MD 30A
Solar Panel Charge Controller – SRNE MD 30A including DC-DC charger for charging LiFePO4 service battery from the vehicle alternator12V 20A & 40A DC to DC Charger On-Board MPPT Battery Charger
Power Up! 12V 20A & 40A charger offers multi-stage charging for AGM, GEL, Lead Acid, Lithium & Calcium via car alternator or solar panel.
Or a dedicated DC-DC. Thinking this one looks good since can charge in both directions which would come in useful when I accidentally drain the starter battery. I know Sterling do good quality kit from using it on a boat:
Battery to Battery Chargers - Saturn Range
Market leaders in power distribution for off-grid purposes. Providing class leading AC/DC and DC/DC chargers, highly customisable charge options and high performance lithium batteries. Sterling aims to be an accessible performance brand.
I've used the combined and separate units.
both have there own advantages and disadvantages.
Renogy is good known brand.
im not keen on Sterling myself.
I've never heard of azeco,
and ECO-w are a ok known brand at the cheaper end.
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more info for you here:
Dellmassive’s "How I Done It" blogs.
-- Dellmassive`s -- "How I Done It" -- thread -- ************************************************** Dellmassive`s -- "how I Done It" -- Thread ************************************************** Kit List And Stuff -- How I Done It & What I Use --...
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As above, combined units and separate units have pros and cons.
Combined are smaller, cheaper, less complex, and some trickle charge the starter battery so have the functionality of 3 devices in 1.
But separate are more powerful, more flexible, you keep some charging if one device dies.
Your choice depends on the size of LiFePO4 battery you're fitting, your usage, your available space, and of course your budget!
I was originally looking at the Renogy IP67 50a DC-DC all in one but eventually went down the full Victron route, I now have up to 70a of charging (50a DC-DC and 20a MPPT) on hand.
Combined are smaller, cheaper, less complex, and some trickle charge the starter battery so have the functionality of 3 devices in 1.
But separate are more powerful, more flexible, you keep some charging if one device dies.
Your choice depends on the size of LiFePO4 battery you're fitting, your usage, your available space, and of course your budget!
I was originally looking at the Renogy IP67 50a DC-DC all in one but eventually went down the full Victron route, I now have up to 70a of charging (50a DC-DC and 20a MPPT) on hand.
I had (still have) the CTEK 250se combined unit. Recently on week 1 of a 10 week trip round Spain it failed. This meant I also had no solar charging and no DC-DC, which was a huge pita. I ended up managing to buy a Victron mppt near Granada and fitted it into my solar cables.
CTEK now working once I sussed the wiring issue back in the UK. But lesson learned.
CTEK now working once I sussed the wiring issue back in the UK. But lesson learned.
I likewise know Sterling from the marine side and the dual direction nature of the DC-DC is interesting, but it's hard to beat the combination of compactness, relative cool running and sheer capability of the new Victron Orion XS in a small van and using the Victron MPPT Solar alongside it makes sense unless you are really pushed for space and need a combined unit. Generally though the DC-DC is the high current side that needs to be close to the battery, if you use separate units then the Solar element is generally lower current and can be sorted a bit more flexibly which can help.
Just remember to get a LiFePo based battery and one with low temperature charge cut off (or heaters) built into the BMS.
Just remember to get a LiFePo based battery and one with low temperature charge cut off (or heaters) built into the BMS.
Thanks so much for the tips. I was thinking of getting built in heaters like you suggested but is the extra cost really worth it? My logic is if you van is stored you wouldn't want to be charging the lithium service battery from solar anyway. If the van is in use, the temperature of our van has never gone down to less than 8 degrees in England, even with no heating. I imagine it could be useful for travelling to colder climates, but we would probably install a heater if we took on that adventure. Your feedback would be appreciated.
Having a low temperature charge cut off isn't a nice to have on lithium, it's an essential safety requirement.
See the posts I linked to here for a picture of an EcoWorthy charged below freezing and contemplate it doing that in your van:
www.t6forum.com
You can still draw power from a lithium battery down to about -20c, you just must not charge it below 0c
Batteries with heaters just divert incoming charge into the heating pads until the cells are warm, one they are the act of charging them will keep them warm.
Heaters are not essential but many popular choices of batteries with built in low temperature cut off tend to have them.
See the posts I linked to here for a picture of an EcoWorthy charged below freezing and contemplate it doing that in your van:
Lithium LifePo4 12v Batteries - Time For An Upgrade?
Did I mention i bought a ECO-Worthy Lifepo4? this was OCT/NOV 2023. . . . but looks like i missed doing the post? 100Ah 12.8v Right, so getting back to this. . . ECO-WORTHY 100Ah Lifepo4 while abroad sunning it up in Spain for a while this popped up. . . £279.99 seemed like a good...
You can still draw power from a lithium battery down to about -20c, you just must not charge it below 0c
Batteries with heaters just divert incoming charge into the heating pads until the cells are warm, one they are the act of charging them will keep them warm.
Heaters are not essential but many popular choices of batteries with built in low temperature cut off tend to have them.
Thanks for the links again and taking the time to respond - appreciated. I have decided to fit separate components following your advice. I have just read the instruction manuals of a charge controller (Lumiax Win-500 - I need a decent IP rating since do a lot of watersports so the van is often damp) I am considering and it has low temperature protection and can also limit charge to 20% at 0 degrees while the cells warm up the battery. But the Renogy DC-DC, Victron Orion-Tr Smart DC-DC Charger, Ecoworthy DC-DC that I have looked into don't have protection. It is strange that most modern solar charge controllers have low temperature protection but not DC-DC chargers. The only one I have found is the Sterling DC-DC which have the added benefit of being able to charge in both directions which could be a very useful feature - 2023 Model 12V to 12V DC to DC Chargers 10A | 15A | 20A | 25A | 40A | 70A | 120A models + Remote Control (optional)
So it is
So it is
We recently put one of the heated Fogstar Drift 105ah LiFePo in my friend’s T6. It’s very compact and light and not too pricey. Easy to fit under the seat and loads of space for other stuff.
It solves the cold temp charging issue and gives peace of mind. We used one of the basic Renogy dc-dc chargers (non Bluetooth) that was about £110. 40amp or manually selectable 20 amp. Basic but works fine. Monitoring is done via the Fogstar app.
It solves the cold temp charging issue and gives peace of mind. We used one of the basic Renogy dc-dc chargers (non Bluetooth) that was about £110. 40amp or manually selectable 20 amp. Basic but works fine. Monitoring is done via the Fogstar app.
Solar MPPT chargers tend to be used with very commodity batteries in banks for off grid storage - and in that case they tend to be the only charger - so it makes sense to have temperature protection in them, likewise many have useful load switching capability.
In "our" situation in van there tends to be 2/3 chargers in play and a single battery - so it makes much more sense to have the protection in the battery. I believe that it is an option on at least some of the Victron DC-DC chargers - but generally only if you have a separate temperature measurement devices on their network.
And honestly the BMS already has all the required capability to turn off the battery for other safety reasons - adding a temperature measuring component and a little more firmware hardly adds to the overall Bill Of Materials - so it's increasingly becoming a sign of people using older BMS systems if they don't offer it.
As an aside not sure why you are looking at little known controllers when the very well regarded Victron MPPT is cheaper - I know you mention IP ratings but unless you are going to seal all the terminals in your install to the same standard it's a little moot - if the underseat electrics are getting that wet then there is a lot of unprotected factory wiring and fuses there that's going to cause you a lot of electrical issues too.
I have been doing some more research and have a quick question. How do you store the internally heated batteries? I asked AI about how to store lithium batteries and it said "ideally stored at 50% state of charge and at 10 to 25 degrees and to disconnect all charging and discharging." If the temperature in the van over winter (when batteries are typically stored) does fall to below freezing what do you do? A greenhouse style external thermostat heater or do you disconnect and bring them inside the house?
The 50% thing is for long term storage when they're not being used at all, IE not connected to anything.
You don't need to do anything special for them when they're in the van over winter, just make sure there's no small drains that could discharge the battery completely.
Depends how long you won't be using the van for though, I suppose.
You don't need to do anything special for them when they're in the van over winter, just make sure there's no small drains that could discharge the battery completely.
Depends how long you won't be using the van for though, I suppose.
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