Dc-Dc Charger

[Eddy]

Hi
Any members care to share what dc-dc chargers they are using in their lithium setups ?
I am looking to use as a backup for when sun doesn't shine for a period of time, the vehicle is a 2005 Patrol so I don't think will have any of the smart alternator type of problems
At this stage the lithiums will be located in vehicle and so will dc-dc charger, 6b&s already installed
This one http://sidewinder.com.au/page247.html is the price range I am looking at or cheaper
Thanks
Eddy

[Wilbor]

What is the price range?

[T1 Terry]

Unfortunately the Sidewinder DC to DC will melt down after a while and certainly not put out its rated output for an extended period. Just how long depends on the temperature but it cuts back its output when it overheats. Not designed for the continuous full output rating because lead acid batteries can't handle the continuous full output rating, lithium batteries can and will demand everything any charger can supply.
Like many manufacturers, they add something they think would be a suitable lithium charging profile and that makes it a lithium charger. Nothing could be further from the truth, the Gel setting of 14.1v and 13.8v float or even down as far as 13.6v float is far closer to the requirements for a lithium battery.

The best value for moey would be the Projecta 25 amp unit, next the Jaycar 30 amp unit and the top priced is the Enerdrive unit. None of them have all the bits required to be a true lithium battery charger because none of them have cell voltage monitoring or connect to a battery BMS that is designed to control a battery charger if a cell goes high voltage.
We make our battery control system to suit what ever chargers are in the system so we can then interface those units into the T1 Lithium control unit. This is part of a custom battery installation, not something we sell as a mail out item.

T1 Terry

[native pepper]

Hi
Any members care to share what dc-dc chargers they are using in their lithium setups ?
I am looking to use as a backup for when sun doesn't shine for a period of time, the vehicle is a 2005 Patrol so I don't think will have any of the smart alternator type of problems
At this stage the lithiums will be located in vehicle and so will dc-dc charger, 6b&s already installed
This one http://sidewinder.com.au/page247.html is the price range I am looking at or cheaper
Thanks
Eddy

I have a 60amp 24v dc to 12v dc charger, can't remember the brand as it has been in the bus for about a decade and is almost impossible to get at. It charges my lifepo4 through a dedicated 60amp solar charge controller and works very well. It only tops of the cells when we've had a few cloudy days and are travelling, it doesn't put huge amounts in as it's driven from a 24v x60amp deep cycle lead acid battery which runs from the bus starter batteries through a redarc controller. The lead acid can only provide a certain amount at a time, so it has never taxed the dc-dc charger.

When we are parked and on grid power, use a 20amp cheap 2 stage battery charger, which runs through a 60amp lifepo4 solar controller. Seems to work pretty well and as yet, no problems. Only been doing this for a few months, as there are no dedicated lifepo4 chargers around, except the solar ones we had built for us and they work fantastic, with cell equalisers.

Also have a cheap 12v x 15amp dc-dc charger from ebay, which drives a 9amp lead acid battery driving the veggie oil fuel pumps, that's been in operation for a while and also works really well.

[bob r]

Last month jaycar had the 40 amp one's that Terry used on special about $300 you might find a store that still has one.

Bob

[T1 Terry]

Last month jaycar had the 40 amp one's that Terry used on special about $300 you might find a store that still has one.

Bob

If you can find one, they are great, but I'm guessing it will be a store by store search. P/N MB3690, they superseded that number to a 30 amp model MB3689 that also works well, but the 40 amp unit would deliver the full 40 amps continuous

T1 Terry

[Firegirl54]

Hi Eddy, Just a suggestion...why bother at this stage?

You have a good old dumb alternator, you have good cables and a fairly shortish run in the car, hopefully something like an ignition-activated relay near the car battery, you will only use this as a back-up to charge the lithiums from a lowish SOC to a moderate SOC ( ie nowhere near full so little risk of a cell runaway).

So try just hooking it directly. Would be surprised if you did not get around 40A....But measure it! You could get a lot more and even overtax you alternator.

We did this witb our old car, only 8b&s all the way to the van, and got around 10A at the lithiums (better than nothing!). With the new car which often drops voltage below 13.7 we were lucky to see an amp or two.

So now we use a 20A dc dc 12V ( 9-16 input) to 19V converter off ebay (under $50) and feed this into a Victron 100/30 mppt, limited to 20A output, and we get a constant 20A into the lithiums when we need to supplement the solar. Measured about 23A at 12.7V from car, 15A at 19.12V from the dc dc gadget, and 20A at 13.9V from the mppt. You could jack up the limit on the mppt to maybe 25A, and still keep the output from the dc dc to under 20A (this cheap gadget does not limit its output.....). We don't, so as not to overload the 8b&s wiring in the car.

Just some food for thought! Cheers, Leslie

[Barboots]

Last month jaycar had the 40 amp one's that Terry used on special about $300 you might find a store that still has one.

Bob

If you can find one, they are great, but I'm guessing it will be a store by store search. P/N MB3690, they superseded that number to a 30 amp model MB3689 that also works well, but the 40 amp unit would deliver the full 40 amps continuous

T1 Terry

Community Service Announcement

If anyone wants one of these I'll buy and mail it to you. They are $349... I expect postage would be under $20.

Cheers, Steve

[Lance]

I just did a store check in my area.....Ringwood Vic.

https://www.jaycar.com.au/search?text=M ... ee9439a1cd

Seem to be plenty about.
$280 for an order of 4

Check Store Stock for your area.

[Barboots]

Wow... the bulk deal is awesome Lance.