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Open Roads Forum  >  Tech Issues

 > generator and alternator charging at the same time

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dave17352

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Posted: 04/03/21 09:41pm Link  |  Quote  |  Print  |  Notify Moderator

I have a new LION ut1300 battery. It can take a charge at 100 amps. So lets say I am running down the road and I have the generator on so there are two charging sources heck lets throw in solar too. So there are three sources of charging.

Alternator generator/converter and solar. Is there a problem. I don't think so, but any advice from those that know and could explain how this works would be appreciated.

Thanks in advance
Dave


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Flute Man

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Posted: 04/03/21 10:17pm Link  |  Quote  |  Print  |  Notify Moderator

That would be fine Running all three together.


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ndrorder

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Posted: 04/03/21 10:57pm Link  |  Quote  |  Print  |  Notify Moderator

Current flows from higher voltage to lower voltage. The one with the highest voltage charges the batteries and will also flow some of its current toward the lower voltage sources if there are no diodes to prevent it.


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pianotuna

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Posted: 04/04/21 12:42am Link  |  Quote  |  Print  |  Notify Moderator

Hi,

Just don't exceed the maximum voltage on the battery.


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, soon to have SiO2 batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

MrWizard

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Posted: 04/04/21 02:49am Link  |  Quote  |  Print  |  Notify Moderator

The voltage won't get any higher than the highest set point of the 3 D.C. Power sources,
As long as the highest one is below damage level for the lithium battery (most likely solar) everything will be ok,
There is no harm in having all three in use, as long as none of them are set too high


I can explain it to you.
But I Can Not understand it for you !

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wa8yxm

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Posted: 04/04/21 04:41am Link  |  Quote  |  Print  |  Notify Moderator

dave17352 wrote:

I have a new LION ut1300 battery. It can take a charge at 100 amps. So lets say I am running down the road and I have the generator on so there are two charging sources heck lets throw in solar too. So there are three sources of charging.

Alternator generator/converter and solar. Is there a problem. I don't think so, but any advice from those that know and could explain how this works would be appreciated.

Thanks in advance
Dave


Two answers. If the LION can take 100 amps charge and the total charge current is less 100 amps or less with all the charge sources in parallel. No problem

If it's over 100 amps. problem so you may need a charge controller with multiple inputs (Some LION battery systems have this built in)

Now. the other item.. Generally only one or two of those sources will provide nearly all the charge current
If the Converter (Generator powered charger Is at 14 volts and the engine alternator is 14.2 Guess which one is doing the work? (hint not the lower voltage device)


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Ivylog

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Posted: 04/04/21 06:27am Link  |  Quote  |  Print  |  Notify Moderator

85% of a 12V Lion battery capacity is between 12.8 and 13.6 making charging voltages at the batteries critical. Just because you have the solar set at 14.5v doesn’t mean it’s putting out that voltage until the batteries are fully charged. ... comments welcome on all of this as I’m working on converting to 600AH of Lion with 4 sources of charging. I’m thinking of leaving a fla battery in the bank as a sacrificial safety feature???

*I’m also thinking of putting a thermal switch on the alternator instead of a dc to dc charge limiting device???

* This post was edited 04/04/21 06:43am by Ivylog *


This post is my opinion (free advice). It is not intended to influence anyone's judgment nor do I advocate anyone do what I propose.
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BFL13

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Posted: 04/04/21 07:05am Link  |  Quote  |  Print  |  Notify Moderator

As long as the chargers' voltages are above the battery's voltage, each charger will supply some of the total amps. How much each supplies is in proportion to its voltage difference.

As the battery voltage rises from being charged, amps will start to taper from the lowest voltage charger of the three until amps get to zero when the voltages are the same, then amps will be tapering on the next highest voltage charger until battery voltage rises to its voltage, and now only the highest voltage charger is supplying amps (to its current limit).

Then, as battery voltage rises, it gets to the absorption voltage for the highest voltage charger so amps taper from it till the battery is full.

If you want the three chargers to add their amps to the highest amps total for the longest time as battery voltage rises, you have to set the charging voltages of the three chargers to as close they can be set, and to the charging voltage spec of your battery.

EDIT--just to make it more fun, the chargers' voltages are as seen by the battery at its end of the wires, so voltage drop is in there too.

The alternator has its own ideas about charging voltage so in real life as it starts at 14.x and then soon is at a lower voltage while you are driving, it could be the lowest voltage and you won't get as many amps from it as you might expect.

The converter could be problem too, where it could be doing 13.6 instead of 14.4. Depends on the converter and its wiring what happens with it. Might not be worth the generator gas to use the converter at all, depending on the converter's voltage.

So if you are hoping to get lots of amps by using all three chargers, you could be disappointed, but it won't hurt anything to have them all on at once, except if you go over the battery specs for charging voltage and current.

You can beat the alternator voltage problem by using a DC-DC charger instead. With that, you can choose a voltage from it's menu and it holds that constant (buck /boost converter in it) and it does its rated amps constant until they taper in the usual way. So with that you can match the solar controller's voltage and maybe the converter's.

You can beat the possible converter problem by using an adjustable voltage one like the PowerMax LK model.

So then you only have to choose the current limit amps size of the converter, DD-DC charger, and solar to be under the battery's current limit. ( 1C max or 0.5C recommended for some 100AH LFPs, eg.)

* This post was last edited 04/04/21 08:11am by BFL13 *   View edit history


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dave17352

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Posted: 04/04/21 08:38am Link  |  Quote  |  Print  |  Notify Moderator

Well thanks for all the great replies! This Lion battery has been very impressive. I put in a victron bluetooth smart shunt and have done several tests of my own. My alternator alone puts in 90 amps even when the battery is at about 70 percent. I disabled that by removing the 250 mega fuse by the chassis battery. I was concerned about over taxing the alternator. That fuse is super easy to get to so if I want to use the alternator it very easy to put it back in.
I also did get that powermax lk55 online for 119.00. I adjusted it to 14.6 which is what LION recommends. If you take the cover off there is second dial and you can adjust the current. I have found that the LION can take so much current so fast the most I can get is 30 to 35 amps when set at 14.6 Two problems when you turn the voltage over 14.6 one is the over current protection shuts off the power in the pm lk55 and if you set it higher than 14.6 the LION BMS shuts it down. Now this only happens at the top of the charge but I feel better running this at 14.6 so the BMD is not always kicking in. I took the cover off the converter and modified it to fit in my wfco 8900 series. I actually bought two of the pm lk55's because the price was right. I also like the idea the converter is not running at its top limits maybe it will last longer.

Thanks again!

pianotuna

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Posted: 04/04/21 08:57am Link  |  Quote  |  Print  |  Notify Moderator

Ivylog wrote:



*I’m also thinking of putting a thermal switch on the alternator instead of a dc to dc charge limiting device???


When the 60 amp fuse kept blowing, I moved to an autoreset 50 amp breaker. I added manual control of the charging path.

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