Batteries charging slow

[Elliot Mess]

On our new-to-us motorhome I installed two 100a/h LifePO4 batteries and replaced the charger with a Progressive Dynamics PD9160ALV 12V Lithium Ion Battery Converter/Charger - 60 Amp.

I have the RV plugged into a 20 amp breaker in my house and am charging the batteries for the first time. It's going really slow.

The SmartShunt shows at times 20amps positive and sometimes much less.

I know a 60amp charger won't charge at that speed the whole time, but what are reasons why I'd be getting such bad performance?

The charger is in the back compartment and the batteries are under the steps.

[PhilFromMaine]

Originally Posted by Elliot Mess

On our new-to-us motorhome I installed two 100a/h LifePO4 batteries and replaced the charger with a Progressive Dynamics PD9160ALV 12V Lithium Ion Battery Converter/Charger - 60 Amp.

I have the RV plugged into a 20 amp breaker in my house and am charging the batteries for the first time. It's going really slow.

The SmartShunt shows at times 20amps positive and sometimes much less.

I know a 60amp charger won't charge at that speed the whole time, but what are reasons why I'd be getting such bad performance?

The charger is in the back compartment and the batteries are under the steps.

Assuming the charger is working properly, the only thing left is the wiring thickness and tight connections on all the wires. The round trip wiring length also tends to lower current.

[tomkatb]

Wire size matters.

On mine i can only read the battery Bluetooth for charging.

Thus I have two charging at 20 amps or 40 total. I too have a 60 amp charger. I have not paid much attention. I just know they are practically 100% all the time. Charge fast.

[Aussieguy]

charging current is based on how depleted the battery is
you may see a sharp drop in current near the end of the charge...
discharge it down again and watch carefully if you get higher readings




disconnect battery
use multi meter to read voltage at the converter output wires
THEN measure the voltage at the battery cable ends

you want to see about 14.2v at the battery end
Check all the connections between converter and battery are clean and tight

MY negatives cable connections were very poor
had scrape/grind the paint off the frame
so cables made good metal to metal connection.
got charging current increase to 50 amp (55amp charger)


if you don't get that voltage after checking the cable / connections
easiest thing to do is add a 120v outlet close to the battery and put the converter in the battery compartment (or close)

the 120v connection is not affected by distance as much as DC volts 120v wire costs a few cents... DC cable can be $50.00 or more

Keep the DC cables from battery to converter short as possible and of the correct size/gauge for the new distance (both ways)

If your converter will stay in same location
you can use less expensive welding cable to go from battery to converter
get the largest your converter output holes can take... insurance policy


---------------------------------------------------------------
If you intend to always / mostly be on shorepower charging speed will not be that important
the first time you charge up may take a while... battery at 60% ?
then subsequent charges depends on how much power you use before you charge again.
If you are a weekend camper and have 5 days of charging between trips ... that will be fast enough.

[Elliot Mess]

Great info people! The batteries were only at 61% after weeks of it sitting around and barely being used. It took hours to get to 71%. I will be keeping an eye on this for a while. We're boondocking Thursday-Sunday so I'll be charging up again next week.

[Aussieguy]

have you got a small generator <2000w will work
just in case..

it only took a couple of hours to trace the negative connections and fix it
(I'm slow at any underneath trailer work)

[Elliot Mess]

I have a creeper but a gravel/crushed stone driveway that is going to be paved this summer. I'm waiting until that before I go under it.

It's charging at 4.5 Amps pretty much. 80% SOC showing on the Victron app. At that rate it will take another 4+ hours to charge, which is fine for now, but I definitely have to trace those wires.

[TacomaJoe]

It's the wire. I have the same converter and had it installed in my WFCO panel. I would get 25A to the batteries at the front. I moved it next to the batteries and now I'm getting 60A into the batteries.

[Twinboat]

Use a volt meter and measure voltage at the charger and then the batteries.

The charger output is controlled by the voltage it senses. If it sense a charged battery it drops the amp output back. That doesn't mean that voltage is getting to the batteries, it may be dropping off thru voltage drop on the wires.

Testing at the points I mentioned will show you how much voltage drop you have.

[Elliot Mess]

If I have a chance tomorrow I'll use my volt meter and check, there's no room under the steps for the charger, but I'll be working on this in July for sure.

First - camping! Northern VT. Island Line Rail trail across Lake Champlain near Burlington.

[CHICKDOE]

just for info purposes, what was the capacity o the converter your replaced. the battery cables will be sized for what ever capacity that converter had.

[TitanMike]

If replacing OE type lead/acid batteries and converter in original location, it's almost always necessary to up-size the wire connecting converter to batteries as well as battery ground wire to frame and converter negative to frame.

Lead acid batteries have high internal impedance and rarely charge over 25% of battery bank capacity. Also charge current tapers off fairly quick.

Lifepo4 batteries have low internal impedance which allows them to accept all the current available from converter/charger unless the smaller wire caused high voltage drop, reducing current.

Since most OE battery connections are made with #8 awg wire, sometimes, #6 awg wire low current and long charge times can be an issue.

For me, #6 awg wire is minimum but the largest wire size that fits the connector lugs on converter is best---------unless one can mount converter/charger real close to batteries. If one can't/won't move converter at least upgrade wire size.

Very important with Lifepo4 batteries if you don't want to live with slow charge times. My two 100ah lifepo4 batteries take less than 2 hrs from 90% to 100% SOC. Converter is a 50 amp unit and has a total of 30" #6 awg wire connecting (round trip) to batteries. Makes for nice, short, generator run times.

[Elliot Mess]

Old convertor was 45 AMPs.

[Elliot Mess]

Last evening it was at 80%, I just got up and checked it and it's at 88% and charging at about 3 AMPS. I looked at the charger. There are three fuses on it, I didn't check them, but if one of them had blown would it still function, only slowly? Too small wires should't throttle it down this much.

[CHICKDOE]

Originally Posted by Elliot Mess

Last evening it was at 80%, I just got up and checked it and it's at 88% and charging at about 3 AMPS. I looked at the charger. There are three fuses on it, I didn't check them, but if one of them had blown would it still function, only slowly? Too small wires should't throttle it down this much.

i'd tend to agree, but i'm not an expert! 3 amps just seems too low.

have you called progressive and asked them why it is charging so slow? also call the battery manufacturer and see if they can offer any advice.

i would think that if any of the fuses were blown it would not charge at all, but that is something that you can ask progressive.

[Elliot Mess]

Ha ha, so I thought, of course - call them! They're on vacation this week. Another reason to do it once we're back.

I will contact LiTime though.

[Elliot Mess]

I found another thread discussing this https://www.forestriverforums.com/fo...ge-273598.html

In it some say that the first charge cycle will do this and that I need to discharge the batteries more and then charge again. When I started this charging they were at 61%, so maybe it will work itself out.

[Aussieguy]

first post states you have a Progressive Dynamics PD9160ALV
It should be set for lithium and requires no "Detecting" ?

if this were my rv

check the battery connections remove paint from frame and ensure GOOD positive and NEGATIVE connections ....

Use multi meter to measure voltage from converter
follow the voltage to any disconnect switch and breaker to the battery
if at any point the voltage drops too low fix that connection , switch or breaker

For testing... you can bypass a switch or breaker for short periods Only while testing!
if during bypass you notice a big improvement then replace that switch/breaker

If you want to do a test...
Take the battery and shunt and some short spare 4-6g (whatever is the largest size you can get into the converter output)

Connect battery and shunt directly to the converter bypassing everything else
Battery must be discharged at least to 60-70% SOC so current will flow


battery will charge slower the closer it get to 100%
at around 90% mine does not take more than 20amps of charging current.

[darrellr]

Different charger, different situation - but I found my solar panels (570w) will cause my converter to underestimate the charge state of the batteries and cause it to back off its output to nearly nothing. Not a huge deal when plugged in (unless you are trying to charge up for a trip) but is a huge deal when using generator to charge batteries during the day. I haven't gotten around to installing it yet, but I will be putting in a disconnect for the solar to disable it while charging off generator or when I need a faster charge.

[Aussieguy]

battery will dictate the rate of charge
so if the battery only accepting 60amps total
it will draw only 60amp total from both chargers

I set my solar it has bluetooth...... to charge at same voltage that converter produces