Protecting your Starter Battery

In my Sprinter I have dumped the inefficient split charge system and replaced my Epever Tracer with a Ring RSCDC30 (initially I thought the Tracer was not doing proper bulk charging but after buying the data logger I realised I was mistaken).

At the same time I fitted a Sterling Power BM12123 to keep the chassis battery charged which is shown towards the end of this. It’s been working perfectly ok for several months and same as the device in the opening post avoids the previous need to connect to ehu every 10 days or so that I had been doing previously to charge the chassis battery.


 
There is one other possible way to avoid this problem. Change the wiring so that the radio, alarm and tracker all run off the leisure battery system. None of them need to be wired to the engine battery, it's just that if the base vehicle was a van, there was no alternative.
 
I politely suggest all the other alternatives are better..
Who wants to do such a re-wiring..Not me
 
jagmanx said:
I politely suggest all the other alternatives are better..
Who wants to do such a re-wiring..Not me
Click to expand...
Easier, perhaps. Better, almost certainly not.
Rewiring the radio is a trivial task. The alarm, probably not. A tracker, dead easy.
 
Changing the wiring for the alarm to use the leisure battery could be a bad idea unless you also rewire all the door switches for the courtesy lights. Many alarms use a sudden voltage drop (such as experienced when a door is opened) to detect unauthorised entry. If the alarm is connected to the Leisure Battery, that feature may well stop working.

Changing the Radio to use the Leisure Battery can be very useful if it is a Non-Canbus unit and can be used for a prolonged duration without the engine running. If it is a Canbus unit, it is a waste of time.

Overall, a Battery Maintainer, whilst not the only possible option, remains the best solution as an automated "Fit and Forget" setup. After all, who wants to fart around with remembering about a little fuse being out/in when they want to use/park up their van, or having multiple chargers.

Just get something that does the job properly, and be able to just relax and enjoy your van without worries!
 
Yes - what we really want is to guarantee the van starting after an extended period standing.
So charging the battery is better than messing about with drains.
 
Last edited:
wildebus said:
Changing the wiring for the alarm to use the leisure battery could be a bad idea unless you also rewire all the door switches for the courtesy lights. Many alarms use a sudden voltage drop (such as experienced when a door is opened) to detect unauthorised entry. If the alarm is connected to the Leisure Battery, that feature may well stop working.

Changing the Radio to use the Leisure Battery can be very useful if it is a Non-Canbus unit and can be used for a prolonged duration without the engine running. If it is a Canbus unit, it is a waste of time.

Overall, a Battery Maintainer, whilst not the only possible option, remains the best solution as an automated "Fit and Forget" setup. After all, who wants to fart around with remembering about a little fuse being out/in when they want to use/park up their van, or having multiple chargers.

Just get something that does the job properly, and be able to just relax and enjoy your van without worries!
Click to expand...
Fixing the cause of a problem is always the best approach. Yes, many alarms do depend on interior lights dropping voltage, but good ones don't.
I agree, it has to be a fit and forget fix. Switching switches or moving fuses is not a good solution.
 
Only just seen this thread - been too busy doing nothing :)


wildebus said:
Some Factory Motorhome Electrical Systems will do a Starter Trickle Charge
Click to expand...
Yes, I'm lucky enough to have one of these (EBL 99, I think). However, I'm sure I was told/I'm sure I read once that they're not designed for continuous use? Not for months at a time? I can't find it now, but I think it was something about how they're for "leisure" use not "continual living." The implication being you'll use up its design life in one go if you leave it on for months.

trevskoda said:
It would take a 40 mile run to get back in what the starter took out
Click to expand...
I've always wondered about this. If a starting current is, say 200A for 3 seconds and if the alternator is capable of, say, 40A max output, why does it take so many minutes to recharge? 200A for 3 seconds is only about .2Ah, and an hour's drive at even 1A charging would be 5 times this much input. I'm sure you're right, but the maths confuses me. (BTW, I was told by a dealer that it was 20 minutes for my old Citroen C5)
 
Some older installed battery chargers aren't smart and continue trickle charging indefinitely at too high a voltage for long term battery condition/safety.
Hence the recommendation to only use them whilst on EHU on a site.
When parked up at home other solutions as suggested above can be used.
The easiest is to make use of any solar already fitted.
 
MarkJ said:
Only just seen this thread - been too busy doing nothing :)



Yes, I'm lucky enough to have one of these (EBL 99, I think). However, I'm sure I was told/I'm sure I read once that they're not designed for continuous use? Not for months at a time? I can't find it now, but I think it was something about how they're for "leisure" use not "continual living." The implication being you'll use up its design life in one go if you leave it on for months.


I've always wondered about this. If a starting current is, say 200A for 3 seconds and if the alternator is capable of, say, 40A max output, why does it take so many minutes to recharge? 200A for 3 seconds is only about .2Ah, and an hour's drive at even 1A charging would be 5 times this much input. I'm sure you're right, but the maths confuses me. (BTW, I was told by a dealer that it was 20 minutes for my old Citroen C5)
Click to expand...
I don't know for sure, but I think the EBL99 Mains Charger is not an intelligent charger and just puts out a constant voltage, and thus is not one that really treats the Leisure Battery in an optimal manner.
Maybe someone with an EBL 99 and has the manual can either confirm or correct my comment about how the charger operates.

Ref Trevs comment about needing 40 minutes to recover the charge used to start the engine. Yes, the battery energy needed to start the engine will need time to put back, but IMHO it won't be anywhere close to 40 minutes unless you have a engine that takes an age to start up.
Squirrelcook could maybe tell us his experience as he has a Victron BMV connected to the Starter Battery on his van?
 
MarkJ said:
I've always wondered about this. If a starting current is, say 200A for 3 seconds and if the alternator is capable of, say, 40A max output, why does it take so many minutes to recharge? 200A for 3 seconds is only about .2Ah...
Click to expand...
The essence of the problem is the nature of lead acid batteries. They take time to absorb the charge and let it sink in. Lithium batteries are much, much faster in these situations.
 
Markd said:
Some older installed battery chargers aren't smart and continue trickle charging indefinitely at too high a voltage for long term battery condition/safety.
Hence the recommendation to only use them whilst on EHU on a site.
When parked up at home other solutions as suggested above can be used.
The easiest is to make use of any solar already fitted.
Click to expand...
When I do a camper setup, I find out from the user how he intends to use his Camper and the likely mix of On-Site vs Touring vs Wild/Off-Grid Camping, plus geographical locations, access to mains at home, and a slew of other info. This data will then lead into where to put the focus into the key charging features and ensure that the primary one is a Smart Charger (be it a Mains, Solar or Battery-to-Battery charger) that treats the battery in the best possible way.
Always want at least one "proper" charger!
 
I found the manual - it does not mention anything about battery charging other then it does it, and it puts upto 2A at an [undefined] float charge to the starter battery.
If I had an EBL 99, I would put a meter on at various times and see what level the voltage out is. Sounds a bit like the Sargent EC155 PDU unit - that is a constant 13.6V (maybe 13.8V? can't recall for sure) for ever - so that never actually charges the battery fully. Other chargers are higher and never let them (the batteries) rest. Neither approach is what you want.
 
Under battery functions it says the leisure float voltage is 13.8V which is more than one ought to have indefinitely.
So some other long term solution needed.
 
Markd said:
Under battery functions it says the leisure float voltage is 13.8V which is more than one ought to have indefinitely.
So some other long term solution needed.
Click to expand...
I didn't see that on the info I looked at. Well spotted :)

13.8V is not too bad. Few Chargers actually have a storage function
The ideal setup is similar to the one below (I've highlighted the Mains Charger functions within the red box)
1586857379852.png
Plug in the charger and it is initially in Bulk mode (the voltage rises, the current is as much as the charger/batteries can handle - this is also known as CC - Constant Current mode); then switches to Absorption mode (Voltage is at its normal maximum, the current starts to drop as the battery starts to complete its full charge - this is also known as CV - Constant Voltage, as the voltage is pretty well static); Then once battery is full, the charger is in Float mode, where the voltage drops to around 13.8V typically; then finally if there is no demand on the battery for a period of time, the charger ideally switches to Storage mode, where the voltage drops again (in the case above, it goes to 13.2V)
Equalize is a special function not usually engaged.

You can see the same basic pattern on a good B2B charger - this is an Ablemail 30A B2B

BT - Ablemail V_C by David, on Flickr
From 11:00 to 15:00 it is in Bulk mode (you see the Voltage increasing, while the Current is steady at the maximum the charger puts out - this is why Bulk is also called CC Mode); then from 15:00 to just before 17:00, it is in Absorption mode (Constant Voltage, with Current decaying); and then switching into Float mode at the lower voltage.
No need for a Storage model in a vehicle B2B as vehicle stops will cut the charger out anyway. If your mains charger has no storage mode and you use at home for an extended period (like in the current lockdown), it can be worthwhile fitting a timer to the socket you plug into that cuts the power periodically to allow the battery some off-charge rest time.
 
wildebus said:
If I had an EBL 99, I would put a meter on at various times and see what level the voltage out is. Sounds a bit like the Sargent EC155 PDU unit - that is a constant 13.6V (maybe 13.8V? can't recall for sure) for ever - so that never actually charges the battery fully. Other chargers are higher and never let them (the batteries) rest. Neither approach is what you want.
Click to expand...
I have a different version of Electronic, but I suspect the charging is the same.
A month or so ago we were staying somewhere with hookup and I was checking the operation of a new battery monitor. So I took notice of what the charger did.
Turns out that the EBL is smarter than I thought. It goes through the bulk stage as you'd expect, then sits at 14.4 or so for a while before dropping back to a commendably low 13.62v float.
If it restarts the cycle, it shortens the absorption stage significantly. I'm not sure about exact timings, but it seemed about right
I hadn't realised that it was as good as it is.
The starter battery feed is a very simple one. Just a slow trickle, slow enough that it won't do any harm.
 
You must log in or register to reply here.

Users who viewed this discussion (Total:0)

Back
Top